Design Considerations

Casting Tolerances

Tolerances depend on the geometry of each part, but the following tolerances are suggested as a guide to designers.

Lengths including hole diameters, held to:

mm inch
Section Tolerance Section Tolerance
0 - 15 ±0.08 0.0 - 0.6 ±0.003
15 - 25 ±0.13 0.6 - 1.0 ±0.003
25 - 50 ±0.25 1.0 - 2.0 ±0.010
50 - 75 ±0.37 2.0 - 3.0 ±0.015
75 - 100 ±0.50 3.0 - 4.0 ±0.020
100 - 125 ±0.60 4.0 - 5.0 ±0.025
125 - 250 ±1.00 5.0 - 10.0 ±0.040

Flatness

Generally held to ±0.13mm (0.005") per 25mm (1.00") square.

Straightness

Generally held to ±0.1mm (0.004") max per linear 25mm (1.00").

Squareness and Angularity

±0.5 degree
Note: Angular tolerances are affected by irregular geometries.

blue and white lightbulb icon

When tolerancing, use of a central feature as a datum may allow detail to be cast that would otherwise carry too large a tolerance. Where a mechanical interface feature is required on a surface, it helps to use the centre of the feature as a datum.

Wall Sections

Constant section thin walls are preferred but large changes of section can be accommodated through critical analysis of the component design and special tooling design features.

Size (cubed) Suggested Wall Thickness
up to 10mm (0.4") 0.2mm - 1.0mm (0.008" - 0.04")
25mm (1.0") 0.5mm - 1.5mm (0.02" - 0.06")
75mm (3.0") 1.0mm - 3.0mm (0.04" - 0.12")
100mm (4.0") 1.5mm - 3.0mm (0.06" - 0.12")
above 100mm (4.0") 2.0mm (0.08") upwards
Macaque in the trees
Cast example of 1mm (0.040") wall thickness throughout
Macaque in the trees
Cast example of thick and thin wall sections
Macaque in the trees
Cast example incorporating ribs to improve flatness and rigidity
blue and white lightbulb icon

Wall thickness and flatness over large surfaces are better controlled if through-holes and ribs are incorporated in the design.

Wall Section Tolerances

mm inch
Section Tolerance Section Tolerance
up to 0.5 ±0.10 up to 0.020 ±0.004
0.5 - 1.0 ±0.15 0.020 - 0.040 ±0.006
1.0 - 2.0 ±0.20 0.040 - 0.080 ±0.008
2.0 - 4.0 ±0.25 0.080 - 0.160 ±0.010
4.0 - 8.0 ±0.30 0.160 - 0.320 ±0.012
Macaque in the trees
Cast example incorporating holes to improve flatness and reduce weight

Sylatech Design Guide

Design Guide v2
Download the Design Guide

Get in touch!

Our sales team will be happy to discuss your requirements.
Contact Us Today