![SEM -VII Descriptive Type Question
P a g e | 19
X’ = X + tx
Y’ = Y + ty
The pair (tx, ty) is called the translation vector or shift vector. The above equations
can also be represented using the column vectors.
P=[X][Y] p' = [X′][Y′]T = [tx][ty]
We can write it as −
P’ = P + T
❖ Rotation
➢ In rotation, we rotate the object at particular angle θ theta from its
origin. From the following figure, we can see that the point PX,Y is
located at angle φ from the horizontal X coordinate with distance r from
the origin.
Let us suppose you want to rotate it at the angle θ. After rotating it to a new location,
you will get a new point P’ X′,Y′.
Rotation
Using standard trigonometric the original coordinate of point PX,Y can be
represented as −
X=rcosϕ......(1)
Y=rsinϕ......(2)](https://image.slidesharecdn.com/ccc-descriptivetypequestion-201222131016/85/CAD-CAM-CAE-Notes-19-320.jpg)
![SEM -VII Descriptive Type Question
P a g e | 20
Same way we can represent the point P’ X′,Y′ as −
x′=rcos(ϕ+θ)=rcosϕcosθ−rsinϕsinθ.......(3)
y′=rsin(ϕ+θ)=rcosϕsinθ+rsinϕcosθ.......(4)
Substituting equation 1 & 2 in 3 & 4 respectively, we will get
x′=xcosθ−ysinθ
y′=xsinθ+ycosθ
Representing the above equation in matrix form,
[X′Y′]=[XY][cosθ−sinθsinθcosθ]OR
P’ = P . R
Where R is the rotation matrix
R=[cosθ−sinθsinθcosθ]
The rotation angle can be positive and negative.
For positive rotation angle, we can use the above rotation matrix. However, for
negative angle rotation, the matrix will change as shown below −
R=[cos(−θ)−sin(−θ)sin(−θ)cos(−θ)]
=[cosθsinθ−sinθcosθ](∵cos(−θ)=cosθandsin(−θ)=−sinθ)
❖ Scaling
➢ To change the size of an object, scaling transformation is used. In the
scaling process, you either expand or compress the dimensions of the
object.
➢ Scaling can be achieved by multiplying the original coordinates of the
object with the scaling factor to get the desired result.
Let us assume that the original coordinates are X,Y, the scaling factors are (SX,
SY), and the produced coordinates are X′,Y′. This can be mathematically represented
as shown below −
X' = X . SX and Y' = Y . SY](https://image.slidesharecdn.com/ccc-descriptivetypequestion-201222131016/85/CAD-CAM-CAE-Notes-20-320.jpg)
![SEM -VII Descriptive Type Question
P a g e | 21
The scaling factor SX, SY scales the object in X and Y direction respectively. The
above equations can also be represented in matrix form as below −
(X′Y′)=(XY)[Sx00Sy]
OR
P’ = P . S
Where S is the scaling matrix. The scaling process is shown in the following figure.
Before ScalingAfter Scaling
If we provide values less than 1 to the scaling factor S, then we can reduce the
size of the object. If we provide values greater than 1, then we can increase the size of
the object.
➢ Reflection
➢ Reflection is the mirror image of original object. In other words, we can say
that it is a rotation operation with 180°. In reflection transformation, the size of
the object does not change.
The following figures show reflections with respect to X and Y axes, and about the
origin respectively.](https://image.slidesharecdn.com/ccc-descriptivetypequestion-201222131016/85/CAD-CAM-CAE-Notes-21-320.jpg)
CAD/CAM/CAE - Notes
- 1. SEM -VII Descriptive Type Question P a g e | 1 Learn With GeekAlign GeekAlign Notes CAD/CAM/CAE | Semester 7 BY - Amit Mahto
- 2. SEM -VII Descriptive Type Question P a g e | 2 Important Questions with Answers (Module Wise) JOIN OUR TELEGRAM CHANNEL FOR MORE UPDATES https://t.me/joinchat/AAAAAFkF7iEpknCDZcNmHA Follows us on Instagram : https://instagram.com/learnwithgeekalign?igshid=1abqnl020kq04 YouTube : https://www.youtube.com/channel/UCDoWuDKv6rVMZazIko9WARA Website : https://learn.geekalign.com/mcq/
- 3. SEM -VII Descriptive Type Question P a g e | 3 University of Mumbai DEPARTMENT OF MECHANICAL ENGINEERING (SEM7) CAD/CAM/CAE MODULE 1 5/10 MARKS QUESTIONS Q1 - Hidden Line removal Algorithm • In hidden-line removal, edges or other vectors in the model that are obscured by visible surfaces are omitted from the display of the image, or displayed as dashed rather than full lines. • An alternative name for the technique is visible line identification. Some of the common hidden line algorithms are a) Floating horizon b) Image space c) List priority d) Object space e) Ray tracing f) Roberts Warnock g) Floating Horizon Algorithm • Floating Horizon Algorithm is most commonly used for representation of 3D surfaces of the form F(x,y,z) = 0. The technique is to convert 3D problem to equivalent 2D problem by intersecting 3D surface with a series of parallel cutting planes at constant values of the coordinate in the view direction. • It could be x, y or z. The function F(x, y,z)=0 is reduced to a planar curve in each of these parallel planes y=f(x,z). It is assumed that the curves are single valued functions of independent variables and the result is projected on to the z=0 plane. • The algorithm first sorts the z=constant planes in increasing distance from the viewpoint beginning from z=0 (closest to viewpoint) • Upper Horizon: If at any given value of x, the y value of the curve in the current plane is larger than the y value for any previous curve at that z value, then the curve is visible, otherwise hidden. • Lower Horizon: If at any given value of x, the y value of the curve in the current plane larger than the maximum y value or smaller than the minimum y value for any previous curve at that z plane then the curve is visible, else hidden.
- 4. SEM -VII Descriptive Type Question P a g e | 4 • The algorithm assumes the value of y is available at every x location. However, if it is not available (crossing of curves), a linear interpolation of known values is calculated to fill the upper and lower floating horizon arrays. • If the function contains very narrow regions (small increments of x) then the algorithm yields incorrect results. The effect is generally caused by computing the function for visibility at a resolution less than that of image space resolution. The problem is overcome by taking more points to evaluate the function in narrow regions. Q2 - Hidden surface removal Algorithm • One of the most challenging problems in computer graphics is the removal of hidden parts from images of solid objects. • In real life, the opaque material of these objects obstructs the light rays from hidden parts and prevents us from seeing them. • In the computer generation, no such automatic elimination takes place when objects are projected onto the screen coordinate system. • Instead, all parts of every object, including many parts that should be invisible are displayed. • To remove these parts to create a more realistic image, we must apply a hidden line or hidden surface algorithm to set of objects. • The algorithm operates on different kinds of scene models, generate various forms of output or cater to images of different complexities. • All use some form of geometric sorting to distinguish visible parts of objects from those that are hidden. • Just as alphabetical sorting is used to differentiate words near the beginning of the alphabet from those near the ends. • Geometric sorting locates objects that lie near the observer and are therefore visible. • Hidden line and Hidden surface algorithms capitalize on various forms of coherence to reduce the computing required to generate an image. • Different types of coherence are related to different forms of order or regularity in the image. • Scan line coherence arises because the display of a scan line in a raster image is usually very similar to the display of the preceding scan line.
