Injection Molding worked example
Plastic Part Weight with part volume from cad of 45 cc: a worked example
What does the result look like when part volume from cad reaches 45 cc? The full calculation is worked below with real intermediate numbers. Use this early in the quoting or mold design phase when you have a 3D model but no physical parts to weigh. The result feeds shot size, resin cost, and machine selection calculations.
The inputs for this scenario
- Part volume from CAD: 45 cc (raised for this scenario; the documented default is 18)
- Resin density (specific gravity): 1.04 g/cc (unchanged)
- Packing factor: 1.03 x (unchanged)
Working through the calculation
- Applying the documented formula (Part weight = Volume x Density x Packing factor) to the inputs above produces each figure below.
- At this operating point the engine returns 48.2 g for result, the number this scenario is built around.
- At this operating point the engine returns 48.2 value for volume x density (unfactored).
- At this operating point the engine returns 1 x for multiplier.
- At this operating point the engine returns 46.8 value for factor a x b.
How this compares with the baseline
- Against the tool's baseline example, where part volume from cad sits at 18 cc and the headline result is 19.28 g, this scenario comes in 150% above the baseline at 48.2 g.
- A figure at this level is achievable when part volume from cad is genuinely sustained, not just peaked for a shift. It assumes uniform density and a generic packing factor; semi-crystalline resins, foaming, and thick sections can shift real weight by a few percent, so confirm against a weighed first article.
Results at a glance
- Result: 48.2 g (headline result)
- Volume x Density (unfactored): 48.2 value
- Multiplier: 1 x
- Factor A x B: 46.8 value
Run it with your numbers
- Every input above is editable in the live Plastic Part Weight calculator, which recalculates instantly and can be shared with the inputs intact.
Last reviewed 2026-05-12.