Plastic parts design assembly

Tres, P. A., Designing Plastic Parts for Assembly, Hanser, 1995. 

Designing Plastics Parts for Assembly, 4th ed. Hanser, Munich, 2000... 

Tres, P, Assembly techniques for plastics. Designing Plastic Parts for Assembly, reference book (ISBN 1/56990-199-6), Hanser/Gardner Publications, Inc., Cincinnati, OH, 1995. 

A projection on a plastic part designed to add strength, facilitate aligmnent during assembly, and provide for fastening. 

Tres, P.A. (1995) Living Hinges. In Designing Plastic Parts for Assembly, (ed. P.A. Tres), Hanser, Munich, p. 140. 

Tres, P. A., Designing Plastic Parts for Assembly, 4 Ed., Hanser, 2002. Troitzsch, J. H., International Plastics Flammability Handbook, Hanser, 1990. Tsai, S. W. et al.. Analysis of Composite Structures, NASA CR-620, 1966. Turner, W. C., Energy Management Handbook, Fairmont Press, 1997. 

Tress PA. Designing plastic parts for assembly. 5th ed. Munich Hanser 2003. 

In the developing the detailed plastic part design, the designer should understand the relationships between the design parameters and the assembly s performance. Some critical variables include the angles of the retention and insertion faces, the width and thickness and length of the snap feature, and amount of interference between the insertion face and catch... 

Contents Introduction to Materials. Manufacturing Considerations for Injection Molded Parts. The Design Process and Material Selection. Structural Design Considerations. Prototyping and Experimental Stress Analysis. Assembly of Injection Molded Plastic Parts. Conversion Constants. 

Large plastics parts are important to the future growth of plastics, and it is interesting to speculate on the part to be played by blow-molded automotive parts and rotocasting large, bulky parts of complex design, a technique that minimizes costs and assembly operations. 

As automakers continuously refine their cars, trucks and SUVs, design capabilities and material science technologies of acoustic baffles become an engineering challenge to fulfill these refinements. Early part designs were cumbersome, bulky and not very efficient in overall performance. A full layer of expanding material was often assembled onto a metal or plastic bracket that functioned as a shelf to span the cavity section to be sealed. These parts were often welded or clipped to the body structure with plastic pins. 

With plastic materials, the designer also has a greater choice of bonding techniques than with many other materials. Thermosets must be adhesively bonded or mechanically joined, but most thermoplastics can also be joined by solvent or heat welding. Additionally, plastic parts can be designed for assembly by means of molded-in, snap-fit, press-fit, pop-on, and threaded fasteners so that no additional adhesives, solvents, or special equipment is required. 

There are basically two methods of mechanical assembly for plastic parts. The first uses fasteners, such as screws or bolts the second uses interference fiL such as press-fit or snap-fit and is primarily used in thermoplastic applications. This latter method of fastening is also called design for assembly or self-fastening. 

Self-fastening joint designs generally produce very high stresses in the plastic part during the assembly operation. With brittle plastics, such as thermosets, press-fit assembly may cause the plastic to crack if conditions are not carefully controlled. In addition, certain plastics, especially thermoplastics, are subject to cold flow under stress. Under continued stress, which is the fundamental adhesive that holds self-fastened parts together, the plastic may relax, causing the joint to fad. 

---