- 5. SEM -VII Descriptive Type Question P a g e | 5 • Frame coherence in a sequence of images designed to show motion recognizes that successive frames are very similar. • Object coherence results from relationships between different objects or between separate parts of the same objects. • A hidden surface algorithm is generally designed to exploit one or more of these coherence properties to increase efficiency. • Hidden surface algorithm bears a strong resemblance to two-dimensional scan conversions. • Types of hidden surface detection algorithms a) Object space methods b) mage space methods • Object space methods: In this method, various parts of objects are compared. After comparison visible, invisible or hardly visible surface is determined. These methods generally decide visible surface. In the wireframe model, these are used to determine a visible line. So these algorithms are line based instead of surface based. Method proceeds by determination of parts of an object whose view is obstructed by other object and draws these parts in the same color. • Image space methods: Here positions of various pixels are determined. It is used to locate the visible surface instead of a visible line. Each point is detected for its visibility. If a point is visible, then the pixel is on, otherwise off. So the object close to the viewer that is pierced by a projector through a pixel is determined. That pixel is drawn is appropriate color. Q3 - Explain Cohen-Sutherland line clipping algorithm ❖ Line Clipping: The concept of line clipping is same as point clipping. In line clipping, we will cut the portion of line which is outside of window and keep only the portion that is inside the window. ❖ Cohen-Sutherland Line Clippings: This algorithm uses the clipping window as shown in the following figure. The minimum coordinate for the clipping region is( XWmin,YWmin)(XWmin,YWmin) and the maximum coordinate for the clipping region is (XWmax,YWmax)(XWmax,YWmax).
- 6. SEM -VII Descriptive Type Question P a g e | 6 • We will use 4-bits to divide the entire region. These 4 bits represent the Top, Bottom, Right, and Left of the region as shown in the following figure. Here, the TOP and LEFT bit is set to 1 because it is the TOP-LEFT corner. • There are 3 possibilities for the line: a) Line can be completely inside the window (This line should be accepted). b) Line can be completely outside of the window (This line will be completely removed from the region). c) Line can be partially inside the window (We will find intersection point and draw only that portion of line that is inside region). ❖ Algorithm: Step 1 − Assign a region code for each endpoints. Step 2 − If both endpoints have a region code 0000 then accept this line. Step 3 − Else, perform the logical ANDoperation for both region codes. Step 3.1 − If the result is not 0000, then reject the line. Step 3.2 − Else you need clipping. Step 3.2.1 − Choose an endpoint of the line that is outside the window.
- 7. SEM -VII Descriptive Type Question P a g e | 7 Step 3.2.2 − Find the intersection point at the window boundary (base on region code). Step 3.2.3 − Replace endpoint with the intersection point and update the region code. Step 3.2.4 − Repeat step 2 until we find a clipped line either trivially accepted or trivially rejected. Step 4 − Repeat step 1 for other lines. Q4- Explain wire frame modelling ? • Wire frame modelling is one of the methods used in geometric modelling systems. • A wireframe model represents the shape of a solid object with its characteristic lines and points. • The word “wireframe” is related to the fact that one may imagine a wire that is bent to follow the object edges to generate a model. • In other words, a wire frame model is an edge or skeletal representation of a real-world 3D object using lines and curves. • Model consists entirely of points, lines, arcs and circles, conics, and curves. In 3D wireframe model, an object is not recorded as a solid. • Instead the vertices that define the boundary of the object or the intersections of the edges of the object boundary are recorded as a collection of points and their connectivity.
- 8. SEM -VII Descriptive Type Question P a g e | 8 One can use a wire frame model to 1. View the model from any vantage point 2. Generate standard orthographic and auxiliary views automatically 3. Generate exploded and perspective views easily 4. Analyse spatial relationships, including the shortest distance between corners and edges, and checking for interferences 5. Reduce the number of prototypes required Advantages of Wireframe model: ✓ Simple to construct ✓ Designer needs little training ✓ System needs little memory ✓ Take less manipulation time ✓ Retrieving and editing can be done easy ✓ Consumes less time ✓ Best suitable for manipulations as orthographic isometric and perspective views. Disadvantages of Wireframe model: ✓ Image causes confusion ✓ Cannot get required information from this model ✓ Hidden line removal features not available ✓ Not possible for volume and mass calculation, NC programming cross sectioning etc ✓ Not suitable to represent complex solids The Different Types of wire frame models are as follows: 1. 2D Wire Frame Model
- 9. SEM -VII Descriptive Type Question P a g e | 9 2. 2 1 2 D Wire Frame Model 3. 3 D Wire Frame Model • 2 D Model: Two dimensional representation is used for flat object. It is basically used for representating objects on any flat plane. All objects which represented on a flat plane come under 2D Model represetation. This plane only give an idea of the compunding boundary of any surface boundary on area enclosed on a flat plane. Here abcd 5 a wire frame model on a flat plane. • 2 1 2 D Wire Frame Model : This goes further than 2D capacity by permitting a 3D Object to be representing as long as it does not have any sides walls (e.g cylinder, canbe). This kind of on object simplifies the datas representation of the object thereby impraing the efficiency of the so frame. • 3D Wire Frame Modelling : This type of model represent the skeleton model. It gives the graphic envelope created by the objects but fails to show the areas,
- 10. SEM -VII Descriptive Type Question P a g e | 10 volume i.e It does not have any finite volume area. It just consist of the wire frame streame , holding no. surface. It does not give a good idea of the 3D model. Diffuculty to analysis as well. Q5 – Explain surface modelling ? • A surface model is a set of faces. • A surface model consists of wireframe entities that form the basis to create surface entities the basis to create surface entities. • A Surface modelling is a model with minimized ambiguous representation than the wireframe modelling but not as good as solid modelling. • The construction of surface modelling is done with the use of geometric entities like surfaces and curves. • Surface Modelling uses B – Splines and Bezier mathematical techniques for controlling curves. • It is used to make technical surfaces (e.g. air plane wing) or aesthetic surfaces (e.g. car’s hood). • It was developed for the aerospace and automotive industries in the late 70s. • Overall on the basis of performance, the surface modelling stays in between wireframe modelling and solid modelling for representing a realism object.
- 11. SEM -VII Descriptive Type Question P a g e | 11 Merits: ✓ It is less ambiguous. ✓ Complex surfaces can be easily identified. ✓ It removes hidden line and adds realism. Demerits: ✓ Difficult to construct. ✓ Difficult to calculate mass property. ✓ More time is required for creation. ✓ Requires high storage space as compared to wire frame modelling. ✓ Also requires more time for manipulation. Q6 – What do you understand by 2 & 𝟏 𝟐 D module ? • 2 D Model: Two dimensional representation is used for flat object. It is basically used for representating objects on any flat plane. All objects which represented on a flat plane come under 2D Model represetation. This plane only give an idea of the compunding boundary of any surface boundary on area enclosed on a flat plane. Here abcd 5 a wire frame model on a flat plane. • 2 1 2 D Wire Frame Model : This goes further than 2D capacity by permitting a 3D Object to be representing as long as it does not have any sides walls (e.g cylinder, canbe). This kind of on object simplifies the datas representation of the object thereby impraing the efficiency of the so frame.
- 12. SEM -VII Descriptive Type Question P a g e | 12 Q7 – Characteristic of Bezier curve • The Bezier curve does not use tangent vectors for controlling its shape • The shape of Bezier curve is controlled by number of data points. • This gives better flexibility in controlling the shape of the curve. • The Bezier curve with ( n+1) data points defined by the polynomial of nth degree. The higher order of polynomial gives higher order continuity. • The Bezier curve is symmetric with respect to ‘u’ and ‘(1-u)’ this means the sequence of control points can be reversed without changing the shape of the curve. • Each control point (P0, P1, P2,… Pn ) is the most influential on the curve shape a u = 𝑖 𝑛 . For example in case of Bezier curve shape u = 0 , 1 3 , 2 3 , and 1 respectively. • A closed Bezier curve can be generated by closing its characteristic polygon i.e. choosing P0 and Pn to be coincident . • The flexibility increases with increases in number of control points
- 13. SEM -VII Descriptive Type Question P a g e | 13 Q8 – Write parametric equation for Bezier curve ? Q9 - Advantages of B- spline curve ? ✓ B-spline curves allow local control over the shape of curve as against the global control in case of the bezier curves.
