AMM presentation final.pptx it's an presentation about advanced machining methods applied in production technology.
- 1. A PRESENTATION ON CHEMICAL MACHINING (CHM)
- 2. Contents Introduction History Steps involved in CHM Cleaning and methods of cleaning Masking and maskants Etching and etchants Demasking Washing Chemical machining methods Applications, advantages, disadvantages conclusion
- 3. Group members Name Roll no Chandrupal gohain DIP/19/ME/017 Neelim Bhuyan DIP/19/ME/12 Rajdeep Gohain DIP/19/ME/15 Roshan Borah DIP/19/ME/14 Lukoranjan Phukan DIP/19/ME/13 Shuvam Kumar Singh DIP/19/ME/16
- 4. Introduction to chemical machining Chemical machining is a well known non traditional machining process, where controlled chemical dissolution of the machined workpiece material is done by contact with a strong acidic or alkaline chemical reagent. Special coatings called maskents protects areas from which the metal is not to be removed. Process is used to remove materials from parts having high strength to weight ratio.
- 6. Products made by Chemical machining
- 7. History CHM is oldest non traditional machining method. It was used to shape copper with Citric acid in ancient Egypt In 2300 BC. Untill the 19th century this process was widely used for decorative etching. The main industrial application of chemical machining developed after the war.
- 8. Steps involved in CHM main steps in Chemical machining are 1. Cleaning 2. Masking 3. Etching 4. Demasking 5. washing
- 9. 1)Cleaning In the cleaning process, the workpieces are cleaned to remove oil, grease, dust, or any substance from the workpiece so that further processing can be completed properly. Cleanings are necessary to ensure proper adhesion of masking material to the workpiece. In the case of masking debugging, stray Etching occurs. There are mainly two methods of cleanings, mechanical & chemical methods. The chemical method is widely used because it causes much less damage than the mechanical method.
- 10. Methods of cleaning Mechanical cleaning method: Mechanical cleaning methods consist of physically disturbing and contaminants, as with wire or fiber brushing, dry or wet abrasive blasting, tumbling and steam jets. These processes are used to remove rust, scale and other solid contaminants. Chemical cleaning method:Chemical cleaning methods usually involve the removal of oil and grease from workpiece surfaces. They consists of solution, saponification, emulsifition, dispersion and aggregation.
- 11. 2)Masking Masking is done using maskents. These masks are inert in nature and do not react with the chemicals used in the machining process. In this masking process, the parts of the workpiece that are not machined are masked using a mask so that the machined part is exposed to the chemical used in the machining process.
- 12. MaskAnts Maskants(masking material) is used to protect workpiece surface from chemical etchant. Basically polymer and rubber are used. Required properties of maskents 1. strong enough to withstand handling 2. well adhering to workpiece surface 3. able to withstand heat 4. easy and inexpensive removal Multiple maskants are used to provide higher etchant resistance and long exposure time is needed. Multiple maskants are used to provide higher etchant resistance and long exposure time is needed.
- 13. Type of maskAnts There are mainly three types of maskents 1. Cut and peel maskents 2. Screen resist maskents 3. Photo resist maskents
- 14. Cut and peel masks Chemically resistant material is applied to the workpiece by dipping, spraying or flow coating Vinyl, styrene and buta diene are used. Accuracy+_0.13mm to +_0.75mm
- 15. Screen resist masks Mask material is applied by printing, using utensils and fine polyester or stainless steel Tolerances: +_0.05 to +_0.18mm. Etching depths are restricted to 1.5 mm
- 16. Photo resist masks Also known as photochemical machining produces finely detailed shapes using a light activated resist material Light activates the photo resist material in areas corresponding to opaque parts. Tolerance +_0.025 to 0.005 mm
- 17. 3)Etching After masking the workpiece, it is immersed in a container containing a chemical that undergoes a chemical reaction with the workpiece. When the workpiece is immersed inside the chemical, the area that is masked does not undergo any chemical reaction, and the area that is not masked undergoes a chemical reaction with the chemical and the material unmasked area of the workpiece. It will start moving away from it. The etching process is usually performed at an elevated temperature. Gas bubbles should not be allowed to become trapped during the process to avoid non-uniform machining.
