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Fastener Commonly Used Testing Instrument
Sep 15, 2017

Fasteners are a kind of mechanical parts that are tightly connected and widely used. Fasteners, industry widely used, including energy, electronics, electrical appliances, machinery, chemical industry, metallurgy, mold, hydraulic, and so on, in all kinds of machinery, equipment, vehicles, ships, railways, Bridges, buildings, structures, tools, instruments, chemical industry, instrument and apparatus, such as the above, you can see all kinds of fasteners, is the most widely used mechanical components. It is characterized by a wide variety of specifications, different performance USES, and a high degree of standardization, serialization and generalization. As a result, some of the fasteners that already have national standards are called standard fasteners, or standard ones for short.

application

Fasteners are a kind of mechanical parts which are tightly connected and widely used. All kinds of fasteners can be seen in all kinds of machinery, equipment, vehicles, ships, railways, Bridges, buildings, structures, tools, instruments, instruments and supplies. It is characterized by a wide variety of specifications, different performance USES, and a high degree of standardization, serialization and generalization. Therefore, there are also some fasteners that have already established national standards as standard fasteners, or standard parts. Fasteners are the most widely used mechanical bases. China joined the WTO in 2001 and entered the ranks of international trade powers. China's fastener products are exported to countries around the world, and the fastener products from countries around the world are also constantly flooding into the Chinese market. Fasteners, as one of our country into the products of the large volume, in line with international standards, to promote China's fastener enterprises move towards the world, promote the fastener enterprises fully participate in international cooperation and competition, all have important practical significance and strategic significance. The specifications, dimensions, tolerances, weight, performance, surface conditions, marking methods, and acceptance inspection, marking and packaging of each specific fastener products are required.

Commonly used testing instrument

The most important part of the development and design of fasteners is quality control. There are several major passes from incoming materials to finished products, which have different inspection methods. The first feed is related to appearance, size, element, performance, hazardous material detection, etc. The process aspect is more appearance, size, percussion experiment, forging streamline; Heat treatment is more about appearance, hardness, torque, pull, gold, etc. Surface treatment is more of some hydrogen embrittlement test, coating, salt mist and so on, including shipment has a harmful material detection.

In terms of size and appearance, the common ones are quadratic, contour measuring instrument, three-coordinate measuring instrument and image sorting machine (this is an all-selecting machine).

In mechanical and chemical testing, there are mainly hardness machines (lolo and vickers), pull machine and metallographic microscope.

There is a spectrum analyzer and salt mist testing machine.

Surface treatment

Fasteners are generally treated with surface treatment, and there are many kinds of fastener surface treatment, which are commonly used in electroplating, oxidation, phosphating, and non-electrolytic zinc coating treatment. However, the plating fastener has a large proportion in the actual use of fasteners. It is more widely used in automobile, tractor, home appliance, instrumentation, aerospace, communications and other industries and fields. However, for threaded fasteners, the application requires not only a certain amount of corrosion resistance, but also the interchangeability of the threads, which can also be called the convolvulatory. In order to meet the requirements of "anti-corrosion" and "interchangeable" dual-use performance in the use of thread fasteners, it is necessary to develop a special standard for electroplating.

Causes and hazards of hydrogen embrittlement of threaded fastener

Threaded fasteners in the manufacturing process (e.g., tempering, quenching and high temperature tempering, cyanide, infiltration of carbon, chemical cleaning, phosphating, electroplating, roller milling and machining (such as improper lubrication and burnt) process) and the service environment, due to the adverse effect of cathodic protection or corrosion reaction, hydrogen could enter the steel or other metal matrix, and stays within the matrix, the lower yield strength (nominal strength of alloy), under the stress state of extensibility, or it could lead to a reduction or loss of bearing capacity, crack (usually submicroscopic), straight to occur in the process of service process or store suddenly rupture, causing severe brittle failure. Thread fasteners, especially high-strength fasteners are cold-drawn, cold forming, grinding, machining, grinding, hardening heat treatment, electroplating treatment, easily damaged by hydrogen embrittlement. There are many reasons for fastener hydrogen embrittlement, but electroplating process is one of the key factors.





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