- 14. SEM -VII Descriptive Type Question P a g e | 14 ✓ Whenever a single control point is moved only those vertices around the moved vertex will be affected and the local portion of the curve is affected while the rest remain unaffected. ✓ In B-spline curves the degree of polynomial representing the curve can be set independently of the number of control points. ✓ B-spline curve give better control. ✓ B-spline curve permit to add or delete any number of control points without changing the degree of polynomial. 1. Confirm Numerical on Bezier curve (Simple Numerical)
- 15. SEM -VII Descriptive Type Question P a g e | 15 MODULE 2 5/10 MARKS QUESTIONS Q1 - Benefits of Artificial Intelligence. • Artificial Intelligence (AI) has been around for quite some time now. From quick suggestions on search engines and auto-focus in smartphones to robot greeters at shopping centers and vehicle cruise control, AI is increasingly becoming a part of our day-to-day lives. • The scope for innovation and development in AI is enormous and it will continue changing the world in diverse ways in the future. • Below are the 10 most remarkable benefits of Artificial Intelligence that are helping to reshape the world that we know of today. ❖ Automation • Automation is one of the most commonly cited benefits of AI technology, and it has had significant impacts on the communications, transportation, consumer products, and service industries. • Automation not just leads to higher production rates and increased productivity in these sectors but also allows more efficient use of raw materials, improved product quality, reduced lead times, and superior safety. • Automation can also help to free resources that can be used for more important things. ❖ Smart Decision Making • Artificial Intelligence has always been used for making smarter business decisions. • AI technology can coordinate data delivery, analyze trends, develop data consistency, provide forecasts, and quantify uncertainties to make the best decisions for the company. • As long as AI is not programmed to imitate human emotions, it will remain unbiased on the matter at hand and will help to make the right decision to support business efficiency. ❖ Enhanced Customer Experience • AI-powered solutions can help businesses to respond to customer queries and grievances quickly and address the situations efficiently.
- 16. SEM -VII Descriptive Type Question P a g e | 16 • The use of chatbots that couple conversational AI with Natural Language Processing technology can generate highly personalized messages for customers, which helps to find the best solution for their needs. • AI tools can also help to reduce the strain from the customer service staff, which will lead to better productivity. ❖ Medical Advances • The use of Artificial Intelligence solutions in the healthcare sector is becoming increasingly popular these days. • Remote patient monitoring technology, for instance, allows healthcare providers to perform clinical diagnoses and suggest treatments quickly without requiring the patient to visit the hospital in-person. • AI can also be beneficial in monitoring the progression of contagious diseases and even predict their future effects and outcomes. ❖ Research and Data Analysis • AI and Machine Learning technology can be used to analyze data much more efficiently. • It can help to create predictive models and algorithms to process data and understand the potential outcomes of different trends and scenarios. • Moreover, the advanced computing capabilities of AI can also speed up the processing and analysis of data for research and development, which could have taken too long for humans to review and understand. ❖ Solving Complex Problems • The developments in AI technologies from basic Machine Learning to advanced Deep Learning models have made it capable to solve complex issues. • From fraud detection and personalized customer interactions to weather forecasting and medical diagnosis, AI is helping businesses across industries to find the right solutions to address their challenges more adequately. • Greater efficiency in solving complex problems means increased productivity and reduced expenses. ❖ Business Continuity • Business forecasting using AI technology not only helps companies make critical decisions but also prepares them for any emergency to ensure business continuity.
- 17. SEM -VII Descriptive Type Question P a g e | 17 • As risk management heavily relies on data management and analysis today, AI-powered tools can help organizations to respond to the crisis proactively. • AI and Machine Learning can also create scenarios to help businesses plan for a speedy disaster recovery strategy. ❖ Managing Repetitive Tasks • Performing recurring business tasks is not just time-consuming but it can also be monotonous and reduce the productivity of the employees over time. • AI-powered Robotic Process Automation tools can automate interactions between different business systems and make the tiresome work easy for the company. • It can imitate the actions of humans within the digital systems in the HR, IT, marketing, or sales departments to execute any business process quickly without needing any manual effort. ❖ Minimizing Errors • Another great benefit of automating regular business tasks using AI tools is that it helps to reduce the chances of manual errors. • As Robotic Process Automation tools take care of the data entry and processing jobs, it can make the digital systems more efficient and less likely to run into or create any problems due to data processing mistakes. • This can be especially beneficial for businesses that cannot afford to make even the slightest of errors. ❖ Increased Business Efficiency • Artificial Intelligence can help to ensure 24-hour service availability and will deliver the same performance and consistency throughout the day. • Taking care of repetitive tasks will not make AI tools get tired or bored either. • This can help to improve the efficiency of the business and reduce the stress on the employees, who can be re-assigned to perform more complex business tasks that require manual intervention. Q2 - Explain Translation, Rotation, & Scaling of 2D Transformation • Transformation means changing some graphics into something else by applying rules.
- 18. SEM -VII Descriptive Type Question P a g e | 18 • We can have various types of transformations such as translation, scaling up or down, rotation, shearing, etc. When a transformation takes place on a 2D plane, it is called 2D transformation. • Transformations play an important role in computer graphics to reposition the graphics on the screen and change their size or orientation. • Homogenous Coordinates ➢ To perform a sequence of transformation such as translation followed by rotation and scaling, we need to follow a sequential process – • Translate the coordinates, ➢ Rotate the translated coordinates, and then ➢ Scale the rotated coordinates to complete the composite transformation. ➢ To shorten this process, we have to use 3×3 transformation matrix instead of 2×2 transformation matrix. ➢ To convert a 2×2 matrix to 3×3 matrix, we have to add an extra dummy coordinate W. • In this way, we can represent the point by 3 numbers instead of 2 numbers, which is called Homogenous Coordinate system. • In this system, we can represent all the transformation equations in matrix multiplication. Any Cartesian point PX,Y can be converted to homogenous coordinates by P’ (Xh, Yh, h). ❖ Translation ➢ A translation moves an object to a different position on the screen. You can translate a point in 2D by adding translation coordinate (tx, ty) to the original coordinate X,Y to get the new coordinate X′,Y′. Translation From the above figure, you can write that −
- 19. SEM -VII Descriptive Type Question P a g e | 19 X’ = X + tx Y’ = Y + ty The pair (tx, ty) is called the translation vector or shift vector. The above equations can also be represented using the column vectors. P=[X][Y] p' = [X′][Y′]T = [tx][ty] We can write it as − P’ = P + T ❖ Rotation ➢ In rotation, we rotate the object at particular angle θ theta from its origin. From the following figure, we can see that the point PX,Y is located at angle φ from the horizontal X coordinate with distance r from the origin. Let us suppose you want to rotate it at the angle θ. After rotating it to a new location, you will get a new point P’ X′,Y′. Rotation Using standard trigonometric the original coordinate of point PX,Y can be represented as − X=rcosϕ......(1) Y=rsinϕ......(2)
- 20. SEM -VII Descriptive Type Question P a g e | 20 Same way we can represent the point P’ X′,Y′ as − x′=rcos(ϕ+θ)=rcosϕcosθ−rsinϕsinθ.......(3) y′=rsin(ϕ+θ)=rcosϕsinθ+rsinϕcosθ.......(4) Substituting equation 1 & 2 in 3 & 4 respectively, we will get x′=xcosθ−ysinθ y′=xsinθ+ycosθ Representing the above equation in matrix form, [X′Y′]=[XY][cosθ−sinθsinθcosθ]OR P’ = P . R Where R is the rotation matrix R=[cosθ−sinθsinθcosθ] The rotation angle can be positive and negative. For positive rotation angle, we can use the above rotation matrix. However, for negative angle rotation, the matrix will change as shown below − R=[cos(−θ)−sin(−θ)sin(−θ)cos(−θ)] =[cosθsinθ−sinθcosθ](∵cos(−θ)=cosθandsin(−θ)=−sinθ) ❖ Scaling ➢ To change the size of an object, scaling transformation is used. In the scaling process, you either expand or compress the dimensions of the object. ➢ Scaling can be achieved by multiplying the original coordinates of the object with the scaling factor to get the desired result. Let us assume that the original coordinates are X,Y, the scaling factors are (SX, SY), and the produced coordinates are X′,Y′. This can be mathematically represented as shown below − X' = X . SX and Y' = Y . SY
- 21. SEM -VII Descriptive Type Question P a g e | 21 The scaling factor SX, SY scales the object in X and Y direction respectively. The above equations can also be represented in matrix form as below − (X′Y′)=(XY)[Sx00Sy] OR P’ = P . S Where S is the scaling matrix. The scaling process is shown in the following figure. Before ScalingAfter Scaling If we provide values less than 1 to the scaling factor S, then we can reduce the size of the object. If we provide values greater than 1, then we can increase the size of the object. ➢ Reflection ➢ Reflection is the mirror image of original object. In other words, we can say that it is a rotation operation with 180°. In reflection transformation, the size of the object does not change. The following figures show reflections with respect to X and Y axes, and about the origin respectively.
