Colorful Connectors Require Good Flow Properties Plus Dimensional Stability

For its new color-coded Aqualok connectors, ITT Cannon uses DuPont Crastin polybutylene terephthalate PBT resin, chosen for its chemical resistance, good moldability and electrical properties, and its dimensional stability.

Tractors made by the Case New Holland (CNH) group are among the first users of Aqualok connectors. For this application, the connectors are held on a custom-designed mounting base, made of glass-reinforced DuPont Zytel nylon, allowing rapid yet foolproof assembly. The color-coding system helps to differentiate the electrical circuits in field use and makes maintenance work easier.

Matthias Raithel from ITT Cannon’s Aqualok project management group says: “These 51-pin connectors have multiple poles in a limited space, so we need a resin with good flow characteristics and outstanding dimensional stability, and it must be capable of accepting a permanent four-color coding system in clear, luminous colors.”

Together with DuPont, ITT Cannon chose Crastin LW9030 for making the Aqualok connector. This glass-reinforced PBT has very low warpage, so that the matching male and female halves can always be easily connected and separated, whatever the outside temperature, without risk of damage to the contact pins. Crastin PBT also has good electrical properties, so that there are no tracking currents, even at high current flow rates.

The mounting base is made to CNH specifications. For this part ITT Cannon uses Zytel 70G20HSL nylon, a heat-stabilized, glass-reinforced type designed mainly for automotive applications, both external and under-the-hood. This resin combines high flexibility with high rigidity, which allows the connectors to be pushed through the holes in the base without damage; snap-fit hooks are integrally molded into the periphery of the holes, so that the connectors are firmly held.

“We optimized the geometry of the hooks with comprehensive FEM calculations,” Raithel continues. “Weld-lines are unavoidable around the holes in the base. However, using Moldflow studies at an early stage of the development, we positioned the weld-lines in such a way that they did not weaken the critical regions of the molded parts.”

DuPont Canada Inc. 905-821-5953