5 Methods for Installing Threaded Inserts in Thermoplastics

When our clients approach Bossard we consider it our duty to present all the relevant information and our experience so they can ultimately make the best design decision for their application. That is why WE TALK REAL when we are asked the question: “There are so many types of inserts that we could install, which one will perform the best?”

Note: this question also applies to compression limiters in the same applications. The response to this depends on a wide range of factors, but if the client is strictly looking for direction on axial (pull-out) and radial performance, we can summarize as follows:

1.???Ultrasonically installed, post-mold

These inserts tend to have about a medium axial (pull-out) with high radial performance but typically have the fastest cycle times for post-mold installation. They also may have a higher investment cost for the installation equipment. There is a high degree of expertise required to correctly set up the installation equipment for maximum performance of the insert.

2.???Thermal installed, post-mold

These inserts have a similar performance as ultrasonically installed inserts but have slower cycle times. The set-up of these machines is also relatively simple and requires a lower up-front cost than ultrasonically installed inserts.

3.???Press-fit installed, post-mold

These inserts tend to have the lowest pull-out (axial) and radial performance but subsequently may have a lower overall cost. They also do not require specialized equipment for installation.

4.???Self-cutting

These tend to have a very high axial (pull-out) strength and have the added benefit of being suitable for tougher materials like thermoset plastic or composite thermoplastics with a high percentage of fill content.?

5.???Mold-in inserts

These inserts usually have the highest axial (pull-out) / radial performances possible but have the added benefit of being a co-mold process, removing the secondary operation, and are suitable for thermoset and thermoplastic materials.

There are many other factors that will impact the performance of an insert or compression limiter such as the hole size, hole geometry, fill content of the plastics, cycle time demands, and lastly the geometry of the insert itself.

To confuse the matter, many producers of inserts have specialized features intended for one purpose or another and it can be difficult to decipher the true functional comparison. Many inserts are not bound to industry standards, such as a DIN 912 Hexagon Socket Head Cap Screw! For example, some inserts marketed for co-molding may also be used for a post-mold thermal or ultrasonic installation (and vice versa) – and the performance of those will compare greatly based on the other variables at play.

Finally, it is always important with threaded inserts for plastic or composite applications, for Bossard to arrange validation testing using the customer’s own materials or coupons.

For more information about your threaded-insert or compression limiter application, please contact us today at [email protected].