- 22. SEM -VII Descriptive Type Question P a g e | 22 1. Translation, Rotation, & Scaling & Magnification of 2D numericals can come
- 23. SEM -VII Descriptive Type Question P a g e | 23 MODULE - 3 Q1 - Write short notes on the absolute versus incremental positioning in NC Machine tools Absolute Positioning: • When many or all of the coordinates on the print are dimensioned from one fixed point. That point is the XY zero position or absolute zero. Incremental Positioning: • When the the print show dimensions going from one location to the next. • Point to point positioning. • Dimensions given from the tools current position to the next location.
- 24. SEM -VII Descriptive Type Question P a g e | 24 Q2 - What is NC machine ? and also Discuss the advantage & disadvantage & application of NC machine Numeric control : • Numerical control is defined as the form of programmable automation in which numbers letters and symbols control the operation. • This instruction is designed to do a particular job. • NC machines has capability to change the program for each job ie when job changes the program instruction is also changed Advantages of NC • Greater manufacturing flexibility – NC can easily adapt to the engineering design changes and a shift in the production schedule. • Reduced manufacturing lead time – the job can easily and quickly set up with NC. • Reduced non-productive time. • Reduced fixturing – the fixture required in NC operation are simpler and less costly because NC tape does positioning instead of jig and fixture. • Reduced inventory - this is the result of fewer setup reduced lead time. • Quality control improved – No risk of human mistakes. It produces the part with high accuracy. It also reduce the man-hour for inspection. • Greater operator safety.
- 25. SEM -VII Descriptive Type Question P a g e | 25 • Reduce the scrap – the high accuracy of NC machine helps to reduce scrap material. • Reduced floor space requirement Disadvantages and Limitation of NC • High investment cost and Maintenance cost – most complex and sophisticated technology cost more than the conventional machine. • Require skilled operator – finding and training of NC personnel should be considered. • Tearing and wearing of punch tape and less reliable punch tape component. • Part programming mistake in punched tape. • No optimal feed and speed – conventional NC machine does not provide an option to change the cutting speed and feed during the operation. Application : Numerical control technology has application in a wide variety of production operation such as metal cutting, automatic drafting, spot welding, press working, assembly, inspection, etc.
- 26. SEM -VII Descriptive Type Question P a g e | 26 Q2 - Difference between NC & CNC Machine Q3 - Difference between CNC & DNC Sr. no CNC DNC 1 In CNC, remote controlling of operation is not possible. DNC facilitate the remote control. 2 CNC is an integral part of the machine. DNC is not integral to machines, DNC computer can locate at a distance from machines. 3 CNC transferring machining instruction. DNC manage the information distribution to the number of machines.
- 27. SEM -VII Descriptive Type Question P a g e | 27 4 CNC computer control one NC machine. Using DNC programmer can control more than one NC machine as required. 5 CNC have low processing power when compared to DNC DNC have high processing power when compared to CNC 6 CNC software is to increase the capability of the particular machine tool. DNC not only control the equipment but also serve as a part of management information system. Q4 - Explain Machining Centers • Machining centres are very important types of CNC machine tools and are multifunction machines equipped with automatic tool changers and are capable of carrying out milling, drilling, reaming, tapping, boring, counter boring and allied operations without operator intervention for change of tools. • Tool changing is carried out using an automatic tool changer and is accomplished in 0.5 to 6 seconds depending upon the machine. • An indexable tool magazine, which can store several tools, characterizes a machining centre. • The tool magazine may carry 16 to 100 tools depending upon its capacity. • Machining centres are often provided with two or more work tables called pallets. • In a 2-pallet machine while the job on one pallet is being machined, the operator can set up the next job on the free pallet. • The automatic pallet changer (APC) then moves away the pallet with the finished job from the working zone and moves the other pallet with the new workpiece to the working zone. • The machining operation on the new workpiece begins with a lapse of only a few minutes. Machining centres are classified according to the spindle configuration as: a) Horizontal spindle machining centres b) Vertical spindle machining centres c) Universal machining centres Horizontal Spindle Machining Centres • Horizontal spindle machining centres are generally single spindle machines with automatic tool changers.
- 28. SEM -VII Descriptive Type Question P a g e | 28 • Some exceptions are machines with turret type tool magazine, combination horizontal/vertical spindles etc. • Horizontal spindle machining centres are generally bed type machines with the structural configuration as shown in Fig. Vertical Spindle Machining Centres Figure shows a typical vertical spindle machining centre. Vertical spindle machining centres are also bed type machines with: a) Single spindle and automatic tool changers b) Multi spindle with turret head (Turret machining centres) • X-axis traverse provided by table or column • Y-axis traverse provided by the saddle or the column or ram • Z-axis traverse provided by the headstock • Vertical spindle machines are not suitable for large widths as this increases the throat distance. • For very large widths horizontal spindle configuration or bridge type configuration (double column planer type) is used.
- 29. SEM -VII Descriptive Type Question P a g e | 29 Universal Machining Centres • These are similar to horizontal machining centres but with the spindle axis capable of tilting from horizontal to the vertical position continuously under computer control. • This constitutes the fifth axis of the machine. In some cases tilting of the table instead of the spindle provides the movement. Such machines facilitate access to the top surface of workpiece mounted on a horizontal machining centre so that all the five sides of a component can be machined in a single set up. • The fifth axis facility is essential for machining of some components, which require the cutter axis to be perpendicular to the surface being machined. • Machining centres can be easily integrated into a flexible work cell Q5 - Short notes on Subroutines & Macros Subroutines: • A subroutine (also called a subprogram) is an abstraction of a process that is called. • The caller passes arguments to the subroutine which accepts them as parameters. • While the caller waits, the subroutine executes (or evaluates) its body, which may cause side effects to the global system state, and optionally returns results to the caller. • A function returns a value or values and is called from within an expression.
