Aluminum die casting mold design is a systematic engineering process that integrates fundamental physical principles, product analysis, and high pressure die casting (HPDC) process requirements to achieve stable, high-quality mass production. From pressure transmission based on Pascal’s principle to flow control based on Bernoulli’s theorem, every design decision directly impacts filling performance, mold strength, and casting quality. A well-structured aluminum die casting mold design must balance machine performance, product geometry, material properties, and thermal control to ensure reliable performance throughout the mold’s lifespan.
In the design process of high-pressure die casting (HPDC), the design process of the die is not merely an independent process, but is actually concluded as part of the overall analysis process. Parameters such as cavity arrangement, selection of die cast machines, parting line design, gating and overflow systems, as well as heating systems are among those that should be systematically specified in order to secure proper metal flow as well as gas venting. Consequently, expert die casting design is imperative in efficient high pressure die casting design.
Basic Theory
1.1 Pascal’s Principle
The pressure applied to a confined fluid is transmitted undiminished throughout the fluid in all directions, i.e., the pressure P is equal everywhere.
P = F1/A1 = F2/A2
Therefore, the force acting on the product (mold expansion force)
F1 = Specific pressure P x Projected area A1 (A1 = a1 + a2 + a3 + a4 + slider area * tgα)
This formula can be used to determine the tonnage of the die casting machine.
1.2. Bernoulli’s Theorem
The flow rate through each cross-section is constant (Q = flow velocity V × cross-sectional area A)
That is, the flow rate at the inlet and outlet are equal. Q = V1A1 = V2A2
This can be used to determine the gate area in the mold,
referencing Bernoulli’s theorem and the empirical values of gate velocity shown in the right figure.
Product Analysis – Mold Scheme
In the early stages of die casting mold design, product analysis is the core link in the entire mold scheme development. Through systematic analysis of product drawings and physical structures, the wall thickness distribution, molding direction, and key functional areas are clearly defined. Combined with technical requirements, die-casting material characteristics, dimensional accuracy, and post-processing areas, a comprehensive assessment of the casting’s formability, filling characteristics, and defect risks is conducted, establishing clear technical boundaries for subsequent mold structure design.
Based on the complete product analysis results, the die-casting mold design stage further determines the appropriate number of cavities and die-casting machine selection, scientifically plans the mold parting surface form, and designs the gating system, overflow and venting structure, and ejection mechanism to ensure stable filling, effective venting, and balanced demolding of the molten metal under high pressure conditions, thereby meeting the appearance quality, dimensional accuracy, and functional requirements of the die-cast parts.
At the same time, in die-casting mold design, reasonable cooling water channels and local temperature control schemes are used to maintain mold thermal balance, reduce thermal fatigue and local overheating risks, and improve mold life and the stability of mass production. Systematic and engineering-based die-casting mold design is an important guarantee for achieving continuous mass production of high-quality die-cast parts.
| Drawings | Product Analysis | Mold Solution | Determine the number of cavities | |
| Actual product | Select the die casting machine | |||
| Technical requirements | → | Mold parting line | ||
| Die-casting material | Gating and overflow system | |||
| Dimensional accuracy | Ejection mechanism | |||
| Post-processing areas | Mold temperature control |
Raidy Molds has a professional HPDC mold design team, providing full support from product analysis to complete mold solutions. Whether it’s cavity layout optimization, parting line design, or gating system and temperature control solutions, we provide proven, efficient solutions to ensure your aluminum die-casting molds have stable performance, long lifespan, and reliable mass production.
Contact Raidy today and let us provide customized design support for your die-casting project!
High Pressure Die Casting Mold Cavity Quantity
3.1 Factors determining the number of cavities:
① For products with simple structures and no core pulling limitations, multi-cavity molds can be considered;
② For products with large production volumes, multi-cavity molds can be considered;
③ For machines with limitations, such as small products on large machines, multi-cavity molds can be considered.
3.2 Raidy Molds’ Real-World Cavity Data Cases
Case 1: GZ***1A Mold: The product quantity is large, but the mold requires core pulling in three directions. Considering the gating system, the mold cavity quantity can only be one cavity per mold.
