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Aluminum Investment Casting Tolerance Capabilities
The following table lists the tolerances recommended by the Investment Casting Institute. With state-of-the-art technology, we are able to extend this list as a guide for larger configurations. Nu-Cast is equipped to handle the demand of today's industry. Your specific configuration is an important criteria in determining dimensional variations from part to part. We would be pleased to consult with you on any tolerances or dimensions you may need that are not listed.| Length | Normal | Premium | To avoid additional cost we recommend that configurations maintain a minimum wall thickness as specified: Casting Size: 1 " to 10 " 11 " to 20 " 21 " to 50 " Nominal Walls .06" ±.02 .09" ±.02 .12" ±.02 RADII As a general rule, a 0.03 maximum corner and a 0.06 minimum fillet are recommended. Smaller radii are possible depending on the complexity of the design. ANGLES Angular tolerances of ±1/2° are normal. FLATNESS AND STRAIGHTNESS When a high degree of flatness and straightness is required, castings must be mechanically straightened; however, proper design can control distortion and minimize straightening functions. Flatness and straightness tolerances are .003 to .005 TIR per linear inch and depend on alloy properites and configuration of part. HOLE TOLERANCES The hole tolerances for round, square and D-holes are: up to .250" I.D ±.003 .250" to .500" I.D. ±.004 over .500" I.D. ±.005 inch/inch SURFACE FINISH NAS 823 visual comparison. Normal - 125 DRAFT Generally, draft allowance can be disregarded. ROUNDNESS The general linear tolerances can be held for diameter. CONCENTRICITY The general section thickness tolerances will prevail. |
|
| up to 1/2" | ±.007" | ±.003" | ||
| 1/2" to 1" | ±.010" | ±.005" | ||
| 1" to 2" | ±.013" | ±.008" | ||
| 2" to 3" | ±.016" | ±.010" | ||
| 3" to 4" | ±.019" | ±.012" | ||
| 4" to 5" | ±.022" | ±.014" | ||
| 5" to 6" | ±.025" | ±.015" | ||
| 6" to 7" | ±.028" | ±.016" | ||
| 7" to 8" | ±.031" | ±.017" | ||
| 8" to 9" | ±.034" | ±.018" | ||
| 9" to 10" | ±.037" | ±.019" | ||
| Larger castings produced at Nu-Cast | ||||
| 11" to 20" | ±.040" | ±.020" | ||
| 21" to 30" | ±.050" | ±.030" | ||
| 31" to 40" | ±.060" | ±.040" | ||
| 41" to 50" | ±.070" | ±.045" | ||
|
Section Thickness |
Normal Variation |
Premium | ||
| .020" to .050" | ±.010" | ±.007" | ||
| .051" to .100" | ±.010" | ±.007" | ||
| .101" to .250" | ±.015" | ±.010" | ||
| .251" to 1.000" | ±.015" | ±.010 | ||
ALUMINUM - BASE ALLOYS
| Alloy Designation |
Preferred Temper |
Common Specifications |
Tensile (KSI) |
Yeild (KSI) |
Elongation (%) |
COMMENTS |
| *A201 | T7 | AMS-A-21180 AMS-4229 |
55/65 | 45/55 | 2/4 | Hot short alloy,very low castability, configuration sensitive. Applications: high-strength castings (design only in consultation with foundry). |
| *C355 | T6 | AMS-A-A-21180 AMS-4215 |
35/44 | 30/33 | 1/3 | Somewhat lower castability than A356 or A357 alloys. Applications: commponents exposed to moderate such temperatures, as turbine engine parts, pumps, etc. |
| *A356 | T6 | AMS-A-21180 AMS-4218 |
33/42 | 27/32 | 2/5 | Moderate strengths, excellent castability, weldability and pressure tightness. Applications: housings, chassis, casting requiring fine detail. |
| *A357 | T6 | AMS-A-21180 AMS-4219 |
36/41 | 28/31 | 3/5 | Excellent castability, moderate high strength, excellent weldability and pressure tightness. Applications: structural components |
| *D712 | T5 | ASTM-B-26 | 34 | 25 | 1/4 | Lower castability, used only for its brazing characteristics. |
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