- 30. SEM -VII Descriptive Type Question P a g e | 30 • A procedure returns no values and is called in a statement, not an expression. But some languages have no statements (only expressions). The languages use some mechanism like "void context" or employ a special return value like nil or () to make functions look like procedures. • A method is a subroutine defined on an object in an object oriented context Macros : • Macro can be called only in the program it is defined. • Macro can have maximum 9 parameters. • Macro can be called only after its definition. • A macro is defined inside: • Macro is used when same thing is to be done in a program a number of times. Q6 - Write a manual part program using G & M codes for a given part below O0001 N5 M12 N10 T0101 N15 G0 X100 Z50 N20 M3 S600 N25 M8
- 31. SEM -VII Descriptive Type Question P a g e | 31 N30 G1 X50 Z0 F600 N40 W-30 F200 N50 X80 W-20 F150 N60 G0 X100 Z50 N70 T0100 N80 M5 N90 M9 N100 M13 N110 M30 N120 % Q7 - Write a manual part program using G & M codes for a given part below N5 G00 G54 G64 G90 G17 X-20 Y-20 Z50 N10 S450 M03 F250 D01 (12.5 MM DIA) N15 C0
- 32. SEM -VII Descriptive Type Question P a g e | 32 N20 Z5 N25 G01 Z0 N30 Z-5 N35 G42 X0 Y0 M08 N40 X80 Y0 N45 X60 Y30 U10 N50 X80 Y50 N55 X50 Y50 N60 G02 X30 Y30 U20 N65 G01 X10 Y30 U8 N70 X0 Y0 N75 G40 X-20 Y-20 N80 G00 Z50 M09 N85 Y100 N90 M30 Q8 - Write a manual part program using G & M codes for a given part below
- 33. SEM -VII Descriptive Type Question P a g e | 33 G90 G01 X0 Y0 X30 G03 X54 R12 G01 X82 G02 X108 R13 G01 X123 X80 Y45 X40 Y75 G03 X35 Y80 R5 G01 X20 G03 X0 Y80 R10 G01 Y0 M30 Q9 - Write a manual part program using G & M codes for a given part below
- 34. SEM -VII Descriptive Type Question P a g e | 34 G90 G01 X0 Y0 X50.0 X70.0 Y35.0 X45.0 X0 Y80.0 Y0 M30
- 35. SEM -VII Descriptive Type Question P a g e | 35 MODULE 4 5/10 MARKS QUESTIONS Q1 - Explain the procedure of kinematic analysis of a structural system with an example • “Motion study” is a catch-all term for simulating and analyzing the movement of mechanical assemblies and mechanisms. Traditionally, motion studies have been divided into two categories: kinematics and dynamics. • Kinematics is the study of motion without regard to forces that cause it; • Dynamics is the study of motions that result from forces. Other closely related terms for the same types of studies are multibody dynamics, mechanical system simulation, and even virtual prototyping. • Kinematic analysis is a simpler task than dynamic analysis and is adequate for many applications involving moving parts. • Kinematic simulations show the physical positions of all the parts in an assembly with respect to the time as it goes through a cycle. • This technology is useful for simulating steady-state motion (with no acceleration), as well as for evaluating motion for interference purposes, such as assembly sequences of complex mechanical system. Many basic kinematic packages, however, go a step further by providing “reaction forces,” forces that result from the motion. • Dynamic simulation is more complex because the problem needs to be further defined and more data is needed to account for the forces. But dynamics are often required to accurately simulate the actual motion of a mechanical system. Generally, kinematic simulations help evaluate form, while dynamic simulations assists in analyzing function. • Traditionally, kinematics and dynamics have followed the classic analysis software method of preprocessing (preparing the data), solving (running the solution algorithms, which involve the solution of simultaneous equations), and postprocessing (analyzing the results). • Even though today’s programs are much more interactive, most programs follow this basic process since it is a logical way to solve the problem. Most solvers are available as independent software programs. • One of the reasons for the popularity of solid modeling is that it sets the stage for many applications. You can practically create working drawings automatically, rendering models that closely resemble the real objects and generating physical models from rapid prototyping equipment.
- 36. SEM -VII Descriptive Type Question P a g e | 36 • Similarly, studying the motion of moving mechanisms and assemblies is rapidly becoming almost a “free” byproduct of solid modeling, helping engineers to do the following: ➢ Simulate mechanisms to help develop workable designs ➢ View physically realistic animations to detect problems and to study aesthetics ➢ Find interferences among moving parts and fix them ➢ Verify an entire mechanical system with numerous, even unrelated, moving components ➢ Plot motion envelopes for designing housings and ensuring clearances. ➢ Create animations of assembly sequences to plan efficient manufacturing ➢ Generate accurate load information for improved structural analysis ➢ Calculate required specifications for motors, springs, actuators, etc. early in the design process ➢ Produce animations for output to video or for posting on web sites to show customers and clients how products will actually work—not just provide a set of pictures of how it might work • The basic output of motion studies are numerous, including animation, detecting interference, trace functions, basic motion data, and plots and graphs. Animated motions are the classic output of simple kinematic analyses. Initially, the designer uses simple animation as a visual evaluation of motion to see if it is what is desired. More sophisticated animations can show motion from critical angles or even inside of parts, a definite advantage over building and running a physical prototype. • The ability to detect and fix interferences without switching between software is one of the primary benefits of integrating motion simulation and CAD. Most systems provide color feedback, for example, by turning to red parts that experience interferences. More useful, however, are systems that turn the interference volume into a separate piece of geometry, which can then be used to modify the parts to eliminate the interference. • Trace functions provide additional information about motion. The motion of a joint or a particular point on a part can be plotted in 3D as a line or surface. Or, the system can leave copies of the geometry at specified intervals. Such functions can provide an envelope of movement that can be used to design housings or ensure clearances. • Motion data, such as forces, accelerations, velocities, and the exact locations of joints or points on geometry can usually be extracted, although such capabilities are more applicable to dynamic simulations rather than kinematic studies. Some systems allow users to attach instruments to their models to simplify specifying what results they want to see.
- 37. SEM -VII Descriptive Type Question P a g e | 37 • Most packages provide a plethora of plotting and graphing functions. Plots and graphs are most commonly used because values vary over time and are more meaningful than a single value at any given time. An especially useful capability for studying design alternatives is to plot the results of two different simulations on the same graph. Such data can also help designers determine the size of motors, actuators, springs, and other mechanism components. • Forces that result from motion are of particular interest because they can be used as loads (or, at least, to calculate them) for structural analysis of individual members. Typically, the highest load for a cycle is used to perform a linear static finite element analysis (FEA) of critical individual components of a mechanism. Integration of solid modeling, motion simulation, and FEA software can greatly streamline this process—especially important when studying design alternatives, where many analyses are required. • Engineers have used specialized software programs for performing various analyses for years in projects such as automobile suspension design. Doing all of the tasks in a single CAD program is becoming routine as solid modelers are being tightly linked to motion simulation software. Q2 - Explain Steps involved in CAE. • Design and manufacturing is very vital to the progress of civilization. Before we dig deeper into CAE, let us first understand the basics of engineering design. • Engineering design of a product can be broken into four steps: 1. Problem definition – in the initial stages of product development, it is necessary to clearly define what the product is meant to achieve and / or do. 2. Creative process - once the objective of the product is identified, it is necessary to synthesize its form. This involves brainstorming sessions where designers and engineers meet and interact. Various forms are evaluated and selected into a set of few workable solutions. 3. Analytical process – Fitting the product into form is the next step. This requires strength and reliability analysis, cost determination, etc. This step is very important and iterative. Multiple solutions for the product may be evaluated till the optimal values are achieved. This is where CAE is blended with CAD. Using CAE software, trained engineers are able to evaluate various parameters of the desired object. 4. Prototype development & testing – this is where the theory is translated into practical. Prototypes are developed and tested, usually using 3D printers for rapid development.
- 38. SEM -VII Descriptive Type Question P a g e | 38 ➢ Computer Aided Engineering ➢ Computer Aided Engineering (CAE) is a fast emerging field that takes CAD to another level. ➢ While CAD is useful in creating 2D and 3D models of a product, CAE software allows a deeper engineering analysis of objects. ➢ CAE thus finds applications in engineering fields like fluid dynamics, kinematics, stress analysis, finite element analysis, etc., typically where product development is concerned. CAE encompasses not only CAD, but also Computer Aided Manufacturing (CAM), ➢ Finite Element Analysis (FEA), Computational Fluid Dynamics (CFD) and some other aspects of engineering. Simply put, you can create 2D and 3D objects using CAD, while you can analyze how that object will behave using CAE tools. ➢ The automated design tools provided by CAE have transformed engineering analysis from a ‘hands on’ experience to virtual simulation. ➢ The CAE Process ➢ In the first stage, the object / product / system is designed, typically using CAD software. Engineers manipulate the parameters of the object / system being evaluated. ➢ These parameters include the physical properties, geometry and the limitations under which the entity is to be developed. ➢ In the second stage, the entity is thoroughly evaluated using CAE processes like FEA, NVH (noise, vibration and harshness), CFD, etc. ➢ As a third step, the results are shown to the engineering design team and the parameters of the system / object are tweaked to get optimum results. The process is iterated till the desired benefits are achieved. ➢ Benefits of CAE ➢ Since simulating reality is less time consuming, CAE processes save on time and money ➢ CAE reduces the errors in design and drawing process ➢ The impacts of changing parameters on a system can be studied with more accuracy ➢ Robustness and performance of components and assemblies can be analyzed ➢ CAE allows for easy visualization and improves designs ➢ CAE aids ease of manufacturing
- 39. SEM -VII Descriptive Type Question P a g e | 39 Q3 - Explain Use of CAE in engineering analysis • Product design begins with an abstract product idea, which is later converted to a physical model. The first step in this conversion process is to determine a basic geometry of the physical model. • Then, computer-aided engineering (CAE) tools are applied to analyze the product behavior. This process of applying CAE tools is known as “analysis.” CAE tools are used to analyze CAD geometry, allowing product designers to simulate and study the expected behavior of the product in different environments. • Analysis helps the design to be refined and optimized. • In order to optimize final product performance, computer-based engineering analyses are conducted during the development stage to investigate and predict mechanical, thermal, electrical, fatigue stresses, as well as characteristics related to fluid flow, heat transfer, and noise/vibration/harshness. • There are different types of software tools for different analyses. Some of these tools include the following: 1) Finite element analysis (FEA) 2) Computational fluid dynamics (CFD) 3) Thermal analysis 4) Kinematics and dynamics analysis 5) Multi-physics analysis 6) Electromagnetic analysis 7) Structural analysis 8) Moldflow analysis 9) Stamping analysis 10) Acoustic analysis 11) Crash testing 12) Product simulation 13) Durability analysis 14) Factory simulation 15) Logic-timing and verification 16) Electronic design simulation (logic simulation and circuit simulation) 17) Design visualization and animation • There are many commercial and free software products available for each of the analyses methods listed. Probably the most widely used method of computer analysis in engineering is finite element analysis.
