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Runner & Regrind Economics — Polypropylene (PP)

Cold-runner material burden for Polypropylene (PP) and the hot-runner payback arithmetic.

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Runner share of shot (%)
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Net material loss ($/yr)
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Hot-runner payback (months)

Runners on small parts routinely outweigh the parts; this division decides hot-runner conversions more than any catalog argument.

Formula

loss = (runner − regrind) × shots × price; payback = HR cost ÷ loss
References: Rosato, Injection Molding Handbook, 3rd ed.

Note: Starting-point process values — the resin grade's datasheet and an in-mold study govern. Verify with a gate-seal study and a cooling-time ladder on the actual tool.

Cold-runner material burden for Polypropylene (PP) and the hot-runner payback arithmetic. A free injection molding cycle & process tool — no sign-up, no upload, instant results in your browser.

About Runner & Regrind Economics — Polypropylene (PP)

Runner & Regrind Economics — Polypropylene (PP) computes the governing relationship loss = (runner − regrind) × shots × price; payback = HR cost ÷ loss live as you type. Runners on small parts routinely outweigh the parts; this division decides hot-runner conversions more than any catalog argument. Defaults are pre-filled with realistic values for this exact scenario, and the worked example substitutes your numbers step by step so the math is never a black box.

How to use Runner & Regrind Economics — Polypropylene (PP)

  1. 1Enter your values — Part weight (all cavities), Cold runner weight, Regrind allowed back in, Resin price and more (sensible defaults are pre-filled).
  2. 2Read the live results: Runner share of shot, Net material loss, Hot-runner payback.
  3. 3Check the "with your numbers" line to see loss = (runner − regrind) × shots × price; payback = HR cost ÷ loss substituted step by step.
  4. 4Adjust inputs until the scenario matches yours, then copy or share the result.

Why use Runner & Regrind Economics — Polypropylene (PP)?

  • ✓Instant, free and private — every calculation runs client-side in your browser; nothing is uploaded
  • ✓Built on the stated formula loss = (runner − regrind) × shots × price; payback = HR cost ÷ loss with authoritative sources cited on the page (Rosato, Injection Molding Handbook, 3rd ed.)
  • ✓Runners on small parts routinely outweigh the parts; this division decides hot-runner conversions more than any catalog argument.
  • ✓Niche-specific defaults give a meaningful worked answer the moment the page loads

Frequently asked questions

What formula does the runner & regrind economics — polypropylene (pp) use?+

It evaluates loss = (runner − regrind) × shots × price; payback = HR cost ÷ loss, exactly as published. Sources: Rosato, Injection Molding Handbook, 3rd ed.. The substituted worked example on the page lets you verify every step against the textbook.

How should I read the result — and how far can I trust it?+

Runners on small parts routinely outweigh the parts; this division decides hot-runner conversions more than any catalog argument. Starting-point process values — the resin grade's datasheet and an in-mold study govern. Verify with a gate-seal study and a cooling-time ladder on the actual tool.

When is this calculator the right tool for the job?+

Cold-runner material burden for Polypropylene (PP) and the hot-runner payback arithmetic. A free injection molding cycle & process tool. Runners on small parts routinely outweigh the parts; this division decides hot-runner conversions more than any catalog argument. For neighbouring scenarios, the related tools below cover the same engine with different presets.

Do I need to install anything or create an account?+

No. The tool is pure client-side JavaScript: open the page and it works, offline once loaded, with no account, no quota and no data leaving your device.

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