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Parts inspection is an important part of the mechanical overhaul process. The machinery and its parts are inspected to determine their technical status and process measures to be taken, and then to determine the technical quality after repair. OEM high quality Customized OEM sheet metal material
- The main content of parts inspection
In mechanical maintenance, parts are generally inspected one by one, and the main contents can be divided into the following aspects:
1) Check the geometric accuracy of parts
Geometric accuracy includes dimensional accuracy and shape and position accuracy, but maintenance work sometimes does not pursue the geometric dimensions of a single part, but requires relative matching accuracy, which is often an important part of inspection work.
The shape and position accuracy commonly used in maintenance include roundness, cylindricity, concentricity, coaxiality, parallelism and perpendicularity.
2) Inspection of surface quality
The inspection of the surface quality of the parts in the maintenance work is not limited to the inspection of the surface finish, but also the inspection of the used parts surface for defects such as scratches, burns and bruises.
3) Inspection of mechanical properties
According to the characteristics of mechanical maintenance, in addition to checking the hardness of the mechanical properties of the part material, other indicators are generally not checked, but some properties encountered in the process of manufacturing and maintenance of parts, such as balance condition, spring stiffness Wait, it can’t be ignored. OEM high quality Customized OEM sheet metal material
4) Inspection of hidden defects
During the manufacturing process of the parts, there may be original defects such as slag inclusions and voids inside, and microscopic cracks may occur during use. These defects cannot be found directly from general observation and measurement, but it may have serious consequences for the machinery. Therefore, in mechanical overhaul, certain parts must be purposefully inspected comprehensively.
- Methods of parts inspection
There are many ways to inspect parts, and new inspection techniques are advancing rapidly. However, from the actual situation of mechanical maintenance work, it can be summarized into the following aspects:
1) Sensory test
This is a method to identify the technical condition of parts without inspecting the equipment and only relying on the intuitive feeling of the inspector. This method is simple, and it is also easier to distinguish the defects of a large number of dismantled parts during mechanical maintenance. However, this method cannot be used to inspect parts with high precision requirements, and requires the inspectors to have rich experience. Add WeChat: Yuki7557 to send 10G CNC tutorial.OEM high quality Customized OEM sheet metal material
2) Instrument and tool inspection method
A lot of inspection work is carried out with instruments and tools. Due to the different working principles and types of instruments and tools, they can be divided into general measuring tools, special measuring tools, mechanical instruments and meters, optical instruments, electronic instruments, etc.
3) Physical inspection method
This is a method of detecting the technical condition of parts by using physical quantities such as electricity, magnetism, light, sound, and heat through changes caused by the workpiece. The realization of this method is also combined with the instrument and tool inspection method. This method is usually used to check the hidden defects inside the part without damaging the part itself, and it is commonly known as non-destructive testing. Non-destructive testing technology is developing day by day in recent years, and magnetic particle method, penetration method, ultrasonic wave and ray method are widely used in production. OEM high quality Customized OEM sheet metal material
- Feeling inspection of parts
1) Visual inspection
The main contents of the sensory inspection during visual inspection, such as fractures and macroscopic cracks of parts, obvious bending and twisting deformation, burns and scratches on the surface of parts, severe wear, etc., can usually be directly identified with the naked eye. In order to improve the accuracy of visual inspection, it can also be carried out with the aid of a magnifying glass in some cases. In order to make up for the lack of visual inspection of the interior of some walls, it can also be inspected with the help of optical fiber as a light transmission endoscope.
2) Auditory examination
The method of judging whether mechanical parts are defective or not by the hearing ability of the human ear is a long-standing inspection method. Routine inspections of railway vehicles have been used in this way for decades. During inspection, the inspected workpiece is knocked. When the parts are free of defects, the sound is clear and crisp, and when there are internal shrinkage holes, the sound is low, and if there is a crack inside, the sound is hoarse. with or without defects. OEM high quality Customized OEM sheet metal material
3) Tactile inspection
Touch the surface of the part with your hand to feel its surface condition. Shake the fittings relatively, and you can feel its fitting condition. By touching the parts of a running machine, you can feel its heating status, so as to judge its mechanism status.
- Measures to ensure the quality of parts inspection
1) Strictly master technical standards
Most mechanical parts and fittings have specified technical standards, which are the main basis for inspection work. If there is no reliable basis for thinking that the standards need to be revised, these standards must be strictly followed, and the standards must never be lowered. Unqualified parts are put into service.
2) Select inspection equipment according to the requirements of the inspection object
In addition to selecting the inspection equipment according to the nature and scope of the inspection items, special attention should be paid to the accuracy requirements. For example, when measuring the length, when the accuracy is required to be in the range of 1mm, a steel ruler can be used; when the accuracy is required to be in the range of 0.1mm, a vernier caliper is generally used; when the accuracy of 0.01mm is required, a micrometer, Sub-meter; when the accuracy of 0.001mm is required, a comparator is required. If the accuracy of the inspection equipment is lower than the accuracy required by the measured object, it cannot meet the quality inspection requirements at all, and care must be taken to prevent it. OEM high quality Customized OEM sheet metal material
3) Improve the technical level of inspection operation
The technical level of inspection operation directly affects the inspection accuracy. Whether it is the self-inspection of the maintenance personnel or the inspection of the full-time inspector, the operator is required to be proficient in the inspection equipment used and the inspection requirements of the inspection object. To this end, attention should be paid to the improvement of inspection technology, special training should be carried out for the use of special and important inspection equipment, and various inspectors should be relatively stable.
4) Reduce inspection errors
There are inevitably errors in any inspection results, and the impact is multi-faceted. Therefore, prevention and elimination should be carried out from the following aspects:
▶Inspection equipment has its own accuracy level, which should be calibrated regularly and maintained to maintain its due accuracy.
▶The error caused by temperature is corrected. Among the environmental factors that affect the inspection accuracy, the influence of temperature is the largest. For example, the influence of linear expansion in length inspection, and the property change caused by temperature change in electronic devices, etc., necessary corrections should be made in more precise measurements. OEM high quality Customized OEM sheet metal material
▶The errors caused by improper operation or inaccurate reading are mostly accidental errors, so the average value of multiple measurements can be taken, which can greatly reduce its degree of error.
5) Establish sound and reasonable inspection rules and regulations
A reasonable inspection system is an organizational guarantee for doing a good job in inspection work. It is necessary to establish a post responsibility system, clarify responsibilities, and ensure that everyone checks, and recommends certain acceptance and handover systems and measurement and calibration systems. OEM high quality Customized OEM sheet metal material
