How do you calculate splice loss in pultrusion?

Divide the feet scrapped at splices by the total feet pulled in the run. With 8 feet lost out of 250 pulled, splice loss is 3.2%.

What is a good splice loss rate?

Well-run lines with disciplined creel changes and quality roving often keep splice loss under 2-3%. The 3.2% in the example is close to that band but leaves room to improve splice technique.

What does the gap to target mean here?

It is the distance between your measured rate and the reference target you set. In the example, comparing a 3.2% rate against a 95% reference yields a 91.8-point gap — read the target as your benchmark and the gap as headroom.

Why do splices cause scrap in pultrusion?

A splice adds local fiber bulk or a discontinuity that can jam the die, create a resin-rich void, or produce a weak spot. Operators cut out the flawed length, and that becomes splice loss.

How can I reduce splice loss?

Stagger splices across packages so they do not stack at one die location, use consistent splice knots or air-splicing, and change creels proactively before a package runs out mid-critical-section.

Does roving package size affect splice loss?

Yes. Larger packages mean fewer splices per thousand feet, which lowers splice frequency and total splice scrap, though each package costs more to handle.

Pultrusion & Continuous Composite Profiles calculator

Splice Loss Calculator

Splice Loss measures how much finished profile you lose to defects and scrap around roving splices — the joints where a fresh package of glass or carbon is knotted or overlapped onto a running strand. Every creel change creates a splice, and a bad splice can thicken, void, or fail cure, forcing operators to cut out and scrap the affected length. Process engineers on a pultrusion line watch this rate because splices are one of the few unavoidable interruptions in an otherwise continuous process, and unmanaged splice scrap quietly erodes yield. Tracking it against a target keeps operators honest about splice quality and creel-change discipline.

What this calculator does

Splice Loss measures how much finished profile you lose to defects and scrap around roving splices — the joints where a fresh package of glass or carbon is knotted or overlapped onto a running strand.
Use it when splice loss in pultrusion and continuous composite profiles needs a clean rate and gap-to-target you can put on a tier board.
It computes the percent of total pulled length lost to splice-related scrap and the gap between that rate and your target ceiling.

Formula used

Splice Loss rate = affected amount ÷ total amount
Gap to target = target rate - calculated rate

Inputs explained

Feet scrapped at roving splices:
Total feet pulled in run:
Target maximum splice loss:

How to use the result

Use it during run debriefs, when qualifying a new roving supplier, or when a yield problem points toward creel changes.
It attributes all entered scrap to splices; it will not distinguish splice defects from unrelated die or pull-speed scrap, so the input feet must be splice-specific.

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.

Common questions

How do you calculate splice loss in pultrusion? Divide the feet scrapped at splices by the total feet pulled in the run. With 8 feet lost out of 250 pulled, splice loss is 3.2%.
What is a good splice loss rate? Well-run lines with disciplined creel changes and quality roving often keep splice loss under 2-3%. The 3.2% in the example is close to that band but leaves room to improve splice technique.
What does the gap to target mean here? It is the distance between your measured rate and the reference target you set. In the example, comparing a 3.2% rate against a 95% reference yields a 91.8-point gap — read the target as your benchmark and the gap as headroom.
Why do splices cause scrap in pultrusion? A splice adds local fiber bulk or a discontinuity that can jam the die, create a resin-rich void, or produce a weak spot. Operators cut out the flawed length, and that becomes splice loss.
How can I reduce splice loss? Stagger splices across packages so they do not stack at one die location, use consistent splice knots or air-splicing, and change creels proactively before a package runs out mid-critical-section.

Last reviewed 2026-05-12.