Dimentional Tolerance of Castings

Dimentional Torlerance of CastingsCasting dimensional tolerance refers to the allowable limit deviation of the size of each part of the casting. Many factors in the casting production process will affect the casting dimensional tolerance. At the same time, the casting dimensional tolerance will have a great impact on the casting production cost within a certain range. Therefore, scientific methods must be adopted. standards to coordinate the requirements of both supply and demand parties.

In China, casting dimensional tolerance standard GB/T 6414-1999 "Castings Dimensional Tolerances and Machining Allowances" is equivalent to ISO 8062:1994 "Castings Dimensional Tolerances and Machining Gold System". This is the basis for casting process design and inspection of casting dimensions. It specifically stipulates the dimensional tolerances of various casting alloys produced by sand casting, metal mold casting, low pressure casting, pressure casting, investment casting and other methods, including the basic dimensional tolerances of castings. Difference value, wrong type value. The tolerances stated are those normally achievable under normal production conditions. It is divided into 16 levels from fine to coarse, named CT1 to CTI6.

The standard also stipulates the dimensional tolerance levels of castings produced in batches and mass production , small batches and single pieces  for easy selection. and for casting dimensional tolerance values.

Tolerance classes for mass-produced rough castings (GB/T6414—1999) (ISO 8062:1994)

Casting Method Tolerance CT
Casting Material
Cast Steel Cast Iron Ductile Iron Malleable Cast Iron Copper Alloy Zinc Alloy Light Metal Alloy Nickel Based Alloy
 Handmade Sand Casting 11-14 11-14 11-14 11-14 10-13 10-13 9-12 11-14
Machine Moldeling Sand Casting 8-12 8-12 8-12 8-12 8-10 8-10 7-9 8-12
Metal Mold Casting or Low Pressure Casting   8-10 8-10 8-10 8-10 7-9 7-9  
Die Casting         6-8 4-6 4-7  
Investment Casting Water Glass 7-9 7-9 7-9   5-8   5-8 7-9
silica sol 4-6 4-6 4-6   4-6   4-6 4-6