- 40. SEM -VII Descriptive Type Question P a g e | 40 • FEA is a complex set of algorithms that uses finite element mathematical methods to solve problems in structural simulation, modeling, and analysis. Aerospace and automobile designers, civil engineers, defense contractors, manufacturers of electronic equipment, and national and university labs use several variants of FEA. • Generally, FEA is used to determine stress, deformation, heat transfer, magnetic field distribution, fluid flow, and other continuous field problems that would be impractical to solve by other methods. • Similarly, kinematics programs can be used to determine motion paths and linkage velocities in mechanisms. Dynamics analysis can be used to determine loads and displacements in complex assemblies such as automobiles. Logic- timing and verification software simulates the operation of complex electronic circuits. • Crash tests are conducted using crash-testing software. Crash testing is a specialized application that uses FEA and CFD techniques to simulate the results of a dynamic impact on several dimensions of the design, including structural integrity, flow of materials, and thermal flow. • Major users of crash-testing software include automotive and aircraft manufacturers. They use it to save money by reducing the need for real-world crash tests and to improve their designs and comply with statutory safety requirements. • During the design process, a 3D solid CAD model is generated, which provides an excellent way of sharing data across the enterprise with the help of visualization and animation tools. • The issues related to functionality, manufacturing, and packaging of the product could be resolved with the aid of Web-based collaborative tools. • As interoperability issues are resolved, engineers can share data related to the model across many different platforms and without the fear of losing valuable information. • The field of computer-aided engineering has grown tremendously in the last twenty years. With the availability of low-cost, powerful personal computers and different types of analysis software to run on them, analysis has moved away from a supercomputer/workstation platform. • In the past, analysis was strictly the domain of the expert or specialist, often with whole departments in larger companies dedicated to the function. But the current explosion of low-cost computing power has brought a matching increase in the number and type of PC-based analysis tools to the engineer. • At the same time, products have become much easier to use with user-friendly features, such as CAD geometry transfer, automatic meshing, in-built error checking, adaptive refinement, and optimization tools.
- 41. SEM -VII Descriptive Type Question P a g e | 41 • This has led to significant amounts of analysis being carried out by engineers throughout the product design cycle. By minimizing (and, in some cases, eliminating altogether) prototype testing and certification, many companies are attempting to cut development costs significantly and further reduce the time-to- market. • Such strategies depend on an increased reliance on the results of engineering analysis as the means of performance verification.
- 42. SEM -VII Descriptive Type Question P a g e | 42 MODULE 5 5/10 MARKS QUESTIONS Q1 - Explain the basic components of CIM system. • The components of CIMS include both hardware and software. The hardware includes computer hardware, network, manufacturing devices, and peripherals. • The software includes operating systems, communication software, database management systems, manufacturing planning and control soft- ware, management information software, design software, office automation software, and decision support software. • These different hardware and software systems have different functions and work together to fulfill the company’s business goals. To make it easier to understand, CIMS is normally decomposed into a number of subsystems interacting with each other. • Unfortunately, no unique and standard decomposition method exists. Every company can define a method according to its specific situation and requirements. One decomposition method is shown in Figure 5. • From Figure, it can be seen that CIMS consists of four functional subsystems and two support subsystems. • The four functional subsystems are management information, CAD / CAPP / CAM, man- ufacturing automation, and computer-aided quality management.
- 43. SEM -VII Descriptive Type Question P a g e | 43 • These functional subsystems cover the business processes of a company. The two support subsystems are computer network and database management. • They are the basis that allows the functional subsystems to fulfill their tasks. The arcs denote the interfaces between different subsystems. Through these interfaces, shared data are ex- changed between different subsystems. ➢ Components of CIMS Management Information System ➢ Management information system (MIS) plays an important role in the company’s information system. ➢ It manages business processes and information based on market strategy, sales predictions, business decisions, order processing, material supply, finance management, inventory management, human resource management, company production plan, and so on. ➢ The aims of MIS are to shorten delivery time, reduce cost, and help the company to make rapid decision to react to market change. Q2 - Explain Concept of Future CIM Systems. • CIM is a manufacturing approach that provides a complete automation of a manufacturing facility. All the operations are controlled by computers and have a common storage and distribution. • The various processes involved in a CIM are listed as follows: ➢ Computer-aided design ➢ Prototype manufacture ➢ Determining the efficient method for manufacturing by calculating the costs and considering the production methods, volume of products, storage and distribution ➢ Ordering of the necessary materials needed for the manufacturing process ➢ Computer-aided manufacturing of the products with the help of computer numerical controllers ➢ Quality controls at each phase of the development. ➢ Product assembly with the help of robots
- 44. SEM -VII Descriptive Type Question P a g e | 44 ➢ Quality check and automated storage ➢ Automatic distribution of products from the storage areas to awaiting lorries/trucks ➢ Automatic updating of logs, financial data and bills in the computer system • CIM is a combination of different applications and technologies like CAD, CAM, computer-aided engineering, robotics, manufacturing resource planning and enterprise management solutions. • It can also be considered as an integration of all enterprise operations that work with a common data repository. ➢ The major components of CIM are as follows: ➢ Data storage, retrieval, manipulation and presentation mechanisms ➢ Real-time sensors for sensing the current state and for modifying processes ➢ Data processing algorithms • The Computer Integrated Manufacturing Open System Architecture (CIMOSA) was proposed in 1990 by the AMCIE consortium to provide an open systems architecture that specifies both enterprise modeling and enterprise integration required by CIM environments. • The CIM approach has found a wide range of applications in industrial and production engineering, mechanical engineering and electronic design automation. CIM increases the manufacturing productivity and lowers the total cost of manufacturing. It also offers great flexibility, quality and responsiveness. Q3 - Short notes on CIM Hardware & Software CIM Hardware comprises the following: i. Manufacturing equipment such as CNC machines or computerized work centres, robotic work cells, DNC/FMS systems, work handling and tool handling devices, storage devices, sensors, shop floor data collection devices, inspection machines etc. ii. Computers, controllers, CAD/CAM systems, workstations / terminals, data entry terminals, bar code readers, RFID tags, printers, plotters and other peripheral devices, modems, cables, connectors etc., CIM software comprises computer programmes to carry out the following functions:
- 45. SEM -VII Descriptive Type Question P a g e | 45 • Management Information System • Sales • Marketing • Finance • Database Management • Modeling and Design • Analysis • Simulation • Communications • Monitoring • Production Control • Manufacturing Area Control • Job Tracking • Computer Integrated Manufacturing 7 • Inventory Control • Shop Floor Data Collection • Order Entry • Materials Handling • Device Drivers • Process Planning • Manufacturing Facilities Planning • Work Flow Automation • Business Process Engineering • Network Management • Quality Management Q4 - Explain nature and role of CIM elements Nine major elements of a CIM system are in Fig They are: 1. Marketing 2. Product Design 3. Planning 4. Purchase 5. Manufacturing Engineering 6. Factory Automation Hardware
