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Resin Purchase Quantity

Turn a good-part order into production shots, startup allowance, and the virgin resin quantity to purchase.

Example starting values are prefilled to demonstrate the calculation. Replace them with your measured, quoted, or job-specific inputs before relying on a result.

Inputs

Order and material inputs

Range: at least 1 parts

Enter a whole-number count; decimal values are rejected during calculation.

Range: at least 0.0

Measured finished-part mass for one active cavity. Enter the unit selected below; positive mass required.

Defaults to lb. Conversion factors: 16 oz/lb; 453.59237 g/lb.

Range: at least 0

Mass discharged with one shot. Enter 0 for hot-runner systems without discharged runner/sprue material.

Defaults to lb; may differ from the part-weight unit.

Range: at least 1 cavities

Enter a whole-number count; decimal values are rejected during calculation.

Range: 0–100 %

Reject rate among attempted molded parts in the production run; startup shots are entered separately. Use a value below 100%. This does not model cavity-specific, time-varying, or correlated rejects.

Range: at least 0

Additional full shots consumed outside the steady-state good-part target. Enter a whole number. Startup and rejected-shot material is not credited back as recovered regrind or inventory.

Range: 0–100 %

Enter a blend percentage already approved for this resin, part, customer, and material history. It is the share of total feed mass, not an addition-on-top ratio. This calculator does not recommend an allowable percentage.

Result

Gross molding feed required (lb)
4.00
Gross molding feed required (oz)
64.0
Molded-part mass per shot (lb)
4.0000
Steady-state production shots (shots)
1
Regrind feed required (lb)
0.00
Total discharged mass per shot (lb)
4.0000
Startup/setup shot feed allowance (lb)
0.000
Total shots including startup (shots)
1
Virgin resin purchase mass (lb)
4.00
Planning interpretation and limitation
Production shots use the specified part rejection rate and active cavity count; startup/setup shots are additional full shots, and their feed allowance is shown separately. Gross feed includes steady-state and startup shots plus discharged runner/sprue material. Virgin purchase mass assumes all regrind feed is available and usable; subtract separately known inventory, purge loss, or supplier package rounding outside this estimate.

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