Two quotations can show the same part, material and annual volume and still differ because one price includes the real forming route while the other does not. For a deep drawn cup, shell, sleeve or housing, the recurring unit price is built from the blank outward: material yield, draw stages, press time, secondary work, finishing, inspection and packing. Tooling sits on top as a one-time cost unless both sides agree to recover it in the piece price.
What drives the unit price of a deep drawn part?
What drives the unit price of a deep drawn part is the blank's material cost, the number of draw or ironing stages, press cycle time, secondary operations, inspection and finishing, plus how tooling is recovered over the ordered quantity. A deep-drawn quote, also called a drawn-shell or drawn-housing piece price, normally contains six to eight recurring cost lines, while tooling is a separate one-time line unless the buyer asks for it to be amortised. Blank size and gross material weight come first: strip layout and scrap affect yield before the press runs. Each additional draw station adds die wear, handling and press time; ironing, annealing or machining may be needed when wall thickness or tolerance cannot be held as drawn. Outside-process treatment and inspection must also be priced explicitly. A 1,000-piece order and a 100,000-piece order can carry the same die cost, but the tooling burden per part differs by 100 times.
The recurring price builds from the blank outward
- Gross material. The blank or strip area, thickness, density and purchase price set the starting material cost. Coil width and nesting determine how much metal becomes the part.
- Forming route. Blanking, the first draw, any redraws, trimming, piercing and ironing each consume press time and tool capacity.
- Material condition. A work-hardening grade may need inter-stage annealing. Bulk heat treatment is managed through a qualified external partner and must appear as its own cost and lead-time line.
- Secondary operations. Machining, deburring, tapping, leak testing or assembly are separate from the drawing cycle and should be itemised.
- Finish and documentation. Plating, passivation, painting, inspection, PPAP evidence, packaging and freight are not free riders on the stamping price.
The general calculation for a stamped quotation is set out in how stamping parts are priced. This guide narrows the question to deep-drawn parts, where the stage count and wall requirement change the route more than the finished outline alone suggests.
How draw stages and wall requirements change the price
A shallow cup may form in one draw. A deeper shell or a housing with a controlled wall may need several draws, a redraw, trimming and an annealing step between operations. Each stage adds press time, handling and die maintenance; it can also force a larger or more complex tool. If the drawing requires a wall that cannot be held by forming alone, ironing or a secondary machining operation has to be priced rather than hidden in a general processing factor.
Why volume changes the comparison
At 1,000 pieces, a 100,000-piece programme can look cheaper per part even when the two suppliers use the same press and material, because the fixed die is divided across more pieces. The opposite mistake is comparing two piece prices without knowing whether one includes tooling recovery, annealing, finishing or packaging. Ask for one-time and recurring costs as separate columns, then add tooling divided by the quantity you will actually order. A forecast is not a commitment; state the expected annual volume, batch size and programme life separately.
What should a buyer put in the RFQ?
- The drawing or model, material grade, temper and thickness, with the dimensions that are functional.
- Finished inside and outside diameters, drawing height, wall thickness and the measuring position for each.
- Annual volume, order batch and programme life, including any expected design changes after first article.
- Whether the wall must remain as drawn, be ironed, or be machined, and which tolerances are truly critical.
- Finishing, inspection, packaging, PPAP and delivery requirements, so external processes and documentation are quoted explicitly.
Key point
Compare deep-drawn quotations line by line: blank yield, draw stages, press time, secondary work, external processing, inspection and tooling recovery. A lower piece price is only comparable when both suppliers included the same route and the same one-time costs.
Zhejiang Balford Mechatronics Co., Ltd. forms deep drawn and stamped parts on presses from 25 t to 350 t, up to a 250 mm maximum draw diameter, with die design and build handled in house. Bulk heat treatment and finishing processes are disclosed as external operations when they are required.
Frequently asked questions
Why is a deep drawn part more expensive than a flat stamped part?
A flat blank mainly pays for material and one cutting stroke. A deep drawn part also pays for blank development, one or more forming stages, press cycle time, possible annealing or ironing, trimming and inspection. The die and the process route are correspondingly more involved.
Does a larger order always reduce the unit price?
It usually reduces the tooling burden per piece, but not every recurring cost. Material, press time, finishing and inspection still scale with quantity. A supplier that gives only a total price hides whether the saving comes from better yield, fewer operations or simply spreading the die over more parts.
How do tolerances affect the price of a drawn housing?
Functional tolerances can change the number of draw stages, the need for ironing or machining, the inspection method and the scrap risk. A tight wall or concentricity callout should be discussed at DFM stage, because the cheapest way to hold it may be a different forming sequence rather than a tighter inspection.
Should tooling be included in the piece price?
Usually it should be shown separately, then divided by the committed volume if the buyer wants an all-in comparison. Keeping the one-time tool cost visible shows what changes if the programme volume, design or tool ownership changes.