Precision Dimensional Tolerances for Steel Castings
Steel casting tolerances refer to acceptable levels of dimensional variation in steel cast parts. Eagle Alloy measures tolerances based on ISO 8062 dimensional standards, which provide a framework for measuring and listing tolerances. Customer-specified tolerances for castings vary widely, and are closely connected to each part’s geometry, alloy, and use case. Whether you’re casting parts for heavy machinery, replacing fabricated components, or scaling from prototype to production, our team provides reliable guidance and inspection throughout the process.
We support both shell and airset casting processes in-house, utilizing rigorous inspection methods to ensure that every part meets design intent. This page outlines our standard dimensional tolerances and recommendations for achieving reliable, repeatable casting results.
Eagle Alloy’s Dimensional Tolerance Standards
Linear Dimensions – Inch (mm)
| DIMENSION RANGE | SHELL (ISO 8062 CT8–CT10) | AIRSET (ISO 8062 CT10–CT12) |
|---|---|---|
| 0″ to 6″ (0–152 mm) | ±0.030″ (0.75 mm) | ±0.063″ (1.60 mm) |
| 6″ to 12″ (152–305 mm) | ±0.045″ (1.15 mm) | ±0.094″ (2.40 mm) |
| 12″ to 18″ (305–457 mm) | ±0.060″ (1.50 mm) | ±0.125″ (3.20 mm) |
| 18″ to 24″ (457–610 mm) | ±0.090″ (2.30 mm) | ±0.188″ (4.80 mm) |
| 24″ to 30″ (610–762 mm) | ±0.098″ (2.50 mm) | ±0.251″ (6.40 mm) |
| 30″ to 36″ (762–914 mm) | ±0.098″ (2.50 mm) | ±0.251″ (6.40 mm) |
| 36″ to 44″ (914–1118 mm) | ±0.098″ (2.50 mm) | ±0.251″ (6.40 mm) |
Note: 3D-printed mold castings follow air-set tolerances.
Miscellaneous Tolerance Callouts
| FEATURE | SHELL | AIRSET |
|---|---|---|
| Across Parting Line (add to linear) | +0.010″ (0.25 mm) | +0.030″ (0.75 mm) |
| Pattern to Core Dimensions (add) | +0.010″ (0.25 mm) | +0.030″ (0.75 mm) |
| Mismatch (Cope to Drag) | ±0.020″ (0.50 mm) | ±0.063″ (1.60 mm) |
| Gate/Riser Contact Areas | ±0.063″ (1.60 mm) | ±0.063″ (1.60 mm) |
Minimum Design Features
| SPECIFICATION | SHELL | AIRSET |
|---|---|---|
| Recommended Minimum Radius | 0.031″ (0.75 mm) | 0.063″ (1.60 mm) |
| Minimum Wall Thickness | 0.188″ (4.76 mm) | 0.250″ (6.35 mm) |
| Angular Dimensions | ±1° | ±1° |
| Draft | 1–2° | 1–2° |
Avoid placing datum locating points on parting lines or near gating features.
Surface Finish Expectations
| CASTING TYPE | SURFACE FINISH |
|---|---|
| Shell Cast | 150–300 RMS |
| Airset Cast | 350–560 RMS |
| 3D-Printed Mold Cast | 250–560 RMS |
How We Ensure Tolerance Accuracy
Our dimensional inspection capabilities include:
- Coordinate Measuring Machines (CMMs)
- 3D Laser Scanning
These tools help us confirm that each part meets our steel casting tolerances and adheres to our customers’ specifications.
Download Our Free Airset Casting Quick Reference Guide
Want to see the complete guide to Eagle Alloy’s airset tolerances, surface finishes, and casting recommendations? We’ve created a free guide with detailed standards for tolerance ranges, inspection capabilities, and design guidelines to support your next project.
Start a Project with Confidence
When precision matters, Eagle Alloy delivers. Whether you’re converting a fabricated part, scaling a prototype, or replacing legacy tooling, we apply tight steel casting tolerances that support accuracy and repeatability.
Request a Quote or Contact Our Engineering Team to discuss your project.