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Basic linear tolerance E1 call outs represent tolerances on one side of the parting line only. For dimensions
that cross the parting line add E2 to E1. For dimensions including features in
both the mold itself and in core add E3 to E1 and/or E2. The amount of
additional tolerance for E2 and E3 is determined by the projected area of either
the casting at the parting line for E2 or the projected area of the core in
contact with the casting for E3.
For dimensions which cross the parting line, are defined in part by core or are
in some other way additive, these tolerances may require some expansion. The
foundry should be consulted and good judgment is recommended.
Many foundries, including St. Paul Brass and Aluminum
Foundry, can produce to substantially tighter tolerances than those
published by the Trade Associations. Consult your foundry for specific
information.
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Basic Linear Tolerance |
(E1) |
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Sand |
Permanent Mold |
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Machined Tooling |
Cast & Polished Mold |
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Up thru 6 in. |
+- 0.030 |
Up through 1 in. |
+- 0.015 |
+- 0.030 |
|
Additional each inch over 6 |
+- 0.003 |
Additional each inch over 1 |
+- 0.002 |
+- 0.003 |
|
Additional Tolerance for Cores or Across Parting Lines
(E2 & E3) |
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Projected Horizontal |
Sand Casting |
Permanent Mold |
Permanent Mold |
Permanent Mold |
|
Area of Casting or Core |
Parting Line & Core |
Parting Line |
Sand Core |
Metal Core |
|
Up to 10 square inches |
+- 0.020 |
+- 0.010 |
+- 0.015 |
+- 0.010 |
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10 - 50 sq in |
+- 0.035 |
+- 0.015 |
+- 0.025 |
+- 0.015 |
|
50 - 100 sq in |
+- 0.045 |
+- 0.020 |
+- 0.030 |
+- 0.015 |
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100 - 250 sq in |
+- 0.060 |
+- 0.025 |
+- 0.040 |
+- 0.022 |
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250 - 500 sq in |
+- 0.090 |
+- 0.030 |
+- 0.050 |
+- 0.032 |
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