Case 2: FF***0B Mold: The product quantity is large, and the mold does not require core pulling. The mold was changed from a two-cavity mold (A mold) to a four-cavity mold (B mold).
Case 3: DK***5A Mold: The product quantity is not large, and the product is small. The mold requires core pulling in one direction. If the mold had one cavity per mold, a 50T die-casting machine would suffice. However, considering the available machines, the mold solution was changed to two cavities per mold, using a 160T machine.
Die Casting Machine Selection
Aluminum Die Casting Mold Design
① F locking force > F expansion force (F expansion force can be referenced from Pascal’s principle)
F expansion force = specific pressure P x projected area A1 (A1 = a1 + a2 + a3 + a4 + slider area * tgα);
Other influencing factors:
② Product weight (affects the filling degree of the pressure chamber, generally 20-50%, 40% is ideal);
③ Mold size (the mold size cannot exceed the effective size of the die-casting machine);
④ Specific performance of the product.
4.2 Die Casting Machine Tonnage Selection Case Study:
Mold Dimensions:
Length x Width x Height: 500 x 580 x 690
Injection Pressure: 60 MPa
According to the formula F = P x A = 60 x 27840
= 1,670,400 N = 167,040 kgf = 167 tons of force
| Product Name | Bracket die casting mold | Mold number | ADC12 | |
| Net Weight | 1400g | Runner weight | ≈550g | ≈70g |
| Total Projection Area | ≈278.4 cm² | Gate cross-sectional area | 1.89 cm² | 10mm |
Raidy Mold Manufacturer has committed itself, since the beginning in 1996, to the design and manufacturing of high pressure aluminum die casting molds and solutions for automotive, motorcycle, and precision manufacturing industries.
We have imported high-precision processing equipment, intelligent testing systems, and more than 200 professional technicians. Combined with 3D modeling and mold flow analysis, we guarantee that every mold is highly accurate, stable in performance, and durable.
Be it the design of the mold, the production linked to die casting, or problem-solving, Raidy is a reliable partner.
Contact us today to get customized aluminum die casting mold solutions and make your production more efficient!
Selection of Mold Parting Surfaces
5.1Key points for selecting mold parting surfaces:
① Ensure the casting is released from the fixed mold and moves with the movable mold during mold opening;
② Ensure the dimensional accuracy of the casting;
③ Ensure good overflow and venting;
④ It should facilitate the removal of the casting, generally selected on the largest cross-section of the casting’s outer contour;
⑤ Use flat parting surfaces as much as possible to simplify mold manufacturing and facilitate venting and slag removal;
⑥ Select surfaces requiring machining as parting surfaces whenever possible;
⑦ Minimize the number of side cores;
⑧ Consider the appearance of the casting, ejector pin marks, burr direction, and the impact of deburring on the product’s appearance.
5.2 Case Description of Mold Parting Surface Selection
In die-casting mold design, there is a type of structure that typically uses the up-and-down direction as the main parting direction, and sets up lateral parting structures (left and right sliders) in the left and right directions to meet the molding requirements of complex lateral structures of the casting. This parting method can effectively ensure the integrity of the molding of key functional parts and important internal cavities, but it places higher demands on the overall flow state of the molten aluminum in the mold cavity. If the parting and filling directions are not properly matched, the molten aluminum is prone to uneven flow during the filling process, the overflow and venting effects cannot be fully utilized, and the gas in the mold cavity is not easily discharged in time.
If the direction of separation and the main path of molten metal filling are consistent with each other, then it will help to ensure a relatively smooth process related to the flow of molten aluminum metal, formation of overflow, and venting. This is quite beneficial in guiding gas in the mold cavity to the area where overflow is formed.
On the other hand, if there is improper parting arrangement, the chance of local erosion and flashes would increase, which would increase the erosion and flashes in the mold, and would also affect the internal density and surface finish of die-cast products.
