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Using Mechanical Fasteners to Assemble Plastic Parts. Dane Taylor Ray McKee Jason Saggese. Purpose. Explain Mechanical Fasteners in Plastics Designing for Various of Fasteners Effects of Using Fasteners. Outline. Types of Fasteners Inserts Effects of Fastener Uses Design Considerations
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Using Mechanical Fasteners to Assemble Plastic Parts Dane Taylor Ray McKee Jason Saggese
Purpose • Explain Mechanical Fasteners in Plastics • Designing for Various of Fasteners • Effects of Using Fasteners
Outline • Types of Fasteners • Inserts • Effects of Fastener Uses • Design Considerations • Material Property Effect
Types • Permanent Assemblies • Pre-molded Insert • Rivets • Key Headed Screws
Types • Non-Permanent Assemblies • Thread Cutting Screws • Thermosetting • High Modulus Materials • Thread Forming Screws • Semi-Crystalline • <200,000 psi Modulus
Types • Non-Permanent Assemblies • Molded-in Threaded Inserts • Positioning • Nuts and Bolts
Types • Specially Designed • Thread Pitch and Angle • Trilobe • 1,000,00 Modulus • Push-in • Double Lead
Inserts • Molded-in Threaded • Expansion • Cap Nuts • Helically Coiled • Ultrasonic Insertion
Effects of Fastener Uses • Machine Screws vs. Plastic Designed Screws • Automated Assembly Lines • Molding Technique
Effects of Fastener Uses • Problems • Thread Stripping from Disassembly/Assembly • Poor Design • Extended Cycle Time
Design Considerations • Bosses • Inner Diameter • Pitch Diameter of Screw • Outer Diameter • 2.5 X ID
Design Considerations • Bosses • Length • Thread forming • Minimum – 2.5 X Pitch Diameter • Thread Cutting • At least – 3 X Diameter
Design Considerations • Assembly • Deflection • Surface Area of Screw Head • Washers • Tapping • Ductile Materials • Cold Flow • Heat During Drilling
Material Property Effects • Stiffness • Acceptance Without Cracking • Crystallinity • Deforms around Screws • Annealing • Reduces Creep • Greater Life Expectancy