Manufacturing Processes FOR STUDENT.pptx

HELPFUL FOR ENGINEERING STUDENTS

1. MANUFACTURING PROCESSES Dr. Anurag Deepak Department of Mechanical Engineering

2. CLASSIFICATION OF MANUFACTURING PROCESSES Fig1: Classification of Manufacturing Processes

3. SHAPING PROCESSES Most shape-processing operations apply heat, mechanical force, or a combination of these to effect a change in the geometry of the work material. There are various ways to classify the shaping processes i.e., into four categories: (1) Solidification Processes: In which the starting material is a heated liquid or semifluid that cools and solidifies to form the part geometry. (2) P articulate Processing: In which the starting material is a powder, and the powders are formed and heated into the desired geometry. (3) Deformation Processes: In which the starting material is a ductile solid (commonly metal) that is deformed to shape the part. (4) Material Removal Processes: In which the starting material is a solid (ductile or brittle), from which material is removed so that the resulting part has the desired geometry.

4. SOLIDIFICATION PROCESS The starting material is heated sufficiently to transform it into a liquid or highly plastic (semifluid) state. Metals, ceramic glasses, and plastics can all be heated to sufficiently high temperatures to convert them into liquids. With the material in a liquid or semifluid form, it can be poured or otherwise forced to flow into a mold cavity and allowed to solidify, thus taking a solid shape that is the same as the cavity. Casting is the name used for metals, and Molding is the common term used for plastics.

5. SOLIDIFICATION PROCESS Fig 2(a): Casting Processes (Pouring the fluid into the mold cavity), 2(b): Molding Processes (Allowing the metal to solidify)

6. CASTING PROCESS

7. Investment Casting

8. Die Casting

9. PARTICULATE PROCESSING The starting materials are powders of metals or ceramics. The common technique involves pressing and sintering , in which the powders are first squeezed into a die cavity under high pressure and then heated to bond the individual particles together. Fig 3: Particulate Processing (Powder Metallurgy)

10. DEFORMATION PROCESSES The starting work part is shaped by the application of forces that exceed the yield strength of the material. For the material to be formed in this way, it must be sufficiently ductile to avoid fracture during deformation. To increase ductility , the work material is often heated before forming to a temperature below the melting point. Deformation processes are associated most closely with metalworking and include operations such as forging and extrusion . Fig 4 : (a) Forging , in which two halves of a die squeeze the work-part, causing it to assume the shape of the die cavity; and (b) Extrusion , in which a billet is forced to flow through a die orifice, thus taking the cross-sectional shape of the orifice.

11. Press Forging Process

12. Extrusion Process

13. MATERIAL REMOVAL PROCESSES Are operations that remove excess material from the starting workpiece so that the resulting shape is the desired geometry. The most important processes in this category are machining operations such as turning, facing, knurling, drilling, boring and milling. These cutting operations are most commonly applied to solid metals, performed using cutting tools that are harder and stronger than the work metal. Grinding is another common process in this category. Other material removal processes are known as Non-traditional processes because they use lasers, electron beams, chemical erosion, electric discharges, and electro chemical energy to remove material. Fig 5 : (a ) Turning , in which a single-point cutting tool removes metal from a rotating workpiece to reduce its diameter; (b) Drilling , in which a rotating drill bit is fed into the work to create a round hole; and (c) Milling , in which a work-part is fed past a rotating cutter with multiple edges.

14. Different Machining Operations

15. PROPERTY ENCHANICING PROCESSES These are performed to improve mechanical or physical properties of the work material. The most important property-enhancing processes involve heat treatments , which include various Annealing, sintering and strengthening processes for metals and glasses. Annealing Is a heat treatment process used to modify the microstructure of a metal to improve its ductility while reducing internal stress and overall hardness. The annealing process involves heating metal to a temperature at which the crystalline structure becomes fluid, but the metal remains in a solid form. The metal is held at this temperature, which allows for any defects in the material to repair themselves. The metal is then allowed to cool back to room temperature at a slow pace to produce a more ductile crystalline structure. Hardening Hardening heat treatments are used to enhance the hardness of the metal’s surface through heating and rapid cooling. The material is heated in a hardening furnace to a temperature that transforms its internal structure without melting it. The metal is then held at this temperature for one hour per every inch of thickness, followed by rapid cooling. The quick cooling process establishes a harder, more stable crystalline structure.

16. PROPERTY ENCHANICING PROCESSES Quenching Quenching refers specifically to heat treatments that rely on rapid cooling of the metal to achieve the desired physical or mechanical properties. Heated materials are often cooled in oil, but can also be quenched using air, water, and brine, depending on the material and desired qualities. Sintering Sintering is a heat treatment applied to a powder compact in order to impart strength and integrity. 

17. SURFACE PROCESSING OPERATIONS Surface processing operations include (1) cleaning, (2) surface treatments (3) coating and thin film deposition processes. Cleaning includes both chemical and mechanical processes to remove dirt, oil, and other contaminants from the surface. Surface treatments include mechanical working such as shot peening and sand blasting , and physical processes such as diffusion and ion implantation that alter the part surface . Coating and thin film deposition processes apply a coating of material to the exterior surface of the work-part. Common coating processes include electroplating, anodizing of aluminum, organic coating (call it painting), and porcelain enameling. Thin film deposition processes include physical vapor deposition and chemical vapor deposition to form extremely thin coatings of various substances.

18. ASSEMBLY OPERATIONS The second basic type of manufacturing operation is assembly , in which two or more separate parts are joined to form a new entity. Components of the new entity are connected either permanently or semi-permanently . Permanent joining processes include welding, brazing, soldering, and adhesive bonding. They form a joint between components that cannot be easily disconnected. Certain mechanical assembly methods are available to fasten two (or more) parts together in a joint that can be conveniently disassembled . The use of screws, bolts, and other threaded fasteners are important traditional methods in this category. Other mechanical assembly techniques form a more permanent connection; these include rivets, press fitting, and expansion fits.