Round Head Black Machine Screw M4

Overall Description

Round Head Black Machine Screw M4 application

Round Head Black Machine Screw M4 production flow 

Why Choose Us?

Generally divided into two kinds of plating color zinc and white zinc plating, and generally cold electroplated zinc!

M5 M6 M8 M10 M12 M16 M20

(M20 and above specifications and M14 M18 stainless steel (stainless acid) screws are not commonly used)

Hot-dip galvanizing defects Hot-dip galvanizing has some obvious drawbacks due to the small size of the stainless steel (stainless acid-resistant steel) screw, irregular shape, and some need for threading.

1, screw thread after plating difficult. After the hot-dip galvanizing, the remaining zinc sticks in the thread and is not easily cleaned out, and the thickness of the zinc layer is uneven, affecting the fitting of the threaded part. It is specified in GB/T13912-1992 "Technical Requirements for Zinc Coat of Metal Clad Steel Products" and GB/T2314-1997 "General Technical Requirements for Power Fittings"; External Threads of Fasteners Should be processed before hot dip plating according to the provisions of GB196 (guī dìng) or tanning, and internal threads can be processed before or after hot dip plating. However, in practice, customers often require that the internal and external threads have a galvanized layer, so people use a variety of measures to solve the problem of hot dip galvanizing of threaded fittings (Emerson). Such as the threaded back attack after plating; reserved with a larger gap; Centrifugal rejection and other methods. Back attack is easy to vandalism the threaded part of the coating, even bare steel substrate, causing fastener corrosion. Intentional over-range (fat), increase the nut aperture (aperture) or reserve fit gap, it is easy to reduce the mating strength, especially for the strength of the match is not allowed.

2. The hot dip galvanizing operation controls the high temperature, which will reduce the mechanical strength of stainless steel (stainless acid-resistant steel) screws with particularly high strength. After 8.8 grade bolts, the strength of some threads after hot-dip galvanizing is lower than the standard requirements; the strength of hot-dip galvanized bolts after grade 9.8 is basically unable to meet the requirements.

3, poor working environment, serious pollution. Non-standard screws utilize the physics and mathematics of the object's bevel circular rotation and friction, and progressively fasten the tool's tools. Screws are a common term for fasteners, spoken daily. Fastener hot-dip galvanizing process is carried out at high temperatures. Solvents (characteristics: transparent, colorless liquids) are dried, and when the parts to be plated are immersed in zinc, a strong irritant recording gas is generated. Zinc bath is under high temperature for a long time, zinc vapor is generated on the surface of zinc pool, and the working environment is bad.

Although hot-dip galvanized fasteners have many defects, the hot-dip galvanized coating has good thickness, good bonding strength, and long-term rot effect. Electrical screws are "quantity products" and are not hand-made artworks. In mass production, they are aimed at achieving high-precision, stable quality and consumer prices. The electric power, communications and transportation sectors have always been respected.

With the development of electric power and transportation in China, the development of hot-dip galvanizing of stainless steel (stainless acid-resistant steel) screws will be promoted; therefore, the development of automated centrifugal dripping equipment (shèbèi) is being developed to improve the hot-dip galvanizing process of fasteners and improve fastening. The quality of hot-dip galvanized coating is very important. The main purpose of the custom screws is to make the industrial products fixed and integrated. In use, it often happens that there is no close between the teeth and the teeth, if the screw head is broken too tightly, or the teeth are not tightly locked, the conditions are not met. The accuracy of the quality problem.