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Products Description

Fasteners are a kind of mechanical parts used for fastening connection and are widely used. Fasteners are widely used in a wide range of industries, 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, instrumentation and supplies, you can see all kinds of fasteners, is the most widely used mechanical base parts. It is characterized by a wide variety of specifications, performance and use of different, and the degree of standardization, serialization, universality is also very high. Therefore, some people have the national standard of a class of fasteners called standard fasteners, or simply referred to as standard parts.

new fastener design 2023

Applications

Fasteners are a kind of mechanical parts which are widely used for fastening connections. A wide variety of fasteners can be seen on all kinds of machinery, equipment, vehicles, ships, railways, Bridges, buildings, structures, tools, instruments, meters and supplies.

It is characterized by a wide variety of specifications, different performance uses, and standardization, serialization, universality of the species degree is also very high. Therefore, some people have the national standard of a class of fasteners called standard fasteners, or simply referred to as standard parts.

Fasteners are the most widely used mechanical base parts. Along with our country joined WTO in 2001 and entered international trading big country cavalcade. A large number of our fastener products are exported to all countries in the world, and the fastener products from all countries are constantly pouring into the Chinese market.

As one of the products with large import and export volume in China, fasteners are of great practical and strategic significance for promoting Chinese fastener enterprises to go to the world and promoting fastener enterprises to participate in international cooperation and competition. Due to the specifications, dimensions, tolerances, weight, performance, surface conditions, marking methods of each specific fastener product, as well as the specific requirements of acceptance inspection, marking and packaging items.

hook and loop fastener screws

Common testing instrument

The most important link in the development and design of fasteners is quality control. There are several key points from the incoming product to the finished product delivery, and these key points have different inspection methods. First of all, the feed is related to appearance, size, elements, performance, harmful substance detection and so on; The process is more about appearance, size, percussion experiment, forging streamline; Heat treatment is more about appearance, hardness, torque, tension, metallography and so on; Surface treatment is more about some hydrogen embrittlement test, coating, salt spray, etc., including shipment has a hazardous substance detection. In size and appearance detection, common are quadratic, contour measuring instrument, CMM, image sorting machine (this is a full selector); Mechanical and chemical testing, the main hardness machine (Lowe and Vickers), tensile machine, metallographic microscope; Material testing, there is a spectrum analyzer, salt spray testing machine.

Parts

It usually includes the following 12 types of parts:

  1. Bolt: A type of fastener consisting of a head and a screw (a cylinder with external thread), which needs to be matched with the nut for fastening the connection of two parts with a through the hole. This type of connection is called a bolt connection. If the nut is unscrewed from the bolt, the two parts can be separated, so the bolt connection is a detachable connection.
  2. stud: no head, only both ends of the class of fasteners with external thread. To be connected, one end must be screwed into the part with the internally threaded hole, the other end through the part with the through hole, and then the nut screwed on, even if the two parts are tightly joined into a single piece. This type of connection is called a stud connection and is also a detachable connection. It is mainly used for the occasion that one of the connected parts is thick, requires compact structure, or is not suitable for bolted connection due to frequent disassembly.
  3. screw: is also composed of a head and screw two parts of a class of fasteners, according to the use can be divided into three types: machine screw, set screw, and special purpose screw. Machine screws are mainly used for fastening connection between a part with a tight threaded hole and a part with a through the hole, without the need for nuts (this connection form is called screw connection, and also belongs to detachable connection; It can also be used with nut for fastening connection between two parts with through holes. Setting screws are used to fix the relative position between two parts. Special purpose screws such as ring screws for lifting parts.
  4. nut: with an internal thread hole, the shape is generally shown as a flat hexagon column, there are also flat square columns or flat cylinders, with bolts, studs, or machine screws, used to fasten the connection of two parts, and make it a whole.
  1. Self-tapping screw: similar to machine screws, but the thread on the screw is a special self-tapping screw thread. It is used to fasten and connect two thin metal components to make them a whole. Small holes need to be made in advance on the components. Because of the high hardness of this kind of screw, it can be directly screwed into the holes of the components to form a response internal thread in the components
  1. Wood screw: It is also similar to a machine screw, but the thread on the screw is special wood screw thread, which can be directly screwed into the wood member (or part), used to fasten a metal (or non-metal) part with a through the hole to a wood member. This connection is also a detachable connection.
  1. Washer: A type of fastener in the shape of a flat ring. Is placed between the supporting surface of the bolt, screw, or nut and the surface of the connecting part to increase the contact surface area of the connected part, reduce the pressure per unit area and protect the surface of the connected part from being damaged; Another type of elastic washer can also act to prevent the nut from loosening.
  1. Retaining ring: it is installed in the shaft slot or shaft hole slot of the machine and equipment and plays the role of preventing the parts on the shaft or hole from moving around.
  1. Pin: mainly for parts positioning around, some can also be used for parts connection, fixing parts, power transmission or locking fasteners.
  1. Rivet: A type of fastener consisting of two parts, a head and a nail rod, used to fasten and connect two parts (or members) with holes so that they become a whole. This form of connection is called rivet connection, riveting for short. Belongs to a non-detachable link. Because if the two parts that are joined together are separated, the rivets on the parts must be broken.
  1. Components and connecting pairs: Assemblies are a type of fasteners supplied in combination, such as machine screws (or bolts, self-supplied screws) and flat washers (or spring washers, locking washers); Connection pair refers to a type of fastener supplied by a combination of special bolts, nuts, and washers, such as a high-strength large-hexagonal bolt connection pair for steel structures.
  1. Welding nail: a different type of fastener composed of a nail rod and a nail head (or no nail head), which is fixed on a part (or component) by welding, so that it can be connected with other parts.
stainless steel metal fasteners screws

