When a stamped part is no longer flat - when it becomes a cup, a box, a shell, or a tube - standard blanking and bending operations hit their limit. That is where deep drawing comes in. For buyers sourcing battery shells, sensor housings, lamp reflectors, or kitchen and industrial containers, understanding this process is the key to getting accurate quotes and avoiding quality disputes.
What deep drawing actually is
Deep drawing uses a punch to push a flat metal blank into a die cavity, forming a hollow shape in a single stroke - or more often, in several sequential draws. The metal flows rather than cuts, so the wall thickness stays close to the original sheet thickness.
The industry benchmark for "deep" drawing is a draw ratio (blank diameter ÷ punch diameter) above 2.0, or a depth exceeding the part diameter. Typical applications include:
- EV battery cases and caps
- Sensor and relay housings
- Lamp reflectors and bezels
- Motor cups and shield cans
- Kitchen and catering containers
Materials that draw well
Not every alloy can be stretched into deep shapes without failing. The best deep drawing materials are:
- DC01–DC05 deep drawing steel: the workhorse for cups and cans, excellent formability
- SPCC/SPCD cold-rolled steel: economical, good for moderate draw depths
- SUS304 / 316 stainless steel: for corrosion-resistant shells, needs stronger presses
- Aluminum 5052 / 1100: lightweight enclosures, watch for wrinkling on deep draws
- Brass C26000: decorative and electrical drawn parts
Three defects to watch for in drawn parts
1. Wrinkling at the flange: caused by insufficient blank holder force. Wrinkles that get ironed into the wall cannot be reworked - the part is scrap.
2. Tearing at the punch radius: a sign the material is being stretched too far in one draw. The fix is more draw stages, not more force.
3. Excessive thinning at the wall: walls that thin beyond 20% of original thickness weaken the part. Critical for pressure or safety
applications.
A professional supplier controls these with proper blank holder pressure, multi-stage drawing, annealing between draws when needed, and consistent lubrication.
Equipment matters
Deep drawing demands tonnage. A shallow 50 mm cup in 1.5 mm steel may need 110–200 ton presses; complex stainless shells often require hydraulic presses for controlled forming speed. Suppliers with only small high-speed presses will quote your drawn part as "difficult" - or worse, take the order and fail at tryout.
At Zhejiang Shangshi Precision Hardware (Shangshi), our press shop covers 25 to 200 tons including hydraulic presses, with an in-house die workshop that builds multi-stage drawing dies. Drawn battery shells, sensor cups, and custom enclosures are among our regular export programs.
Planning a drawn part? Send your drawing to ella.shangshi@gmail.com or WhatsApp +86 13968763726 - our engineers will confirm draw stages, material recommendation, and a quotation within 24 hours.
