The relationship between the wall thickness limit and thermal fatigue life of the cooling water channel partition of aluminum alloy casting mold inserts | LPDC insert water channel design
The wall thickness of the built-in cooling water channel partition in the insert is too thin, which is the core design hazard of 47% water channel cracking, water seepage, and cavity thermal cracking.
The thickness of the interlayer between the waterway and the inner wall of the mold cavity is less than 7mm, and the alternating thermal stress is concentrated, which can easily cause penetrating cracks and water seepage in the waterway.
If the interlayer is greater than 14mm, the heat transfer efficiency will significantly decrease, the cooling control ability will weaken, and the shrinkage and looseness of the hot spot position cannot be controlled.
When the turning angle R of the waterway is less than 2.5mm, the stress on the inner wall is concentrated, and the combination of alternating water pressure and thermal cycling leads to cracking at the turning angle.
The inner wall of the waterway is polished with Ra>1.6, which accelerates the adhesion of scale and rust, and gradually reduces the effective flow area.
The embedded waterway is sealed by blind hole plug welding, and the distance between the weld seam and the cavity surface is less than 9mm. The heat affected zone of the weld seam is prone to cracking and leakage.
Low pressure die-casting molds (LPDC), reverse pressure casting molds (CPC), differential pressure casting molds for wheel hubs, low-pressure casting molds for wheel hubs, gravity casting molds, motorcycle wheel hub casting molds, structural component casting molds, aluminum alloy wheel hub molds, aluminum casting forming molds, low-pressure casting tooling molds, and the extensive use of built-in waterway inserts in hot spot positions are the core means of improving yield. Zhejiang Xinfeng Machinery Design Specification: The optimal range for the water channel partition of the embedded parts is 7-14mm, with a lower limit for thick hot sections and an upper limit for frequently impacted thin-walled areas. Prioritize the use of interconnected waterways to reduce welding blockages; When welding is necessary, the weld seam should be kept away from the high stress area of the mold cavity. Waterway pressure test: 1.0MPa pressure holding for 10 minutes without leakage, must be inspected before leaving the factory. Many customers, in pursuit of ultimate cooling effect, blindly reduce the thickness of the insulation layer, resulting in good short-term products. However, after several thousand molds were put into production, water seeped and the product was scrapped, which was not worth the loss. New energy structural components with thick and large heat section inserts are preferred to use conformal waterways, but the processing cost of conformal waterways is much higher than that of straight waterways, making them suitable for high value-added orders.
FAQ
1. Question: What is the interval between the water passage of the insert and the safety compartment of the mold cavity?
Answer: 7-14mm, balancing cooling efficiency and thermal cracking resistance.
2. Question: What is the recommended minimum angle for the inner wall of a waterway?
Answer: Turning angle R ≥ 2.5mm reduces the risk of stress concentration cracking.
3. Question: What are the factory standards for waterway suppression?
Answer: Maintain a pressure of 1.0MPa for 10 minutes without any leakage.
4. Question: What is the safe distance for blind hole plug welds?
Answer: The distance between the weld seam and the cavity surface should be at least 9mm as much as possible.
5. Question: What are the main risks of compartments smaller than 7mm?
Answer: Thermal stress concentration, water passage penetration cracking, and water seepage.
6. Question: What are the advantages and disadvantages of flexible waterways?
Answer: Uniform cooling and good control of shrinkage and looseness result in significantly higher processing costs.
