Aluminum radiators are widely used in residential and commercial heating systems. As pressure-bearing components, they demand high density, zero leakage, and consistent heat dissipation performance. Die casting is one of the most efficient manufacturing methods for aluminum radiators. Understanding the complete process and potential pitfalls helps factories improve yield and reduce reject rates.
Full Die Casting Workflow for Aluminum Radiators
1. Melting, Degassing and Slag Removal
Aluminum ingots are melted at 700~730°C. Rotation degassing and slag skimming remove hydrogen and oxide inclusions. Poor degassing is the top cause of hidden pores and water leakage of finished radiators.
2. Mold Preheating and Release Agent Spraying
Preheat the die casting mold to 180–220°C. Spray water-based release agent evenly on the cavity and dry thoroughly. Uneven mold temperature will lead to cold shut defects on thin cooling fins.
3. Mold Clamping and Automatic Ladling
The machine closes and locks the mold. A robotic ladle delivers a precise volume of molten aluminum to the shot sleeve to avoid underfilling or excessive flash.
4. Shot Filling and Pressure Holding
Low-speed shot pushes molten aluminum forward to exhaust air inside the cavity. Switch to high speed to fill thin radiator fins, then apply intensified pressure and hold until solidification. Vacuum die casting is highly recommended to minimize trapped gas and porosity.
5. Mold Opening and Part Ejection
After cooling, open the mold and eject the casting. Balanced ejector pin layout is essential to prevent deformation of multi-fin radiator structures.
6. Trimming and Deburring
Cut off sprues and overflow tanks, grind flash and burrs on parting lines and fins.
7. CNC Machining & Pressure Leakage
Test Machine threads for water inlet and outlet ports. Every radiator must go through air or hydraulic leak testing. Minor micropores can be sealed via impregnation, while severely porous parts must be scrapped.
8. Surface Powder Coating
Pretreat castings by degreasing and phosphating, then apply electrostatic powder coating for anti-corrosion protection.
Critical Notes for Radiator Die Casting
- Mold design: Keep wall thickness consistent. Add radius at sharp corners to avoid hot tearing. Arrange enough vents and overflow troughs at the end of thin fins to discharge trapped air. Balanced mold cooling channels prevent sticking and part distortion.
- Process parameter control: Do not overheat molten aluminum above 730℃, which will enlarge grain size and increase porosity. Excessively high injection speed causes air entrapment. Sufficient pressure holding time guarantees compaction at thick threaded ports.
- Quality inspection: 100% pressure test is non-negotiable for pressure-bearing radiators. Internal porosity is a fatal defect that may lead to water leakage during operation.
- Safety: Take protective measures during aluminum melting and pressure testing to prevent scalding and component bursting accidents.
To realize stable mass production of high-quality leak-proof aluminum radiators, it is essential to select professional and reliable die-casting production line equipment. With more than 40 years of professional experience in die casting machine manufacturing, Longhua is able to provide complete and customized full-set production and processing lines for aluminum radiators. We focus on equipment research and development and process optimization, matching efficient, stable and low-defect production solutions for radiator manufacturers, helping enterprises reduce production costs, improve product qualification rate and achieve efficient mass production.
