Shrinkage Compensation Calculator
Calculate mold cavity dimensions with full shrinkage compensation — in the flow direction and cross-flow direction. The calculator accounts for shrinkage anisotropy, which is critical for parts with tight dimensional tolerances.
Input Parameters
Results
Fill in the data and click Calculate
ARGUS automatically accounts for shrinkage anisotropy for every material
Anisotropic shrinkage is critical for precision parts — ARGUS combines shrinkage data with the plant's production history and corrects values based on actual results.
How do we calculate shrinkage compensation?
Shrinkage compensation is the process of determining mold cavity dimensions that — after accounting for processing shrinkage — will yield a part with the required nominal dimensions. Unlike a simple one-dimensional calculation, this calculator accounts for shrinkage anisotropy: the difference between shrinkage in the flow direction and shrinkage in the perpendicular direction.
The calculator applies an anisotropic shrinkage model with directional correction factors. Shrinkage in the flow direction is typically higher than in the perpendicular direction due to polymer chain orientation.
Scross = S × fcross
Lcavity = Lpart × (1 + Sflow/100)
Wcavity = Wpart × (1 + Scross/100)
fflow — flow direction factor (typically 1.0)
fcross — cross-flow factor (typically 0.7–0.9)
Shrinkage anisotropy is particularly significant for semi-crystalline materials (PP, PA, POM) and glass fiber reinforced materials, where fiber orientation in the flow direction can reduce shrinkage in that direction by up to 50%. For amorphous materials anisotropy is smaller, but still relevant at tight tolerances.
When does shrinkage anisotropy matter?
Shrinkage anisotropy is critical in the following situations:
GF-reinforced materials — PA6-GF30, PBT-GF30 (strong fiber orientation)
Large parts — length >300 mm (error accumulation)
Technical parts — gears, bearings, fitted components
For glass fiber reinforced materials (GF) the ratio of flow-direction shrinkage to cross-flow shrinkage can be as high as 1:3. For example PA6-GF30: flow direction shrinkage 0.3–0.5%, cross-flow direction 0.8–1.2%. This causes warpage that must be accounted for at the mold design stage.
Directional factors
The flow direction factor (f_flow) is typically 1.0 for unfilled materials and 0.7–0.9 for glass fiber materials. The cross-flow factor (f_cross) is 0.7–0.9 for unfilled materials and 1.1–1.5 for GF materials. Exact values depend on the specific material grade and processing conditions — the best source is manufacturer data or in-plant measurements.
ARGUS automatically corrects shrinkage based on actual measurements from your plant
See it for yourself — book a presentation and discover how ARGUS connects shrinkage data with production history.