Why are there tolerances on drawings?
In manufacturing and engineering design, the main purpose of marking tolerances on drawings is to ensure that the manufactured parts meet the design requirements while maintaining dimensional and shape accuracy within a certain acceptable range. Here are some important reasons for marking tolerances on drawings:
Assembly requirements: A product usually contains multiple parts, and these parts need to be assembled. By marking tolerances on drawings, it is ensured that the fit and assembly of different parts is feasible. Tolerances allow certain variations so that parts can fit together correctly without being too large or too small, causing assembly difficulties or impairing functionality after assembly.
Production process: In actual manufacturing, it is difficult to ensure that each part is completely accurate to the dimensions specified in the design. Factors such as the physical properties of the material and the accuracy of the manufacturing equipment all affect the size of the final part. By marking tolerances on drawings, variations during the manufacturing process can be fully taken into account, ensuring that the final product is within acceptable limits.
Economic Considerations: Manufacturing each part with complete accuracy can result in a significant increase in production costs. Marked tolerances allow for certain manufacturing tolerances, making the manufacturing process more cost-effective while meeting product performance and quality requirements.
Material properties: Physical properties such as thermal expansion and contraction of materials will affect part size. By marking tolerances on drawings, the impact of these material properties on dimensions can be taken into account, ensuring the stability of the part under different environmental conditions.
Quality control: Tolerance marking helps establish a quality control system to ensure that dimensional deviations can be discovered and corrected in a timely manner during the production process, ensuring the quality of the final product.
Therefore, the marking of tolerances on drawings is an important design practice that helps achieve design goals, improve production efficiency, reduce costs, and ensure the quality of the final product.