Deep draw stamping and deep drawn metal stamping describe the same operation: a blank is pulled into a die so the wall is formed from the flange, and stamping finishes what drawing starts. If you are comparing the two vocabularies, the process guide on drawn sheet metal and deep drawing covers the drawing side in full.
Deep Drawn Stamping: Where Drawing Ends and Stamping Begins
By Yu Lianbo — Tooling Design Engineer
What is deep drawn stamping?
Deep drawing forms a flat blank into a seamless cup or housing; stamping covers the operations that finish it - trimming, piercing, flanging, embossing, tapping. In production the two run inside the same tool or the same line, which is why the phrase deep drawn stamping is used for the combined route.
The four numbers that decide a deep draw
Number
Why it matters
Draw ratio per stage
Each grade has a limit; 304 is the reference, 310S is the most demanding. Exceed it and the part cracks at the base radius.
Blank size
Sets material cost and coil width, and follows from the surface area of the finished part
Draw force
Sets press tonnage. Balford runs 25 t to 350 t and draws up to Ø250 mm.
Die clearance
Controls wall thinning and the surface of the drawn wall
How many stages will the part need?
More than the diameter alone suggests. A deep housing in 310S needs more stages than the same housing in 304, and an intermediate anneal is added where the material work-hardens beyond what the next draw can take. Where the wall has to be thinner than the blank, the operation is ironing rather than another draw: the part is pushed through rings so the wall thins while both the inside and outside diameter stay under control.
Where stamping finishes the drawn part
Trimming the flange and piercing holes or slots.
Forming steps, flanges and locating features.
Machining sealing faces and bearing seats where the tolerance has to be tighter than a drawn surface can hold.
In-die tapping where the thread can be formed in the press.
A drawn wall is a formed surface, so its tolerance is a different class from a machined one. Fine resolution - to 0.001 mm - applies only to selected key machined features and has to be confirmed against the drawing.
A deep drawn metal bushing on a Balford press - seamless wall, no welded joint.The hydraulic press shop where the drawn stages run.
Both clips are our own production, shot in the Zhuji plant. The point of showing them is that a deep drawn part has no seam: the wall is continuous from the base to the rim, which is what makes a drawn housing leak-tight and dimensionally stable compared with a welded shell.
Deep drawing compared with the neighbouring processes
Process
What it does
Where it fits
What it cannot do
Deep drawing
Forms a flat blank into a seamless cup or housing
Housings, cups, shells, sleeves
Very tight tolerances on the drawn wall itself
Ironing
Thins the wall while both diameters stay controlled
Thin-wall sleeves and solenoid housings
Anything but a closed cylindrical form
Stamping
Trims, pierces, flanges and embosses
Finishing a drawn part, flat parts, brackets, shields
Forming a deep seamless body on its own
Spinning / flow forming
Forms a rotating blank against a mandrel
Large shells, small batches
High-volume thin-wall parts at a competitive piece price
Machining from bar
Cuts the shape out of solid material
Prototypes, very tight features, low volume
Competing with a drawn part on material cost at volume
Frequently asked questions
What is the difference between deep drawing and stamping?
Deep drawing forms a flat blank into a seamless cup or housing. Stamping covers the operations that finish the part: trimming, piercing, flanging, embossing, tapping. In production both run in the same tool or the same line, which is why the combined route is called deep drawn stamping.
What is a normal draw ratio in one stage?
It depends on the grade. Austenitic stainless steels are the reference for most sensor and valve housings; ferritic grades such as 430 are less forgiving and need more conservative stages. In practice the first draw is the deepest and each following stage takes a smaller reduction, which is why the number of stages is confirmed against the drawing rather than assumed.
When is ironing used instead of another draw?
When the wall has to be thinner than the blank. Ironing pushes the part through rings so the wall thins while both the inside and the outside diameter stay under control - that is how thin-wall sleeves and solenoid housings are made.
When is intermediate annealing needed?
When the material has work-hardened beyond what the next draw can take. 310S hardens fast and usually needs annealing on deep parts; 304 tolerates more deformation per stage. The decision is made from the draw ratio, the grade and the wall thickness.
Can a drawn wall hold a tight tolerance?
A drawn wall is a formed surface, so its tolerance is a different class from a machined one. Where a tight callout is genuinely needed - a sealing face, a bearing seat - the feature is machined after forming. Fine resolution, to 0.001 mm, applies only to selected key machined features and has to be confirmed against the drawing.
What wall thickness can be achieved?
Balford's published sensor housing configurations record walls from 0.25 mm to 1.00 mm, with 0.50 mm the most common value in the catalogue. The usable range depends on diameter, depth and grade, and is confirmed per drawing.
Which materials are drawn most often here?
Stainless steel dominates: SUS 301, 304, 305, 309, 310, 316 and 430, plus brass and copper for thermal parts, aluminium for lightweight housings, DC01 / DC04 class carbon steel for solenoid housings and 65Mn spring steel for spring cups.
How do I get a manufacturability opinion before tooling?
Send a 2D drawing or 3D model with the material, annual volume and the tolerances that matter. The DFM review covers draw ratio, blank size, forming stages, thinning, wrinkle and tooling-cost drivers, and comes back before steel is cut.