1. Chapter 15 part 2

2. Drape Forming
Eliminates inconsistent wall thicknesses found in vacuum forming
Sheet of plastic is clamped then heated
Then drawn down over the mold
Sometimes the mold is forced into the plastic
Vacuum is applied

4. Extrusion 2nd most common process Similar to squeezing toothpaste
to Injection molding
Similar to squeezing toothpaste
Extruder heats plastic into a continuous melt
The melt is forced through a die to produce long shapes
Used to make
House siding
Garden hose
Pipe
Straws
Rods

5. Pultrusion Pulls continuous roving through three basic stages
Pulled through a resin bath
Pulled through a preforming fixture to partially shape and remove excess air
Pulled through heated dies for final forming
Cured in an oven

6. Film Blowing Polymer is melted into a single screw extruder
Then pumped into a tubular die
Air is forced into the die
The tubular plastic shape is air chilled
Then collapsed by pinch rollers
Anything less than .01 thickness is considered a film
Used to make:
Plastic bags
Plastic sheets

7. Wire Coating Extrusion process to coat wire
Wire is pulled through a mandrel and surrounded by liquid plastic
Plastic is cooled
Wire is inspected then coiled by a machine

8. Extrusion Blow Molding
Heated plastic is melted in an extruder
Plastic is forced through an extrusion die form a parison
Parison is expanded by air pressure against mold

9. Open Molding
Processes that use mold that doesn’t completely surround the workpiece
Two types:
Hand layup
Spray layup
Uses thermosetting resin, fiberglass reinforcement and a catalyst

10. Casting Some thermoplastics and thermosets can be cast
Thermoplastics require an additive

11. Sheet casting
High viscosity syrup poured in one end of highly polished stainless steel belts
Heating and curing takes place while transported down the belt
Most common for acrylics
Used to produce plastic sheets
Skylights
Greenhouse panels
Mirrors

12. Nylon Casting
Casting nylon can be more economical than injection molding and extrusion
Four steps
Melting the nylon lactam monomer
Adding the catalyst and activator
Mixing
Pouring

13. Potting and Encapsulating
Used to add insulation materials to electronic devices and components
Protect from moisture and mechanical abrasion

14. Potting Encapsulating
Done by applying compound through a dispensing gun or through automation
Device is placed in a mold or pot, and resin is added until it is filled
Encapsulating
Can be done just to cover a specific area of the part
Can be done with a squirt applicator
Can cover the entire part
Done by a dip coating

15. Centrifugal casting Create pipe, tubing and other round parts
Saturated fiberglass strands are placed in a hollow mandrel that serves as the mold
Mandrel is heated in an oven and rotated
Centrifugal forces throw the material against the outside walls of the mandrel