How do you calculate a clamp-force risk score?

Multiply each input by its weight and add them: severity x 0.40 + occurrence x 0.35 + detection x 0.25. With scores of 8, 5 and 6 that is 3.2 + 1.75 + 1.5 = 6.45 on a 1-10 scale.

What is a good clamp-force risk score?

Lower is better. On a 1-10 scale, anything under about 4 is low priority, 4-7 warrants a scheduled tonnage check, and above 7 should be reviewed before the next production run. The example value of 6.45 sits in the mid-high band.

Why is severity weighted highest?

A clamp shortfall on a high-pressure or food-contact part can scrap a whole lot or breach the parting line, so severity carries 0.40 — the largest share — followed by occurrence at 0.35 and detection at 0.25.

Does this tell me the clamp tonnage I need?

No. Required tonnage comes from projected part area times maximum blow pressure plus a safety factor. This score only ranks which combinations to investigate; run the physics calc on the ones that score high.

Clamp-force risk score vs RPN?

A classic FMEA RPN multiplies severity, occurrence and detection and ranges 1-1000. This calculator weights and sums them on the original 1-10 scale, which keeps the result interpretable and stops one mid-range factor from masking the others.

How do I keep scores consistent between machines?

Use one fixed rubric for what a 1, 5 and 10 mean on each axis and apply it to every comparable mold and machine. Scores are only comparable when the same scale is used across the fleet.

Blow Molding & Hollow Plastic Products calculator

Clamp Force Estimate Calculator

In blow molding, clamp force has to overcome the internal blow pressure pushing the mold halves apart, and a shortfall shows up as flash at the pinch-off, parting-line splits, and scrap. This calculator turns three judgement calls — how bad a clamp shortfall would be (severity), how often it tends to happen on a given mold/machine pairing (occurrence), and how reliably you would catch it before parts ship (detection) — into a single weighted clamp-force risk score. Process engineers and tooling leads use it to rank which mold-and-machine combinations get a clamp-tonnage audit first. It is an FMEA-style triage tool, not a tonnage calculator: it tells you where to point your attention, not the newtons you need.

What this calculator does

Score clamp-force risk for blow molded bottles, containers, tanks, or hollow parts using severity, occurrence, and detection ratings tied to mold opening or flash issues.
a blow molding team needs to rank clamp-force shortfall risk before moving a mold to a machine or raising blow pressure
It computes a single weighted clamp-force risk score from severity (0.40), occurrence (0.35) and detection (0.25) scores so molds can be ranked.

Formula used

Clamp-force risk score = clamp shortfall severity score × 0.40 + clamp shortfall occurrence score × 0.35 + clamp issue detection score × 0.25
Use the same scoring scale across comparable molds and machines.

Inputs explained

Clamp shortfall severity score:
Clamp shortfall occurrence score:
Clamp issue detection score:

How to use the result

Use it when prioritizing which blow-mold/machine pairings to review for clamp tonnage adequacy across a plant or product family.
The output is a relative priority score, not an engineering tonnage value; it only ranks risk and never replaces a projected-area times blow-pressure clamp-force calculation.

Current U.S. benchmarks

The producer price index for plastic resins and materials stands at 319.371 (BLS, May 2026), up 19.5% from a year earlier. Quotes priced off last quarter's material cost miss this move.
The U.S. has 9,635 plastics product manufacturing establishments employing about 677,302 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate a clamp-force risk score? Multiply each input by its weight and add them: severity x 0.40 + occurrence x 0.35 + detection x 0.25. With scores of 8, 5 and 6 that is 3.2 + 1.75 + 1.5 = 6.45 on a 1-10 scale.
What is a good clamp-force risk score? Lower is better. On a 1-10 scale, anything under about 4 is low priority, 4-7 warrants a scheduled tonnage check, and above 7 should be reviewed before the next production run. The example value of 6.45 sits in the mid-high band.
Why is severity weighted highest? A clamp shortfall on a high-pressure or food-contact part can scrap a whole lot or breach the parting line, so severity carries 0.40 — the largest share — followed by occurrence at 0.35 and detection at 0.25.
Does this tell me the clamp tonnage I need? No. Required tonnage comes from projected part area times maximum blow pressure plus a safety factor. This score only ranks which combinations to investigate; run the physics calc on the ones that score high.
Clamp-force risk score vs RPN? A classic FMEA RPN multiplies severity, occurrence and detection and ranges 1-1000. This calculator weights and sums them on the original 1-10 scale, which keeps the result interpretable and stops one mid-range factor from masking the others.

Last reviewed 2026-05-12.