Tips to simplify designs
Die casting is a powerful net shape production process that can deliver near-finished and in many cases fully finished metal parts in a variety of metals and alloys. It uses openable steel cavity tools which are filled with melt under a variety of pressure and temperature conditions.
The critical factors that differentiate die casting processes demand an overall DFM approach that suits the process and delivers optimum part outcomes.
Relative advantages of Die Casting that drive DFM decisions
The DFM issues vary slightly between styles if equipment/process – gravity, low pressure and high pressure die casting – but the advantages are similar and the DFM considerations follow same basic considerations:
- Speed: Die casting offers high-speed production capabilities, allowing for the rapid creation of complex parts.
- Automation: The process can be highly automated, further enhancing production rates and consistency.
- Tight Tolerances: Die casting achieves tight dimensional tolerances, reducing the need for additional machining.
- Consistency: Each part produced is virtually identical, ensuring high-quality standards across large volumes.
- Intricate Designs: Die casting can produce complex shapes with intricate details that would be challenging or impossible with other methods.
- Thin Walls: The process supports the creation of thin-walled parts, which can be lighter and more material-efficient.
- Smooth Surfaces: Die cast parts typically have excellent surface finishes that often require minimal post-processing.
- Texture Options: Various textures can be incorporated directly into the mold, providing versatility in surface design.
- Minimal Waste: The process produces minimal scrap compared to machining and other subtractive manufacturing methods.
- Recyclability: Die casting alloys are often recyclable, contributing to sustainability and cost-efficiency.
- Strength and Durability: Die cast parts often exhibit superior mechanical properties, such as high tensile strength and good fatigue resistance.
- Thermal Conductivity: Certain die casting alloys, such as aluminum, offer excellent thermal conductivity, making them suitable for heat-dissipating applications.
- High Volume Production: Die casting is cost-effective for high-volume production runs, as the initial mold cost is offset by the efficiency and speed of the process.
- Reduced Assembly: Parts can be designed with integrated features that reduce the need for assembly, saving on labor and assembly costs.
- Wide Range of Alloys: A variety of alloys, including aluminum, zinc, and magnesium, can be used in die casting, each offering unique benefits.
- Customization: The process allows for a high degree of customization to meet specific application requirements.
These advantages make die casting an attractive manufacturing option for industries such as automotive, aerospace, consumer electronics, and more, where precision, efficiency, and high-quality production are critical.
DFM principles
Draft angles
Ensure all vertical surfaces have adequate draft angles (typically 1-3 degrees) to facilitate easy ejection from the mold.
Undercuts and recesses
Avoid or minimize undercuts and deep recesses that can complicate mold design and increase manufacturing costs.
Uniformity, features and thickness
Maintain uniform wall thickness to avoid issues with material flow and cooling, which can lead to defects such as porosity and warping.
Typical wall thickness ranges from 1.5mm to 4mm depending on the material and part size.
Use ribs to add strength and reduce weight, but ensure they are properly sized and spaced to avoid sink marks.
Apply filets to internal and external corners to improve material flow and reduce stress concentrations.
Position parting lines in areas that are not critical to the appearance or function of the part to minimize post-processing work.
Simplify the parting line as much as possible to reduce mold complexity and cost.
Ensure the design is suitable for the expected production volume, as high-volume production can justify more complex and costly molds.
Ejection, vents and gates
Design parts with flat surfaces where ejector pins can be placed to facilitate smooth ejection without damaging the part.
Consider the placement of ejector pins to ensure that any marks they leave are in non-critical areas.
Position gates in areas that allow for smooth and consistent material flow, and avoid placing them in areas that are visually or functionally critical.
Design adequate venting to allow trapped gasses to escape during the casting process, which helps to prevent defects.
Material selection
Choose materials that are compatible with the die casting process and the intended application of the part.
Consider material properties such as strength, thermal conductivity, and corrosion resistance when selecting the alloy.
Design parts with appropriate allowances for material shrinkage that occurs as the metal cools and solidifies.
Precision and post processing
Specify realistic tolerances that the die casting process can consistently achieve.
Design parts with sufficient material in areas that will require post-casting machining.
Consider the desired surface finish and design accordingly to minimize the need for extensive finishing operations.
Conclusion
Following a recognized and thorough Design for Manufacturing (DFM) process through the design and production of die castings will improve every aspect, driving down costs and improving quality. The emphasizing of design considerations that align with the die casting process helps streamline production, reduce waste, and deliver effective outcomes.
DFM principles guide the creation of designs that possess inherent compatibility with the die casting process, leading to parts that are easier and more cost-effective to produce. Simplified designs, thoughtful consideration of material flow, and optimized tooling reduce the need for complex post-casting operations and minimize material wastage. This not only cuts production costs but also enhances the precision and consistency of the final products.
DFM fosters better communication between design and manufacturing teams, ensuring that potential issues are identified and addressed early in the development process. This proactive approach leads to fewer production delays, reduced rework, and a more reliable manufacturing schedule.
