Compound Weight per Foot
Get the cross-sectional area from the profile drawing or die, multiply by specific gravity and length, and you have net weight per foot. Hollow and sponge profiles need care: sponge EPDM weatherstrip has a lower density after blowing, so compound consumed per foot differs from finished weight. Extrusion also needs swell and shrink allowances, since the profile expands after the die and changes with cure.
Use measured weight from trial runs to correct the calculation. Compound is the main cost for large, dense profiles and a smaller one for thin, fast-running profiles.
Line Speed, Cure Method and Throughput
Throughput is limited by extruder output, cooling and the cure method. Continuous vulcanization options include hot air tunnels, salt baths, microwave and steam, and each has a speed range set by profile thickness and compound. Dense profiles run slower than thin ones.
Sponge compounds need a blowing and cure balance. Quote on a realistic average line speed that accounts for stops, not the best speed seen on a trial. Include the downtime to change dies and clean the line between compounds or colors.
- Cure method: hot air, salt bath, microwave, steam or batch autoclave
- Profile wall thickness limits cure speed
- Colors and compounds require purge and cleanout
- Average line speed after stops is the real rate
Start-Up and Changeover Scrap
Every run begins with feet of off-spec material while temperatures stabilize and dimensions are dialed in, and short runs suffer most. A 500 foot order with 150 feet of start-up scrap pays a large fixed penalty that a 20,000 foot order barely notices. Build minimum run charges or setup fees from the real scrap and time at start-up, and quote them separately.
Capture scrap by reason: start-up, die adjustments, splice rejects, dimensional rejects and cure issues. Without that, you cannot tell whether poor yield is a process issue or an order-size issue.
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Sheet Metal Part Cost Calculator
Calculates the price of a cut and bent sheet metal part from material weight, utilization, cutting and bending time, finishing, setup and markup, and shows price per square foot.
Dies, Tooling and Secondary Operations
Dies are cheaper than molds but not free, and often require several iterations to hit the profile due to swell. Decide who pays for die development and ownership. Secondary operations include cutting to length, mitering, splicing into frames or loops, punching, applying pressure-sensitive adhesive tape, flocking or coating, packaging and kitting.
Each should be a routing step with its own rate. Splicing and corner molding in particular are labor intensive and often underpriced.
When Per-Foot Quoting Needs Care
For standard catalog profiles with stable runs, a price list works. For custom profiles in short runs, a quoting model with setup fees, minimum quantities and yield by order size avoids losing money on small jobs. Check actual yield from completed jobs in your ERP and update the model quarterly.
Frequently asked questions
How do you price rubber extrusion per foot?
Combine compound cost per foot (area times specific gravity times price, with scrap), line cost per foot (rate divided by average line speed), secondary operations, and amortized die and setup costs. Add a minimum run charge for short orders because start-up scrap is a fixed cost.
What affects rubber extrusion line speed?
Profile thickness and mass, compound formulation, cure method and its length, cooling capacity and extruder output all limit speed. Thin profiles cure faster than thick ones, and sponge compounds need a controlled cure balance, so trial data gives the best basis for quotes.
Why is scrap so high on short extrusion runs?
Start-up produces a fairly fixed amount of off-spec material while the process stabilizes. On a short order, that fixed amount is a large share of total output. Charging a setup fee or minimum quantity covers it.
Netray can search your past extrusion jobs by profile, compound and order size, and draft quote inputs grounded in actual yield and line speed for an estimator to approve.