In this guide 6 sections
To quote a rubber moulded part, work out compound weight with a scrap allowance, divide press time by cavity count, then add trimming, post-cure, inspection and packing. Cost the tooling separately. Build the quote from recorded figures on past jobs, not from memory.
Start with the part and its compound weight
Take the drawing and find the volume of the part. Multiply by the compound density to get the cured weight, then add the weight lost to flash, runners and sprue.
Add a scrap allowance for the reject rate this part type has shown before, because a fine O-ring and a bonded metal insert have very different histories. Use the real history of each family. Do not guess.
Price the compound by the kilogram at the current mixing cost, including the mixing charge and not just the raw polymer.
- Part volume from the drawing or sample
- Compound density and cost per kilogram
- Flash and runner weight
- Scrap allowance for this part family
Cavity count and cure time set the press hours
The mould decides how many parts leave the press each cycle, and cure time plus loading and unloading sets the cycle length. Divide one cycle by the cavity count and you have the press time per part.
Apply the hourly press rate your plant actually carries, including the operator, power, platen heat and depreciation. A thick-section part with a long cure can look cheap in material and still lose money on the press.
Check which presses can take the tool. Size matters. A small platen limits how many cavities can run.
Add the work around the press
Parts rarely leave the press finished. Deflashing, cryogenic trimming, post-cure in an oven, bonding primer and visual inspection all take hands and time, and each belongs in the quote as its own line.
Include packing and the cost of any dimensional checks or first-article report. Customers in automotive and medical work ask for these, and they eat hours that are easy to forget.
- Trimming or deflashing time per part
- Post-cure oven batch cost
- Insert preparation and bonding agent
- Inspection and first-article report
- Packing and labelling
Cost the tooling on its own line
A new mould is a separate charge, quoted with its lead time and its number of cavities. Say who owns it, where it will be stored, and who pays for repairs as the cycles pile up, you or the customer.
If you absorb tooling into the piece price, say so in writing. Then watch the order quantity, because a small run will not repay it.
Why quoting from memory leaves margin on the press
A senior estimator can price quickly and be right most of the time. The trouble is the other times, since nobody checks the quote against what the job really used and the same errors repeat, job after job.
Keep each quote with its figures, then compare them to actual compound, press hours and scrap when the job closes. After a few months the gaps show where your standards are wrong.
Pick your last five closed jobs. Compare quote to actual this week.
Moulded part quote build sheet
A one-page template laid out as a cost stack. Rows run from compound weight and scrap to cavity count, cure time, press rate, trimming, post-cure, inspection, packing and tooling. Two columns sit side by side, quoted and actual, so a closed job shows exactly where the margin went.
Open a blank worksheet to printQuestions owners ask
How do I allow for scrap in a rubber moulding quote?
Use the reject history of similar parts, split by mould type and compound, and add it as its own line so you can see it. A single blanket figure across all jobs hides the costly ones.
Should tooling be included in the piece price?
Either works if it is stated plainly. A separate tooling charge is cleaner for short runs, while folding it into the piece price suits long contracts with a firm annual volume.
What press rate should I use?
Use a rate built from your own costs: operator, power, platen heat, maintenance and depreciation, divided by productive hours. Do not borrow a rate from another plant.
How often should quotes be checked against actual cost?
At every job close, even briefly. A monthly review of the biggest gaps is enough to correct your standards before they cost real money.