Today we look at one of the technical questions that we received from our customers. Do the heads of the screws with large diameter have to be polished and opaque?
The problem
The AISI 316/A4 stainless steel M27x100 samples of screws are delivered to your warehouse. Open the box and the screws are opaque head (see image below).
What to do? Is it normal or not? In these cases it is always better to ask questions to your supplier.
The answer
In these cases it is useful to know that the screws have heads with large diameters (hot stamping) are almost always opaque. Since we are accustomed to seeing always the polish of stainless steel A4 screws, this at first sight could destabilize us. Certainly, given the large sizes, it is feasible to an electro-polishing process in order to obtain a high polish finish. It is not therefore a qualitative defect of the screw itself (so it does not depend on bad quality) but a hallmark for this type of screw.
What about smaller screws?
Smaller screws (for example those until the 20/24) are polished because they are cold formed. They don’t have surface opacity because they haven’t been subjected to thermal shock.
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