Plastic Filter Pump Assembly

A pump and valve manufacturer contacted SPIROL to help solve an issue with their filter pump. The filter pump consisted of a cover fixed to the pump housing. With internal pressure and applied torque, the assembly needed to resist 22 N-m. They were using six Expansion Inserts with M8 bolts within 30% glass filled polypropylene plastic. A sub-contractor was manually installing each Insert at the perimeter of the housing flange. When required pressure was applied, the Inserts were coming off with the bolts resulting in the pump opening up. The client was looking for a reliable and efficient solution to meet his specifications.
app inserts compression limiters plastic filter pump problem
Defective assembly with Expansion Inserts. Notice the Inserts pulled out of the host component.
app inserts compression limiters plastic filter pump solution
Efficient assembly with CL800 Compression Limiters (left) and Series 20 Inserts (right).
model hp
Standard HP machine used to install the Inserts.
After review of the application, SPIROL Engineering determined that the diameters of the cover’s holes were bigger than the diameter of the Inserts; thus creating a jack-out condition. It was recommended that the customer use SPIROL’s Series 20 Headed Heat Installed Inserts combined with CL800 Compression Limiters. This style of Insert offers the greatest ease of alignment and installation with the added benefit of a head for increased bearing surface to prevent jack-out. It also has higher torque and pull-out values than Expansion Inserts. The Compression Limiters offer added bearing surface to avoid jack-out and prevent plastic creep during assembly life.

SPIROL also suggested that the customer use a semi-automatic HP Model Heat Installation Machine to install the Inserts.

This solution provided a high quality product and an efficient assembly process while exceeding the application’s performance requirements.

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.