Jürgen Eixler, Director of Engineering, Bossard Switzerland
"Greater productivity means satisfied customers"
In manufacturing, productivity is affected by numerous factors, and one of the most important is a low defect rate. Troubleshooting costs money and takes up valuable time as one of our customers who manufactures power and voltage transformers for utilities can attest. The customer was having galling problems with stainless screws in aluminum housings during final assembly of a large voltage converter. The galling was requiring costly, time-consuming repair to the housings. Sometimes repair wasn‘t even possible, so housings had to be scrapped.
There were three issues with the obvious solution
So the production manager started looking into how to improve the situation and contacted us engineers at Bossard. The obvious solution was to lubricate the screws, but in this case there were three problems involved, the first of which was the extra time this would take, which would negatively impact productivity. Secondly, this would create the possibility of fouling, which would create a leakage problem in the housings. And thirdly, lubrication is a somewhat vaguely defined activity which every fitter performs a bit differently.
So what we proposed was to coat the screws using a Bossard coating solution – an applicationspecific tribological dry lubricant coating. A dry lubricant reduces friction like a conventional lubricant, so less torque is required. To ensure maximum process reliability, we analyzed this effect and friction coefficients in the Bossard application technology lab. In parallel, our customer started conducting initial trials using dry-coated screws.
The coating solution persuades
This preliminary work was successfully completed, no issues being found with implementing the Bossard coating solution in production. The results were impressive, as the number of housing repair cases due to fastening problems in final assembly fell to zero. Considering that such repairs could take up more than half a day, the Bossard coating solution likely boosted productivity by a whopping 20 %. What‘s more, since the end customers sometimes had to loosen and re-tighten the screws, they too had had problems with fastener galling. Complaints and costly repairs were the result. But this too became a thing of the past after Bossard coated screws were introduced.