Tolerance Limits Calculator
Determine the tolerance limits of an injection-molded part and the corresponding cavity dimensions. The calculator accounts for material shrinkage and tolerance class (fine, standard, coarse) — key data for mold design and quality control.
Input Parameters
Results
Fill in the data and click Calculate
ARGUS automatically verifies tolerances and flags the risk of non-achievability
Tolerances determine quality and manufacturability — ARGUS checks tolerance achievability based on material, process and production history.
How do we calculate tolerance limits?
Dimensional tolerances for injection-molded parts are defined according to DIN 16742 or ISO 20457 and depend on material, process and tolerance class. The calculator determines the part tolerance limits (nominal dimension ± tolerance) and converts them to cavity dimensions accounting for mold shrinkage.
The calculator applies a shrinkage-compensated tolerance model — transferring part tolerances to cavity dimensions with the shrinkage factor applied.
Dlower = Dnom − T/2
Dcavity_upper = Dupper × (1 + S/100)
Dcavity_lower = Dlower × (1 + S/100)
Dnom — nominal dimension [mm]
T — tolerance [mm]
S — shrinkage [%]
Tolerance classes per DIN 16742: fine class — IT10–IT12, requires process optimization and material control. Standard class — IT12–IT14, achievable in normal production. Coarse class — IT14+, easy to maintain. Amorphous materials allow tighter tolerances than semi-crystalline ones.
Tolerance Achievability
PP, PE — ±0.15–0.30 mm (per 100 mm)
PA6, POM — ±0.10–0.25 mm (per 100 mm)
GF materials — ±0.05–0.15 mm (in GF direction)
Tighter-than-standard tolerances require: a stable process (SPC), controlled material (moisture, lot consistency), optimized mold cooling and regular maintenance. Process capability (Cpk > 1.33) should be confirmed statistically.
Mold and Tolerances
The mold should be machined to tolerances 3–5× tighter than the part tolerance. For a part tolerance of ±0.10 mm the mold should have a tolerance of ±0.02–0.03 mm. Also account for mold wear over time — cores wear faster than cavities.
ARGUS automatically verifies tolerances and monitors process capability (Cpk)
See for yourself — book a presentation and explore the tolerance analysis in ARGUS.