Typical spring clips are self-retaining, one-piece fasteners that slip into a mounting hole or onto a flange or panel edge. Secondary fastening devices such as rivets, studs, or screws are not needed because the clips are held by spring tension and do not loosen easily through vibration. The clips also compensate for tolerance buildup and misalignment.
The basic spring-clip material is steel with 0.50 to 0.80% carbon. Generally, fasteners are hardened to Rockwell C 45-50. Varied spring tensions are obtained by controlling the width and thickness of the steel.
Some other metals are used but cannot match the spring properties of high-carbon steel. Plastic fasteners have replaced metal spring clips in many applications. However, plastic designs are limited by their holding capabilities and by some environmental conditions.
Coatings can be used to meet special requirements. For example, on metal parts, neoprene and vinyl dips provide a soft cushion to prevent chafing and damage. Zinc mechanical plating also provides an attractive finish without danger of hydrogen embrittlement.
Many plastic clamps and fasteners are self-retained to panels by an integral dart shape, an expandable leg, or high-strength contact adhesive.
Dart-shaped, panel-retaining spring clips have "hips" to engage within panel or component holes. They are commonly used to join two panel surfaces, as in refrigerator door liners. Other configurations are used to fasten cables, molding trim, gaskets, and fabrics. Most dart-type clips are easily removable and require a mounting hole and space behind the mounting panel to accommodate the dart. They may be installed with finger pressure for light duty or with power tools for heavy applications.