How to avoid blistering and bubbles on the polyamide thermal break profiles in aluminum windows
By Bogdan Grebenyuk, Product Manager at Thermevo
on Jan 27, 2018
The manufacturers of polyamide details often face one common problem - the appearance of bubbles and blistering on the paint. We have conducted a research to find a solution for this kind of problem and we got some interesting results. This article will tell you about it.
The polyamide is a polymeric material of constructional and antifriction appointment. It is used in many industries: mechanical engineering, machine-tool construction, metallurgy, and in particular in the manufacturing of high thermal insulation aluminum windows.

The invention of polyamide caused a significant energy efficient modernization of heat-insulating windows. This material has a low coefficient of friction on metal, high wear resistance, even working in an environment with abrasive particles. The product made of polyamide is 7 times lighter than the product made of steel or bronze, and its maintenance interval is twice as long.

There are several types of polyamide. First of all, polyamide varies according to the method of fabrication: polyamide, manufactured by extrusion and polyamide, manufactured in a casting process, the use of various additives makes it possible to use polyamide for various purposes.

The polyamide PA 6.6, which we use in manufacturing the insulating strips has a high resistance to deformation. It is also characterized by good mechanical strength and resistance to cyclic loads and cracking, it is resistant to vibration and soundproof. Another advantage of the PA 6.6 is a climatic and chemical resistance. In particular, this polyamide is resistant to petroleum products, lubricants, and solvents of organic origin. It is able to keep its shape constantly at temperatures up to +180°C and temporarily at +200°C.

But the manufacturers of polyamide details often face one common problem - the appearance of bubbles and blistering on the paint:

We have conducted a research to find a solution for this kind of problem and we got some interesting results.

We had a theory that the appearance of bubbles on the paint is directly related to the temperature of the powder coating and the humidity of the environment where we store our polyamide details. We have proven our theory by the experimental method.

On the chart you can see that with increasing temperature of the powder coating and the residence time of parts in such temperature conditions, the likelihood of appearing bubbles on the paint is significantly increasing:
We have also tested our hypothesis concerning the humidity of the environment where we store our polyamide details and proven that the increase of humidity leads to noticeable changes in the dimensions of the parts:
We can conclude that in order to avoid blistering and bubbles on your Thermal break Aluminum window you should store the polyamide insulation profiles in dry conditions and set the temperature of powder coating as low as possible.

We hope that this material was useful for you and that you will use our advices.

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