Drilling machine class
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This document discusses drilling machines and drilling operations. It describes different types of drilling machines including bench drilling machines, radial drilling machines, and upright drilling machines. It also covers drilling tools and operations such as reaming, boring, counterboring, countersinking, spot facing and tapping. Safety precautions for operating drilling machines and definitions of cutting speed, feed rate, and depth of cut are provided.
Drilling machine class
- 1. Drilling machine By Polayya ( Asst Prof, Mech Dept) Lendi Institute of Engineering &Tech
- 2. Introduction Drilling is a metal cutting process carried out by a rotating cutting tool to make circular holes in solid materials. Tool which makes hole is called as drill bit or twist drill.
- 3. Drilling machine A power operated machine tool which holds the drill in its spindle rotating at high speeds and when actuated move linearly against the work piece produces a hole.
- 4. Types of drilling machine. Portable drilling machine Bench drilling machine Radial drilling machine Upright Drilling machine Gang drilling machine Multiple drilling machine
- 6. Bench drilling machine These are light duty machines used in small workshops. Also called Sensitive drilling machines because of its accurate and well balanced spindle. Holes of diameter 1 mm to 15 mm.
- 8. parts Vertical main column Base Moving drill head Work table Electric motor Variable speed gear box and spindle feed mechanism.
- 9. working Work piece with the exact location marked on it with the centre punch is clamped rigidly on the work table. spindle axis and center punch indentation are in same line. Machine is started and drill bit is lowered by rotating feed handle. Drill bit touches the work and starts removing material.
- 10. Radial drilling machine These are heavy duty and versatile drilling machine used to perform drilling operate on large and heavy work piece. Holes up to 7.5 cm.
- 11. parts Heavy base Vertical column Horizontal arm Drilling head
- 12. working Work piece is marked for exact location and mounted on the work table. Drill bit is then located by moving the radial arm and drill to the marked location. By starting drill spindle motor holes are drilled.
- 13. Up-Right Drilling Machine Drill holes upto 50mm Table can move vertically and radially
- 14. Drilling And Drills Types of drills – Twist drill: most common drill – Step drill: produces holes of two or more different diameters – Core drill: used to make an existing hole bigger
- 15. Drill Materials The two most common types are 1. HSS drill - Low cost 2. Carbide- tipped drills - high production and in CNC machines Other types are Solid Carbide drill, TiN coated drills, carbide coated masonry drills, parabolic drills, split point drill
- 17. Drilling machine operations Reaming Boring Counter boring Counter sinking Spot facing Tapping
- 18. Reaming It is a process of smoothing the surface of drilled holes with a tool. Tool is called as reamer. Initially a hole is drilled slightly smaller in size. Drill is replaced by reamer. Speed is reduced to half that of the drilling.
- 19. Reaming
- 20. Boring It is process carried on a drilling machine to increase the size of an already drilled hole. Initially a hole is drilled to the nearest size and using a boring tool the size of the hole is increased.
- 21. Counter boring This process involves increasing the size of a hole at only one end. Cutting tool will have a small cylindrical portion called pilot. Cutting speed = two- thirds of the drilling speed for the same hole.
- 22. Counter sinking This is an operation of making the end of a hole into a conical shape. Cutting speed = half of the cutting speed of drilling for same hole.
- 24. Spot facing It is a finishing operation to produce flat round surface usually around a drilled hole, for proper seating of bolt head or nut. It is done using a special spot facing tool.
- 27. Tapping Process of cutting internal threads with a thread tool called as tap. Tap is a fluted threaded tool used for cutting internal thread Cutting speed is very slow.
- 29. Types of cutters Reamers :- Multi tooth cutting tool Accurate way of sizing and finishing the pre-existing hole. Accuracy of 0.005mm can be achieved Boring Tool:- Single point cutting tool. Boring tool is held in the boring bar which has the shank. Accuracy of 0.005mm can be achieved.
- 30. Countersinks :- Special angled cone shaped enlargement at the end of the hole Cutting edges at the end of conical surface. Cone angles of 60°, 82°, 90°, 100°, 110°, 120° Counter Bore Tool:- Special cutters uses a pilot to guide the cutting action . Accommodates the heads of bolts.
- 31. Step Blocks Clamps V-Blocks Angles Jigs T- Slots Bolt Work Holding Devices
- 32. Definitions Cutting Speed (v):- It’s the peripheral speed of the drill v = *D*N where D = dia of the drill in m N = Speed of rotation in rpm Feed Rate (f):- It’s the movement of drill along the axis (rpm) Depth of Cut (d):- The distance from the machined surface to the drill axis d = D / 2
- 33. Material Removal Rate:- It’s the volume of material removed by the drill per unit time MRR = ( D2 / 4) * f * N mm3 / min Machining Time (T) :- It depends upon the length (l) of the hole to be drilled , to the Speed (N) and feed (f) of the drill t = L / f N min
- 34. Precautions for Drilling machine Lubrication is important to remove heat and friction. Machines should be cleaned after use Chips should be removed using brush. T-slots, grooves, spindles sleeves, belts, pulley should be cleaned. Machines should be lightly oiled to prevent from rusting
- 35. Safety Precautions Do not support the work piece by hand – use work holding device. Use brush to clean the chip No adjustments while the machine is operating Ensure for the cutting tools running straight before starting the operation. Never place tools on the drilling table Avoid loose clothing and protect the eyes. Ease the feed if drill breaks inside the work piece.