1. Extrusion A typical extruder.
Extrusion is the method that produces the largest volume of plastic products
Extruded products are generally long uniform and solid or hollow complex cross-sections

2. Sheet and Film Extrusion
Other types: Tubing, Electrical wire coating, Pipes
To extrude thin film, air is forced into an extruded sheet and then either pinched or cut.
A common dye to produce sheets is referred to as the coathanger dye.

3. Injection Molding
Injection molding is similar to extrusion only a mold replaces the die.

4. Injection Molding Process
The polymer is pushed into the mold.
The part is cooled within the mold.
Once cooled, the part is eased out of the mold with ejector pins

5. Molds Cold runner, Two-plate mold Cold runner, Three-plate mold
Hot runner mold

6. Machine Cost range: $85,000 - $140,000 Die cost: $20,000 - $200,000
Mold cost: approx. $100,000
Process: 5 sec. – 60 sec.

7. Extrusion Blow Molding
A polymer is extruded and clamped within a mold. Air is then pushed is and the part is made. The mold is removed and excess pieces are removed as well.

8. Injection Blow Molding
The polymer is injected into a closed mold with a blow pin and parison. Air is blown in and the part is made. The blow pin is then removed.

9. Thermoforming
Sheets available in multitude of sizes, thicknesses, and fillers (to create specific properties).
Parts cannot include holes and openings.
Material: thermoplastics, must exhibit high, uniform elongation
Packaging trays, signs, appliance housings, refrigerator liners, shower stalls

11. 19.7 – Compression Molding
Done at temperatures of 200 C (400 F) and higher
Pressures range from psi
Material: usually thermosetting plastics, sometimes thermoplastics
Cures in die
Dishes, handles, container caps, fittings, electrical components, housings
Fiber reinforced parts with chopped fibers use this process exclusively.

14. 19.8 -Transfer Molding Pressures may reach 43,000 psi
Viscous flow also raises temperature and homogonizes material
High complexity and dimensional control
More expensive

16. 19.9 - casting Thermosets and thermoplastics may be used
Slow and simple yet cheap
Flexible molds can be used
Continuous casting can be used
Centrifugal casting
Potting and encapsulation (electrical components)

17. 19.10- foam molding Polystyrene beads are the raw material.
Beads, blowing agent, and heat
Pre-expanded beads may be shaped just as plastics
Structural foam molding created hard outer shell and light cellular core, outside is cooled rapidly
Polyurethane foam processing utilizes chemical reactions to create foam which is poured into molds or sprayed on surfaces for insulation.

19. 19.11- cold forming and solid phase forming
Many of the cold working processes that apply to metals can also be used on plastics.
Thermosets are used because of their ductility at room temperature.
Advantages: strength, toughness, improved dimensional accuracy, and faster cycle times
Solid phase forming is carried out at temperatures C. Below the melting point.

21. 19.12 Processing Elastomers
Processing elastomers uses processes similar to shaping thermoplastics
These include:
Extrusion (tubing, hoses, molding)
Injection molding (components for automobiles

22. Calendering Used to form rubber and thermoplastic sheets. Process:
Warm mass fed into series of rolls to create a flat sheet
End product usually 0.3 to 1mm thick
Uses:
Tines
Belts for machinery

23. Dipping Process: Uses: Dip metal form into a liquid elastomer compound
Compound adheres to form, creating item
Uses:
Rubber gloves

24. 19.13 Processing Polymer-Matrix Composites
Polymer-matrix composites are also known as reinforced plastics
Special methods required to shape due to complex structure:
Molding
Filament winding
Pultrusion
Pulforming
Motorcycle parts made of reinforced plastics

25. Prepegs
Process: continuous fibers aligned and subjected to surface treatment, then dipped into a resin bath to form a tape
Uses: flat architectural panelling
Example of use: F-14 fighter jet horizontal stabilizer
F-14 fighter jet

26. Sheet-Molding Compound (SMC)
Process: continuous fibers cut into short fibers and deposited in random orientation over layers of resin paste
Use: random orientation gives the product strength in many directions, instead of just one, like in unidirectional fiber products

27. Molding of Reinforced Plastics
Different types of molding used for reinforced plastics:
Compression molding
Vacuum bag molding
Contact molding
Mold for hull of a catamaran

28. Compression Molding
Process: Polymer-Matrix composite is placed between two molds and compressed

29. Vacuum-Bag Molding
Process: material is placed in a mold, covered by a plastic bag, and a vacuum is created to compress the material into the shape of the mold

30. Contact Molding Two types:
Spray Lay-up: spray into mold evenly to the thickness desired
Hand Lay-up: painted onto the mold
Jet ski hull made by hand lay-up

31. Filament Winding Resin and fibers are combined at curing
Process: fiber wound on a rotating mandrel while within resin bath.
Benefits: very strong and heavily reinforced
Uses: Aircraft (engine ducts, propellers), spherical pressure vessels
(a)
(b)

32. Pultrusion
Process: prepeg pulled through resin bath, heated in a die, and but to length after sufficient cooling time
Uses: parts with uniform cross-sections that are made continuously (aluminum ladders)

33. Pulforming Process: similar to pultrusion
Prepeg pulled through resin bath, then clamped between two halves of die. Cut piece and repeat.
Uses: parts with non-uniform cross-section

34. 19.14 Processing Metal-Matrix and Ceramic-Matrix Composites
Metal-Matrix Composites (MMC)
Liquid-phase processing
Solid-phase processing
Two-phase (liquid-solid) phase processing
Ceramic-Matrix Composites (CMC)
Slurring infiltration
Ceramic-matrix turbine
wheel

35. Liquid-Phase Processing:
Casting together liquid material (ex. Aluminum) and solid reinforcement (ex. Graphite)
Solid-Phase Processing:
Consists of powder metallurgy techniques.
Proper mixing important to obtain even distribution of fibers (ex. Tungsten-carbide tools)
Tungsten-Carbide
tools

36. Two-phase processing Slurry infiltration
Involves liquid and solid states
Reinforcing fibers are mixed with a matrix that contains liquid and solid phases of the metal
Slurry infiltration
Slurry: mixture of matrix powder, carrier liquid, and organic binder
Prepare a fiber preform, and hot press it with the slurry

37. Chapter 20 Rapid Prototyping
Produces and example of a part from a CAD drawing before production.
Additive, subtractive and virtual.

38. 20.3 Additive Processes
Parts are broken down into layers and constructed slice by slice, usually in. thick.
Stereolithography, fuse-deposition modeling, ballistic-particle manufacturing, three-dimensional printing, selective laser sintering and laminated-object manufacturing.

39. Fuse-deposition Modeling
(a)
(a)

40. Stereolithography

41. Selective Laser Sintering

42. Selective Laser Sintering