The high pressure die casting process is a common manufacturing method widely used in the aluminium die casting industry, particularly in the automotive, electronics, and machinery sectors. While this method is highly efficient, it is also associated with various defects. Common defects include porosity, shrinkage, cold shut, misruns, flash, and warping, among others. Preventing these defects requires optimizing the die casting process and improving mold design.
This article explores common defects in the aluminum die casting process, their causes, and how CEX Casting prevents them as a professional die casting supplier. Keep reading to learn more about high pressure die casting defects and their solutions.
High Pressure Die Casting Defects
Gas Porosity
Description: Gas porosity occurs when small gas bubbles become trapped in the metal during solidification. These bubbles create voids that weaken the casting’s mechanical properties.
Causes: This defect is caused by air entrapment during injection, excessive die lubricants, poor mold venting, or moisture contamination in raw materials.
Shrinkage Porosity
Description: Shrinkage porosity results from the natural contraction of the metal as it cools and solidifies. If the molten metal lacks sufficient feeding, internal voids will form.
Causes: Poor gating and riser design, rapid cooling rates, or improper metal flow control contribute to this issue.
Cold Shut
Description: Cold shut defects occur when two separate metal flows fail to fuse properly, resulting in a weak seam in the casting.
Causes: The defect is caused by low injection temperature, insufficient metal flow speed, or turbulence from poor gating design.
Misruns
Description: Misruns happen when molten metal fails to fill the mold cavity, leading to incomplete or missing sections in the casting.
Causes: This defect is usually caused by low pouring temperatures, slow injection speeds, poor metal fluidity, or inadequate mold venting.
Flash (Burrs)
Description: Flash is the excess metal that forms at the parting line or along mold edges.
Causes: It occurs due to excessive injection pressure, improper mold clamping, or worn-out mold components.
Cracks (Hot and Cold Cracks)
Description: Cracks in aluminium die casting components develop due to thermal stress or excessive solidification shrinkage. Hot cracks form when residual stress builds up as the metal cools too quickly, while cold cracks occur after solidification due to external mechanical stress.
Causes: Uneven cooling, poor mold design, and improper alloy selection contribute to these defects.
Oxide Inclusions
Description: Oxide inclusions are non-metallic impurities trapped in the casting, weakening the material and creating surface defects.
Causes: These inclusions form when molten metal reacts with oxygen during pouring. Poor filtration, excessive turbulence, or prolonged exposure to air can worsen this issue.
Metal Inclusions
Description: Metal inclusions occur when foreign metal particles or debris become embedded in the casting.
Causes: These inclusions often come from eroded mold surfaces, contaminated raw materials, or improper handling during the casting process.
Soldering (Die Sticking)
Description: Soldering happens when molten die casting aluminum adheres to the mold surface, creating rough spots on the casting.
Causes: The issue arises when mold temperatures are too high or improper die lubricants are used. Certain alloy compositions also promote adhesion.
Flow Marks and Lines
Description: Flow marks appear as visible streaks or lines on the surface of a casting.
Causes: They occur due to uneven metal flow within the mold cavity. This defect happens when the injection speed is too low, the mold temperature is inconsistent, or the gating design is inadequate.
Segregation
Description: Segregation occurs when different alloying elements solidify at different rates, leading to uneven material distribution within the casting. The issue is common in thick metal sections.
Causes: It is influenced by improper cooling rates, excessive impurities, and poor alloy mixing.
How CEX Casting Prevents Defects
As a professional aluminum die casting manufacturer, CEX Casting employs advanced technologies and rigorous quality control measures to prevent defects.
Our prevention strategies focus on two key areas: optimizing mold design and refining the high pressure die casting process.
Mold Design Optimization
During the mold design phase, we use casting simulation software to perform mold flow analysis and generate DFM reports for our customers. This helps predict and eliminate defects before production begins.
Additionally, we regularly perform mold maintenance and equipment calibration to prevent casting defects.
Casting Process Optimization
CEX Casting ensures defect prevention through process enhancements, including:
-
Centralized melting to purify raw materials
-
Vacuum-assisted casting system
-
Unique feeding system
-
Optimized feeding rates
-
Precise temperature control
-
Unique cooling design
-
Stress relief treatments
As a trusted die casting company, CEX Casting provides comprehensive solutions, from mold design to final product delivery.
With ISO 9001 and IATF 16949 certification, in-house mold development, and the optimized die casting process, we can provide you with industry-leading aluminum die casting products.
Conclusion
Defects in the high pressure die casting process can significantly impact product quality and performance.
Common defects like porosity, misruns, flash, and warping can be effectively minimized by optimizing mold design and refining the process.
As a leading die casting supplier, CEX Casting combines technology and in-house tooling capabilities to deliver aluminum die casting components with minimal defects.
Contact us today to discuss your die casting project and discover how we can help enhance your product quality!