Introduce the processing technology flow of stamping stainless steel strips

Stamping stainless steel strip refers to the process of processing stainless steel strip materials through stamping technology to obtain components or semi-finished products of specific shapes and sizes.

Stamped stainless steel strip

Stainless steel strips feature high strength, corrosion resistance, good ductility and smooth surface finish. Combined with the high efficiency and high precision of stamping process, they are widely used in electronics, automobiles, home appliances, medical devices, hardware and other fields.

The processing technology flow of stamping stainless steel strips is to transform stainless steel strips into components with specific shapes, sizes and properties through a series of orderly stamping procedures. The entire process needs to be combined with material properties, mold design and equipment parameters to ensure efficient and high-precision production.

I. Preparatory stage

Material selection and inspection

Select the grade of stainless steel strip (such as 304, 316, 430, etc.) based on product requirements (such as corrosion resistance, strength, stamping formability), and determine the thickness of the strip (usually 0.02 to 3mm), width and surface condition (such as mirror finish, matte finish, cold-rolled state).

Conduct incoming inspection on stainless steel strips: Check the thickness tolerance (which should meet the requirements of ±0.01 to ±0.1mm), surface defects (scratches, oxide scale, oil stains), and mechanical properties (hardness, elongation, to ensure that they meet the plasticity requirements for stamping).

Product and mold design

Design the stamping process plan based on the part drawings, determine the process combination (such as single-process stamping or continuous stamping), and plan the layout diagram (optimize material utilization rate and reduce waste).

Design special stamping dies

Simple parts (such as gaskets and punched parts) can use single-process dies (blanking dies, punching dies).

Complex parts (such as porous, curved and stretched parts) require progressive dies (continuous dies) to integrate multiple processes in one set of dies, achieving continuous automated production.

Mold material selection: Considering the high hardness and wear resistance of stainless steel, Cr12MoV and high-speed steel (such as W6Mo5Cr4V2) are commonly used for mold cutting edges, and quenching treatment is carried out (with a hardness of HRC58-62) to extend the service life.

Equipment debugging

Select the appropriate press based on the thickness of the strip and the stamping process (such as blanking, drawing) : for small parts, use a bench press or a high-speed precision press (with a speed of 50 to 500 times per minute), while for large parts, use a four-column hydraulic press or a mechanical press.

Debug the parameters of the punch press: including the slider stroke, stamping speed, and closing height, to ensure they match the die and avoid die damage or part deformation due to excessive impact force.

Ii. Core Stamping Processing Stage

According to the complexity of the parts, stamping processes can be classified into single-process stamping (suitable for simple parts) and continuous stamping (suitable for complex parts and mass production). The core processes are as follows:

1. Unrolling and leveling

Uncoiling: The coiled stainless steel strip is uncoiled through the uncoiler and, in conjunction with the feeding mechanism (such as roller feeding or servo feeding), the strip is continuously and evenly fed into the stamping die. The feeding accuracy is controlled within ±0.05mm (to ensure the consistency of part dimensions).

Leveling: If the strip material is bent or warped, the internal stress should be removed through a leveling machine (multi-roll leveling) to ensure the strip material is flat and prevent dimensional deviations of parts or die jamming caused by material deformation during stamping.

2. Basic stamping process

Blanking/shearing: The stainless steel strip is punched or cut through the die's cutting edge to obtain the initial blank of the part (such as round or square sheet materials). The cutting edge must be sharp to avoid burrs (the height of the burrs should be ≤0.03mm, otherwise it will affect subsequent assembly).

Punching/trimming: Punch out the required holes (circular or irregular holes) on the strip or blank, or remove the excess material on the edge to ensure the hole position accuracy (position tolerance ±0.02 to ±0.1mm) and smooth edge.

3. Forming stamping process

Bending: The strip is bent into a specific Angle (such as 90°, U-shaped, Z-shaped) through a bending die. According to the springback characteristics of stainless steel (especially austenitic stainless steel, which has a higher springback rate), die compensation (such as designing an excessive bending Angle) is required to ensure that the dimensions after bending meet the requirements.

Stretching: It is suitable for three-dimensional shaped parts (such as cup-shaped and cylindrical). Through the stretching die, the strip is drawn to the required depth. The stretching coefficient (the proportion of diameter reduction in each stretching) needs to be controlled to avoid cracking of the material due to excessive stretching (austenitic stainless steel has the best stretching performance and can be stretched multiple times).

Flanging/pressing ribs: The edges of parts are folded (such as flanging round holes into flanges), or reinforcing ribs are pressed (to enhance the rigidity of parts). During flanging, it is necessary to ensure that there are no wrinkles on the edges and the depth of the pressing ribs is uniform.

4. Precision finishing (optional)

For parts with high-precision requirements (such as electronic connectors), secondary finishing is necessary, including fine blanking (to improve the surface finish of the blanking), shaping (to correct dimensional deviations after bending or stretching), and deburring (to remove edge burrs through grinding, electrolysis or laser).

Iii. Subsequent processing Stage

Cleaning and degreasing

The stamping oil used in the stamping process (for lubrication and cooling) needs to be removed through a cleaning process. Common cleaning methods include:

Solvent cleaning (such as alcohol, cleaning agents) : Suitable for small parts;

Ultrasonic cleaning: Suitable for complex-structured parts, ensuring thorough removal of oil stains in crevices and holes.

Surface treatment

Select the surface treatment process based on product requirements

Passivation treatment: By treating with nitric acid or chromate solution, an oxide film is formed on the surface of stainless steel to enhance its corrosion resistance (especially for austenitic stainless steels such as 304 and 316).

Polishing: To enhance the surface smoothness (such as mirror-like effect), used for decorative parts or food contact parts.

Electroplating: such as nickel plating or chromium plating, to enhance surface hardness or change appearance (less used for stainless steel as it already has strong corrosion resistance).

Inspection and Packaging

Inspection: The dimensions, shape tolerances and surface quality of the parts are inspected by measuring tools (calipers, micrometers), image measuring instruments, etc., and non-conforming products are removed.

Packaging: Select the packaging method (such as blister boxes, trays) based on the characteristics of the parts to prevent scratches or deformation due to compression during transportation.

Iv. Process Characteristics and Key Controls

High efficiency and continuity: By adopting progressive dies and automated feeding systems, continuous production can be achieved. The daily output of a single production line can reach tens of thousands to hundreds of thousands of pieces, making it suitable for large-scale standardized parts.

Critical Control points

Mold accuracy: It directly affects the dimensional tolerance of parts. Regular maintenance of the cutting edge is required to prevent wear from causing dimensional deviation.

Lubrication effect: The stamping oil should be matched with the stainless steel material and process (such as high-viscosity extreme pressure oil for drawing) to prevent material scratches or overheating of the die.

Springback control: By optimizing process parameters (such as stamping speed and temperature) or die compensation, the shape deviation of the formed parts is reduced.