Therefore, in the die-casting mold design stage, the rational selection of the parting direction and lateral parting structures is an important prerequisite for ensuring stable filling and product quality.
Die Casting Mold Design – Gating System
6.1 Definition:
The channel through which the molten metal fills the mold cavity under pressure during the die-casting process is called the gating system.
The gating system mainly consists of the sprue, runner, and gate. The shape of the gating system is generally determined by factors such as the die-casting machine model, product shape, and the number of mold cavities
6.2 Design Points for the Sprue:
① Plunger chamber diameter D: Determined according to the required injection pressure ratio and plunger chamber filling degree of the casting.
a. Filling degree calculation formula: K = 4V/∏LD² = 4G/∏ρLD² (generally 20-50%, 40% is recommended)
b. Relationship between plunger chamber diameter D, casting pressure, plunger diameter, and gate velocity
② Empirical values for biscuit thickness:
160-400T: 12mm;
500-650T: 15mm;
800-1200T: 20mm;
1350-3500T: 25mm
③ Plunger design speed: 3m/s
6.3 Design Points for the Runner:
① The total cross-sectional area of the runner should gradually decrease from the sprue to the gate;
② The runner should have appropriate thickness and length. If the runner is too thin, heat loss will be significant; if it is too thick, the cooling speed will be slow, affecting production efficiency. Maintaining a certain length of the runner is beneficial for stabilizing and guiding the molten metal flow;
③ A slag trap or blind runner is often set at the end of the runner, which can improve the thermal balance conditions and accommodate cold material, coating residue, and exhaust gases from the runner;
④ The surface roughness of the runner part of the mold should not exceed Ra0.4μm;
⑤ Common runner forms in aluminum alloy die-casting molds include: fan-shaped runners and comb-shaped runners.
6.4 Key Design Points for the Ingate:
①. The cross-sectional area of the ingate should be smaller than the cross-sectional area of the runner;
②. The ingate should be positioned to facilitate the flow of molten metal from the thickest section of the casting to the thinnest section;
③. The ingate should be positioned for easy removal, and the impact of the removal mark on the product surface should be considered;
④. The ingate should be positioned so that the molten metal does not immediately seal the parting line when filling the mold cavity, and ideally, it should not directly impact the core.
Ingate Cross-sectional Area Calculation Method:
According to Bernoulli’s theorem: Q = V1A1 = V2A2
Empirical values for ingate velocity can be found in the table below.
| Wall thickness (mm) | Gate velocity (m/s) |
| 10.8 | 46-55 |
| 1.3-1.5 | 43-52 |
| 1.7-23 | 40-49 |
| 2.4-2.8 | 37-46 |
| 2.9-3.8 | 34-43 |
| 4.6.-.5.1 | 32.-40 |
| 6.1- | 28-35 |
Of course, in addition to the design points mentioned earlier, aluminum die casting mold design also includes critical aspects such as overflow channels, venting systems, ejection mechanisms, mold temperature control, and mold core pulling systems. For ease of systematic explanation, we will divide this content into two articles for detailed description, comprehensively explaining the overall engineering logic and key technical elements of HPDC mold design.To learn more, please click on “Aluminum Die Casting Mold Design – Part 2” to read and view.
If you are developing aluminum high pressure die casting molds, our engineering team at Raidy Mold Manufacturer can provide you with comprehensive support, from early product analysis to complete aluminum die casting mold design solutions. Please contact us to discuss your HPDC design requirements, and we will provide you with technically validated mold solutions and die casting molds that meet your production goals.
To achieve successful aluminum die casting mold design, there is a fundamental engineering basis, as well as intimate knowledge required for the high pressure die casting process. In using pressure and flow principles, comprehensive product analysis, optimum cavity, machine tonnage, parting line, gating systems, and thermal control, the design for high-pressure die casting molds can successfully achieve filling, ejection, or extended mold life. Systematic design for high pressure die casting molds is not only effective in reducing defects in casting or trial casting, but also in meeting accuracy in mass production. Professional investment in die casting mold design is an essential step for effective, scaled-up, or high-performance aluminum die casting.
