Customers often ask, do non-standard screws have other colors besides substance? Yes, screw manufacturers tell you that non-standard screws not only have substance, but also black, sandblasted and chrome-plated, dacromet, etc.

Then, in addition to the passivation treatment of stainless steel, there are the following types of black treatment commonly used, and the name is plated with environmentally friendly black zinc:

Its advantages are that the name is relatively black and bright, and the unit price of environmental protection is relatively moderate. The disadvantage is that it may appear whitened if it needs more than 50 hours of salt spray test.

Surge treatment is the electroplating VIP in the treatment method of non-standard screw manufacturers. The name not only has bright and pleasant colors, but the unit price is also VIP price. The salt spray resistance will take longer than the environmentally friendly black zinc. Custom inspection method for non-standard screws: The inspection method for standard fasteners is specified in the technical conditions of the product. Professional standards have been developed for fastener testing methods (dimension and geometric accuracy).

The black Dacromet is the second-generation rich with non-standard screw processing, which is invisible and simple. The unit price is relatively moderate, and the important thing is that it is resistant to salt spray for a long time. Therefore, we individually advocate for customers who not only require salt spray testing, but also care about the appearance of the name. , taking this treatment method, its nominal comparability after treatment is commensurately high. Non-standard screws are divided into three parts, namely size, mechanical properties and surface defects. The specific inspection items of each part have different regulations according to different products. Screw customization, for example, the dimension inspection items for hexagonal nuts are specified as thread general gauge, thread stop gauge, thread minor diameter, opposite side width, diagonal dimension, nut height, and the perpendicularity of the nut bearing surface and the thread axis; while the flat washer is specified as the inner diameter , outer diameter, thickness, coaxiality of the outer circle to the inner hole and flatness, etc. As for the mechanical performance inspection items, hardness and tensile strength are specified for hexagonal nuts, while only hardness is specified for flat washers.

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