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SHELLCAST FOUNDRIES INC.
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TOLERANCES
Investment castings should be designed with the manufacturing process, as well as the function of
the item in mind. Dimensional tolerances of investment castings are shown in the tables below. They
are grouped into two levels - normal and premium.
Normal tolerances are those that can be expected for production
repeatability of all casting dimensions.
Premium tolerances will require added operations at an additional cost, and should be considered
for selected dimensions which are deemed critical. In all cases, there should be close cooperation
between the investment casting supplier and the customer.
- As a general rule, normal linear tolerances are as follows:
Up to
1" - ±.010". For each additional inch
thereafter, ±0.003".
- Table 1 should be utilized as a guideline for the selection of
acceptable linear tolerances.
- Thinwall sections should be considered seperately and as a guideline
tolerances should not be closer than ±0.010" (0.25mm).
- Flatness and straightness tolerances can be held to ±0.003" (0.08mm) - .005" (0.13mm)
per linear inch. This takes account of overall flatness only. Local
depressions should not be considered within overall flatness values.
- Angular tolerances should not be specified closer than ± ½o.
- Concentricity tolerances depend on the overall geometry of the casting and each casting should
be considered individually. However, generally Table 1 is applicable.
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TABLE 1 LINEAR TOLERANCES
| DIMENSIONS | NORMAL | PREMIUM |
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up to 0.5"
up to 1"
up to 2"
up to 3"
up to 4"
up to 5"
up to 6"
up to 7"
up to 8"
up to 9"
up to 10"
Max. Variation |
± .007"
± .010"
± .013"
± .016"
± .019"
± .022"
± .025"
± .028"
± .030"
± .032"
± .035"
±
.040"
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± .003"
± .005"
± .008"
± .010"
± .012"
± .014"
± .015"
± .016"
± .017"
± .018"
± .019"
±
.020"
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up to 12mm
up to 25 mm
up to 50 mm
up to 75 mm
up to
100 mm
up to 125 mm
up to 150 mm
up to 175 mm
up to 200
mm
up to 225 mm
up to 255 mm
max. variation |
.18 mm
.25 mm
.33 mm
.41 mm
.50 mm
.56 mm
.63 mm
.71 mm
.75 mm
.82 mm
.89 mm
1.0 mm |
.08 mm
.13 mm
.20 mm
.25 mm
.30 mm
.36 mm
.38 mm
.41 mm
.43 mm
.46 mm
.48 mm
.50 mm
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- Table 2 indicates typical tolerances for holes of all shapes.
- Blind holes should not be deeper than 1.5 x dia.
- Tolerances on center to center dimensions of holes should be determined in accordance with Table 1
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TABLE 2 HOLE TOLERANCES
| DIA. | NORMAL | PREMIUM |
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up to .080"
up to .125"
up to .500"
up to 1.0"
over 1.5" | ± .003"
± .004"
± .005"
± .006"
as per Tabel 1 | ± .002"
± .003"
± .0
04"
± .005"
as per Tabel 1 |
up to 2.0 mm
up to 3.0 mm
up to 12.0 mm
up to 25.0 mm
over 37.0 mm
| .08 mm
.10 mm
.13 mm
.15 mm
as per Table 1 | .05 mm
.08 mm
.10 mm
.13 mm
as per Table 1 |
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