Poor size of pipe fittings is mainly due to the failure of size control throughout the production process, often caused by four key issues:
1. Raw material issues
The diameter and thickness of the raw material itself exceed the tolerance, or the material is uneven, which makes it difficult to adjust to the qualified size in subsequent processing;
2. Process loss of control
Processing links such as molding (mold wear, parameter errors), cutting (tool damage, positioning deviation), welding (thermal deformation), etc., with parameters or equipment accuracy not meeting standards;
3. Improper cooling/heat treatment
Uneven cooling rate, incorrect heat treatment temperature, and shrinkage/deformation deviation caused by thermal expansion and contraction;
4. Detect missing items
Not fully inspecting the dimensions, or the testing standards are vague, causing deviation parts to flow out.