Selection of shims

Shim blocks generally do not have specific specifications; they are usually custom-made according to the equipment’s weight as indicated in the design drawings. However, the commonly used specifications include 100*50, 120*60, 120*80, 150*80, 160*80, 200*100, 200*120, 200*15, 240*120, 300*150, etc. The precision of shims is generally △12.5 for shims with ordinary roughness; △6.3 for shims with medium precision; △3.2 for shims with high precision; and △0.8 for precision shims. Its purpose is to prevent the equipment from tilting or vibrating during operation, ensuring that it remains level and stable, thereby reducing wear on the equipment and guaranteeing its proper functioning as well as high precision in the processing of workpieces. General rules for inclined shims and flat shims in mechanical equipment installation projects: (1) The material for inclined shims can be ordinary carbon steel ； The material for flat shims can be ordinary carbon steel or cast iron. (II) The fabrication of inclined shims and flat shims shall meet the following requirements: 1. The specifications and dimensions shall be in accordance with the regulations. 2. The thickness H can be determined based on actual requirements as well as the material’s properties and specifications. The slope of the shimming iron should be 1/10 to 1/20 ； For equipment with significant vibration or precision devices, the slope of the shims can be 1/40. (III) When inclined shims are used, their code should be used in conjunction with flat shims of the same code. (IV) Shims should be used in pairs, and pairs of shims should have the same slope.