How do I calculate line speed for a target wall thickness?

Line speed follows from mass balance: the extruder output in pounds per hour divided by the weight per foot at your target wall thickness gives feet per hour, then divide by 60 for feet per minute. The Line Speed By Wall Thickness calculator does this using resin density, outer diameter, and wall. Thinner walls run faster at the same output, so if you thin the wall you must raise haul-off speed to hold the same pounds per hour.

What screw RPM do I need to hit a given output rate?

Output scales roughly linearly with screw speed once the screw is filled, so throughput per revolution stays fairly constant for a resin and screw geometry. The Screw RPM Throughput calculator estimates pounds per hour from RPM and specific output, or back-solves the RPM needed for a target rate. Verify against actual weigh-per-minute checks, since head pressure, melt temperature, and screen pack condition all shift the pounds-per-rev figure.

How much die swell should I allow when sizing a die?

Die swell is the ratio of extrudate dimension to die gap, and for many polyolefins it runs 1.1 to 1.5 depending on shear rate, melt temperature, and draw-down. The Die Swell Allowance calculator estimates the correction so your die opening plus swell, minus haul-off draw, lands on the finished dimension. Higher line speed and lower melt temperature increase swell, so recheck the allowance whenever you change rate.

What is melt residence time and why does it matter?

Melt residence time is how long polymer sits in the melt state inside the barrel and die. Too long at temperature degrades heat-sensitive resins like PVC or PET, causing yellowing, black specks, or gel. The Melt Residence Time calculator estimates it from barrel volume, output rate, and melt density. Lower output at a given screw size means longer residence, so on slow runs watch degradation and consider a smaller extruder.

How do I figure resin usage and cost per foot of pipe?

Weight per foot is the cross-sectional area of the wall times resin density times length. The Pipe Weight Per Foot and Resin Usage Per Foot calculators compute this from OD, wall, and density, and Extrusion Cost Per Pound rolls in resin price, regrind blend, and scrap. For a SDR-rated pipe, wall is a fraction of OD, so a small wall increase raises both weight per foot and material cost noticeably across a long run.

How does trim scrap and regrind affect my true cost per pound?

Edge trim on film and flash on profiles is scrap you paid full resin price for, even if you regrind it. The Trim Scrap Cost and Regrind Blend Rate calculators quantify how much virgin resin you displace and what percentage of trim you can blend back before properties drift. At 8 to 12 percent trim, capturing and blending regrind can cut net material cost meaningfully, but excessive regrind lowers melt strength and gauge stability.

Manufacturing calculator category

Plastics Extrusion - Pipe, Film & Profile calculators

This hub collects free calculators for pipe, film, and profile extrusion lines. It covers extruder output, screw RPM throughput, line speed by wall thickness, resin usage, cooling dwell, and trim scrap. It is built for line operators, process engineers, and estimators who need to balance rate, gauge, and cost before a run.

What this hub covers

Free extrusion calculators covering extruder output, line speed by wall thickness, resin usage, haul-off, melt residence time, and finished roll capacity for pipe, film, and profile lines.
Browse plastics extrusion - pipe, film & profile calculators for manufacturing planning, quoting, quality, capacity, and operations decisions.

Best calculators in this category

Extrusion Output Rate: Compare actual extruder output against the planned pounds per hour or feet per hour target for a pipe, film, sheet, or profile line.
Effective Extruder Throughput: Estimate effective extruder throughput from measured pounds produced, run hours, and a realistic screw speed efficiency factor.
Effective Line Speed: Estimate usable haul-off line speed from produced footage, run minutes, and a wall thickness or cooling efficiency allowance.
Resin Usage Per Foot: Estimate resin required for a run from finished footage, pounds per foot, and expected yield or transfer efficiency.
Melt Residence Time: Estimate melt residence time from melt system volume or material hold-up, extruder output rate, and a safety allowance.
Die Swell Allowance: Calculate the percent allowance between target finished size and expected extrudate swell at the die.
Cooling Tank Dwell: Estimate cooling tank dwell time from required cooled length, line speed, and an allowance for thicker walls or hot melt conditions.
Haul-Off Speed: Calculate practical haul-off speed from good footage, elapsed minutes, and an allowance for slippage, trim, or speed loss.
Trim Scrap Cost: Estimate the cost of edge trim, slitter trim, or start-up scrap from scrap weight, resin cost, capture factor, and fixed handling cost.
Extruder Energy Cost: Estimate extrusion energy cost from metered kilowatt-hours, utility rate, load capture factor, and fixed demand or support cost.
Extrusion Cost Per Pound: Build a run cost per pound from finished pounds, conversion cost per pound, yield factor, and fixed setup or changeover cost.
Pipe Weight Per Foot: Estimate pipe weight per foot from cross-section area, resin density, unit conversion, and any ovality or wall tolerance multiplier.

Common manufacturing problems solved

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extrusion
pipe
film
profile
line speed
resin usage
wall thickness
film gauge
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Category questions

How do I calculate line speed for a target wall thickness? Line speed follows from mass balance: the extruder output in pounds per hour divided by the weight per foot at your target wall thickness gives feet per hour, then divide by 60 for feet per minute. The Line Speed By Wall Thickness calculator does this using resin density, outer diameter, and wall. Thinner walls run faster at the same output, so if you thin the wall you must raise haul-off speed to hold the same pounds per hour.
What screw RPM do I need to hit a given output rate? Output scales roughly linearly with screw speed once the screw is filled, so throughput per revolution stays fairly constant for a resin and screw geometry. The Screw RPM Throughput calculator estimates pounds per hour from RPM and specific output, or back-solves the RPM needed for a target rate. Verify against actual weigh-per-minute checks, since head pressure, melt temperature, and screen pack condition all shift the pounds-per-rev figure.
How much die swell should I allow when sizing a die? Die swell is the ratio of extrudate dimension to die gap, and for many polyolefins it runs 1.1 to 1.5 depending on shear rate, melt temperature, and draw-down. The Die Swell Allowance calculator estimates the correction so your die opening plus swell, minus haul-off draw, lands on the finished dimension. Higher line speed and lower melt temperature increase swell, so recheck the allowance whenever you change rate.
What is melt residence time and why does it matter? Melt residence time is how long polymer sits in the melt state inside the barrel and die. Too long at temperature degrades heat-sensitive resins like PVC or PET, causing yellowing, black specks, or gel. The Melt Residence Time calculator estimates it from barrel volume, output rate, and melt density. Lower output at a given screw size means longer residence, so on slow runs watch degradation and consider a smaller extruder.
How do I figure resin usage and cost per foot of pipe? Weight per foot is the cross-sectional area of the wall times resin density times length. The Pipe Weight Per Foot and Resin Usage Per Foot calculators compute this from OD, wall, and density, and Extrusion Cost Per Pound rolls in resin price, regrind blend, and scrap. For a SDR-rated pipe, wall is a fraction of OD, so a small wall increase raises both weight per foot and material cost noticeably across a long run.

Last reviewed 2026-05-12.