To ensure the efficiency of mechanical machining and the qualification of manufactured products, the following four principles must be followed during the machining process.

1.Principle of Datum First: Machine the precision datum surfaces first. This provides a positioning reference for subsequent operations, ensuring machining accuracy when other surfaces are processed based on this datum.

2.Principle of Separating Rough and Finish Machining: Remove most of the material during rough machining, and ensure dimensions and surface quality during finish machining. This prevents stresses and deformations from rough machining from affecting the accuracy of finish machining.

3.Principle of Surfaces Before Holes: For workpieces such as brackets that require both surface and hole machining, machining the surfaces before the holes helps minimize errors in hole accuracy.

4.Principle of Finishing Operations: This principle refers to processes such as grinding and polishing, which are typically performed after the entire structure of the product is completed.