Mold Cooling Methods for Stable Temperature Control in Warm Forging and Continuous Production
During continuous mold production, the punch and die remain in repeated contact with high-temperature blanks. As production continues, the temperature of the convex and concave mold surfaces rises steadily, which can sharply reduce mold strength and hardness. This temperature increase not only shortens mold life, but also makes the mold more susceptible to deformation under high extrusion stress, affecting both part shape and dimensional accuracy.
To maintain stable performance, mold temperature should generally be controlled within the range of 150–300°C through structural cooling design or external cooling methods.
1. Why Mold Cooling Is Important
When mold temperature rises excessively during prolonged production, several problems may occur:
- Reduced hardness and strength of the mold material
- Higher risk of thermal deformation under forming pressure
- Lower dimensional accuracy of forged or extruded parts
- Accelerated wear and shorter mold service life
Proper cooling helps maintain process stability, improve product consistency, and extend tooling life in both small-batch and large-scale production.
2. Cooling Methods for Small Batch Production
In small batch production, mold temperature can often be controlled with simple manual or semi-manual methods. After each forming cycle, working components such as male and female molds can be cooled with compressed air.
Another practical method is to increase the time interval between warm forging cycles. This allows the mold to cool naturally before the next forming operation, reducing heat buildup during production.
3. Cooling Methods for Large-Scale Continuous Production
In high-volume production, more systematic measures are required to keep mold temperature stable within the target preheating range. Several effective mold cooling methods can be used individually or in combination.
Adjusting Press Stroke Rate
When using a mechanical press for continuous production, the number of strokes per unit time can be adjusted appropriately. Reducing the production rate gives the mold more time to release heat between cycles and helps prevent excessive temperature rise.
Internal Cooling Through Mold Holes
Cooling holes can be designed inside the mold to improve internal heat dissipation. For example, lubricant under a pressure of 0.12–0.14 MPa can be pumped through internal channels to cool the punch area. Compressed air at 0.4–0.5 MPa can also be introduced to cool the die and ejector sections.
This method improves cooling efficiency directly inside the tooling structure and helps stabilize working temperature during continuous operation.
Spray Cooling
Spray cooling is particularly useful in areas where liquid lubricant cannot flow effectively because water evaporates too quickly under high mold temperature. Controlled spray cooling helps dissipate heat from exposed mold surfaces and can supplement other cooling methods.
Water Cooling Devices
For demanding production conditions, dedicated water cooling devices can be integrated into the mold system. Water cooling is one of the most effective ways to control mold temperature and is widely used when stable thermal conditions are critical to maintaining part accuracy and tool life.
4. Combining Cooling Methods for Better Results
In many applications, the best results are achieved by combining multiple cooling methods. Press speed control, internal cooling channels, spray cooling, and water cooling can work together to maintain more consistent mold temperature across the production cycle.
By selecting the right cooling strategy based on production volume, mold structure, and forming temperature, manufacturers can reduce thermal deformation, improve dimensional stability, and extend the working life of forging and extrusion molds.