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Previously we reported to SAE 2002 the basic principles in materials selections for the fastening of plastics. In this current paper, we will try to increase the understanding of the automotive community regarding the usefulness and applicability of aluminum made self-tapping screws in the fastening of various thermoplastic components. Utilization of the light alloys for the manufacturing of fasteners for plastic applications allowed us to manage efficiently the stiffness considerations, short- and long-term performance of the assembled plastic components. The results presented in this study will help designers, technologists, thermoplastic and fastener developers and fastener manufacturers, to optimize mechanical performance of assembled automotive components, where self-tapping screws will be used.

In this current paper, we will try to increase the understanding of the engineering community regarding the usefulness and applicability of aluminum made self-tapping screws in fastening of various automotive thermoplastic parts. Utilization of the light alloys for manufacturing of fasteners for plastics applications allowed us to manage the stiffness considerations, short-term (strength) and long-term (life) performance of the assembled plastic parts. The results presented in this study will help designers, technologists, plastics and fasteners developers and manufacturers, to optimize mechanical performance of assembled automotive thermoplastic parts, where self-tapping screws will be used.

Resent developments were oriented on two high-flow, high-modulus grades fiber-glass reinforced nylon 6 (HMG series) grades for transportation, autos and other industrial applications requiring high stiffness, high strength and high fatigue resistance. These materials combined the following improved technological (injection molding, vibration and hot plate welding, etc.) and mechanical performance properties such as greater dimensional stability, higher short-term (strength and stiffness) and long-term (fatigue and creep with the influence of temperature effects). Both HMG series grades Capron®1 HMG10 and Capron® HMG13 - are for injection molded parts where stiffness, strength, impact resistance, and good surface and improved appearance are preferred. The current and possible applications of these plastics includes auto mirror housing brackets, clutch pedals, clutch master cylinders, ski bindings, steering wheels, levers, auto seat frames, door handles and door lock mechanisms.

A comparative study of the mechanical performance of welded polyamide joints is evaluated. Under optimized welding (linear and orbital vibration, hot plate, transmission laser) conditions, the tensile strength of welded polyamide/nylon (filled and fiber-reinforced) is close or slightly higher (up to 14%) than the tensile strength of the base polymer (non-filled polyamide). In this study, the influence of two important effects (local reinforcement and “memory”) on the mechanical performance of polyamide/nylon welds is analyzed and discussed. The results presented in this study will help plastic part designers, material developers and manufacturers, choose optimized welding conditions for polyamide/nylon parts in a wide range of industrial applications.