Wednesday, January 16, 2019

Understanding the Cold Drawing Process

Cold drawn metal, particularly steel, is common in many different types of consumer products. Drawn
metal is passed through a series of dies until it achieves the desired shape. Each die applies a specific
amount of pressure to the metal, assisted by a machine press. Drawn metal typically passes through
the dies multiple times. Cold drawn metal is manufactured at room temperature. Here is what you
should know about the process.
Before cold drawing takes place, the raw material must undergo several preparatory steps:
Hot Rolling: Bars or coils of the raw metal are created through hot rolling at temperatures of
approximately 1700 to 2200 F. This produces a scaled, rough surface, and may also create size
Cleaning: The bar or coil is carefully cleaned to remove abrasive scaling and smooth the surface.
Coating: The cleaned surface of the bar or coil is liberally coated with a lubricant to reduce friction
and improve the drawing process.
Pointing: The lead end has several inches removed from its diameter to allow the piece to pass
smoothly through the drawing dies. This is necessary because the die openings must be smaller than
the original bar or coil to apply the required pressure during drawing.
Cold Drawing
After the metal bar or coil has cooled to room temperature, the pointed end of the bar or coil passes
through the die and enters a gripping device on the drawing machine. The machine then pulls (draws)
the remainder of the bar or coil through the die. This reduces its diameter, increases its length, and
shapes its profile.
The finished product, referred to as either cold drawn or cold finish, appears bright and polished. Cold
drawing allows for more precise measurements and tighter dimensional tolerances than other forms of
metalworking, as well as sharper corners. Cold drawn metal also has a higher yield strength and
tensile strength than hot rolled metal.
Additional Processing
Depending on the product that is being created, cold drawn metal may undergo additional processing:
Multi-Pass Drawing: For complex shapes or profiles, the bar or coil may need to be drawn multiple
times. Multi-pass drawing pulls the metal through a series of gradually smaller die openings.
Annealing: Annealing is a thermal treatment that softens the material, modifies the microstructure,
and changes the mechanical properties. It can also remove internal stresses. Annealing may be
performed at any point in the drawing process. It is almost always performed between passes in
multi-pass drawing to improve ductility.
Ready to Start?
Atlas Bronze is a leading U.S. distributor of bronze, copper, brass, iron, and more. Contact us today at 1-800-478-0887 to place an order or learn about our custom products.

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