Cold Forming Stainless Steel: The Ultimate Guide

With the right knowledge on cold forming stainless steel, you can make a range of parts and components. This guide takes you through the fundamental aspects you should know about cold forming stainless steel.

What Is Cold Forming?

It refers to a forging method used for shaping metal materials at ambient temperature through various upsetting and extruding steps. Essentially, this technique helps to retain or enhance a material’s tensile strength while still enabling extreme intricate manipulation.

Advantages Of Cold Forming Stainless Steel

Improved Product Quality
Improved Product Quality

Work hardening process that the parts go through in this process enables them to attain high quality parts.

Excellent Strength And Durability
Excellent Strength And Durability

It optimizes the metallurgical properties of the part, and this is vital in keeping part integrity and making it stronger and more hard-wearing.

Gives Better Reproducibility
Gives Better Reproducibility

Parts in this process are manufactured inside a tool with extremely consistency leading to high repeatability levels.

Immense Waste Reduction
Immense Waste Reduction

It yields excellent raw materials with no excess machine shavings or scrap since you’re manufacturing part in its near-net state.

Large Volume Production
Large Volume Production

The machinery work at high speeds, thus making it easy to produce several millions of pieces per year efficiently.

This process guarantees full-scale production, thus easy to handle high demands all the time.

High Cost-Savings
High Cost-Savings

Most operations of this process are automated, thus reduces the need for manual labor, which allows you to cut recurring expenditures significantly.

High Speed And Efficiency
High Speed And Efficiency

It is a naturally fast process and allows you to attain about 350 parts per minute or more for simple parts. Ideally, the process is sequential; thus, parts are completed during every blow.

Types Of Stainless Steel Best For Cold Forming

They include the following;

Type 304 Stainless Steel Cold Forming; It is quite popular and largely used in different applications in various industries.  This stainless steel grade offers excellent corrosion resistance from most oxidizing acids. Besides, it is quite durable and easy to sanitize.

Type 305 Stainless Steel Cold Forming; This type of stainless steel is austenitic chromium-nickel with a moderate work hardening rate making it suitable for the cold forming process.

Type 384 Stainless Steel Cold Forming; It is also austenitic stainless steel with relatively high tensile strength and an ideal work hardening rate.

Types Of Stainless Steel Best For Cold Forming

Bending Stainless Steel

Bending Stainless Steel
Bending Stainless Steel

It is a stainless steel forming where punch press is open type single hydraulic or mechanical transmission with a long and narrow table. Cold bending stainless steel material produces parts with length dependent on original thickness and type of stainless steel used.

Additionally, the machine power and specific size of installed tools determine the actual length of such parts. To minimize abrasion on stainless steel parts during cold bending process, it is advisable to have a punch press made of 12% chromium with a plastic film for advanced protection.

Using a general mold cold bending punch press is more economical when producing small-batch parts. However, a special mode is needed to produce unique shape parts.

Also, producing a large batch is more economical since this method reduces cost of mold. Moreover, advanced technology allows more enterprises to use stainless steel bending technology to produce several parts.

You can learn more about bending stainless steel.

Stamping Stainless Steel

Stamping Stainless Steel
Stamping Stainless Steel

It is a technology adopting the punch and die to produce the desired shape. This method of stainless steel forming process is common in many sectors. Punch press used in this process can either be hydraulic or manual.

However, the former is recommended since it can offer a full load of pressure in entire deep drawing process. Ordinarily, stainless steel stamping consumes a lot of pressure hence the need for using the press frame to bear such pressure.

Additionally, it is advisable to avoid scratches, particularly the high temperature and high friction stamping stainless steel that scratch the surface. Therefore, consider specialized lubricating oil or stamping oil with extreme pressure additives rather than using emulsion or soap.

On the contrary, such high-pressure additives can corrode stainless steel surfaces. Therefore, always remove the oil on the workpiece’s surface immediately after stamping forming.

You can learn more about stainless steel stamping.

Hydroforming Stainless Steel

Hydroforming Stainless Steel
Hydroforming Stainless Steel

This is a cold forming stainless steel technique that applies pressurized liquids media to produce a workpiece with definite shapes. In most instances, it is always cost-effective to hydroform stainless steel, leading to a high-quality product.

