Knowledge

Five of the most common issues with pressure die casting and their solutions are discussed below:

Porosity: Porosity in solid cast metal parts manifests as holes or voids that can vary in size from microscopic to several cubic millimeters or larger. This defect primarily stems from two causes: solidification shrinkage and gas porosity. Solidification shrinkage happens as the injected molten metal cools too swiftly, contracting against the cooler mold walls. This contraction creates voids within the cooling molten metal away from the mold walls. On the other hand, gas porosity occurs when air or gas becomes trapped within the mold, leading to the formation of pockets. This can happen under several conditions, such as inadequate venting or improper mixing of materials during the mold-filling process. To mitigate these issues, manufacturers may adjust the mold design or casting procedures to promote uniform cooling, minimize shrinkage, or lessen the chance of air entrapment. The appropriate strategy is determined based on the underlying cause of the porosity.

Cold Shuts: Cold shuts, also known as cold laps, occur when two fronts of molten metal flow meet but do not properly fuse, resulting in a weak spot or seam. This flaw often results from inadequate gating system design or insufficient molten material fluidity. To prevent cold shuts, manufacturers can: adjust the gating system, raise the pouring temperatures, or enhance the mold's ability to vent gases.

Misruns: Caused by insufficient molten metal flow or premature solidification before the mold is fully filled, leading to incomplete castings or parts that are not fully formed. The solution here is similar to that of cold shuts. It involves reviewing and potentially modifying the design of the mold, the configuration of the gating system, and the fluidity of the molten metal to ensure complete mold filling.

Flash: Excess thin layers of metal that escape from the mold cavity at the parting line or around ejector pins, requiring additional trimming operations. To solve the issue of flash in die casting, it's essential to increase the clamping force of the machine to ensure mold halves are tightly sealed, regularly inspect and maintain molds for damage or misalignment, and adjust injection parameters to optimal levels. Additionally, revising mold design for better venting and thermal balance, controlling the molten metal temperature, improving the gating system, implementing consistent process controls, and using appropriate release agents can effectively minimize or eliminate flash.

Blisters: Blisters are a type of gas porosity that manifest as visible, raised bubbles on the surface of a component. They occur when air or gas, trapped at high pressure within the casting, expands and pushes the material outward after the casting is ejected from the mold. To rectify blisters, the same approach is used for internal gas porosity: minimizing trapped air. These solutions might include: altering the mold's cooling rate, tweaking water circulation, extending the cooling period, or quenching the part immediately after it's ejected from the mold. Adjusting the temperature of the alloy to decrease the thermal disparity between the mold and the metal is another effective strategy.

Is Pressure Die Casting Cost-Effective?

Yes. High-pressure die casting is especially cost-effective for high-production runs. This method enables the production of large volumes of parts quickly, often making it the most economical choice for high-volume production. The speed and accuracy of casting cycles lead to minimal waste and high efficiency, thereby decreasing the cost per unit over time.

Vigor's products will be produced and inspected in strict accordance with customer needs, and we will provide you with all process control and quality control documents to ensure that our customers can keep track of the production progress and inspection results. If you are interested in Vigor's mechanical products, please don't hesitate to get in touch with us to get the best quality products and the best service.