Automotive Specialty Vacuum Fitting

A manufacturer of plastic automotive engine components was experiencing problems during the installation of a specialty vacuum fitting. The area around the mounting hole through which an M5 bolt passes was cracking when the torque load exceeded the specification. Controlling the torque within the required limits was difficult. It was also difficult to ensure the quality of the final product because the cracking did not always occur immediately upon installation. They needed a more robust design; one that was able to withstand more torque without fear of failure. A complete redesign of the part was not possible due to model year time constraints.

Most plastics are not able to handle the stresses imparted by the tightening torque of machine cap screws. For these types of applications, SPIROL has developed a comprehensive line of Compression Limiters. The Compression Limiters are able to withstand the torque loads and prevent excessive compression of the plastic host. In plastics, such as this, that can only withstand limited stress, SPIROL recommends the use of Brass Series CL800 Compression Limiters installed with a Model HP Pneumatic Heat Insert Driver. The heat installation causes the plastic material to melt and flow into the retention features on the Limiter which positively prevents it from falling out, and eliminates most internal stresses in the host. To install the Limiters, the operator simply places the molded part and the Compression Limiter on a two-stepped spring loaded alignment pin, and activates the machine. The heated tip advances, engages the Compression Limiter, heats and installs it to the proper depth, and then withdraws. The completed assembly is automatically ejected and the process repeated.

The use of SPIROL's Series CL800 Compression Limiter eliminated the issue with the cracking plastic assemblies. The Model HP Heat Insert Driver was extremely easy to use and provided a consistent quality end product.

Complimentary Applications Engineering Support: SPIROL Engineers will review your application needs and work with your design team to recommend the best solution.