What casting defects can be caused by design errors in the cooling water circuit of LPDC molds
The unbalanced layout of the cooling water circuit in LPDC molds can lead to the concentration of hot spots in castings, an increase in the incidence of porosity and porosity defects, and is also a high-frequency stepping point for overseas foundries.
When the distance between the cooling water circuit and the surface of the mold cavity is less than 12mm, the local temperature difference of the mold is too large, the occurrence cycle of thermal fatigue cracks is shortened by 40%, and the service life of the mold decreases.
This distance is a commonly used reference threshold in the industry. If the distance is too close, it can easily cause the mold surface to cool down, while if the distance is too far, the heat dissipation efficiency will be insufficient.
The distance between waterways exceeds 25mm, the temperature gradient in the cavity is out of control, the solidification lags behind in areas with thicker wheel hubs, and the shrinkage channel is closed in advance to form internal looseness.
Such defects account for the highest proportion of returns and rework in the mass hub production lines in Mexico and Türkiye.
The difference in water flow rate between the inlet and outlet of the waterway exceeds 15L/min, and the cooling rate in different areas of the same set of molds is inconsistent. The fluctuation amplitude of the casting size increases by more than 0.2mm.
Exceeding the size tolerance will directly lead to insufficient machining allowance in the future, and overseas customers generally have strict control over machining tolerances.
The annular wheel hub mold prioritizes the use of partitioned independent water circuits and single loop temperature control. Compared to series water circuits, the average casting yield is increased by about 7%.
The low temperature at the inlet and high temperature at the outlet of the series waterway result in a large temperature difference between the front and rear cavities, making it difficult to maintain stable sequential solidification conditions.
During the LPDC mold CAE simulation phase, Xinfeng Machinery will synchronously output temperature field cloud maps to verify the rationality of the waterway layout in advance.
Many small and medium-sized foundries only focus on the cavity structure when purchasing molds, ignoring the review of cooling schemes, and only discover defects in the later stage of mold testing.
Modifying the completed mold waterway typically incurs a cost of 12% -20% of the total mold price, while also extending the delivery cycle.
The environmental temperature in the factory area under high temperature conditions in the Middle East is always above 38 ℃, and the heat dissipation load of the molds is higher. The diameter of the waterway needs to be enlarged by one level for redundant design.
Many factories in Southeast Asia have insufficient purification of cooling water, and impurities in the water can easily block the fine water channels. It is recommended to reserve detachable cleaning joints.
Google backend data shows that overseas process engineers often search for LPDC mold cooling circuit design, but there is a significant gap in content.
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There is no unified standard for the design of cooling water circuits, which requires comprehensive iteration based on casting wall thickness, filling pressure, and circulating water temperature. Templates cannot be directly applied.
For new energy chassis structural component molds, the difference in wall thickness is greater, and the necessity of zone cooling will be further increased compared to wheel hub molds.
Some customers hope to rely on increasing water pressure to compensate for the design defects in the waterway. The water pressure has been raised to above 0.6 MPa, but the cooling improvement effect is limited.
Excessive water pressure can also increase the risk of sealing leakage, and mold leakage can cause aluminum liquid to explode, posing significant production safety hazards.
## FAQ
Q: What is the safe distance between the waterway of LPDC mold and the mold cavity?
A: The general recommendation is to control it within the range of 12-20mm, taking into account both heat dissipation efficiency and mold strength.
Q: Which is more stable, a connected waterway or an independent partitioned waterway?
A: Partition independent waterway temperature control is more uniform, and mass-produced wheel hub molds are preferred.
Q: What are the consequences of waterway blockage?
A: Local heat dissipation has deteriorated, resulting in loose heat nodes and a large number of porosity defects.
Q: Does the high-temperature factory area need to adjust the waterway plan?
A: If the environmental temperature remains high for a long time, the diameter of the waterway can be appropriately enlarged to reserve redundancy.
Q: Can the waterway design be adjusted after the trial mold is completed?
A: The cost of changing the waterway in the later stage is high, so priority should be given to completing verification in the simulation phase.
Q: Is there a relationship between cooling water circuit and mold life?
A: Uneven temperature control can accelerate thermal fatigue and significantly shorten the service life of molds.
Q: What is the appropriate control range for cooling water flow difference?
A: It is recommended to control the difference in inlet and outlet water flow rate of a single circuit within 5L/min.
Q: What are the difficulties in designing the waterway for chassis mold?
A: The wall thickness variation is complex and requires independent temperature control in multiple areas to match the solidification rhythm.
2026-11-06 22:18:41
