Casting Dimensional Tolerance Class
Casting dimensional tolerance levels are usually defined according to specific standards and specifications. ISO 8062 and ANSI/ASME Y14.5 are two common standards that define grade systems for dimensional tolerances in castings.
The ISO 8062 standard defines dimensional tolerance classes for castings for international use. The standard uses letters and numbers to represent different tolerance levels, as shown in the following example:
1. IT series: The IT series is a series suitable for engineering castings with higher precision requirements, and its tolerance levels increase from IT1 to IT16. IT1 indicates a very tight tolerance range, while IT16 indicates a relatively loose range.
2. CT series: CT series is a series suitable for precision casting parts, and its tolerance levels increase from CT1 to CT14. These tolerance levels are typically tighter than the IT series.
3. HT series: HT series is a series suitable for high-strength castings, and its tolerance levels increase from HT1 to HT12. These tolerance levels are typically looser than the IT series.
Additionally, the ANSI/ASME Y14.5 standard defines dimensional and tolerance standards adopted by the American National Standards Institute (ANSI) and the American Society of Mechanical Engineers (ASME). This standard uses a different system in which tolerance levels are represented by GDT (Geographical Dimensions and Tolerances) notations, usually represented by a combination of letters and numbers, such as MMC (Maximum Material Condition) and LMC (Minimum Material Condition).
The specific casting dimensional tolerance level should be selected based on the requirements of the project and application and needs to be determined in conjunction with the designer, manufacturer and quality control department of the part. Different industries and applications may use different standards and grade systems, so adjustments will need to be made on a case-by-case basis.