Or, use hot-melt adhesive-lined heatshrink over a properly-crimped connection, apply heat, and call it done.

As more pressure is applied to the connection, metal in the wire strands begins to stretch and flow. This loosens and drives off any surface oxides that might have increased the resistance of the connection. With more pressure comes more deformation of the wire bundle until the formerly round cross-section of each strand is gone, replaced by a collection of strands with flattened sides snugged up next to each other in a honeycomb pattern. The result is cold-welded, gas-tight junctions between the strands and the crimp connector. Aside from the object lesson in experience sometimes trumping education, I always wondered about that “bad crimp” proclamation. What could go wrong with a crimp to so subtly futz with a circuit that engineers were baffled? How is it that we can rely on such a simple technology to wire up so much of the modern world? What exactly is going on inside a crimped connection anyway? We tend to think of soldered joints as the king of electrical connections. Something about the act of heating up a joint and flowing molten solder into it lends a feeling of permanence and quality to the finished product. And soldering was basically the only show in town for the early days of the commercial electronics industry. But soldered joints have their problems, both electromechanically and in terms of production – after all, an assembly worker can only sling solder around so fast. In the early 1950s, AMP Corporation came out with the first crimp connections for production use, the F-Crimp or open-barrel design. Using this crimping design, AMP sold a wide range of connectors that could be rapidly and repeatably applied to conductors, and that lent themselves to automated fabrication methods in a way that soldering would never be able to achieve. Squeeze PlayCrimping takes advantage of the properties of metals to achieve electrically and mechanically sound connections. Metals used in crimp connectors, like copper, brass, aluminum, or bronze, are both ductile and malleable. A metal’s ductility is the degree to which it can deform under tension, while malleability is a measure of how metal deforms under compression. Crimping involves applying significant compressive forces onto the crimp connector and the wire, so the malleability of each element is an important factor in crimp quality. But ductility plays a role too as both connector and wire undergo significant stretching during the crimping process. Cross-section of a good F-crimp. Source: ETCO Incorporated Most crimping tooling also takes care of strain relief by lightly crimping a second set of legs onto the plastic insulation of the wire. Care is generally taken not to pierce or otherwise mar the insulation; usually these strain relief crimps just wrap the insulation firmly and direct the force of bending into the insulation and away from the wire’s conductors. A third set of legs may also be formed into a circle by the tooling to permit the finished termination to be inserted into a plastic body. A properly executed crimp connection is electrically reliable and mechanically strong, and knowing what’s happening inside that tool is the first step in achieving consistent results. For a more in-depth hands-on tutorial on crimping, see our guide to proper crimping procedures. Crimping connectors onto wires requires the right tool, and the most important for this task is – surprise – the crimping pliers. These pliers press the crimping wings of the connector into each other, a task made much easier on the non-ratcheting pliers if you use a rubber band to hold the jaws of the crimping pliers open just enough to hold a crimp connector.

This is standard fare for residential well pumps, with butt splices that are subjected to vibration, reasonably high current, and continuous submersion in water. 20 years later and the pump wiring is just fine. The general theory for crimping all types of connectors is to strip a little bit of insulation off the wire. Then, put the connector into a suitably sized space in the jaws, insert the wire, and crimp it down. For non-ratcheting pliers, it’s suggested the connector be re-crimped with the next smallest hole in the jaws. Step 3: ignore all other advice from people who, especially those who claim to “know how to crimp – I don’t need to read no instructions…”

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Because of these guys saying to only use the brand that you know is Approved by some sort of Authority for your connector. That means that other companies can’t offer generics to compete on price, it means there is a significant barrier to entry into this market. Therefore, the price will not approach the cost of production at all, it will stay at whatever the market can bear for the niche that trusts said Authority. I had a friend who was an electronics assembly tech for a big defense contractor. He was a production floor guy who had a chip on his shoulder for the engineers with their fancy book-learnin’ who couldn’t figure out the simplest problems. He claimed that one assembly wasn’t passing QC and a bunch of the guys in ties couldn’t figure it out. He sidled up to assess the situation and delivered his two-word diagnosis: “Bad crimp.” The dodgy connector was re-worked and the assembly passed, much to the chagrin of the guys in the short-sleeved shirts.

Putting crimp connectors on wires is one of the most tedious things you’ll do. It’s not easy, either, unless you have some practice. Before you start digging in to a pile of connectors, crimp terminals, and wire, it’s a good idea to know what you’re getting into and Gogo:tronics has a great tutorial on how to crimp electronics connectors. Crimped, unsoldered connections keep your car on the road. They keep your DSL and cable modem connection going. They keep airplanes in the sky. There is nothing wrong with them if the connection is (or can be) properly crimped.

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Crimp tooling is a critical part of a quality crimp. The business end of any crimping tool is the die set. This is generally a tool-steel anvil and hammer, the specific configuration of which is determined by the connector type.

The nice thing about Team Crimper-Forever is that they have a built-in No True Scotsman; it is only properly crimped connections that are great, so they get to ignore whatever the average crimp quality is. For mass-produced items from actual factories, it is typical to have a few strands hanging out of crimped connections. Maybe the True Assembly Master would never do that, but who wants to be a master of assembly? Probably not the engineer who has to choose which connection method to use! ;) And the production manager has stories where both the tech and the engineer get it wrong, because they don’t really consider the average case. If some entry-level worker is going to be doing the work then soldering has a certain advantage; the steps have clear reasons, and can be visually inspected. Sure, some guy who has been in a “tech” job for decades without advancing can sometimes spot a bad crimp visually, but it that really anything to be impressed by? Do you have enough of those guys to do visual inspection of crimp joints, or is there something better for the rare people with lots of crap experience to do?