This process can handle stainless steel material with a diameter of up to 32 inches. Technically, the sheet is cut into blanks and put in a hydroforming press over a punch one at a time.

Hydraulic pressure is applied from above as the punch rises, thus forming the blank into desired shape. Where heat treatment is necessary as a part of forming process, the parts are shifted to vacuum treating, ideal for treating stainless steel materials.  This technique is a highly cost-effective approach for making irregular parts, given it eliminates the need for hardened tools, expensive dies, and additional polishing.

Here is more information about hydroforming stainless steel.

Fluid Cell Forming Stainless Steel

Fluid Cell Forming Stainless Steel
Fluid Cell Forming Stainless Steel

This process forms stainless steel sheet materials into complex shapes using a bag or fluid cell press. Ideally, the press exerts relatively high pressure of up to 11,600 psi onto a flexible diaphragm. This diaphragm creates sheet metal into complex shapes which meet the desired precise tolerances. This stainless steel forming process was traditionally used to manufacture large aerospace parts and components.

However, several industries, including medical devices, commercial lighting, and mid-sized aerospace, are presently using this technique to form various parts. In essence, fluid cell forming stainless steel offers high productivity, faster design prototyping, and excellent design flexibility. You can form several parts simultaneously in a day resulting in significantly faster prototyping, lower tooling costs, and shorter lead times. The fluid cell press limits the amount of surface abrasion, translating into fewer resources spent on finishing.

Cold Heading Stainless Steel

Cold Heading Stainless Steel
Cold Heading Stainless Steel

It refers to a multistep process for forming stainless steel parts at ambient temperature. Simply put, this process is performed without the need to heat stainless steel workpiece beyond recrystallization temperature. In this process, large stainless steel material is placed into a blank and pulled through a drawing machine.

The drawing equipment compresses the material to the desired diameter before it passes in cold heading machine. Blank is hit between punch block and die inside cold heading machine to push the material into a die and create desired shape. Punch block forces the material out of the die to yield a head larger than the original blank.

You can use forward or backward extrusion. The former has smaller cavities that create compression. In backward extrusion, stainless steel material is forced backward through a punch to form a cavity or hole.

Cold Extrusion Stainless Steel

Cold Extrusion Stainless Steel
Cold Extrusion Stainless Steel

This is a cold forming stainless steel technique that involves forcing the material through a die at ambient temperature to produce a continuous part with a consistent cross-section. It is available in three main variations, which include forward, backward and upsetting extrusion.

Forward extrusion pressures the metal to flow through a hole in a die in a similar direction as descending punch to form desired part shape and dimension. Backward extrusion pushes the metal to flow upwards around descending punch. Upsetting refers to a gathering of metal in specific sections along the part length.

This technology allows forming parts to a desired size and shape by shifting metal at ambient temperature into the die. Adequate force is needed to exceed the stainless steel yield strength and ensure plastic deformation results. This enables metal to fill out the cavities hence attain closer tolerances.

Cold Drawing Stainless Steel

Cold Drawing Stainless Steel
Cold Drawing Stainless Steel

It involves forcing a piece of stainless steel metal through a single or series of dies, thus reducing the original part’s cross-section size. This cold forming stainless steel process produces a dimensionally consistent final product while enhancing both tensile and yield strength. It generates a clean surface free from many defects and other defects.

In cold drawing stainless steel, a stationary platform known as a drawn bench is used for holding the die in position. The bench contains an infeed and out-feed side, with the latter consisting of a longer roller platform for catching finished stock after forcing it through die.

Stainless steel metal stock is loaded into an in-feed section. One side of the stainless steel metal stock is reduced in size to enable it to fit through the die. Hydraulic cylinder pulls the metal through the die and onto the outfeed rollers.

Hot Vs. Cold Rolled Stainless Steel

Hot Rolled Stainless Steel
Hot Rolled Stainless Steel

It is manufactured through rolling and pressing stainless steel above the recrystallization temperature of around 1100°C. The essence is to refine the microstructure grains and improve mechanical properties of the parts. It is easier to make and relatively affordable than cold-rolled stainless steel. Besides, it is free from internal stress, often from work-hardening and quenching. However, it has a rough surface texture and few-dimensional distortions.

