Rotational Molding worked example

Powder Charge Weight with part surface area of 50 in²: a worked example

Here is what the math looks like when conditions slip. We hold every other input steady and drop part surface area to 50 in², then walk the calculation through step by step. Powder charge weight is the amount of resin, typically polyethylene powder, you drop into a rotational mold to build a given wall thickness across the part's surface.

The inputs for this scenario

  • Part surface area: 50 in² (the input this scenario stresses; the baseline uses 100)
  • Target wall thickness: 4 mm (held at the documented default)
  • Powder density conversion factor: 0.01 x (held at the documented default)
  • Powder yield / scrap allowance multiplier: 1 x (held at the documented default)

Working through the calculation

  • The calculation starts from the formula this tool documents: Powder Charge Weight = first factor × second factor × conversion factor × process multiplier.
  • Result works out to 1 lb at these inputs, and this is the headline figure for the scenario.
  • Base product works out to 1 value at these inputs.
  • Multiplier works out to 1 x at these inputs.
  • Factor A x B works out to 200 value at these inputs.

How this compares with the baseline

  • Against the tool's baseline example, where part surface area sits at 100 in² and the headline result is 2 lb, this scenario comes in 50% below the baseline at 1 lb.
  • The practical read: the gap between this scenario and the baseline is entirely attributable to part surface area, so recovering it is worth quantifying in dollars before considering equipment or staffing changes. It assumes uniform wall thickness and even powder distribution; deep draws, sharp corners, and bridging can leave localized thin or thick spots that a single average charge cannot correct.

Results at a glance

  • Result: 1 lb (headline result)
  • Base product: 1 value
  • Multiplier: 1 x
  • Factor A x B: 200 value

Run it with your numbers

  • To rerun this with your own numbers, open the live Powder Charge Weight calculator, set part surface area to your actual value, and adjust the remaining inputs to match your operation.

Last reviewed 2026-05-12.