Main causes and manifestations of failure of mechanical parts

Date：2022-07-21 17:41:28Views：910

The failure of mechanical parts refers to the partial or complete loss of design function of parts in the process of use. The parts are completely damaged and cannot continue to work; Or the parts have been seriously damaged, and if you continue to work, you will lose safety; Or although it can work safely, it has lost the design accuracy and other phenomena, which belong to failure.

In order to prevent the failure of parts, it is necessary to analyze the failure of parts, that is, by judging the failure form of parts, determining the failure mechanism and cause of parts, selecting materials pertinently, determining a reasonable processing route, and putting forward measures to prevent failure.

1. Failure form of mechanical parts

The common failure modes of mechanical parts can be divided into three types: excessive deformation failure, fracture failure and surface damage failure.

(1) Excessive deformation failure: failure caused by excessive deformation of parts beyond the allowable range. It mainly includes excessive elastic deformation, plastic deformation and creep at high temperature.

(2) Fracture failure: the phenomenon that parts are separated into two or more parts that are not connected with each other due to excessive load or fatigue damage. Fracture is the most serious failure form, which includes ductile fracture failure, low temperature brittle fracture failure, fatigue fracture failure, creep fracture failure and environmental fracture failure.

(3) Surface damage failure: failure caused by damage or dimensional change on the surface of parts due to relative friction on the surface or corrosion by environmental media when the parts are working. It mainly includes surface wear failure, corrosion failure, surface fatigue failure and other forms.

It should be pointed out that the same kind of mechanical parts often work in more than one failure mode. However, generally, one way plays a leading role in causing the failure of parts. The core problem of failure analysis is to find out the main failure mode.

2. Causes of failure of mechanical parts

There are many and complex factors that cause the failure of mechanical parts, including structural design, material selection, material processing and manufacturing, product assembly, use and maintenance, etc.

(1) Unreasonable design: it mainly refers to the incorrect or unreasonable structure and shape of parts, such as notches, small arc corners, transition areas of different shapes, etc. On the other hand, it refers to the insufficient estimation of the working conditions and overload conditions of the parts, resulting in the insufficient actual working capacity of the parts, resulting in the early failure of the parts.

(2) Unreasonable material selection: the failure form of parts is judged incorrectly in the design, and the selected material performance cannot meet the needs of working conditions; The performance index on which the material is selected cannot reflect the resistance of the material to the actual failure form, and the wrong material is selected; The selected materials are of poor quality and cannot meet the design requirements due to unqualified composition or performance, which are all unreasonable materials.

(3) Unreasonable processing technology: improper processing technology of parts may produce various defects, resulting in early failure of parts in the process of use. Such as overheating, overburning and banded structure during hot processing; Decarburization, deformation and cracking occur during heat treatment; Deep knife marks and grinding cracks appear during cold machining.

(4) Improper installation and use: the assembly and installation process does not meet the technical requirements, such as too tight and loose fitting during installation, inaccurate alignment, unstable fixation, etc., which may lead to the parts not working properly or premature failure; In addition, illegal operation, overload, overspeed, untimely repair and maintenance during use will also cause premature failure of parts.

The above is the failure related content of mechanical parts compiled by the core detection team. I hope it will be helpful to you. Shenzhen Chuangxin Online Testing Technology Co., Ltd. is a well-known professional testing institution for electronic components in China, with 3 standardized laboratories covering an area of more than 1000 square meters. The scope of testing services covers: electronic component testing and verification, IC authenticity identification, product design and material selection, failure analysis, function testing, factory incoming material inspection, component X-ray testing, taping and other test items.