Default General Tolerance Standards

  • CNC Milling service does not display dimensions or tolerances other than diameter information and length when 3D CAD data is uploaded, assuming that the customer specifies their desired tolerances.

Default General Tolerance Standards for Machined Dimensions (Excerpts from JIS B 0405:1991/JIS B 0419:1991)

  • The following standards are applied to the datum according to machining standards.
  • The datum can be positioned at any location.
Length, Excluding Chamfer, Dimensional Tolerances

[mm]

Tolerance Grade Base Dimensions
Symbol Description ≥0.5 ≤3 >3 ≤6 >6 ≤30 >30 ≤120 >120 ≤400 >400 ≤1000
m Medium ±0.1 ±0.1 ±0.2 ±0.3 ±0.5 ±0.8
Tolerances for Chamfer Length Dimensions (Corner Radius and Corner Chamfer Dimensions)

[mm]

Tolerance Grade Base Dimensions
Symbol Description ≥0.5 ≤3 >3 ≤6 >6
C Coarse ±0.4 ±1 ±2
Angle Dimensional Tolerances
Tolerance Grade Length of the Shorter Angle Edge
Symbol Description ≤10 >10 ≤50 >50 ≤120 >120 ≤400 >400
m Medium ±1° ±30’ ±20’ ±10’ ±5’
General Tolerances of Perpendicularity

[mm]

Tolerance Grade Nominal Length of the Shorter Edge
Symbol ≤100 >100 ≤300 >300 ≤1000 >1000 ≤5000
K 0.4 0.6 0.8 1
*This does not apply if Hardening is included in the process.
Geometric Tolerance Standards for Lathe Machining
The following tolerance values are also guaranteed for Hardening. However, this may not apply to certain product shapes such as thin-walled products, long products, and products with a high material removal rate.

[mm]

Geometric Tolerance Completed on One Side with Maximum Diameter as the Origin Geometric Tolerance for Both Sides with Maximum Diameter as the Origin
Outer Diameter Inner Diameter Outer Diameter Inner Diameter L (Length) K (Geometric Tolerance Value)
Perpendicularity Perpendicularity_Outer Diameter Perpendicularity_Inner Diameter Perpendicularity_両側_Outer Diameter Perpendicularity_両側_Inner Diameter L ≦ 100 0.06
100 < L ≦ 300 0.1
300 < L ≦ 500 0.15
L < 500 0.2
Coaxiality Coaxiality_Outer Diameter Coaxiality_Inner Diameter Coaxiality_両側_Outer Diameter Coaxiality_両側_Inner Diameter L ≦ 100 0.1
100 < L ≦ 300 0.2
300 < L ≦ 500 0.3
L < 500 0.5
Parallelism Parallelism_Outer Diameter Parallelism_Inner Diameter Parallelism_両側_Outer Diameter Parallelism_両側_Inner Diameter L ≦ 100 0.06
100 < L ≦ 300 0.1
300 < L ≦ 500 0.15
L < 500 0.2
Roundness Roundness_Outer Diameter Roundness_Inner Diameter
  • *Roundness should be equal to the dimensional tolerance value for the diameter, but it must not exceed the specified tolerance value of circular runout in the radial direction.
  • e.g.1 : ø100 without tolerance = Roundness 0.1 mm
  • e.g.2 : ø100 with ±0.02 mm tolerance = Roundness 0.04 mm

Tip

Reasons for disparities in precision between one side and both sides
    • ■ One side
​
    • Workpiece does not need replacing, and machining is completed in one direction
​​
    • ■ Both sides
​
    • Workpiece needs replacing, and machining is in two directions
​​
片側とは 両側とは​

[mm]

Tolerance Grade Nominal Length
Symbol ≤10 >10 ≤30 >30 ≤100 >100 ≤300 >300 ≤1000
K 0.05 0.1 0.2 0.4 0.6
*This does not apply if Hardening is included in the process.

Surface Roughness

  • The surface roughness is √Ra6.3 (√Rz25).
  • The surface roughness is displayed in the lower left corner of the 3D viewer, and the roughness symbol can be customized in the user settings.
  • You can select √Ra6.3/3.2 for surface roughness in User Settings > Initial Quotation Conditions.
 

Tip

As shown in the figure below, you can select the value for surface roughness from √Ra6.3/3.2 in the tree view. You can also change the default values in Initial Quotation Conditions in User Settings.

External Corners, Cylinder Internal Corners, Chamfered Edge

  • Models with external corners of less than C/R0.5 will have C/R 0.1 to 0.4 mm or edge breaking.
  • If the internal corners of the cylinder are smaller than 0.5, the tool edge will leave a finish of R0.4 mm.

Caution

Specification of “no chamfering” is not supported.

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