Crimp tools are designed for the connection of electrical and metal components by cutting, stripping, bending, and deforming. Crimpers differ mainly by the die of tool, which vary depending upon the item to be crimped. As a portable, cold-working technique, crimping is extensive in the electrical and metal-forming industries. Crimping was developed as a high-quality, low cost replacement for soldered terminations.
A crimping tool is an essential part of the crimping process, the other parts being the terminal and wire. Terminal size is largely universal and can accept many sizes of gauged wire, which can also vary widely within the same nominative value. As such, the crimp tool is a means of compressing the terminal to both the wire's insulation (for positioning) and the wire's brush (for conduction).
The quality of the tooling determines the quality of the crimp design. Common considerations include if the volume of crimping deserves an automated wire stripping and process machine, or if the application is better suited by an on-site, handheld crimping tool. Many tools will have two crimping cavities to properly roll the terminal's crimps, and possibly more if there are two conductors in the wire. Some crimp tools will feature several gauge sizes and possibly a stripper to enhance the crimper's utility. Crimp tools may also feature interchangeable dies. Die-less crimpers are meant for general applications.
When a terminal is crimped to a wire, microconnections are created that allow current to flow through the connection. While it might seem that a tighter crimp is better, over-tightened terminals will reduce the wire cross section. Other crimping errors, like a loose crimp or wrong ratio of wire to terminal, may result in hotspots or burnout. Quality crimps should last at least a decade.
Terminals will feature one of two barrel types, open-barrel or closed-barrel. Closed-barrel terminals represent a larger segment of the terminal market, offering styles of insulation, quick-connect varieties, and unique terminal shapes and bends. The wire is inserted into a tubular section of metal, and then the terminal is crimped into a shape similar to an ellipse. Open-barrel styles assure maximum resistance to vibration and corrosion, and are more easily automated since the wire is laid onto the connector. The most common crimp style of an open-barrel terminal is known as an 'F crimp', and the terminal features two flanges: one for connection to the wire, and the second to clamp onto the wire's insulation which provides strain relief. Piercing of the insulation is acceptable only when accomplished with manually-actuated handtools; power tools will damage the conducting wire.
There are several destructive tests an operator can utilize to ensure the quality of the crimp.
Bend test: A quality connection will be able to accommodate 90° bends in several directions without misplacing the insulation or wire crimps.
Crimp height testing: Measured from the top surface of the formed crimp to the bottom radial surface, this provides a metric for the mechanical and electrical reliability of the connection. A caliper or crimp micrometer is used for this test, and it provides a good measure of terminal compression and process control.
Pull test: Attaching hanging weights to the wire for one minute, or using a mechanical pull tester, are means of test
Crimping processes serve applications where soldering has been deemed too expensive, complex, or time consuming to install. There is overall less processing, and the connection will be more durable due to strain relief. Coaxial cable installations require extensive use of crimping, as well as automotive and electrical industries. Bullets are actually crimped into their shells, as well as lures in forms of fly fishing.