A high-performance, ultra-light bicycle racing helmet uses two thermoformed shells made of PC sheet, supplied by Sheffi eld Plastics Inc., Sheffi eld, Mass., along with a complex insert-molding process that incorporates carbon and titanium components. The thermoformed outer and back shell of the Titan Carbon helmet from Louis Garneau Sports, Saint-Augustin-de-Desmaures, Que., is 0.060 in. thick, about twice the thickness of typical bicycle helmets. Highly accurate registration ensures precise positioning of the screen-printed sheet. Since radiation absorption varies among the several colors on the sheet, the oven temperature must be fi nely controlled to maintain quality. The thermoforming molds are made with two movable cam inserts to accommodate the helmet's several undercut angles. The sheet is cut with a fi ve-axis CNC machine and the toolpath is made with a digitizing arm. The two thermoformed shells and several other integral parts are then manually inserted into an EPS mold and backfi lled with bead foam at an average thickness of 19 mm. Other key parts include a V-shaped carbon-fi ber reinforcement that connects the two shells, a titanium ring that lines the EPS, and four plastic inserts to hold the visor and the helmet's stabilization system. Cycle time is 5 min. Sheffield Plastics: (800) 254-1707 . www.sheffieldplastics.com
Sheffield Plastics Inc
119 Salisbury Rd Sheffield, MA 01257
Phone Fax (800) 457-3553
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