Page 70


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“Strippables” Applied as Coatings, Not Films Continued from page 67


durable strippable over the top to protect the finish from getting


scratched or marred,” says Chin. The automotive industry also utilizes strippables to protect vehicle


surfaces during transport to ensure arrival in pristine condition. In such cases, the coatings


have been formulated to spray in thicknesses ranging from 3 to 4 mil (0.08 to 0.1 mm). At these thickness- es, the strippable coating provides sufficient protection from rocks kicked up by trucks and other vehi- cles on roadways.


Coating Applications According to Chin, in a typical


application, a coil processor would apply the color coating in the first stage of the process, and the liquid strippable coating in the second stage. “Applying the liquid strippable


coating often occurs on the entire coil before the coil is slit to specific widths,” he says. “The coating can also be sprayed on pre-cut sheets or finished parts.” Strippable coatings, such as


Unichem’s uniGuard product, for example, can also be applied to pol-


March, 2019


ished metals, metals coated with ther- moset coatings and some polyvinyli- dene difluoride (PVDF) coatings. According to Chin, liquid strip-


pables are adding increasing value as an alternative to film laminates on kitchen appliances and construction products. While such coatings are primari-


ly applied during coil processing, the coatings can even be applied using screen printing techniques. Screen printing the liquid strippable has been used to apply a strippable coating over appliance control panels. In this way, the coating can protect the precise area required. There are a number of technolo-


gies available for products which need protection using liquid strip- pables. Determining the various per- formance requirements is key to suc- cessful application and protection. Contact: Unichem, 1975 Fox


Lane, Elgin, IL 60123 %


847-931-1700 Web: www.unicheminc.com


Common Misconceptions in wire stripper The programmable Mira 340 is designed for


universal use while maintaining maximum precision. It is perfect for processing wires and insulation material with demanding requirements. The Mira 340 is fitted with a rotary head with 4X-blades and offers unique functions designed to reduce production time and increase quality. Thanks to sequential processing, multi-conductor cables and multi-layer insulation material can be processed quickly, thereby saving time and increasing productivity.


MIRA 340


Testing Electrical Cables Continued from page 66


may risk unintended collateral dam- age to insulation or otherwise good components. Insulation nicks and pinholes,


and connectors that are too close together, can be detected with a high-voltage test only under statisti- cally unlikely conditions — affected by a large number of variables that include fault size, alignment, spac- ing, humidity, and cleanliness. Detection is even less likely


komaxgroup.com


when nick and pinhole faults are in a single isolated wire. Creative test plat- forms could be employed to increase the likelihood of detection, such as testing in an environmental chamber to optimize conditions for discharge. Often, you should be checking


resistance even if there are no resis- tors in a cable, in order to check the quality of the connections. Yes, low- resistance connections ensure good electrical connections in cables, but a cable’s application tells you where to set the pass/fail threshold. Setting it lower than you need


to may create false positives, which can result in failures against an unrealistic standard that wastes time and may lead to unnecessarily scrapped product. Setting the thresh- old too high, or not testing resistance at all, may permit product to reach its application with a time-bomb type of fault. Cut strands or insulation-cap-


ture crimp errors are highly undesir- able but cannot be detected by pro- duction-practical resistance meas- urement. These problems will disap- pear with improved production prac- tices and possibly by machine vision inspection of crimps. However, combining continuity,


resistance and intermittence testing with the use of appropriate test set- tings (wire resistance values, toler- ances, dwell times, etc.) provides con- fidence in the electrical integrity of the part, backed by direct empirical evidence.


Insulation nicks and pinholes,


and connectors that are too close together can be detected with a high- voltage test only under statistically unlikely conditions. A lightning dis- charge can travel thousands of feet between clouds and ground, when tens of millions of volts develop across that distance. Applying 1,500V between two


bare-wire conductors in a cable will not cause a discharge until the dis- tance is reduced to less than half a millimeter. No discharge or leakage will occur at conductor distances that are easily visualized unless the volt- age used is high enough to cause hair to stand on end. Contact: CAMI Research, Inc.,


42 Nagog Park, Suite 115, Acton, MA 01720 % 978-266-2655 fax: 978-266-2658 E-mail: info@camiresearch.com Web: www.camiresearch.com r

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