Allowance
1 Scope
This standard specifies the steel die forgings (hereinafter referred to as "forgings") tolerances and machining allowance levels and technical content.
This standard applies to die forging hammers, hot die forging presses, screw presses, flat forging machines and other forging equipment production of structural steel die forgings.
Other steel forgings can also be used as reference. This standard applies to forgings with a mass less than or equal to 500kg and a length (maximum size) less than or equal to 2500mm.
2 Level of Tolerances and Machining Allowances
2.1 The tolerance is divided into two levels: ordinary level and precision level.
Ordinary tolerances apply to forgings that meet the technical requirements of general die forging processes.
Precision tolerances apply to forgings with higher technical requirements and can be used for the full size of a forging and for local dimensions.
2.2 The Machining Allowance is Only One Level.
3 Technical Content
3.1 The main factors to determine forging tolerance and machining allowance
3.1.1 Forging Mass mf
Forging quality are estimated according to the following procedure:
The basic dimensions of the part drawing → Estimate the machining allowance → Draw the forging drawing → Estimate the forging quality, and determine the tolerance and machining allowance according to this quality check table.
3.1.2 Forging Shape Complex Factor S
The forging complex shape factor is the ratio of the forging mass mf to the corresponding forging external shell mass mN, see Equation (1):
S=mf/mN (1)
The forging profile containment mass mN is the calculated mass of the cylinder or cuboid containing the largest profile of the forging as the entity, and is calculated according to formula (2) or formula (3):
a) Round forgings (Figure 1)
mN=1/4•π•d2•h•ρ (2)
Where:
ρ——Steel density(7.85g/cm3)
Foreword i
1 Scope
2 Level of Tolerances and Machining Allowances
3 Technical Content
Annex A (Informative) Forging Tolerance Application Example
Allowance
1 Scope
This standard specifies the steel die forgings (hereinafter referred to as "forgings") tolerances and machining allowance levels and technical content.
This standard applies to die forging hammers, hot die forging presses, screw presses, flat forging machines and other forging equipment production of structural steel die forgings.
Other steel forgings can also be used as reference. This standard applies to forgings with a mass less than or equal to 500kg and a length (maximum size) less than or equal to 2500mm.
2 Level of Tolerances and Machining Allowances
2.1 The tolerance is divided into two levels: ordinary level and precision level.
Ordinary tolerances apply to forgings that meet the technical requirements of general die forging processes.
Precision tolerances apply to forgings with higher technical requirements and can be used for the full size of a forging and for local dimensions.
2.2 The Machining Allowance is Only One Level.
3 Technical Content
3.1 The main factors to determine forging tolerance and machining allowance
3.1.1 Forging Mass mf
Forging quality are estimated according to the following procedure:
The basic dimensions of the part drawing → Estimate the machining allowance → Draw the forging drawing → Estimate the forging quality, and determine the tolerance and machining allowance according to this quality check table.
3.1.2 Forging Shape Complex Factor S
The forging complex shape factor is the ratio of the forging mass mf to the corresponding forging external shell mass mN, see Equation (1):
S=mf/mN (1)
The forging profile containment mass mN is the calculated mass of the cylinder or cuboid containing the largest profile of the forging as the entity, and is calculated according to formula (2) or formula (3):
a) Round forgings (Figure 1)
mN=1/4•π•d2•h•ρ (2)
Where:
ρ——Steel density(7.85g/cm3)
Contents of GB/T 12362-2016
Foreword i
1 Scope
2 Level of Tolerances and Machining Allowances
3 Technical Content
Annex A (Informative) Forging Tolerance Application Example
