What is Cold Forging
Cold forging, unlike hot forging, deforms metal below its recrystallization point - near to or at room temperature. A preferred forging method for softer metals (such as aluminum), cold forging is less expensive and has the ability to produced forged parts that require little no finishing processes.
A cold working process, cold forging entails bar stock to be inserted into a die and then squeezed with a second closed die.
Similar to the cold heading process (the difference that cold forging makes use of vertical presses instead of horizontal cold heading machines), the workpiece is squeezed between two dies until it assumes the desired shape of the die.
Deformation occurs at room temperature, causing a change in the size and shape of the metal. Note here that this forging method is volume specific and generally compliments the cold heading processes by adding more intricate shapes to the blank used in cold heading processes.
Basic equipment types used for the forging method range to include vertical presses, either fully automatic or manually fed. Also note that these vertical presses used can be either hydraulically powered or mechanically powered.
A reliable and cost effective process, some of the parts produced using cold forging includes those for use in the automotive electrical industry and range to include:
- Parts for car seats and alternators (such as the claw-pole).
- Different types of gears used on other parts.
- Parts for starter motors such as transmission solenoid body, core and plunger, to name but a few examples).
- Motorcycle parts such as those for flywheel magnetos.
- Parts that are hollow with shafts and stems.
- Parts used for valves and switches.
- Cold forging is also used to produce anti-vibration spiders and parts.
The Benefits of Cold Forging
This particular forging process, like hot forging , offer manufacturers a number of advantages, including:
- No heating is required in cold forging processes.
- This forging process offers a better interchangeability as well as reproducibility.
- A better surface finish is achieved and contamination problems experienced are minimized.
- Cold forging offers a superior dimensional control.
- The capability to impart directional properties onto the metal being formed.
The Disadvantages of Cold Forging
Cold forging has the following disadvantages:
- The production of an undesired residual stress.
- Metals forged are less ductile and higher forces are required during cold forging processes.
- Because of the higher forces required in this process, heavier and more powerful equipment is needed as well as stronger tooling.
- Though capable of imparting directional properties onto the metal, these properties may be detrimental.
- The surfaces of the metals used must be clean and scale free.
- Because of the loss of ductility that accompanies strain hardening, intermediate anneals may be required.
Back to Main Page: Metal Forging
Further Suggested Reading:
- What is Hot Forging
- What is Cold Forging
- Metal Forging Processes
- Materials Used in Metal Forging
- Tolerances in Metal Forging
- Finishes for Forged Parts