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Screws refer to a tool that gradually tightens a part using the mathematical and physical principles of the beveled circular rotation and friction of an object. Screws are a common fastener that is widely used in daily life and production. The general material is plastic or metal, and the grooves engraved on the surface are called threads, which are cylindrical.
Screws are ubiquitous in industrial production and daily life. Therefore, screws are also known as the rice of industry. The application scope of screws includes electronic products, mechanical products, digital products, power equipment, and electromechanical mechanical products. Screws are also widely used in vehicles, ships, chemical experiments, hydraulic engineering, and so on.
Dongguan KENENG International Trading Co., Ltd is a professional screws manufacturer and trading integrating company, specializing in the design, production, and sales of various carbon steel, stainless steel, copper parts, titanium alloy products such as British and American standard Cup heads, hexagon bolts, self-tapping screws, drilling screws, drywall screws, stud bolts, U-bolts, anchor bolts, welding screws, eye bolts, SEM screws, set screws, carriage screws, nuts, gaskets, electronic small screws, pin shafts, springs, car parts, high-grade building expansion bolts, etc. It is widely used in machinery, mold, automobile, motorcycle, aerospace, agricultural machinery, electronics, construction, household appliance, and other fields. We have a large number of quantities of standard Metric and Inch screws in stock. For a long time, we have been serving new and old customers with the concept of honesty, pragmatism, innovation, and win-win, and have a good reputation in the hardware industry.
A custom fastener is needed when engineering specifications require a fastener to function in an application that is not an industry standard. KENENG is also a custom screw manufacturer. Customized fasteners are available for special lengths, and tolerances regarding length or body diameters. Or due to certain strength requirements or corrosion situation requirements, these special cases may require special materials. In many of these situations, the customer’s engineering department will provide a CAD drawing showing all aspects of the fastener required for the company’s production.
KENENG can produce both standard and non-standard screws, we have a professional R & D team to produce all kinds of non-standard screws according to customers’ requirements. We are able to produce electronic precision screws, extra-long screws, step screws, shoulder screws, color screw, self drilling screw, wood screws, machine screw, drywall screw, brass screw, and self tapping screw, as well as other kinds of special-shaped screws.
KENENG is a professional screw manufacturer with more than 20 years of experience, which can provide customized services, any quote is warmly welcomed.
Surface treatment is a process method, which refers to the artificial formation of a surface layer on the surface of the substrate material with different mechanical, physical, and chemical properties from the substrate. The purpose of surface treatment is to meet the requirements of product wear resistance, corrosion resistance, decoration, and so on.
In the selection of screws, in addition to the main consideration, the color of the appearance and corrosion resistance should also be considered. Common surface treatment processes for screws include oxidation, electrophoresis, electroplating, dacromet, and so on.
Black Oxidation Treatment
Black oxidation treatment is a common method of chemical surface treatment, the purpose is to produce an oxide film on the metal surface to isolate the air and prevent rust.
The process is to use a strong oxidant to oxidize the surface of the steel into dense and smooth ferroferric oxide. This thin layer of ferroferric oxide can effectively protect the inside of the steel from oxidation. Divided into low temperature and high temperature.
Ferroferric oxide formed at low temperature (about 350°C) is dark black, also known as blackening. Ferroferric oxide formed by oxidation at high temperatures (about 550°C) is sky blue, also known as bluing treatment. The blue treatment is commonly used in weapon manufacturing, and the black treatment is commonly used in industrial production.
Oxidizing the steel surface to dense, smooth ferroferric oxide requires a strong oxidant. The strong oxidant is composed of sodium hydroxide, sodium nitrite, and trisodium phosphate. When it turns blue, treat the steel with a strong oxidant melt, and when it turns black, treat it with an aqueous solution of a strong oxidant.
Electroplating
Electroplating is the process of using electrolysis to coat a layer of other metal films or alloy films on the metal surface. The purpose is to improve wear resistance, corrosion resistance, and aesthetics.
There are 2 types of black plating: black zinc plating and black nickel plating.
Black zinc plating is a kind of anti-oxidation processing of metal, which is suitable for hardware products. Zinc is chemically active and easily oxidized and darkened in the atmosphere. After galvanizing, it is treated with chromate to cover a chemical conversion film on the zinc, so that the active metal is in a passive state, which is the passivation treatment of the zinc layer. The passivation film can be divided into white passivation (white zinc), light blue (blue zinc), black passivation (black zinc), green passivation (green zinc), etc.
Usually, the process of electroplating black zinc is degreasing-cleaning-weak acid etching-electro-galvanizing-cleaning-passivation-cleaning-drying-sealing paint.
The black nickel coating obtained from the black nickel bath contains 40-60% nickel, 20-30% zinc, 10-15% sulfur, and about 10% organic matter. The black color is caused by the presence of black nickel sulfide in the coating due to the reduction of thiocyanate on the cathode to release sulfide ions. The copper bottom is added in the process, and the main function is to make nickel plating easier in the post process and to improve the corrosion resistance of the screw.
Electrophoresis
Electrophoresis refers to the phenomenon in which charged particles move toward electrodes of opposite electrical properties under the action of an electric field.
Black electrophoresis is the use of an external electric field to make particles such as pigments and resins suspended in the electrophoresis solution directionally migrate and deposit on the substrate surface of one of the electrodes. Electrophoretic black is widely used in the industry, taking the black process as an example: degreasing – cleaning – phosphating – electrophoretic paint – drying. It can be divided into anodic electrophoresis (resin becomes negative ions after ionization) and cathodic electrophoresis (resin becomes positive ions after electrophoresis). Compared with the painting process, it has better construction performance, less pollution and harm to the environment and its resistance to neutral salt spray is 300 hours or more, and the cost and corrosion resistance are similar to those of the dacromet process.
