Other Design Considerations

Hole Design
Although the split seam compression limiters have a broken edge, this is kept to a minimum in order to maintain the maximum bearing surface area. Accordingly, it is recommended that a radius be molded as a lead-in to the hole in the plastic component to facilitate insertion. This radius is not necessary for solid compression limiters, as the pilot is smaller than the hole. When a draft angle is required, the hole should taper within the recommended hole size for the length of the compression limiter.

Recommended Tightening Torque
The integrity of the bolted joint requires that none of the components, including the bolt, be stressed beyond the elastic limit. We recommend a clamping load equal to 75% of the proof load of the bolt. The recommended torque values to produce this clamping load are provided in the supplemental data.

Mating Component Material
The clamping load of the bolt is transferred to the mating component through the compression limiter. It must be evaluated whether the material of the mating component is strong enough to withstand the clamping force of the bolt. The stress imparted onto the mating component can be calculated by dividing the clamping load applied to the compression limiter by the cross sectional area of the compression limiter. If this stress exceeds the yield strength of the mating component material, localized permanent deformation may occur, resulting in a loss in clamping load.

Headed Compression Limiters
In addition to providing a larger contact area, headed compression limiters eliminate the need for a washer. The length and length tolerance under the head needs to be determined following these design guidelines for compression limiters to avoid the risk of exceeding the elastic limit of the plastic component. Headed compression limiters are only available as solid components.

Use of O-Rings
O-rings can be used to provide a sealed joint but the length and length tolerance of the compression limiter is still application-dependent and needs to be determined following these design guidelines in order to achieve a properly tensioned and secure bolted joint.

Use of Gaskets
When gaskets are used, the length tolerance of the compression limiter is dependent on the minimum and maximum specified gasket compression. Stated in formula mode:

Lc max = Lp min + max gasket thickness - max gasket compression
Lc min = Lp min + min gasket thickness - min gasket compression

Where:
Lc - is the length of the compression limiter
Lp - is the thickness of the plastic component

This is based on the assumption that the plastic component is significantly stiffer than the gasket material, having an elastic modulus at least 15 times greater than the gasket material.