High pressure die-casting to LPDC modification plan, including a complete set of key points for wall thickness, gate, exhaust, heat treatment, and tolerance modification
More and more customers are considering switching to low-pressure casting due to leakage and inability to heat treat die-casting shells; Directly using the die-casting drawing to create a low-pressure mold is likely to result in poor cold insulation and filling. The structural logic of die-casting and low-pressure is completely different, and a systematic modification of the drawing is necessary.
1、 Key points for quantifying the structural transformation of drawings
Wall thickness upgrade: Conventional die casting 1.2-1.8mm, thickened to ≥ 2.5mm after switching to low pressure; locally isolated thin walls are thickened or transition ribs are added to eliminate cold insulation at the filling end.
Wall thickness transition: Die casting allows for severe wall thickness differences, and low pressure requires a wall thickness ratio of ≤ 2:1 as much as possible. The thick area should have rounded corners to prevent looseness in the hot section.
Demoulding: Die casting demoulding can be done at 0.8-1 ° C, and it is recommended to increase the low pressure to 1.2-2 ° C. The mold temperature is higher, which makes it easier to stick aluminum and strain.
Rounded corner enlargement: Die casting R0.8 is acceptable, and the low-pressure inner rounded corner is uniformly R ≥ 1.5mm, reducing the risk of hot joints and heat treatment cracking.
Machining allowance: Single side allowance for die-casting is 0.5-1.0mm; when converted to LPDC, it is increased to 1.2-2.0mm, with reserved T6 heat treatment deformation.
Xinfeng Machinery undertakes the project of converting die-casting to low voltage, first making DFM revisions, then conducting simulations, and then opening molds to avoid trial mold failures.
2、 Gate, exhaust, and process route renovation
Die casting with multiple side gap gates and multi-point feeding; Low pressure priority bottom injection type liquid lifting gate, the gate is placed in the thick area of the casting, and a bottom-up sequential solidification is established.
Die casting exhaust groove is dense, thin, and short; The number of low-pressure exhaust slots has been reduced, and the length of a single exhaust duct has been extended to 0.2-0.3mm, with a focus on the highest and distal filling points.
Process route change: Delivery of die-casting as cast state; LPDC has added T6 heat treatment, and the material labeling on the drawings has been changed from A380 to A356, while simultaneously updating the mechanical and non-destructive testing standards.
Tolerance adjustment: Stable die-casting dimensions; Low pressure heat treatment causes deformation, and the tolerance of the free contour is appropriately relaxed. Calibration fixtures are reserved for key sealing surfaces.
3、 Differences in die-casting to low-pressure transformation for overseas customers
Most of the renovations in Southeast Asia involve simply increasing the wall thickness without adjusting the gating scheme, and there are many problems with loose cold seals in the trial molds.
North American new energy customers are switching to low voltage, updating drawing specifications, PPAP, S-N fatigue, salt spray requirements, and conducting type tests again.
European hydraulic customers switch to low pressure, prioritize optimizing the structure to reduce stress concentration, use T6 to increase elongation, and improve vibration leakage.
Middle Eastern customers' die-casting brackets are being converted to low pressure, with a focus on improving impact resistance, thickening heat nodes, relaxing appearance, and strengthening X-ray inspection.
4、 Directly switching to production without changing the diagram will result in a failure chain
Continuing to use die-casting thin-walled → filling the end with cold insulation, not fully filled;
Using the multi-point side gate of die-casting → sequential solidification failure, resulting in large areas of looseness;
Using die-casting with small allowance → heat treatment deformation, insufficient wall thickness after machining;
The grade cannot be changed (A380) → T6 heat treatment is not possible, and the transformation is meaningless.
5、 Long tail traffic layout ideas
Transformation from die-casting to low-pressure casting, HPDC to LPDC, water-cooled shell die-casting to low-pressure, aimed at R&D and project engineers.
keywords convert HPDC design to LPDC low pressure casting、die casting to low pressure casting redesign；
Problem class: Wall thickness change when switching from HPDC to LPDC;
Comparative category: HPDC gating design vs LPDC bottom gating.
Suitable for process upgrades and product redesign special pages.
6、 Common misconceptions in the industry
Misconception 1: Directly opening low-pressure molds on die-casting drawings only involves changing the equipment for production, resulting in completely different filling and solidification systems.
Misconception 2: Thickening the wall thickness is enough, and the gate, exhaust, allowance, and heat treatment standards all need to be adjusted synchronously.
Misconception 3: The grade can continue to use A380, but A380 is not suitable for T6. Pressure bearing parts must be switched to A356.
FAQ
Q: What is the minimum wall thickness for die-casting to low-pressure conversion?
A：≥2.5mm。
Q: What are the commonly used grades for die-casting?
A：A380； Switch A356 for low-pressure pressure components.
Q: Changes in gate form?
A: Die casting side gate, low-pressure priority bottom injection lifting gate.
Q: Adjustment of machining allowance?
A: Upgrade from 0.5-1.0mm to 1.2-2.0mm.
Q: Requirements for rounded corner transformation?
A: Inner fillet R ≥ 1.5mm.
Q: Why do we need to change the exhaust?
A: Low pressure filling speed is slow, and the exhaust logic is different from that of high-speed coiling in die-casting.
Q: The biggest purpose of the change?
A: Implement sequential solidification, support T6 heat treatment, and solve leakage.
Q: What are the consequences of directly switching production without changing the drawings?
A: Cold insulation, looseness, and heat treatment deformation exceed the tolerance.
