Machining Plastics Joe Latchaw Carl Caldwell Doug French
Why? For small production volumes Prototype production Shapes impossible by injection molding Create certain features more precisely Threads Lower stresses
Why? (cont.) For long holes Unacceptable injection molding aspects Parting line, ejection marks, flash, draft Large or thick section parts Short lead time Secondary operations on injection molded parts
Common Machining Processes Drilling Sawing Milling Turning
Common Machining Processes (cont.) Routing Waterjet cutting Laser cutting
Tooling Requirements Sharp Highly positive
Other capabilities Micro parts Annealing Polishing While being machined Flame Vapor Mechanical buffing
Applications Any applications Medical Electrical Aerospace Fiber optics
Common Materials Acetal Acrylic ABS Nylon PEEK
Common Materials (cont.) Polycarbonate Polyethylene Polypropylene PVC
Plastics Machining Shop Metal machining contaminants Material knowledge Material discount Plastic based equipment Higher quality Lower cost
Advantages Smaller quantities Less tooling problems & delays No common effects of injection molding Lower nitial cost CNC benefits
Advantages (cont.) Lower stresses Consistent properties Tighter tolerances Thicker parts
Disadvantages Longer cycle times Higher part cost Waste Thermal Expansion Dissipate heat slower