Compression Limiters are metal inserts designed to protect molded plastic components from the compressive loads generated by the tightening of bolts or screws. Tubular Compression Limiters may be inserted molded directly into an assembly, or may be pressed in after molding.
Design Considerations of Compression Limiters
There are many styles of Compression Limiters made from a wide variety of materials with or without protective coatings and finishes. Choosing the right Limiter for your application depends on several factors.
● Distilled Spirits manufacturing
● Fastener Grade and Type Being Used
● Installation Method (Insert Mold or Post Mold)
● Environment of Intended Use
● Estimated Annual Usage/Quantity Required
● Shape Needed (Round, Obround, Oblong, Square, etc.)
Addressing these design issues prior to requesting quotes will insure you are using the most cost effective Limiter for your application. For example, an ISO 10.9 grade fastener will require a Compression Limiter made from higher strength materials, or a heavier wall cross section, than an assembly using an ISO 5.8 grade fastener. Likewise, in some cases, stainless steel may be a better option than zinc plated steel due to the environment of the end application.
Compression Limiters from Wisconsin Stamping & Manufacturing
Our engineered split seam design Compression Limiters are produced in the USA at our state of the art facility conveniently located in suburban Milwaukee, Wisconsin. Made from highly accurate rolled strips, our split seam design often will allow for significant cost savings when compared to machined inserts or cut tubing. Our Compression Limiters are available in both butt seam configuration suitable for overmolding or insert molding applications, as well as in an open seam configuration suitable for press-in post molding.
Open/Gap Seam Compression Limiters
Sometimes called gap seam bushings, open seam Compression Limiters are manufactured with an “open” or “gap” seam which is designed to compress upon insertion into a smaller diameter hole, much like a roll pin or spring pin. This “spring” action helps facilitate insertion into the hole while enhancing the retention force of the bushing. Retention force results from innate “memory” or “spring back” within the bushing material. This open seam configuration is used primarily in applications where the Limiter is pressed into a hole after molding and readily adapts to automated insertion or vibratory feeding. Caution must be exercised to be sure the gap width is smaller than the wall thickness to avoid the potential for interlocking.
Closed/Butt Seam Overmold Compression Limiters
Sometimes called “Butt Seam” bushings, closed seam Compression Limiters are typically inserted into the mold or die cavity prior to plastic being injected into the mold. The fully closed seam configuration prevents the molten plastic from intruding into the ID of the limiter. Once the plastic has cooled, the Limiter is permanently molded into the assembly and will not separate from the component housing. Often, the Limiter has coined impressions around the perimeter of the OD to allow a void area for the molten plastic to flow, improving the retention strength of the Limiter in the molded part.