What is tolerance？
In the field of mechanical engineering, a tolerance is the permissible variation in the value of an actual parameter. Parameters, both geometrical parameters in machining and parameters in physics, chemistry, electricity and other disciplines. For mechanical manufacturing, the purpose of developing tolerances is to determine the geometric parameters of a product so that the amount of variation is within a certain range in order to achieve the requirements of interchangeability or fit. For example, dimensional tolerance is the allowable error range of the size of the part or product; geometric tolerance, which can also be referred to as shape tolerance, is the allowable error range of the shape of the part; and fit tolerance, which defines the condition of the fit between the parts, such as clearance fit, overfill fit and transition fit.
Factors that affect tolerances include:
Raw materials and manufacturing errors. Tolerances and distortion of raw materials, as well as manufacturing errors and wear on moulded parts, can affect tolerances.
Different machining processes (e.g., cutting, cold-drawing, extruding, coiling, etc.) and the stability and accuracy of machining equipment can affect tolerances.
Environmental factors. Temperature, humidity, and vibration in the working environment can also affect tolerances.
Design requirements. Design requirements such as size, shape, and function of the part affect the setting and calculation of tolerances.
Material Properties. Physical properties such as hardness and strength of the material can affect the size and accuracy of the tolerance.
Machining quantities and surface finishes. Machining quantities and surface finishes also affect tolerances.
Equipment Capability. The machining capability and accuracy of the equipment affects the tolerances.
Product type and use. Product type and use also affect tolerances.
These factors interact with each other and together determine the size and accuracy of a product's tolerances.