- 18. Etchants Etchants are the most influential factor in the chemical machining of any material. Various etchants are available due to workplace material. The best possible etchants should have properties as follow: 1.High etch rate. 2. Good surface finish. 3. Minimum undercut material capacity. 6. Economic regeneration. 7. Easy control of process. 8. Personal safety maintenance. Ferric chloride (Fecl3) is the most widely used etchants in chemical machining. It is mainly used for etching iron-based alloys as well as cooper and its alloys, aluminium, etc. Cupric chloride (CuCl2) is generally applied for copper and copper-based alloys in electronics industry because various regeneration systems are available for the waste etchant Alkaline etchants are introduced to the fabrication of electronic components such as printed circuit board
- 19. Demasking After the etching process, the masks are removed from the area of the workpiece, which is not mechanized, and the oxide layer is also removed from the area of the workpiece, which is mechanized.
- 20. Washing After the demasking process, the workpiece is thoroughly rinsed under fresh water to completely remove any substances, etc., from the surface of the workpiece. Apart from all these steps, one step is used optionally, which is the Etchant of heating and cooling:- According to the temperature, the temperature of the waiter is maintained in the container using a heating or cooling rod.
- 21. Chemical machining methods There are various chemical machining methods The process can be applied to a wides variety of operations such as milling, blanking, and engraving. The various chemical machining processes can be classified as follows: Chemical Milling Chemical engraving Chemical blanking
- 22. 1)Chemical milling Chemical milling is sometimes called Chem milling or contour machining, or Etching. It is used to produces shapes by selective or overall removal of metal parts from relatively large surface areas. Components are cleaned & degreased by immersion in trichloroethylene vapor. Or some alternative chemicals cleaner followed by washing in clean water The components are then coated with a cut & peel maskant by brushing, dipping, or spraying (up to 0.2 mm). Thises can be a suitable fluid with a neoprene base. Or some alternative plastics solutions impervious to the action of the etchings agent (permitting Etching depths up to 10 mm). The part is then dipped completely into tanks of chemicals that will dissolve (etch) away from the exposed metal
- 23. 2)Chemical engraving Printed circuit cards, other engraving operations, and cuttings of complex designs can be chemically blanked using photoresist maskants. Very thin metals (0.005 mm) can be dug well. High accuracy of the orders of +0.015 mm can be maintained. High production rates can be accomplished using an automated photographic technique.
- 24. 3)Chemical blanking In this process, the materials are completely removed from many areas by chemical action This process is mainly used on their sheets and foils. Almost any metals can be worked by this process; however, it is not recommended for thinning of materials more than 2 mm. The workpiece is cleaned, reduced, and selected by acid or alkali. The cleaned metal is dried, and the photoresist material is applied to the workpiece by dipping, whirl coating, or spraying. It is then dried and cured
- 25. Applications of CHM 1) It is used for producing complex configurations in delicate parts. 2) It is also used in aviation industries for making aircraft wing panels. 3) It is used to manufacture very thin laminations without burrs. 4) It is used for Printed Circuit Boards (PCB). 5) Some sheet metals are also produced by Chemical Machining to be used in welding or riveting. 6) Industrial applications include fine screens and meshes.
- 26. Advantages of CHM It produces High precision metal parts. It can done Machining of any shape & size. Machining of work-piece from all sides of work-piece at same time. Less skilled labors can handle process. High surface finish obtained. High machining accuracy.
- 27. Disadvantages of CHM The metal removal rate is slow. Metal thicker than 2 mm can not be usually machined. High operator skill is required. Corrosive etchant damages the equipment. Required the handling of dangerous chemicals. Disposal of potentially harmful byproducts.
- 28. Conclusion