CNC Machining Polished Deep Drawn Stainless Steel Parts

Polished external deep-drawn stainless steel cover

Deep drawing stainless steel parts

Corrosion-resistant, strong, heat-resistant and chemical-resistant; it is no wonder that so many companies choose stainless steel as the material for their key components. Although stainless steel is ubiquitous in many industries from aerospace and defense to healthcare and power generation, forming and deep drawing stainless steel into frame parts, medical containers or components for gas turbines still require high skills and a deep knowledge base.

The benefits of stainless steel deep drawing

Compared with metal spinning and welding operations, the cycle time for each part is shorter.

The integral part can be made of a sheet or plate.

A fairly uniform material thickness can be achieved in the stainless steel shape.

Stainless steel deep drawing: how it works

Through deep drawing, stainless steel can be used to produce strong, corrosion-resistant parts, from fuel tanks to kitchen sinks. The process of deep drawing stainless steel involves applying pressure to stretch a flat piece of material on a template in a mold. According to the depth and width of the drawing, certain parts must undergo a series of stretching to reach the required specifications. Standard "pan" or "pot" shaped parts can be easily drawn to a depth of 5 inches. For deepening, process annealing is required to remove work hardening. Stainless steel is usually deep drawn by cold working at room temperature. It will harden at room temperature, but can be heat treated later to increase strength.

Two types of stainless steel can be made into deep-drawn parts: 400 series (ferrite group) and 300 series (austenite group). The 300 series metals are especially suitable for deep drawing forming due to their high nickel alloy content. Nickel gives them ductility and superior corrosion resistance without reducing strength. 304 DDQ (deep drawing quality), 304 EDD (extra deep drawing quality) and 316 stainless steel are the best choices for applications that require severe drawing.

Challenges associated with deep drawing stainless steel

Due to the unique properties of stainless steel, special treatment is required in the deep drawing process. First of all, the hardening speed of stainless steel workpieces is faster than that of carbon steel. Therefore, almost twice the pressure is required to stretch and form. This pressure must be adjusted according to the type of material to prevent cracks or wear. Secondly, the chromium oxide surface film of stainless steel (which prevents corrosion) will increase friction during the deep drawing process, which means that the mold must be carefully coated and lubricated to minimize wear costs. Finally, the speed of deep drawing stainless steel must be optimized to solve high friction, high pressure, deep drawing and other factors. Failure to calibrate the speed correctly can cause cracks or wrinkles. Generally, the more serious the tie, the slower the speed required.

Many metal stamping companies and tool shops, especially those that mainly use carbon steel, find that their standard processes cannot produce sufficient results for stainless steel parts. Customers should be cautious in cooperating with deep drawing suppliers who usually produce high-quality parts from stainless steel.