Introduction 

In the world of High-Pressure Die Casting (HPDC), production efficiency and part quality are paramount. Mold temperature control is the key factor for achieving both. Although new cooling technologies (e.g., point cooling, jet cooling) are emerging, conventional water cooling still dominates the market because of its proven reliability, costeffectiveness, and high heatremoval capability. This article explains the working principle, major advantages, and design fundamentals of traditional water cooling, illustrated with a classic 1 mold 2 cavities.

What is Conventional Water Cooling?

Conventional water cooling refers to a system in which cooling passages are machined directly into the mold. A temperaturecontrol unit (TCU) continuously circulates cooling water through these passages, removing heat from the mold.
The water leaves the TCU, enters the mold through the inlet, and flows through a network of channels that closely follow the contour of the cavity and core. Heat from the hot mold metal is transferred to the water, which then returns to the TCU via the outlet, is cooled, and recirculated, forming a closedloop temperaturecontrol system.

The Significant Advantages of Conventional Water Cooling

• High Cooling Efficiency, Short Cycle Time: Water’s high specific heat capacity allows it to absorb large amounts of heat. The high flow velocity in the passages quickly transfers heat from the mold, dramatically reducing solidification and cooling times, and thus increasing production rhythm.
• Excellent Cost-Effectiveness: Compared with more complex systems such as point cooling or mistcooling, conventional water cooling requires lower initial investment and lower operating costs. Its main components are the machined passages and a standard TCU, resulting in a simple structure, low failure rate, and predictable operating expenses.
• High Reliability and Durability: A well-designed and precisely machined mold cooling circuit can last as long as the mold itself. As long as clean water is used and regular maintenance is performed, it can provide stable service for years with almost no need to replace core components.
• Ensures Consistency of Casting Quality: A uniform and rational layout of cooling channels effectively prevents local superheating or supercooling of the mold. This greatly reduces defects in castings caused by thermal stress, such as deformation, shrinkage porosity, and hot cracks, ensuring dimensional stability and consistent internal quality across production batches.

Scope of Application

Small to Medium-Sized Casting Production: Ideal for production lines with high-volume demand where stable cycle times and low per-unit costs are essential.

High-Volume, Long-Cycle Projects: Suitable for projects characterized by high production volumes and extended cycle times.

Relatively Simple Mold Structures: Facilitates the design and machining of linear or gently curved gating channels (waterways).

Detailed Analysis of Water Cooling Design in a 1 mold 2 cavities

Figure 1 (below) shows a classic watercooling layout for a 1 mold 2 cavities mold, where two identical parts are produced in a single injection cycle. This configuration places stringent demands on cooling uniformity.

Symmetrical layout – The cooling circuit is perfectly mirrorsymmetrical. Each cavity has its own independent but identical passage network, guaranteeing that heat is removed from both cavities at the same rate and that the two castings exhibit identical quality.

Seriesparallel combination – The water flow often combines series and parallel sections. For example, water may first travel in series through the core of one side, then split to flow simultaneously through the two cavity passages (parallel) before recombining and exiting. This arrangement balances flow resistance with temperature uniformity.

Following the cavity contour – The most effective passages closely follow the cavity geometry. In the figure, the channels tightly wrap around each cavity, especially in thickwall or highheatgeneration zones where the spacing is reduced to provide intensified local cooling.

Orings and sealing – To prevent highpressure water from leaking at the parting line or at insert seams, all channel interfaces are sealed with hightemperatureresistant Orings. Proper sealing is a critical detail that ensures longterm stable operation of the cooling system.

Conclusion

Conventional water cooling is by no means an outdated technology; it is a time-tested, efficient, and reliable cornerstone of mold temperature control. It is directly related to the production efficiency, operating costs, and final part quality of a die-casting factory. A clear water circuit diagram and a well-designed, perfectly machined cooling system are the indispensable “blood circulation system” within the mold. As die-casting professionals, deeply understanding and expertly applying conventional water cooling is a fundamental skill for building high-quality molds and enhancing market competitiveness.