In the field of precision manufacturing, die casting is one of key technologies for mass production of complex structures and high-precision parts. Whether it's consumer electronics, automotive components, or industrial equipment, an excellent die casting mold directly determines quality, cost, and production efficiency of product.
However, in your actual work, have you ever encountered these pain points:
Unreasonable product wall thickness design leading to frequent shrinkage and porosity?
Inaccurate demolding angle affecting demolding or even damaging mold?
Gating system design based on experience, resulting in incomplete filling after multiple trials?
Improper venting and overflow channel design, leading to surface flow marks and porosity that cannot be eliminated?
Therefore, we have thoroughly compiled a die casting mold design process standard from a leading industry company, transforming its core content into a practical guide to help you systematically master the key parameters and practical methods of die casting mold design.

1. Reasonable Wall Thickness: Uniformity is Key
Uneven wall thickness easily leads to defects such as shrinkage, hot cracking, and porosity. Recommended wall thickness range varies for different alloys. For example, for aluminum alloys with an area ≤ 25cm², normal wall thickness is recommended to be 0.8mm, while for magnesium alloys under same conditions, it is 0.7mm. Remember: keep wall thickness as uniform as possible and avoid drastic changes.
Optimal wall thickness of die-cast parts is related to structure of casting, alloy properties, and die-casting process. To meet various requirements, a reasonable and uniform wall thickness is preferred. Products with uneven wall thickness are prone to defects such as shrinkage, hot cracking, porosity, and incomplete filling.

 

2. Demolding Angle: Height Determines Angle
Demolding angle is not a fixed value and needs to be adjusted according to casting height. For heights ≤ 5mm, a slope of 3°-5° is recommended; for heights > 10mm, it can be appropriately reduced to 1°-2°. Principle: Within allowable range, use a larger slope to facilitate demolding.
Size of draft angle is related to casting's geometric shape, such as height, wall thickness, tolerances, and surface condition of mold cavity or core, such as roughness. Within allowable range, a larger draft angle is preferred.

 

3. Casting Fillets: Avoiding Stress Concentration
Fillets not only optimize metal flow but also reduce risk of cracks. Inner fillet radius is recommended to be ≥ 0.3mm, and outer fillet is recommended to be ≥ 1.0mm.
Casting fillets allow for smooth flow of molten metal, facilitate gas escape, and prevent cracks caused by sharp corners. Calculation of casting fillet radii can be referenced in the table below.

 

4. Casting Holes and Grooves: Small Structures Require Great Attention
Die casting can directly cast deep holes, but attention should be paid to ratio of hole diameter to depth. For example, depth of through holes in zinc alloy can reach 4 times diameter, while for blind holes, it is recommended not to exceed 2 times. Width, depth, and length of casting channel must also be strictly controlled to avoid insufficient filling.
Casting Holes
One of characteristics of die-casting process is its ability to directly cast relatively deep small holes. Relationship between diameter and depth of small holes can be seen in the table below.

Casting Channel

Note: The smaller value of b, the smaller range of values for s and h.

 

1. Clamping Force Calculation: Basics Cannot Be Ignored
Formula: T = K × A × P
Where: T is clamping force, in N;
K is safety factor, generally 1.2 for cold chamber die casting machines and 1.3-1.5 for hot chamber die casting machines; A is projected casting area, in mm² (including casting, sprue, runner, overflow well, etc., approximately 1.8 times casting area); P is injection pressure, in MPa; Unit conversion: 1 T = 10 KN = 10000 N.
Where K is safety factor (1.2 for cold chamber, 1.3-1.5 for hot chamber), A is the total projected area (approximately 1.8 times casting area), and P is injection pressure. Note units: 1T ≈ 10KN
2. Injection Pressure: Applying Pressure According to Material
Different alloys and product types require different injection pressures. For example, 30-40 MPa is recommended for general aluminum alloy parts, while pressure-resistant parts may require 80-120 MPa. 20-30 MPa is recommended for zinc alloy plated parts. Choosing correct injection pressure improves density and surface quality.
Reference Table for Injection Pressure
Recommended Injection Pressure (Final Value) for Hot Chamber Die Casting  (Unit: MPa)

Recommended Injection Pressure (Boost Pressure) for Cold Chamber Die Casting   (Unit: MPa)

