Standard parts
Standard parts refer to commonly used components whose structure, dimensions, drawing methods, markings, and other aspects have been completely standardized and are produced by specialized factories, such as threaded parts, keys, pins, rolling bearings, etc. In a broad sense, it includes standardized fasteners, connectors, transmission parts, seals, hydraulic components, pneumatic components, bearings, springs, and other mechanical parts. In a narrow sense, it only includes standardized fasteners. The term "standard parts" commonly used domestically is an abbreviation for standard fasteners, representing a narrower concept, but the existence of the broader concept cannot be excluded. In addition, there are industry-specific standard parts, such as automotive standard parts and mold standard parts, which also fall under the broader category of standard parts.
Basic Introduction
In a broad sense, standard parts refer to mechanical parts and components with clearly defined standards. The standards used mainly include Chinese national standards (GB), American Society of Mechanical Engineers (ANSI/ASME) standards, and other standards such as Japanese (JIS) and German (DIN) are also widely used around the world.
Mechanical parts and components that are highly standardized and have strong industry applicability are also known as general-purpose parts.
Standard parts in a broad sense include fasteners, connectors, transmission parts, seals, hydraulic components, pneumatic components, bearings, springs, etc., all of which have corresponding national standards and are highly versatile across industries.
The concept of "industry standard parts" is a commonly used term within the industry and is not explicitly defined. Common examples of industry standard parts include mold standard parts and automotive standard parts. When a product is widely used in the industry, it is called a general-purpose part. Standards for general-purpose parts are usually formulated by leading companies in the industry and widely accepted within the industry. In this way, the company standard becomes the de facto industry standard, and thus can be called an industry standard part.
Standard mold components include injection mold bases, ejector pins and ejector tubes, and hot runner molds.
There are many types of standard automotive parts, such as spark plugs, door locks, shock absorbers, and automotive fasteners. For details, please refer to the "Automotive Standard Parts Handbook".
The more mature an industry is, the higher its degree of standardization and generalization, the more standard parts it will have, and the lower its industry costs will be. However, it is important to avoid excessive standardization, which can lead to a monotonous range of products and low-end competition.
Broadly speaking
Connecting parts (also known as fasteners) include threaded connections (also called fasteners), hub connections, pin connections, riveted parts, adhesive connections, welded parts, etc.
Transmission components, belt transmission components, chain transmission components
Gear transmission components: including involute cylindrical gears, bevel gears, and worm gears, etc.
Friction wheel, reducer, continuously variable transmission, shaft extension
Couplings, clutches and hydraulic couplings
Pneumatic transmission components, hydraulic transmission components
Flywheel (similar to a transmission component, but actually an energy storage component), bearing, sliding bearing, rolling bearing
Springs, cylindrical springs, disc springs, rubber springs, leaf springs, ring springs, and similar products
These components are not exactly standard mechanical parts, but they are highly standardized and closely related to the machinery industry; they include: lubricating oil, grease and lubrication devices, lifting and handling parts and operating parts (pulleys and ropes, etc.), electric motors and limit switches, etc.
In addition, there are commonly used materials such as cast iron, cast steel, steel and steel products, copper and alloys, aluminum and alloys, engineering plastics, rubber products, composite materials and other non-metallic materials and products, which are highly standardized, universal and relevant.
Narrowly defined standard parts
In a narrow sense, standard parts refer to standardized fasteners, which are actually a type of connector. However, due to their wide variety and application, they are often considered a separate category in practice, or even simply referred to as standard parts. They typically include the following 12 types of parts:
1. Bolt: A type of fastener consisting of a head and a threaded shank (a cylinder with external threads), which requires a nut to fasten two parts with through holes. This type of connection is called a bolted connection. Since the two parts can be separated by unscrewing the nut, a bolted connection is a detachable connection.
2. Stud: A type of fastener without a head, consisting only of threads at both ends. For connection, one end must be screwed into a part with an internally threaded hole, and the other end passes through a part with a through hole. Then, a nut is screwed on, thus securing the two parts together as a single unit. This type of connection is called a stud connection and is a detachable connection. It is mainly used in situations where one of the connected parts is thick, a compact structure is required, or frequent disassembly is necessary and bolted connections are not suitable.
3. Screws: Also a type of fastener consisting of a head and a shank, screws can be divided into three categories according to their use: machine screws, set screws, and special-purpose screws. Machine screws are mainly used for fastening a part with a set threaded hole to a part with a through hole, without the need for a nut (this type of connection is called a screw connection, which is also a detachable connection; they can also be used with a nut for fastening two parts with through holes). Set screws are mainly used to fix the relative position between two parts. Special-purpose screws include eye bolts for lifting parts.
4. Nut: It has an internal threaded hole and is generally shaped as a flat hexagonal prism, but it can also be flat square or flat cylindrical. It is used with bolts, studs or machine screws to fasten two parts together to make them a whole.
Special categories of nuts:
High-strength self-locking nuts are a type of self-locking nut, characterized by high strength and reliability. Primarily developed using European technology, they are used in road construction machinery, mining machinery, and vibrating equipment. Very few domestic manufacturers produce this type of product.
Nylon self-locking nuts are a new type of high vibration-resistant and anti-loosening fastening part, applicable to various mechanical and electrical products in temperatures ranging from -50°C to 100°C. The demand for nylon self-locking nuts has surged in aerospace, aviation, tank, mining machinery, automotive transport machinery, agricultural machinery, textile machinery, electrical products, and other types of machinery. This is because their vibration-resistant and anti-loosening performance is significantly higher than other anti-loosening devices, and their vibration life is several times or even dozens of times longer. Currently, over 80% of mechanical equipment accidents are caused by loose fasteners, especially serious in mining machinery. Using nylon self-locking nuts can prevent major accidents caused by loose fasteners.
5. Self-tapping screws: Similar to machine screws, but the threads on the shank are special self-tapping screw threads. Used to fasten two thin metal components together as a single unit. Small holes need to be pre-drilled in the components. Due to their high hardness, these screws can be directly screwed into the holes in the components, creating the corresponding internal threads. This type of connection is also considered a detachable connection.
6. Wood screws: Similar to machine screws, but with special wood screw threads. They can be directly screwed into wooden components (or parts) to securely connect a metal (or non-metal) part with a through hole to a wooden component. This type of connection is also detachable.
7. Washers: A type of fastener with a flat, round ring shape. They are placed between the supporting surface of bolts, screws, or nuts and the surface of the connected parts, serving to increase the contact surface area of the connected parts, reduce the pressure per unit area, and protect the surface of the connected parts from damage; another type, elastic washers, can also prevent the nut from loosening.
8. Retaining ring: It is installed in the shaft groove or hole groove of a machine or equipment to prevent the parts on the shaft or hole from moving left or right.
9. Pins: mainly used for positioning parts, and some can also be used for connecting parts, fixing parts, transmitting power or locking other fasteners.
10. Rivet: A type of fastener consisting of a head and a shank, used to fasten two parts (or components) with through holes together, making them a single unit. This type of connection is called a riveted connection, or simply riveting. It is a non-detachable connection because to separate the two connected parts, the rivets on the parts must be broken.
11. Assemblies and fastener pairs: Assemblies refer to a type of fastener supplied as a set, such as a machine screw (or bolt, self-tapping screw) supplied as a set with a flat washer (or spring washer, locking washer); fastener pairs refer to a type of fastener supplied as a set of special bolts, nuts and washers, such as high-strength large hexagonal head bolt fastener pairs for steel structures.
12. Weld stud: A type of fastener consisting of a shank and a head (or no head), which is fixed to a part (or component) by welding so that it can be connected to other parts.
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