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Little knowledge of automotive fasteners

Little knowledge of automotive fasteners

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  • Time of issue:2020-07-30
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(Summary description)Special knowledge of automobile fasteners. Today, the Austrian standard will teach you some knowledge about the surface outlets and inspection methods of screw fasteners. As the so-called insiders watch the doorways, the outsiders watch the excitement, then let's also come to the experts to see the excitement Right!

Little knowledge of automotive fasteners

(Summary description)Special knowledge of automobile fasteners. Today, the Austrian standard will teach you some knowledge about the surface outlets and inspection methods of screw fasteners. As the so-called insiders watch the doorways, the outsiders watch the excitement, then let's also come to the experts to see the excitement Right!

  • Categories:Company news
  • Author:
  • Origin:
  • Time of issue:2020-07-30
  • Views:0
Information

Special knowledge of automobile fasteners. Today, the Austrian standard will teach you some knowledge about the surface outlets and inspection methods of screw fasteners. As the so-called insiders watch the doorways, the outsiders watch the excitement, then let's also come to the experts to see the excitement Right!

Surface treatment and fastener inspection. Surface treatment refers to the process of forming a covering layer on the surface of the fastener through some methods. After the surface treatment of the fastener, it can show a more beautiful appearance. The anti-corrosion ability of the parts itself will also be improved. The surface treatment methods of fasteners are as follows:

The mechanical plating of fasteners refers to the use of specific physical and chemical means to impact the surface of the fastener with the powder of the plated metal, so that the plated metal forms a coating on the surface of the fastener through cold welding to reach the surface Treatment effect. The mechanical plating of fasteners is mainly applicable to spare parts such as screws, nuts and washers.

Hot-dip galvanizing of fasteners involves immersing fasteners of carbon steel components in a bath of molten zinc with a heat of about 510°C, so that the iron-zinc alloy on the surface of the fasteners will be converted into passivated zinc. Obtain the surface treatment effect. The price of hot-dip galvanizing of fasteners is higher than that of electroplating, about 1.5 to 2 yuan per kilogram.

Fastener electroplating refers to immersing the part of the fastener that needs to be electroplated into a specific aqueous solution. The aqueous solution will contain some deposited metal compounds, so that after the current passes through the aqueous solution, the metal substances in the solution will precipitate and adhere to On the immersed part of the fastener. Electroplating of fasteners generally includes zinc, copper, nickel, chromium, copper-nickel alloys, etc.

The main purpose of the surface treatment of fasteners is to make the fasteners have anti-corrosion ability to increase the reliability and adaptability of fasteners. Therefore, the quality judgment of the surface treatment of fasteners is mainly to check Whether the corrosion resistance of fasteners has been effectively increased, and whether the increase is in line with the expected requirements.

Appearance quality requirements: The appearance inspection of stainless steel screws is from the appearance, plating layer and other aspects.

Inspection of screw coating thickness

1. Measuring tool method: the amount used includes micrometer, vernier caliper, plug gauge, etc.

2. Magnetic method: The magnetic method to measure the thickness of the coating layer is a non-destructive measurement of the non-magnetic coating layer on the magnetic substrate with a magnetic thickness gauge.

3. Microscopy: The microscopy method is called the metallographic method, which is to magnify the etched fasteners on a metallographic microscope with a micrometer eyepiece to measure the thickness of the coating on the section.

4. Time flow method

The timing flow method is to use a solution that can dissolve the coating to flow onto the local surface of the coating, and calculate the thickness of the coating according to the time required for the partial coating to dissolve. There are also plating spot method, anode dissolution coulometric method and so on.

There are many methods for testing the adhesion strength of the screw coating and evaluating the adhesion between the coating and the base metal, usually the following.

1. Friction polishing test;

2. File method test;

3. Scratch method;

4. Bending test;

5. Thermal shock test;

6. Extrusion method.

The corrosion resistance of the stainless steel screw coating is tested. The corrosion resistance of the coating is tested as follows: atmospheric exposure test; neutral salt spray test (NSS test); acetic acid salt spray test (ASS test), copper accelerated acetic acid salt spray test (CASS) Test); as well as corrosion paste corrosion test (CORR test) and solution spot corrosion test; immersion test, inter-immersion corrosion test, etc.

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