Bonding Cost

Adhesive Cost Per Part: How to Quote Bonding Work

What actually drives adhesive cost per part, how to build a quote that holds up, and the hidden losses that sink margins.

Material is the headline but rarely the whole story. Applied material cost per part is grams per part times price per gram, but you must price the delivered gram, not the drum. A 20 kg pail of structural epoxy at 900 dollars is 0.045 dollars per gram; at 6.5 g per part that is 0.29 dollars of adhesive. Two-part cartridges in 400 mL packs often run 2 to 4 times the per gram cost of bulk pails because you pay for the static mixer and the small format. The Adhesive Cost per Part calculator turns grams and pack price into a clean per unit number.

Waste is where naive quotes bleed. Purge on a meter mix machine, cartridge dead volume, expired pot life, and rejected beads all add up to 8 to 25 percent over the theoretical usage on real lines. A static mixer nozzle holds 5 to 12 mL that goes to scrap every purge; at 30 purges a shift on a 400 mL cartridge system that can be 3 to 5 percent of throughput. Quote at net usage, not gross: if theoretical is 6.5 g and your line runs 15 percent waste, cost your material at 7.5 g. The Sealant Usage and Adhesive Coverage calculators help pin the theoretical baseline before you add the waste factor.

Labor and cycle time usually dwarf the adhesive itself on manual lines. If an operator loaded at 45 dollars per hour fully burdened bonds 90 parts per hour, that is 0.50 dollars of labor per part, well above the 0.29 dollars of epoxy. Anything that slows the operator, fixture fumbling, manual mixing, wiping squeeze out, costs more than the glue. Automating dispense to lift the rate from 90 to 200 parts per hour cuts labor per part to 0.225 dollars, a 0.275 dollar swing that often justifies the robot faster than the material savings do.

Machine and fixture time carry real cost even when unattended. A cure oven pulling 12 kW at 0.12 dollars per kWh costs 1.44 dollars per hour to run; spread over 400 parts per hour that is 0.0036 dollars per part, small, but the oven dwell also ties up floor space and WIP. UV cure lamps, induction coils, and clamp fixtures each add depreciation and maintenance. Allocate them as a machine rate per hour divided by parts per hour, and watch the denominator: a slow cure that halves throughput can double every fixed cost per part even when energy looks trivial.

Scrap and rework are the estimate killers because they multiply the finished cost, not the raw material cost. A joint that fails after assembly wastes the substrate, the labor, and often downstream value, so a 2 percent bond failure on a part with 40 dollars of accumulated value costs 0.80 dollars per good part in scrap alone. Weak joints from wrong mix ratio, blown pot life, or thin bond lines are the usual culprits. Track first pass yield and load its inverse into the quote; assuming 100 percent yield is the single most common way bonding quotes go underwater.

Overhead and consumables ride along and are easy to forget. Static mixers at 0.50 to 1.50 dollars each, wipes, gloves, primer, surface cleaner, and IPA all belong in the bill of material. Primer alone can add 0.05 to 0.20 dollars per part on hard to bond plastics. Roll storage, temperature controlled inventory, and shelf life write offs matter too: adhesive that expires unused at 5 to 15 percent of purchases on low volume programs is pure loss. Add a consumables and overhead line rather than burying it in a vague markup a customer can challenge.

Build the quote as a stack so each line is defensible. Net material at 7.5 g times 0.045 dollars is 0.34 dollars, labor 0.50 dollars, machine 0.02 dollars, consumables 0.12 dollars, scrap loading 0.05 dollars, sums to 1.03 dollars per part before margin. A customer can argue any single line, but the total holds because every number traces to a rate and a quantity. Quotes that lump everything into a dollars per part guess lose the negotiation and usually lose money, because the estimator cannot show where the number came from when volumes shift.

Sensitivity is what separates a quote from a gamble. Rerun the stack at 80 percent and 120 percent of expected volume and at plus 5 percentage points of scrap. If a 15 percent volume drop turns a 12 percent margin negative, your fixed cost allocation is too aggressive and you need a minimum order or a tiered price. Price adhesive at the current pail cost but note that raw resin has swung 10 to 30 percent in a year, so add an index clause on long programs. A quote that survives these shocks is one you can defend and still profit on.

Published 2026-07-01.