Microsectioning without terminals?
Terminal microsections can tell us a lot about the internal structure of a crimp connection. But what if you don't happen to have a microsection and still need to check the inside of the crimp connection?
For optimal quality control of crimp connections,The use of profile analyzers is one of the most important quality control instruments in wire harness production today。Microsections provide important information about the degree of compression of the conductor strands, the curl on the crimped sides, damage to the wire crimping area, and more.
But,Profile analyzerCost is a major obstacle to investing in such a high-quality tool, especially for small wire harness manufacturers, many wire harness factories still find it too expensive to set up a laboratory or buy a profile analyzer. Equipment used for other tests, such as pull-out tests, is often found in small wire harness factories. However, crimped microsections offer better possibilities for evaluating the quality and troubleshooting of crimped connections. Therefore, those who attach great importance to quality should sooner or later consider making a budget for buying a profile analyzer.
But what if you don't have the budget now and still need microsectioning?
First of all, there are external vendors, such as laboratories or systems vendors for wire processing machines, who create and evaluate microscopes with test reports. The sample (crimp connection) is sent to them and the results are available after some time. If you are not in a great hurry, you can wait a few days, which can be a cost-effective solution. One of the great benefits of this approach is that this specialized microsection documentation can also be provided to your customers as proof of quality.
But in some cases, the time component can also be a potential drawback. Due to the mailing of the sample and the preparation processing time of the microscopy**, it takes an average of one week to hold the corresponding results in your hands. It can become very annoying when you find that the crimp connection is not working properly and you have to optimize the crimp result by changing the settings of the crimp tool. Because who is willing or able to interrupt longer production times?
Then, when you need to quickly illustrate the crimp results, you can create a "quick microsection".
This is where a benchtop grinder with thick and thin discs is required, or a belt grinder is used. A manual grinder can also do the job.
1) Separate the crimp contact from the wire crimping area, e.g. with a saw. Please do not use scissors as it will squeeze and deform the conductor crimp area.
2) After cutting, grind the crimp contact point on the coarse grinding disc to the middle or so of the wire crimping area. The resulting grinding surface is then briefly rested against the fine grinding disc.
Make sure the grinding surface is created at an angle of approximately 90°!
Remember: When separating and grinding crimp contacts, they must not be subjected to mechanical or thermal stress. Of course, these factors can ruin the test results.
Therefore, it is important to pay attention to the grinding direction and that no heat is generated during the grinding process (e.g., frequent cooling with water).
After cutting and grinding the surface, you will notice that there are not many internal contours of the crimp connection when you look at the results. Therefore, it is necessary to clean the cross-section at this time.
Microsections after cutting and polishing.
There are basically two possibilities for this: some people use corrosive substances, such as nitric acid, however, these corrosive agents are harmful to health and are therefore not recommended!
Instead, electrolysis is used as a cleaning method. This much less dangerous method is well known in the cleaning of metal surfaces, such as weld cleaning. You will find off-the-shelf cleaning equipment for crimping microsections on the market. Or, the crafters among you might even want to consider building your own cleaning equipment.
The procedure is as follows: using a (preferably adjustable) 12V DC power supply, the crimp contacts are connected to the negative electrode by means of a clip. A carbon fiber brush or dye pen is attached to the positive pole. A carbon fiber brush moistened with an electrolyte (e.g. KCl 3M) is fixed to the surface to be cleaned, and the cleaning process takes place as long as the current flows.
With the help of a powerful magnifying glass or microscope, the contours of the crimp connection can be seen.
Important:With a microscope created in this way, you can only see the trend of the crimp connection.
How does the crimp wing get involved?
Is there any damage to the crimping cylinder wall, such as cracks or burrs?
Are all the strands trapped in the crimp?
Are all strands irregularly shaped?
Is there a cavity in the crimping area?
Of course, this method is only a temporary one. Logically, it is not possible to make crimp measurements or obtain truly reliable data or test reports. But in some cases, it can quickly indicate the need for further action in a quick and inexpensive manner.