Die casting creates high-strength, high-precision metal parts by injecting molten aluminum or zinc alloys into steel molds. Injection molding produces lightweight, flexible, and detailed plastic parts by injecting molten plastic into mold cavities. The die casting process is ideal for complex metal parts that require high strength and structural stability; injection molding excels in rapid production, design diversity, and unit cost, and is widely used in plastic product manufacturing.
This article will compare die casting and injection molding in terms of material compatibility, temperature and pressure conditions, mold cost, design complexity, surface treatment, strength, and application areas. Read on to find out which process is more suitable for your product and production needs.
Material Compatibility
Choice of Metals and Plastics
Die casting mainly uses non-ferrous metals such as aluminum, zinc, and magnesium to manufacture high-strength, structurally stable parts.
Injection molding uses thermoplastics and thermosetting plastics, which have higher lightness and design flexibility.
Material selection depends on whether the product focuses more on performance or plasticity.
|
Feature |
Die Casting | Injection Molding |
|
Main Materials |
Aluminium, zinc, magnesium alloys | Thermoplastics, thermosetting plastics |
|
Process Temperature |
600–1100°C | 150–300°C |
| Pressure Requirement | 100–200 MPa or higher |
50–200 MPa |
| Material Strength | High, suitable for structural parts |
Medium, varies by plastic type |
| Design Flexibility | Moderate |
High |
Temperature and Pressure Requirements
Thermal Energy Input
Die casting usually requires melting metals such as aluminum and zinc at high temperatures of 600–1100°C, which requires high equipment and energy consumption.
Injection molding requires lower temperatures to heat thermoplastics, generally 150–300°C, so energy costs are lower and operations are easier to manage.
Pressure Conditions
High-pressure die casting usually requires 100–200 MPa or even higher to inject molten metal into complex steel molds to ensure complete filling and dense structure.
Injection molding can be formed within a medium pressure range of 50–200 MPa, and most plastic parts can be formed with high precision at lower pressures.
Energy Efficiency Performance
Injection molding is particularly suitable for high-capacity automated production due to its low heating temperature, fast cooling speed, and short cycle time, and has lower overall energy consumption.
Although die casting requires higher temperatures and pressures, and consumes more energy per piece, its higher energy consumption is reasonable in scenarios with high requirements for strength, heat resistance, and service life.
Molds and Cost Considerations
Initial Investment
Die casting molds are usually made of high-hardness steel, and the cost of a single set is about $3000-$10000, but the life span can reach hundreds of thousands of molds, which is suitable for long-term mass production.
Injection molds (especially aluminum molds) cost as little as $1000-$7000, which are suitable for proofing, small batches, and rapid development, but the mold life is short.
Production Efficiency and Cycle
The injection molding cycle is generally 2-5 seconds/mold (thin-walled parts can be as low as 1-2 seconds), which is suitable for automated high production capacity; about 80-90% of the time is used for cooling.
The die casting cycle varies depending on the process, with hot chamber die casting of small parts about 4s/mold; high-pressure cold chamber die casting of large parts, such as engine castings, about 80-90 seconds per mold.
Waste and Recycling
Taking aluminium alloy die casting as an example, about 5-15% of edge material and overflow will be generated, but aluminum alloy can be 100% recycled without affecting material properties.
Injection molding waste is very small, and the scraps can be ground and recycled and mixed into the reproduction. The recycling rate of thermoplastic materials such as PP and PE is as high as 95% or more.
|
Item |
Die Casting Mold | Injection Mold |
|
Mold Material |
High-hardness steel | Aluminum or hardened steel |
|
Mold Cost Range |
$3,000 – $10,000 | $1,000 – $7,000 |
| Mold Life | Up to hundreds of thousands |
Shorter lifespan, good for prototyping |
| Suitable for | Mass production |
Prototyping and small batches |
| Production Cycle Time | 4 – 90 seconds |
1 – 5 seconds |
Design Flexibility and Complexity
Geometric Design Capabilities
Injection molding can easily achieve complex geometries, such as undercuts, inserts, and multi-material co-injection.
It has a high degree of design freedom and is suitable for plastic parts with integrated structure and function.
Die casting parts can form complex metal shapes, but it is limited by metal fluidity and demolding requirements.
Features such as deep holes and blind cavities often require post-processing.
Dimension Tolerance and Precision
The conventional dimensional tolerance of die casting is ±0.05–±0.1 mm, which is suitable for high-precision structural parts, especially in automotive and industrial applications.
