SPIROL Introduces New Precision Machined Compression Limiters to Protect Plastic Assemblies

SPIROL is pleased to introduce the new Series CL6000 lightweight, lead-free, Aluminum Precision Machined Compression Limiters. Compression Limiters are designed to reinforce high stress joints in plastic assemblies where bolts are used to connect two components to each other.

Automotive Transmission Valve Body

The manufacturer/assembler of an automotive transmission valve body contacted SPIROL to evaluate their application. The valve body was designed to utilize several pins to secure the solenoids within the aluminum housing. Each solenoid required 2 pins in order to retain it to the body of the assembly. This particular application called for 7 solenoids. These solenoids are extremely costly and the overall performance of the assembly is paramount to ensure successful functioning of the automatic transmission. The total cost of this assembly was being monitored very closely. The customer was in search of a product that met all their performance requirements, as well as improved the overall assembly cost and productivity.
app solid pin transmission valve body
app solid pin transmission valve body close up
app solid pin transmission valve body pin
Based on the original requirements, a standard SPIROL® Coiled Spring Pin was recommended since this represented the lowest installed cost for a press fit pin. However, during the proposal stage, the customer revealed that they really did not want a press fit so that they could easily remove the pins from the blind holes to allow for servicing the assembly.

In consideration of this new information, SPIROL Engineering recommended a Series DP100 Cold Headed Solid Pin (without any retention features). SPIROL designed the pin to be a slip fit through the top part of the aluminum valve body, travel freely through a square slot within the solenoid, and then bottom out in a blind hole in the lower portion of the valve body. A plastic electrical cover assures that the free fit pins do not fall out of the top of the valve body assembly. The pins are therefore trapped between the plastic cover and the blind hole so that they can not fall out of the assembly in either direction.

Standard SPIROL® Solid Pins are cold headed and offer a significant savings over Machined Solid Pins since the speed of cold heading is significantly faster than machining. In this application, there is no mechanical or performance advantage that would require a tightly toleranced Machined Pin, therefore the Cold Headed Pin is an excellent solution for this particular assembly.

Following a successful launch of this program, SPIROL was able to work with this customer in a VA/VE (Value Analysis / Value Engineering) effort to reduce the overall cost of the Solid Pin. It was determined that the original strength requirements provided by the customer were overstated, therefore SPIROL recommended changing from a 6150 heat treated pin to a 1022 low carbon steel pin. The strength was reduced by 50%, but the 1022 pin provided all the strength that was required for this assembly. By changing to a low carbon steel pin, not only was the cost of the material reduced, but the heat treating operation was also eliminated which resulted in additional significant savings.

Need help finding the right solution?

SPIROL offers complimentary Application Engineering support. We will assist on new designs as well as help resolve issues, and recommend cost savings on existing designs.