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Some Tips On Making a Quality Crimped Joint

Views: 68     Author: SEILSOUL     Publish Time: 2019-03-05      Origin: Site

Crimped Joint


Crimp systems are designed to compact the wire strands together to a set level so that no interstitial spaces (gaps) are left between the strands. This stops both moisture and oxygen entering the crimp and therefore prevents corrosion from occurring.  If this is correctly carried out, soldering the rear of a crimp (as some people will recommend) will have no effect on the corrosion resistance of the joint as there will be no space for the solder to enter. Ultimately the crimp process aims to deform the wire and crimp to a preset level, to eliminate the spaces as well as cold work the wire to a pre-determined level.

Under-crimping which can be achieved by using the wrong tool or die for the crimp, not cycling the tool to fully closed, using pliers type tools or by incorrect selection of crimp and wire, will leave these interstitial spaces open, allowing moisture and oxygen to enter, ultimately allowing corrosion and hence a high resistance joint, or mechanical failure. If under-crimped, the joint will also have reduced mechanical strength, and at an extreme level will pull out with very low force. Whilst the pull strength of the joint isn’t an ideal test (due to over-crimping issues described next), it is a common test that is quick to apply in a factory environment and is hence commonly used as a quality control check.

Over crimping of the joint can have equally disastrous results- at an extreme level, the imposed stress on the wires can lead to complete failure, which is likely to be obvious. A less obvious issue is a greater sensitivity to fatigue, which will occur in places with vibration where the failure may not become apparent for some time. This type of failure is analogous to what happens when you keep flexing a paperclip- the material work hardens and then eventually fails. Over crimping is more difficult to detect as a simple pull test won’t necessarily pick up the issue, due to this other quality control techniques tend to be used, although none of these are practical for the DIYer;

Microsectioning- this is a destructive test that is the only completely definitive method of determining the quality of a crimp- It is therefore often used in industry to ensure the design/ calibration and set up of crimp machinery is correct, where samples can be taken and analysed. The process consists of cutting a crimped joint through the crimped area, mounting and polishing the section and inspection and measurement with a microscope. The criteria for a good joint are mostly to determine if correct consolidation has occurred- i.e no void spaces, no inclusions of foreign matter or oxides and approximately hexagonal sections of the crimped wire strands.

Pull tests- by hand this can be a gentle tug on a joint, but in a production environment a calibrated tester is usually used to apply a force until the joint fails, noting the yield force achieved. This can be a quick in-process check which will detect under-crimping, but not necessarily over-crimping.

Crimp height- measurement of the height of the terminated wire in the crimp area is a good method for quality control as it is non-destructive, and can pick up both over and under crimping simply.

Crimp force- many automated crimp tools measure the force applied during the crimping process. This is another reliable method of getting an indication of crimp quality, and has the advantage that it is an in process check- no need to stop machines or remove samples.

Soldering- you may see recommendations to solder crimps elsewhere. There is absolutely no need to solder any crimp. In fact you may reduce the reliability of the crimp by doing so. Crimps are designed to control the flexure of cable at the entry point. Soldering can stiffen the joint and result in premature failure.

Esoteric tools- Due to the dangers of over-crimping described above, and the difficulty of detecting it, I would strongly advise against using a hammer type tool, or anything else that is not specifically designed for the type of crimp. This includes squeezing in a vice, squeezing with a vice with a nail to indent, using ground pliers, whacking it with a hammer or any other brutal method that might come to mind. You might get a reasonable result, but there is a very high risk you won’t and the joint will fail prematurely.


Seilsoul Electrical CO.,LTD is a production and trading company specializing in the production of PVC insulated terminalsnon insulated terminalsheat shrink terminal connectorsnylon insulated terminalsferrule terminals and wire accessories. The company has more than ten years of production experience in the field of terminal & connector. Our products have been exported to more than 30 countries in recent years. Exported to Amazon, Alibaba and other international trading websites, and received unanimous praise from customers and the industry.



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