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Linear Tolerances, As Cast.
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Simple linear tolerances where parting line not involved.
The tolerance on a dimension "A" will be the value shown in
the tables below. This tolerance will increase where the parting line of
the die, or die moving parts affect the dimension.
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Tolerances
for Critical dimensions in mm
(One or two Decimal Places) |
| Length
of Dimension "A" |
Diecasting
Alloy |
| Zinc |
Aluminium |
Magnesium |
Basic
tolerance.
Up to 25mm |
+/- 0.08 |
+/- 0.10 |
+/- 0.10 |
Additional
tolerance
for each additional 25mm. |
Over 25 mm
to 300 mm |
+/- 0.03 |
+/- 0.04 |
+/- 0.04 |
| Over 300 mm |
+/- 0.03 |
+/- 0.03 |
+/- 0.03 |
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Tolerances
for Non-Critical dimensions in mm
(Un-toleranced or rounded to nearest whole number.) |
| Length
of Dimension "A" |
Diecasting
Alloy |
| Zinc |
Aluminium |
Magnesium |
Basic
tolerance.
Up to 25mm |
+/- 0.25 |
+/- 0.25 |
+/- 0.25 |
Additional
tolerance
for each additional 25mm. |
Over 25 mm
to 300 mm |
+/- 0.04 |
+/- 0.05 |
+/- 0.05 |
| Over 300 mm |
+/- 0.03 |
+/- 0.03 |
+/- 0.03 |
Note that the values represent normal production
practice at the most economical level. Greater accuracy should only be
specified where required to avoid additional costs.
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Parting line tolerances
Parting line tolerances, in addition to Linear dimensional tolerances,
must provide for the movement of the die. The "Projected Area" is the area of the diecasting in square
centimeters at the parting plane.
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| Additional
Tolerance in Millimetres |
Projected
Area of
Diecasting in cm2 |
Diecasting
Alloy |
| Zinc |
Aluminium |
Magnesium |
| Up to 325 cm2 |
+/- 0.10 |
+/- 0.13 |
+/- 0.13 |
| 325 to 650 cm2 |
+/- 0.15 |
+/- 0.20 |
+/- 0.20 |
| 650 to 1,300 cm2 |
+/- 0.20 |
+/- 0.30 |
+/- 0.30 |
| 1,300 to 2,000 cm2 |
+/- 0.30 |
+/- 0.40 |
+/- 0.40 |
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Moving Die Part Tolerances.
 Moving
die part tolerances, in addition to Linear dimensional tolerances must
be provided when a moving die part affects the dimension. The
"Projected Area" is the area, in square centimetres of the
portion of the diecasting affected by the moving die part.
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| Additional
Tolerance in Millimetres |
Projected
Area of
Diecasting in cm2 |
Diecasting
Alloy |
| Zinc |
Aluminium |
Magnesium |
| Up to 65 cm2 |
+/- 0.10 |
+/- 0.13 |
+/- 0.13 |
| 65 to 130 cm2 |
+/- 0.15 |
+/- 0.20 |
+/- 0.20 |
| 130 to 325 cm2 |
+/- 0.20 |
+/- 0.30 |
+/- 0.30 |
| 325 cm2 and Upwards |
+/- 0.30 |
+/- 0.40 |
+/- 0.40 |
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Tolerance for Flatness.
The flatness should be measured with a feeler gauge from three widely
separated points on a continuous plane surface of the diecasting. In the
table below, "Dimension" means the maximum dimension
(Diameter of a circular surface or diagonal of a rectangular surface.)
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Flatness
Tolerances.
As Cast. (mm) |
| Dimension of diecasting. |
All Alloys |
Basic Tolerance.
Up to 75 mm |
0.20 |
Additional Tolerance.
For every 25 mm. |
0.08 |
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