Best Practices in Crimp Applicator Maintenance
A few years ago, I was asked to give a presentation at the Electrical Wire Processing Technology Expo on best practices for crimp applicator maintenance. At the time, I assumed that everyone knew how to maintain their crimp applicators. After all, one of the most significant factors in crimp quality is an applicator that is in good condition. With quality standards getting tighter and tighter and the implementation of crimp force monitors continuing to rise, applicator maintenance is a key factor in any crimp process. However, it’s become clear that many companies neglect this key task or simply don’t know what is needed. Therefore, I decided to put my presentation into an article.
In addition to Schleuniger’s recommendations, I gathered feedback from other industry experts on crimping applicators such as TE, Panduit, Molex, Hanke, Applitek, and Mechtrix. The following is a culmination of the recommendations on how to best maintain crimping applicators to ensure high quality output and years of trouble-free performance.
What is likely the most important thing about applicator maintenance is probably the simplest: keeping the applicator clean and free from excessive dirt and terminal scraps. Applicators should be cleaned using a soft bristle brush and never with compressed air. Compressed air tends to blow particles into cracks and crevices where it shouldn’t be.
Applicators should get a basic cleaning daily, or after every shift. They should get a thorough cleaning at least once a week or every 25,000 cycles. A thorough cleaning would consist of completely disassembling the applicator so that dirt and metal scraps can be removed from the tooling, the slides, and the feed track. This is also a wonderful time to check the condition of the crimping dies and anvils to ensure that they are not damaged.
Applicators should be lubricated once per day. Synthetic lubricants and greases such as Permatex (with PTFE), Superlube and Chevron Ultra Duty were commonly recommended. Synthetic motor oil such as SAE 20 or 30 was also recommended because it is relatively inexpensive and easy to purchase. A simple 3-in-1 oil is also commonly used.
A light coating of lubricant is all that is needed on any component that might see friction. Ensure the slides and tooling are thoroughly coated but don’t put on too much. Too much grease tends to attract and hold dirt and debris which might work against you.
Finally, a terminal oiler is recommended for gold plated terminals. Because gold is so soft, it will rub off and start to coat the crimp tooling. Eventually, the buildup causes the terminals to stick excessively in the crimp tooling. A terminal oiler minimizes this buildup.
To prevent excess wear, tooling must be mounted properly. Therefore, when tooling must be replaced, take extra precautions to ensure that mounting surfaces are clean and in good condition. Crimp tooling must sit flush with the base plate and applicator ram. The upper tooling, or crimp dies, must be centered over the lower crimp anvil. A simple method to ensure that the upper ooling is centered is as follows:
- Install the lower and upper tooling and hardware but do not completely tighten the screws.
- Gently install the applicator ram ensuring the upper tooling does not contact the lower tooling.
- Lay a thin strip of paper over the lower crimp anvil.
- Gently but firmly push the upper tooling down over the anvil. While keeping downward pressure on the ram, tighten the screws to secure the upper and lower tooling.
Once you are sure that the tooling is installed properly, ensure that the terminal feed adjustment provides accurate terminal placement. This applies for pneumatic, mechanical, or motorized feeds. However, when working with a mechanical feed applicator, consider the press it will go into. Depending on the quality of the terminal brake, the feed adjustment might differ between a slower press, such as an older bench press, or faster presses, which are common on automatic machines.
Prevent tooling crashes
Most applicators are shipped with ram collars. The ram collars (red piece shown in the photo) prevent collisions between the upper and lower tooling when the applicator is not installed in a press. Such collisions may damage the tooling prematurely. Signs of tooling damage may be:
- Scarring or marking inside the upper crimp die. This might also appear as consistent marking on the crimped terminal.
- Rounded edges on the crimp anvil. This might reveal itself with excessive flash or burrs on the terminal.
Whenever an applicator is installed into a press, it is recommended to either hand-cycle or cycle the press in jog mode two or three times to ensure the tooling closes properly without collisions.
Presses should be checked regularly to confirm that they are set for the proper shut height. For most mini-style applicators, the standard shut height is 135.78mm ± 0.02 or 5.345” ± 0.0008. If the shut height on one press is set too low, this may cause the tooling to crash. Furthermore, when presses are properly adjusted for shut height, consistent results can be expected when applicators are moved between presses. Shut heights can be confirmed using simple shut height gauges or with press analyzers which are readily available on the market.
All machinery, including crimp applicators, should have a detailed preventive maintenance plan outlining service intervals and required steps. The plan should be well documented and key personnel should be thoroughly trained to ensure it is properly carried out.
Sometimes applicators must be taken out of use and stored for a long time. Prior to long term storage, make sure the applicator is well cleaned, lubricated and wrapped in plastic to prevent rust. This will ensure that it will be in good condition if it is needed again in the future.
A thorough training program can save costs and increase efficiency. Operators and technicians should be trained on crimp quality indicators and other indicators surrounding basic applicator operation such as setup and handling. They should also be trained on cleaning and the preventative maintenance procedure. Catching defects or seeing indicators early will minimize scrap and perhaps tooling damage and thereby minimize tooling costs.
Properly maintained applicators will not only save unwanted downtime and headaches, but they will also ensure better crimp quality. Hopefully these recommendations will help keep your applicators functioning at peak performance for years to come.