Injection molding can reach ±0.02–±0.05 mm on small plastic parts, and is often used in precision fields such as electronic housings and medical devices.
Customization and Appearance
Injection molding supports a variety of appearance customization, including color matching, surface texture, transparency, multi-material combination, and in-mold logo.
Die casting products emphasize structural performance, and the original surface is relatively rough, usually requiring shot blasting, powder spraying, or anodizing to improve the appearance.
Surface Treatment and Post-Processing
Surface Quality
The surface of die casting parts is relatively smooth, with an Ra value of 1.6–3.2 μm, but there may be pores or flow marks, and the appearance parts usually needs to be sandblasted, polished, or sprayed.
Injection molding can directly achieve mirror, texture, or matte effects in the mold, with good appearance consistency.
Post-Processing Requirements
Die casting parts often require machining of threaded holes, assembly surfaces, and other structures, especially in parts with high precision requirements.
Injection molding has high precision, and most plastic parts can be molded in one go, without post-processing, only simple trimming, and with higher production efficiency.
Strength and Service Life
Mechanical Strength
The tensile strength of die castings can reach 200–400 MPa, and the structure is dense, suitable for load-bearing structures, connectors, and impact-resistant conditions, such as automobile brackets, gearbox housings, etc.
The strength of injection molded parts varies depending on the material. General plastics such as ABS are about 40-60 MPa, and glass fiber reinforced nylon can reach 100-150 MPa, but it is still lower than metal and is not suitable for heavy-duty structures.
Thermal Stability
Aluminium die casting components can withstand operating temperatures up to 300°C, with stable performance, and are not easily deformed.
They are suitable for hot environments such as engines and gearboxes. Most injection molded plastics have a heat resistance of around 80-120°C.
Some engineering plastics, such as PPS and PEEK, can reach 200-250°C, but the cost is high and still lower than metal.
Product Life
Die castings have good wear resistance and high fatigue strength. The service life is usually up to 10-20 years, which is suitable for industrial and automotive parts with long service lives.
Injection molded parts are prone to aging and poor impact resistance. The service life is usually 3-5 years, which is suitable for frequently updated or non-critical parts.
|
Aspect |
Die Casting | Injection Molding |
|
Tensile Strength |
200–400 MPa | 40–150 MPa (depends on material) |
|
Heat Resistance |
Up to 300°C | Typically 80–120°C, max 250°C |
| Service Life | 10–20 years |
3–5 years |
| Typical Applications | Engine housings, brackets, gears |
Electronics housings, packaging, toys |
| Surface Finish | Requires post-treatment |
Customizable in-mold finish |
Typical Applications
Die Casting Applications
Die casting is commonly used in structural parts such as automobile engine housings, gearboxes, wheels, brackets, etc., and is suitable for industrial scenarios that require high strength, high precision, and heat resistance.
It is also widely used in the manufacture of large quantities of metal parts such as aviation parts, motor housings, and mechanical housings.
Injection Molding Applications
Injection molding is suitable for lightweight and high-appearance products such as TV frames, electronic housings, medical device covers, food packaging, toys, etc., and widely serves industries such as consumer electronics, home appliances, medical, and daily necessities.
CEX Casting: Dual Professional Capabilities of Die Casting and Injection Molding
Dual Process Services
CEX Casting has both aluminum alloy die casting and plastic injection molding production capabilities, providing one-stop solutions for mold design, material analysis, and technical support.
We evaluate the optimal process path for each project to ensure high cost performance and product quality.
Die Casting Capabilities
The self-developed patented aluminum alloy squeeze casting technology is used to replace the traditional die casting process, which can achieve strength comparable to forged aluminum alloys, and there are almost no pores inside the castings.
It also has DFM analysis, centralized smelting, internal quality inspection capabilities, and supports X-ray detection, helium leak testing, and mechanical strength testing.
Injection Molding Capabilities
We are equipped with multiple automated injection molding production lines equipped with hot runner systems, with high production efficiency and stable molding.
With independent mold design and manufacturing capabilities, we support rapid prototyping to large-volume order delivery.
Conclusion
Die casting is suitable for products with high requirements for metal strength and service life, while injection molding is more suitable for plastic parts that require lightweight, fast, and flexible production.
The choice of which process should be based on the material, function, and production goals of the product.
As a dual-process manufacturer, CEX Casting provides full-process support from design to delivery to ensure reliable quality and efficient operation.
Contact us now to get professional advice and customized quotes for your next project.