- 46. SEM -VII Descriptive Type Question P a g e | 46 7. Warehousing 8. Logistics and Supply Chain Management 9. Finance 10. Information Management 1. Marketing: The need for a product is identified by the marketing division. The specifications of the product, the projection of manufacturing quantities and the strategy for marketing the product are also decided by the marketing department. Marketing also works out the manufacturing costs to assess the economic viability of the product. 2. Product Design: The design department of the company establishes the initial database for production of a proposed product. In a CIM system this is accomplished through activities such as geometric modeling and computer aided design while considering the product requirements and concepts generated by the creativity of the design engineer. Configuration management is an important activity in many designs. 3. Planning: The planning department takes the database established by the design department and enriches it with production data and information to produce a plan for the production of the product. Planning involves several subsystems dealing with materials, facility, process, tools, manpower, capacity, scheduling, outsourcing, assembly, inspection, logistics etc 4. Purchase: The purchase departments is responsible for placing the purchase orders and follow up, ensure quality in the production process of the vendor, receive the items, arrange for inspection and supply the items to the stores or
- 47. SEM -VII Descriptive Type Question P a g e | 47 arrange timely delivery depending on the production schedule for eventual supply to manufacture and assembly. 5. Manufacturing Engineering: Manufacturing Engineering: Manufacturing Engineering is the activity of carrying out the production of the product, involving further enrichment of the database with performance data and information about the production equipment and processes. In CIM, this requires activities like CNC programming, simulation and computer aided scheduling of the production activity. 6. Factory Automation Hardware: Factory Automation Hardware: Factory automation equipment further enriches the database with equipment and process data, resident either in the operator or the equipment to carry out the production process. In CIM system this consists of computer controlled process machinery such as CNC machine tools, flexible manufacturing systems (FMS), Computer controlled robots, material handling systems, computer controlled assembly systems, flexibly automated inspection systems and so on. 7. Warehousing: Warehousing is the function involving storage and retrieval of raw materials, components, finished goods as well as shipment of items. In today’s complex outsourcing scenario and the need for just-in-time supply of components and subsystems, logistics and supply chain management assume great importance. 8. Finance: Finance deals with the resources pertaining to money. Planning of investment, working capital, and cash flow control, realization of receipts, accounting and allocation of funds are the major tasks of the finance departments. 9. Information Management: Information Management is perhaps one of the crucial tasks in CIM. This involves master production scheduling, database management, communication, manufacturing systems integration and management information systems. Q5 - Short notes on - Socio-techno-economic aspects • The computer integrated manufacturing has brought the significant technological change in the field of manufacturing. • However, this technological change is accompanied by some social and economic impacts. • Some of the socio-techno-economic aspects of CIM are discussed below:
- 48. SEM -VII Descriptive Type Question P a g e | 48 Technological Aspect: • The CIM has brought in technological revolution in the field of manufacturing. • Some of the positive changes brought by technological revolution of CIM are as follows: i. increase in productivity ii. increase in plant efficiency iii. improvement in product quality iv. reduction in the cost of product v. increase in demand for the product vi. high customer satisfaction Social Aspect: Along with some positive changes, CIM has brought some challenging social aspects. some of them are as follows: i. Increase in unemployment: • Implementation of CIM has reduced the requirement of workforce drastically, and hence led to the downsizing of workforce. • The downsizing of workforce has created the problem of worker unrest and unemployment. ii. Lower demand for traditional skill sets: • With implementation of CIM the demand for traditional labour skill sets in the area of turning, drilling, milling, grinding etc. has reduced iii. Increase in demand for new skill sets: • The implementation of CIM has created increase in demand for new skill sets in the area of modeling, finite element analysis, simulation, CNC programming computer operation etc iv. Government policy : • Because of opposition from trade unions and existing workforce to the implementation of CIM, the government policies trade a balance between social aspects and support to technological development. v. Change in education system: • The implementation of CIM has created the increased demand for workforce with higher professional qualifications and new skill sets.
- 49. SEM -VII Descriptive Type Question P a g e | 49 • The traditional educational system is not changing at the required pace to provide right kind of education. Economic Aspect: • Implementation of CIM has led to the increase in profit to the companies more revenue through taxes to the government and high salary for highly skilled and downsized workforce. • However the implementation of CIM affects the workers who lost their job. Q6- Role of CAD/CAM in CIM The step by step evalution of product cycle with CIM is shown in fig ➢ Computer aided design (CAD) : The cad of the product is carried out using the various CAD tool such as : geometric modelling, FEA, and simulation. From geometric model the detail 2d drawing of the product and its components are created automatically. This is known as computer aided drafting. At this stage the complete description and information of the product and its component is available in the CAD/CAM database. ➢ Computer aided manufacturing planning and control (CAMPC) : In the next step the activities are shifted to CAMPC. Using the geometric model of the product stored in the database , production planning and computer aided process planning (CAPP) Is carried out. CAPP is followed by master scheduling, material requirements planning and manufacturing resource planning. ➢ Computer aided manufacturing (CAM) : the next step is CAM of the product using CNC machine , FMS, transfer lines etc. the computer aided manufacturing is assisted by robots and AGVs for material handling. In quality assurance the computer are used for inspection and its components ➢ Computer aided business function ( CABF) : The various departments coming under CABF are : purchase, stores, cost planning and control, marketing and sales , finance and accounts, and human resources and development. It is important to note that all activities and function in CIM are performed by keeping customer at center point
- 50. SEM -VII Descriptive Type Question P a g e | 50
- 51. SEM -VII Descriptive Type Question P a g e | 51 MODULE 6 5/10 MARKS QUESTIONS Q1 - Explain Rapid prototyping and its significance • By definition, rapid prototyping is the production of a scale model (prototype) of a physical part or product using multi-dimensional computer-aided design (CAD) software. • The actual construction of that part or product is done via 3D-printing or additive layer manufacturing technology. • And, in fact, the terms three-dimensional printing or additive manufacturing are often used interchangeably to describe the process of rapid prototyping. • Very often, when product designers want to demonstrate how new products will look, feel, and perform, they do so through digital models; while this is the more inexpensive method, it may not be conducive to gaining approval for the design from management and/or clients. Because these groups often want to see new products in physical rather than virtual form. • But building a physical model can be time-consuming, not to mention expensive. Especially if it is found after testing that the prototype needs to be altered before going to production • Rapid prototyping is an excellent alternative to the traditional approach of creating full-scale prototypes; it allows the designers and the end-users to validate the dimensions, assembly, and functionality of new part or product without the need for special tools or experienced technical support, with the additional advantages of cost-efficiency and time-efficiency. • There are several processes that can be used for rapid prototyping; the most common are: ✓ Stereolithography (SLA) ✓ Selective Laser Sintering (SLS ✓ Fused Deposition Modelling (FDM) ✓ Selective Laser Melting (SLM) ✓ Laminated Object Manufacturing (LOM) ✓ Multi Jet Modelling (MJM)
- 52. SEM -VII Descriptive Type Question P a g e | 52 ✓ Digital Light Processing (DLP) • Significance ✓ Faster and more cost-effective than constructing a full-scale model ✓ Eliminates the cost and time need to develop special molds and tools ✓ Minimizes waste; uses only the material needed to build the prototype ✓ Can make parts of miniscule size and/or that have complex geometries ✓ Provides a realistic three-dimensional design vs a computer screen image ✓ Permits the identification of any design flaws prior to any mass production ✓ Design changes can be done without the need to modify the entire process ✓ Easier testing – properties of the material closely resemble the final product Q2 - Short note on Laminated object manufacturing, • Laminated object manufacturing (LOM) is a method of 3D printing. It was developed by the California-based Helisys Inc. During the LOM process, layers of plastic or paper are fused — or laminated — together using heat and pressure, and then cut into the desired shape with a computer-controlled laser or blade • LOM is defined by its use of laminates, which are covered in an adhesive so that they bind together after being deposited by the 3D printer.