Lock

Fasteners include bolts, studs, screws, nuts, washers, and pins. Locking or biting often occurs on fasteners made of stainless steel, aluminum alloy, and titanium alloy. These metal alloys themselves have anti-corrosion properties. When the surface is damaged, a thin oxide layer is created on the metal surface to prevent further corrosion. When the stainless steel fastener is locked, the pressure and heat generated between the teeth will destroy the oxide layer, causing the metal threads to block or shear, and then the phenomenon of adhesion. When this occurs continuously, the stainless steel fastener will lock completely and cannot be removed or relocked. Usually, this series of blocking _ cutting _ adhesive _ locking action takes place in just a few seconds, so the correct understanding of the use of this type of fastener can prevent this phenomenon.

  1. Before use, confirm whether the mechanical properties of the product can meet the requirements, such as the tensile strength of the screw and the guaranteed load of the nut. The length of the screw should be selected appropriately, with 1-2 teeth spacing of the nut exposed after tightening. b. Before use, check whether the thread is rough and whether there is iron filings or dirt between the threads, which often lead to locking. c. The fasteners can be lubricated before use. It is recommended to use butter, molybdenum disulfide, mica, graphite or talcum powder for lubrication.
  2. The speed and force of screwing should be appropriate, not too fast and too large. Choose torque wrench or socket wrench as far as possible, and avoid using adjustable wrench or electric wrench. Too much speed will cause the temperature to rise rapidly and cause the lock. b. In the direction of force, the nut must be screwed perpendicular to the axis of the screw. c. The use of washers can effectively prevent the problem of overlocking.

Standard

Stainless steel fastener product size standards: specify the content of the basic size of the product. Product with thread.

No standards in terms of product technical conditions. Specifically, it also includes the following standards:

Standards for tolerances of fastener products: Specify tolerances of product size and form and position.

Standards for mechanical properties of fastener products: specify the marking method of mechanical properties grade of products and the content of mechanical properties items and requirements; Some fastener products will change this content to product material performance or work performance.

Standards for surface defects of fastener products: specify the types of surface defects and specific requirements of products.

The standard for surface treatment of fastener products: specify the type and specific requirements of surface treatment of products.

Fastener product test standards: specify the above performance requirements of the test content.

Standards for acceptance inspection, marking, and packaging of stainless steel fasteners.

The standard for marking method of fastener products: specify the content of the complete marking method and simplified marking method of the product.

Other standards for stainless steel fasteners, such as fastener terminology standards, fastener product weight standards, etc.

Machinery industry

The machinery industry is one of the main users of fasteners. Due to the late recognition of the important position of mechanical foundation parts in the machinery industry in China, the long-term lack of investment resulted in the poor foundation of the whole industry, a thin foundation, and weak strength.

Especially with the improvement of China’s main engine level, the bottleneck phenomenon of mechanical base parts lagging behind the main engine is increasingly apparent. Today, although in the technology introduction, technological transformation, scientific research, and development, the state has given a certain amount of support, compared with the current market demand and foreign level, there is still a large gap, in specific performance in product varieties, low level, unstable quality, the early failure rate is high, poor reliability.

Fasteners as the main basic parts of the mechanical industry, and the development of the mechanical industry, also put forward higher requirements for fastener products. Domestic standard fasteners have been in oversupply, and high-grade fasteners (high temperature, special shape, titanium plastic composite, special performance fasteners) are in short supply, but also rely on imports. The National Machinery Administration lists “standard fasteners” as restricted products and “high strength deformed fasteners” as currently encouraged products. With the improvement of the national industrialization level and technical progress, the use of high-strength fasteners is gradually increasing.

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