Linear Tolerance
| Dimensions |
Normal Tolerance |
| up to 1" |
+/- 0.010" |
| up to 2" |
+/- 0.013" |
| up to 3" |
+/- 0.016" |
| up to 4" |
+/- 0.019" |
| up to 5" |
+/- 0.022" |
| up to 6" |
+/- 0.025" |
| up to 7" |
+/- 0.028" |
| up to 8" |
+/- 0.031" |
| up to 9" |
+/- 0.034" |
| up to 10" |
+/- 0.037" |
| > 10" allow +/- 0.005" per inch |
|
An exception to the Linear Tolerance exists on wall thickness
where the tolerance must be a minimum of +/- 0.020".
Out of Roundness
| Diameter |
TIR or 1/2 difference
between diameters |
| 1/2" |
0.010" |
| 1" |
0.015" |
| 1-1/2" |
0.020" |
| 2" |
0.025" |
| On larger diameters, linear tolerances apply |
|
Visual Standards
- Positive Metal - Due to the nature of the
investment casting process, random positives
are encountered and these vary by alloy and part
configuration. Unless otherwise
agreed, thesewill be limited to a size of
0.015-0.030" high by 0.125" by 0.125" and no
more than one per 1" square.
Smaller defects of all sizes may be present at random
but not in places where they interfere with the
function of the part - such as holes, knurls,
or lettering. Positive metal requirements
other than this will be specified by the customer at time of quotation.
- Surface Pits - Random negatives may also occur.
These will be limited to 0.030-0.060"
by 0.030" deep in size, no more than one of those per 1" square.
Unless otherwise specified by the customer, smaller negatives may
be present, providing they do not interfere with the function of the part.
- Nonfill - Edges may be rounded up to 0.015"
radius even though tooled sharp. Sharper or more rounded edges can be provided as agreed
between purchaser and foundry.
- Cleanliness - Castings will be sand, grit or shot blasted to remove casting and heat
treatment scale or other foreign material. Stainless steel castings will not be
pickeled or passivated unless specified. Castings will be provided with sand
blasted, grit blasted or vibropolished surfaces and be of uniform appearance typical of
those processes. Unless the purchaser specifies a rust preventive
treatment, some light rusting may be present.
- Linear Indications - Parts will contain no linear cold shuts, visual cracks, or visual
shrinkage, except as agreed with customer.
- Surface Texture - The surface texture standards for investment casting will be
125 RMS maximum.
- Soundness
- The foundry will establish a casting method that
is capable of producing castings that show less than 10% shrinkage porosity in any
cross section area. Shrinkage will not be present in an area where subsequent machining
will reveal it as a visual surface defect.
- Internal Defects
- Some limited quantity of internal defects, including gas holes, slag entrapment,
non-metallic inclusions, or porosity may be encountered by the purchaser.
If these render the casting unusable, methods of inspection and
acceptance limits to exclude such defects will be established by the purchaser and
the foundry prior to further production of the casting.
- Note:
- This is not, or intended to be an all-inclusive specification, but is meant more
as a guideline. Any quality conditions or inspection criteria not addressed here or
that are beyond the tolerances or specifications listed here can be negotiated in the
purchase agreement.