This standard specifies the machining allowances and tolerances for open die forgings - shaft without steps, shaft with steps and single throw crankshaft, as well as permissible limit deviation of forging without machining.
This standard is applicable to open die forgings of carbon steel and alloy steel with carbon content not exceeding 0.9% and the total content of other alloying constituents not exceeding 4%.
If the open die forging exceeds the specified range in this standard, its allowance and tolerance are determined through negotiation between the supplier and the purchaser separately.
2 Normative References
The following normative documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments (excluding corrections), or revisions, of any of these publications do not apply to this standard. However parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies.
GB/T 21469 Machining Allowances and Tolerances for Steel Open Die Forgings on Hammer - General Requirement
JB/T 9179.2 Machining Allowance and Tolerance of Open Die Forgings on Hydraulic Press - Round Shaft, Square Shaft and Rectangular Cross-section
JB/T 9179.3 Machining Allowance and Tolerance of Open Die Forgings on Hydraulic Press - Stepped Shaft
3 Open Die Forgings - Shaft without Steps
3.1 The dimension L of open die forgings - shaft without steps, with round, square, hexagon or rectangular (B/H ≤5) cross-section shall be greater than 2.5D (or A, B, S).
3.2 The machining allowances and tolerances for open die forgings - shaft without steps shall be in accordance with Figure 1 and Table 1.
