Powder coating cost estimator

Area sets the material, mass sets the oven

Two parts with the same 0.8 m² of surface can differ in coating cost by 60%. A 1.2 mm panel weighs 7.5 kg and heats in two minutes. A 6 mm bracket frame of the same area weighs 37.7 kg and spends five times as long in the oven, holding a rack slot the whole time. Coating is priced on area for the chemicals and on mass for the cycle, and a quotation that gives one number per part hides which one is driving it.

The cost model

cost per part = A × (c_pre + c_apply + m_powder × c_powder) + n_mask × c_mask + c_handling + c_inspect

A is the coated area per part in m², c_pre the pretreatment rate, c_apply the booth and labour rate, m_powder the powder mass per m², c_powder the powder rate per kg, n_mask the masked features and c_handling the oven and rack occupancy per part. Every rate is an input. The ones quoted here are planning defaults you should replace with your own data.

Pretreatment is priced per m² and per load

The seven-tank line — degrease, rinse, derust, rinse, activation, phosphating, rinse — costs the same per m² whether the part is simple or awkward. What changes is loading: a small bracket with a 0.05 m² area still takes a hook position, so the line rate per m² for small parts is set by rack density, not chemistry.

Powder coverage follows film thickness, not gun time

The mass of powder needed for a given film is fixed by physics: 1 µm over 1 m² is 1 cm³ of solid.

powder (g/m²) = ρ (g/cm³) × DFT (µm) / transfer efficiency

With a polyester at 1.5 g/cm³ and 65% transfer efficiency on a flat panel, a 70 µm film needs 162 g/m². Reclaim and a well-set corona gun lift transfer to about 90–95% on simple geometry; deep channels and returns drop it to 45%.

Masking is the line that gets left out

Every thread, earth stud, mating face, hinge and connector cut-out that must stay bare needs a plug, cap or tape before the part enters the booth. Fifteen to thirty seconds per feature is normal, plus removal, plus chasing threads that filled anyway.

A part with six masked features costs more in masking than in powder. If the design can use weld studs fitted after coating, or a masked zone consolidated into one area, the saving shows up immediately.

Cure time is a function of section mass

The powder flows and cross-links when the metal reaches temperature, not when the oven air does. Polyester powders typically need 180–200 °C metal temperature held for 10–15 minutes.

A mixed load runs to the heaviest part. Putting a 10 mm base frame on the same rack as 1.2 mm cover panels gives every panel the heavy cycle, and the extra oven time is charged to the panel.

Inspection is time, not material

A DFT gauge reading per batch, a cross-hatch adhesion test, a gloss reading and a colour check against the approved sample take minutes, but they need a cured part, a record and someone qualified to sign it. On small batches that overhead is a real share of the price. On large batches it disappears.

The area you measure is not the area on the drawing

CAD gives projected area. A booth sprays developed area, including the reverse of a folded flange, the inside of a channel and the 2% added by edges and returns. A 0.55 m² projected panel bends into roughly 0.8 m² of developed surface. Coating both faces doubles it again, and a part coated on one side only still receives overspray on the other, which either has to be accepted or masked.

Estimates go wrong in three predictable ways: the projected area is used instead of the developed area, the reverse face is forgotten on parts that show from both sides, and masking is estimated from the drawing rather than from the part in the fixture. Each of those is a 15–25% error on a line item that is already the largest in the coating price.

Specification levers

A specification that says "powder coated, colour to approval" prices nothing. One that names the powder chemistry, the RAL, the DFT range, the masking, and the adhesion and salt-spray tests prices everything.

What Ganesh runs

Coating runs through a seven-tank pretreatment line, a 16 ft × 16 ft shot blast chamber, an 18 ft × 14 ft electrostatic powder booth, a wet paint booth and a curing oven, with a DFT gauge and cross-hatch adhesion testing on the bench. The plant holds ISO 9001:2015 and ISO 14001:2015 and runs an effluent treatment plant for the pretreatment discharge.

For the substrate-specific routes, read degreasing before powder coating, why powder coating fails on outdoor enclosures and the paint shop capability. The coating guides cover the failure diagnosis.

What to put in the RFQ

• Coated area per part, or the drawing with all faces identified.
• Substrate and its condition: oiled, rusted, galvanised or bare.
• Powder chemistry and RAL, plus gloss level.
• DFT range and the measurement standard.
• Masking list with a marked-up drawing.
• Tests required and the batch size they apply to.
• Packing method, because coated parts scratch in transit more often than in the booth.

Enclosure panel, 0.8 m² per part, quantity 50, one coat, two masked M6 studs, DFT 70 µm. Planning defaults, all editable: pretreatment ₹60/m², booth application ₹45/m², polyester powder ₹280/kg at 1.5 g/cm³ and 65% transfer, masking ₹6 per feature, cure and handling ₹12 per part, inspection ₹250 for the lot.

Step 1 — Total area: 0.8 × 50 = 40 m².

Step 2 — Pretreatment: 40 × ₹60 = ₹2,400 → ₹48.00 per part.

Step 3 — Powder mass: 105 g/m² at 100% transfer ÷ 0.65 = 162 g/m²; 0.162 × 40 = 6.48 kg. At ₹280/kg = ₹1,814 → ₹36.29 per part.

Step 4 — Booth application: 40 × ₹45 = ₹1,800 → ₹36.00 per part.

Step 5 — Masking: 2 features × 50 parts = 100 × ₹6 = ₹600 → ₹12.00 per part.

Step 6 — Cure and handling: 50 × ₹12 = ₹600 → ₹12.00 per part.

Step 7 — Inspection: ₹250 → ₹5.00 per part.

Total = ₹7,464, or ₹149.28 per part and ₹186.60 per m².

Now move the DFT call-out to 120 µm. Powder becomes 277 g/m², or 11.08 kg at ₹280 = ₹3,102, and the heavier film adds about ₹5/m² of application time (₹2,000). Pretreatment, masking and inspection are unchanged. Total = ₹8,952, or ₹179.04 per part and ₹223.80 per m² — 20% more for a film change nobody re-quoted.