- 53. SEM -VII Descriptive Type Question P a g e | 53 ❖ Working • An LOM apparatus uses a continuous sheet of material — plastic, paper or (less commonly) metal which is drawn across a build platform by a system of feed rollers. Plastic and paper build materials are often coated with an adhesive. • To form an object, a heated roller is passed over the sheet of material on the build platform, melting its adhesive and pressing it onto the platform. • A computer-controlled laser or blade then cuts the material into the desired pattern. The laser also slices up any excess material in a crosshatch pattern, making it easier to remove once the object is fully printed. • After one layer of the object is formed, the build platform is lowered by about one-sixteenth of an inch — the typical thickness of one layer. • New material is then pulled across the platform and the heated roller again passes over the material, binding the new layer to the one beneath it. • This process is repeated until the entire object has been formed. • Once an object is done "printing," it is removed from the build platform, and any excess material is cut away. • Objects printed in paper take on wood-like properties, and can be sanded or finished accordingly. Paper objects are usually sealed with a paint or lacquer to keep out moisture ❖ Advantages ✓ Uses very inexpensive paper ✓ Fast and accurate ✓ Good handling strength ✓ Environmentally friendly ✓ Not health threatening. ❖ Disadvantages ✓ Need for decubing, which requires a lot of labor ✓ Can be a fire hazard ✓ finish, accuracy and stability of paper objects not as good as materials used with other RP methods ❖ Applications ✓ Investment casting patterns ✓ Concept verification ✓ Masters for silicone-rubber injection tools ✓ Fit-check
- 54. SEM -VII Descriptive Type Question P a g e | 54 ✓ Direct use Q3 - Short note on fused deposition modeling ❖ Working • Objects created with an FDM printer start out as computer-aided design (CAD) files. Before an object can be printed, its CAD file must be converted to a format that a 3D printer can understand usually .STL format. • FDM printers use two kinds of materials, a modeling material, which constitutes the finished object, and a support material, which acts as a scaffolding to support the object as its being printed. • During printing, these materials take the form of plastic threads, or filaments, which are unwound from a coil and fed through an extrusion nozzle. • The nozzle melts the filaments and extrudes them onto a base, sometimes called a build platform or table. Both the nozzle and the base are controlled by a computer that translates the dimensions of an object into X, Y and Z coordinates for the nozzle and base to follow during printing. • In a typical FDM system, the extrusion nozzle moves over the build platform horizontally and vertically, "drawing" a cross section of an object onto the platform. This thin layer of plastic cools and hardens, immediately binding to the
- 55. SEM -VII Descriptive Type Question P a g e | 55 layer beneath it. Once a layer is completed, the base is lowered — usually by about one-sixteenth of an inch — to make room for the next layer of plastic. • Once an object comes off the FDM printer, its support materials are removed either by soaking the object in a water and detergent solution or, in the case of thermoplastic supports, snapping the support material off by hand. Objects may also be sanded, milled, painted or plated to improve their function and appearance. ❖ Advantages ✓ Consistently and accurately creates geometric structures ✓ Parts with great stability and durability ✓ Wide variety of thermoplastics ❖ Applications ✓ FDM printed parts are used for a massive amount of applications across industries. ✓ From prototypes to final parts, companies in the automotive, aerospace, medical, maritime and railway have already adopted FDM as a manufacturing process. Q4 - Write short notes on 3D modeling ? • 3-D modeling is the use of software to create a virtual three-dimensional model of some physical object. • 3-D modeling software generates a model through a variety of tools and approaches including: ➢ simple polygons. ➢ 3-D primitives -- simple polygon-based shapes, such as pyramids, cubes, spheres, cylinders and cones. ➢ pline curves. ➢ NURBS (non-uniform rational b-spline) -- smooth shapes defined by bezel curves, which are relatively computationally complex ❖ 3D Modeling Work
- 56. SEM -VII Descriptive Type Question P a g e | 56 • An artist usually begins by generating some type of primitive like a cube, sphere, or plane. The primitive is just a starting shape to begin modeling. • The artist will build upon this basic form and manipulate it using various modeling tools. For 3D modeling it’s almost always a good idea to start simple and work towards complexity. • 3D modeling is a precise workflow often involving the painstaking placement of individual vertices to achieve the correct contours of the desired object. • The exterior of the mesh is composed of polygons which can be subdivided into smaller shapes to create more detail. These subdivisions are especially necessary if the 3D model is to be animated. • Any joints that need to bend—such as a character’s knee or elbow—will need these additional polygons to ensure smooth motion. • Several tools exist to speed up the modeling process. Most programs include a mirroring technique that lets the artist build a symmetrical model by only working on one half—or even one quarter—of the object. • This is especially useful in character design as an artist only needs to model one side of the character and the software will mirror their work along the desired axis creating a perfectly symmetrical object. • Other tools allow for the quick deformation of a model’s surface. • For instance, a noise texture can be used to displace the mesh to get a more organic surface. • Or a subdivision surface tool can be used to simulate a higher polygon count. In this way the artist can work “non-destructively” in a process that preservers their original work. ❖ Applications ✓ 3D modeling is used in various industries like film, animation and gaming, interior design and architecture. ✓ They are also used in the medical industry to create interactive representations of anatomy.
- 57. SEM -VII Descriptive Type Question P a g e | 57 Q5 - Short note on Selective Laser Sintering (SLS), ❖ Working • The Selective Laser Sintering (SLS) process uses a powdered polymer build material, typically nylon, is transferred from containers holding fresh powder material onto the build stage in the process chamber with a recoating tool. • A high power laser then selectively scans the thin layer of powder, sintering together powder particles in the shape of the cross-section of the first layer of the 3D part. • The build platform then descends one layer depth and the recoater transfers more fresh powder from the hopper to the surface of the first layer. • Just like the first layer, the second cross-section of the 3D model is scanned and sintered. • The laser scanning process simultaneously generates the current layer and adjoins it to the previous layer, making a solid part ❖ Advantages ✓ No need for support structures ✓ Fast ✓ Excellent layer adhesion
- 58. SEM -VII Descriptive Type Question P a g e | 58 ❖ Disadvantages ❖ Prone to shrinkage and warping ❖ Produces a lot of waste ❖ Expensive ❖ Applications ➢ Complex and durable production parts ➢ Parts with snap fits/living hinges ➢ Medical devices ➢ Jigs, fixtures and tools ➢ Investment casting patterns ➢ Elastomeric and urethane parts, such as gaskets, seals and hoses Q6 – STL file generation • The different 3D CAD package use different algorithms to represent solid object . therefore in order to achieve uniformly and standardize the 3D model for rapid prototyping , CAD file format is converted to STL file format (.STL). all the majpr CAD-CAM vendors supply CAD-STL interface • STL (standard tessellation language or stereolithography ) file format has been opted as the standard file format by rapid prototyping industry • STL file format represent a 3D surface as an assembly of planer triangles like the facets of a cut jewel as shown in fig . the more number of triangles have to be used for highly curved surfaces • STL file describe only the surfaces geometry of 3D object without representation of color , texture or other CAD model attributes. • The surface geometry is expressed in terms of triangles • The STTL file contains the coordinates of the vertices of triangles and the direction of the outward normal to each triangle as shown in fig • The triangles in STL file must mate with other triangles at the vertex and there should bnot be any gap.
- 59. SEM -VII Descriptive Type Question P a g e | 59 Q7 – Benefits & application of RPS Benefits of rapid prototyping can be classify into 2 category 1. Direct benefits 2. Indirect benefits Direct benefits : • Benefits to design department • Benefits to manufacturing department Indirect benefits : • Benefits to marketing department • Benefits to customer Application of RPS are as follows 1. Design : verification of CAD model , visualization of parts, verification of concepts 2. Engineering , analysis and planning : scaling of parts , stress analysis of parts, flow analysis of parts 3. Manufacturing & tooling : direct tooling, indirect tooling, soft tooling, hard tooling, 4. Industries : aerospace, automotive, coin, jewellery, medical science