Effect of Post Consumer Recyclate on SMA Copolymer Boss/Joint Performance

The use of Post Consumer Recyclate (PCR) or Post Industrial Regrind (PIR) to manufacture thermoplastic (or thermoset) automotive parts and components has significantly increased over the last 10 years. Due to this increase in use, automotive designers are continuously challenged with the question of how PCR or PIR material differ in performance from the virgin material? To compound the dilemma, automotive OEMs are requiring increased durability of thermoplastic attachments (joints), so that warranty costs associated with interior squeak and rattle (from ill-fitting joints) are minimized. To answer this question, there exist several techniques for finding thermoplastic joint durability performance. Some of them are: strip-to-drive torque ratios, screw pull-off force and clamp load fall-off. A thermoplastic attachment (i.e. boss) which experiences clamp load fall-off will lead to a loose fitting joint and subsequently result in squeaks and rattles. Also, if a boss has a low strip-to-drive ratio (≤ 3:1), there is a potential for assembly and/or field failure. This paper addresses the changes in drive-to-strip, clamp load and hoop stress that are experienced when virgin versus recycled content containing bosses are evaluated for their joint performance.