Analysis of sheet metal deep drawing process: How to create high-precision stainless steel deep-drawn steel cover parts?

1. What is sheet metal deep drawing?

Deep drawing is a processing method that uses a stamping die to stretch a metal sheet (such as stainless steel, carbon steel, aluminum, etc.) into a desired shape under pressure. It is widely used in the manufacture of precision parts such as stainless steel deep drawn steel covers, shells, containers, etc. Its features include:

One-time forming: reduce welding or splicing, and improve structural strength.

High precision: tolerance can be controlled within ±0.1mm.

High material utilization rate: suitable for mass production and reduce costs.

Typical applications:

Stainless steel deep drawn steel covers (food machinery, medical equipment)

Automobile fuel tanks, battery shells

Electronic equipment shells (such as routers, server chassis)

2. Processing flow of stainless steel deep drawn steel covers

(1) Material selection

304/316 stainless steel: strong corrosion resistance, suitable for food and medical industries.

430 stainless steel: low cost, suitable for general industrial use.

Deep drawing special steel (such as SPCC-SD): good ductility, reducing the risk of cracking.

(2) Mold design and manufacturing

Punch and die: key components that determine the final shape, requiring high hardness (HRC58-62) and surface finish (Ra≤0.8μm).

Blank Holder: controls the flow of the sheet to prevent wrinkling.

(3) Deep drawing process

Material cutting: laser cutting or blanking preparation.

Lubrication: coating with drawing oil (such as chlorinated paraffin) to reduce friction.

First drawing: forming the general outline (the drawing ratio must be controlled to be ≤2.0).

Multiple drawing: gradually reducing the diameter and increasing the depth.

Trimming/punching: removing excess burrs and completing precise dimensions.

3. Four key technologies for high-precision deep-drawn steel covers

• Drawing ratio control

Limiting drawing ratio (LDR): stainless steel is usually 1.8-2.2, exceeding which is prone to cracking.

Multi-pass stretching: complex parts need to be formed in steps, and annealing is added in the middle (such as 304 stainless steel needs annealing at 1050℃).

• Balance between wrinkle and crack prevention

Blank force optimization: too little pressure → wrinkle; too much pressure → crack.

Die radius design: R angle ≥ 4t (t is material thickness) to reduce stress concentration.

• Surface quality control

Mold polishing: avoid scratching the workpiece surface.

Lubricant selection: extreme pressure resistant lubricant is required for high temperature working conditions.

• Springback compensation

Offset the springback amount through overbending of the mold.

4. Common problems and solutions

5. Metal Processing Sheet Metal Deep Drawing Stainless Steel/Deep Drawing Steel Cover Parts FAQ

• Q1: What special designs are required for deep drawing dies?

A:

Punch/die: Hardness HRC58-62, surface polished to Ra0.4μm

Blank holder: Pressure control system with nitrogen spring

Guide structure: Precision ball guide column to ensure centering

Quick die change system: Suitable for multi-variety production

• Q2: What should I pay attention to when choosing a press?

A:

Tonnage: Usually requires material tensile strength × projected area × 1.5 coefficient

Stroke: At least 2 times the height of the part

Control accuracy: servo press is more conducive to the molding of complex parts

• Q3: How to detect the quality of deep drawing parts?

A:

Dimension detection: three-coordinate measuring machine (critical dimensions ±0.1mm)

Surface inspection: visual/optical detection of scratches and wrinkles

Thickness test: ultrasonic thickness gauge (thinning rate ≤20%)

Air tightness: helium mass spectrometer leak detection (medical/food grade requirements)