Case Study: Thread Forming Screws for Space Constrained Application

Small Changes Sometimes Upset Industrial Processes

Thermoplastic materials can produce a wide array of products that get used in industrial processes, including auto manufacturing. When an automaker wants to make a design change to an existing injection molding tool, there may be costly consequences.

This was exactly the case when an automotive client came to us a few months ago with a thread-forming fastener request for their PC+ABS thermoplastic assembly.

Not Enough Space for the Ideal Type of Screw

Since they had already made the tooling for their injection molding process, they wanted us to try and fit a screw into their existing design. The existing hole diameter was 5mm with space for an 8mm long screw. However, the recommended thread engagement length for this type of screw in thermoplastic materials was 10mm, or roughly twice the diameter. In addition, they had space constraints around the head of the screw. They needed us to find a solution and supply fasteners quickly for a rapid ramp-up.

Simulation Technology Reveals a Solution

To resolve the space constraint issues around the head of the screw, we considered using flat head screws. However, our simulation technology showed that switching to a Torx head screw with a round washer head was the only option suitable to achieve the performance requirements for their soft thermoplastic material.

Production Starts with Proper Parts in Place

Ultimately the customer did have to make minor changes to the existing boss, but once the design was finalized, we located inventory of the thread forming Torx screws quickly for prototypes and testing. Today we are supplying parts for production.

For more information about automotive fastener needs in thermoplastic materials, email us at ProvenProductivity@bossard.com to speak with a Bossard engineer.