3. Filling Time: Thin Walls Require Faster Filling
Filling time is closely related to wall thickness. For a wall thickness of 0.8 mm, filling time is only 0.005-0.008 seconds; for a wall thickness of 6.4 mm, it can be extended to 0.08-0.3 seconds. Mastering time window avoids cold shuts or turbulence.
Calculation of Filling Time
t = k [(Ti - Tf + 64) / (Tf - Td)] x T
Where: k = 0.0346; Ti = Molten metal entry temperature into mold; Tf = Minimum flow temperature; Td = Mold temperature; T = Casting thickness.
Reference Value for Filling Time

4. Gate Design: Speed, Area, and Thickness in Coordination
Gate speed: Magnesium alloy can reach 40-90 m/s, aluminum alloy 20-60 m/s, and zinc alloy 30-50 m/s.
Gate area: Calculated based on filling volume, speed, and time.
Gate thickness: Selected according to wall thickness and complexity, for example, 0.5-1.0 mm is recommended for thin-walled complex magnesium alloy parts.
Alloy Properties Reference Table

 

5. Overflow and Venting: Mold's "Respiratory System"
Overflow channel: The total volume accounts for 10%-30% of alloy volume, overflow area is approximately 60%-75% of gate area, and thickness is 0.25-0.5 mm.
Vent channel: The total cross-sectional area should be greater than 1/3 of gate area, depth is usually 0.1-0.5 mm, and segmented design can improve effect.
Recommended Trapezoidal Overflow Channel Dimensions Table

 

Mobile Phone Casing (Suitable for 88T-200T Hot Chamber Die Casting)
Magnesium Alloy: Inner gate thickness 0.5-0.6mm, overflow gate 0.3mm, three-stage venting (0.5/0.3/0.2mm).
Zinc Alloy: Inner gate 0.4-0.5mm, overflow gate 0.2mm, venting depth can be appropriately reduced.
Laptop Casing (Suitable for 500T Hot Chamber Die Casting)
Magnesium Alloy: Inner gate thickness 0.8mm, overflow gate 0.4mm, can be combined with venting blocks to enhance venting effect.
Runner dimensions can be widened to 40mm * 8mm to accommodate large flat surface filling.

1. Pre-mold Flow Analysis
Before mold manufacturing, use software such as Magma to simulate filling, solidification, and stress, predicting defects in advance and optimizing gating and cooling systems.
2. Standard File and Layer Management
Clear layering of casting drawings: Runners, gates, products, overflow channels, and venting channels are modeled as separate entities.
Standardized file naming: e.g., "AD0001-1-Cast-V01.prt", version control for easy collaboration.
Unified STL export tolerance of 0.1mm to ensure analysis accuracy.

 

Gate Area Calculation
After casting design is completed, measure casting volume (product + overflow). Once filling time and filling speed of die-casting are selected, gate area can be calculated using following formula:
Selection of Gate Thickness

Selection of Gate Width and Principles of Gate Design

Principles of gate design:
Molten metal should fill from thicker wall section to thinner wall section of casting;
Molten metal should not immediately close parting surface, overflow groove, and vent after entering mold cavity;
Gate should be positioned so that molten metal flows first to the area furthest from gate;
Molten metal entering from gate should not directly impact core;
Gate should be easy to remove;
Avoid creating hot spots at gate;
Flow direction of molten metal after entering mold cavity should follow ribs and heat sinks on casting;
When selecting gate position, molten metal flow path should be as short as possible.
Holding Pressure Time and Mold Dwell Time
Holding pressure time refers to time during which injection system maintains pressure after molten metal has filled mold cavity. Following table shows reference values for holding pressure time based on wall thickness of die-cast part:

Mold dwell time is the time from end of holding pressure period to opening of mold and ejection of die-cast part. Following are reference values for mold dwell time based on wall thickness of die-cast part:

Locating Pin Design Standards
Locating pins can be designed on water passages and flow channels.

 

Die Casting Machine Specifications
Magnesium Alloy Machine Dimensions

Aluminum Alloy Die Casting Machine Specifications

Zinc Alloy Die Casting Machine Specifications

Notebook Product Manufacturing Standards
Suitable for 500T Magnesium Alloy Hot Chamber Die Casting

 

3. Knowledge Accumulation and Reuse
Establish an internal enterprise process standard library, design specifications, and case library, transforming experience into sustainable and reusable digital assets.

Die casting mold design is a comprehensive technology that integrates materials science, fluid mechanics, thermodynamics, and structural design. Mastering core parameters, understanding process logic, effectively utilizing digital tools are essential to finding optimal balance between efficiency and quality.
Whether you are a process engineer, mold designer, or project manager, we hope this summary will inspire you and help you design higher-performance, more reliable, and more economical die casting molds in your next project.