Cold Rolled Stainless Steel
Cold Rolled Stainless Steel

Essentially, this is a type of stainless steel drawn from hot rolled stainless steel at room temperature to attain accurate dimensions and a smooth polish. It has better surface finish quality, straightness, and precise tolerances than hot-rolled stainless steel. Moreover, it is also harder and stronger than hot rolled stainless steel. However, it tends to be more expensive and available in fewer shapes than hot rolled stainless steel.

Cold Forming Stainless Steel Vs.

Hot Forming Stainless Steel

Cold Forming Stainless Steel
Cold Forming Stainless Steel

Cold forming stainless steel is a metalworking process for shaping parts below their recrystallization temperature. It occurs at a relatively low room temperature, and it distorts crystal grains and inclusions, making the metal stronger, stiffer, and harder. You can perform it using various simpler and cheaper processes than hot forming stainless steel, such as extruding, forging, coining, drawing, flanging, flattening, etc.

Hot Forming Stainless Steel
Hot Forming Stainless Steel

It is a stainless steel forming process that runs above the material’s recrystallization temperature to form shaped parts. The sheet metal recovers and softens during stainless steel hot forming process. It eliminates springback hence enhances accuracy in addition to producing complex shapes manufactured more simply with tighter radii. While hot forming, the material avoids thinning and prevents cracking.

Disadvantages Of Cold Forming Stainless Steel

Needs Greater Surface
Needs Greater Surface

Ordinarily, this process requires a greater surface for manipulating shape and sizes of stainless steel workpieces. It arises since this metal is harder, thus requiring heavier equipment, harder tools, and greater forces.

Requires High Level Of Cleanliness
Requires High Level Of Cleanliness

It is necessary to clean workpieces in cold forming since the presence of dirt contaminants is likely to affect part dimensions adversely.

Prone To Springback
Prone To Springback

This phenomenon involves cold-worked stainless steel springing back to the original shape once it is deformed. Cold forming is thus likely to cause springback in parts, whether partly or typically to its original shape.

Limited Deformation
Limited Deformation

Typically, metal is less malleable and ductile, and these limit the extent of deformation that you can obtain.

Cold Forming Stainless Steel Applications

Automotive Industry
Automotive Industry

The common cold formed parts used in automotive industry include bolts, nuts, rivets, shafts, and gears. Such parts are used in assembling different components such as suspension systems, engine parts, transmission systems, etc.

Aerospace Industry
Aerospace Industry

Nuts, bolts, screws, shafts, and rivets are used in automotive industry for making interior trims of air crafts.

Electronics
Electronics

Different electronics use a wide range of cold-formed stainless steel parts such as contacts, plugs, and heat sinks.

Fittings Industry
Fittings Industry

A wide range of bolts, nuts, screws, and rivets come in handy in fitting and fastener industry. These parts are essential in ensuring various components are assembled to provide single functional units.

Heating Engineering
Heating Engineering

Conduit pipes are the main cold formed stainless steel parts used in this industry for conveying regulated air to respective applications.

Mechanical Engineering
Mechanical Engineering

Different mechanical equipment and machinery use various cold formed stainless steel parts in assembling the components. Nuts, screws, bolts, and washers are some notable parts used considerably in mechanical engineering.

People Also Ask:

Can Stainless Steel Be Cold Formed?

Yes.

Most stainless steel can easily be cold formed, but some specific grades offer best results since they are more suitable than others.

Can You Cold Forge Stainless Steel?

Yes.

Stainless steel exhibits more hardening properties than most metal alloys, making it easy to cold form since it has high forging loads.

What Are The Common Problems During Cold Forming Stainless Steel?
  • Sliding contact between the materials arises from some cold forming processes.
  • Cold hardenability due to high strength of stainless steel
  • Damaging passivation coating of this material due to surface corrosion.
  • Scratches, dirt, and double skin of surface material
What Is Stainless Steel Cold Heading Wire?

It is a material used cold for manufacturing bolts, rivets, screws, and nails to form the desired shape.

More Resources:

Cold Working

Hot Working

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