Leading High Pressure Die Casting Companies

The inadequacies of the original gravity die casting method led to the development of cold die casting, which was able to cast high melting point metals like aluminum. The cold die casting method opened the door for a wider range of metals to be shaped. From the early part of the 20th century, adjustments, innovations, and changes were made to the die casting process that led to the introduction of high pressure die casting (HPDC). As HPDC has been perfected and improved, it has become an essential part of producing castings with thinner and more intricate designs.

Metals for High Pressure Die Casting

High pressure die casting is used to cast non-ferrous metals that have the appropriate melting point. Cold chamber high pressure die casting metals are metals with a high melting point and include aluminum, brass, and magnesium. This choice of metals is due to the resilience and strength of the castings.

Hot chamber high pressure casting works best with metals that have a low melting point, such as lead, zinc, tin, and magnesium. It is a high production process that rapidly casts high quality small sized castings in high volume. The speed and rapid cycle times require the use of metals that melt and solidify quickly.

• Aluminum – Aluminum is one of the most popular metals used in manufacturing due to its strength, corrosion resistance, malleability, and ductility. Although there is a long list of aluminum alloys, the ones most commonly used for casting are alloy 3890, B390, 413, and 430, which have the desired melting point and durability.

• Zinc – The formability of zinc makes it ideal for the manufacture of complex components and castings with small intricate shapes and holes. It is the easiest metal to cast, which is the reason it was one of the original metals used. Zinc has high ductility, a factor that makes it ideal for precision casting. The softness of zinc is ideal for high pressure die casting since its use does not damage dies or molds.

• Copper Alloys – Much like aluminum, copper is the perfect metal for high pressure die casting. The many alloys of copper come in different hardnesses such that there is a form of copper for nearly every type of casting project. The choice of copper alloys for high pressure die casting is due to copper’s thermal and electrical conductivity.

Advantages of High Pressure Die Casting

Die casting is an expensive process, regardless of the variant being used. Of the different types of die casting, high pressure die casting is the most expensive due to the quality of the casting produced and the cost of the equipment. A factor that needs to be considered when choosing it to produce a part or component.

Volume

Volume is one of the main reasons that high pressure die casting is chosen as a production method. Typically, high pressure die casting equipment can produce between 200 and 300 castings per hour. As the castings get smaller, the number of castings per hour rapidly increases and can number into the thousands. This aspect of high pressure die casting offsets the initial cost of the process.

The highest turnaround times are with hot chamber high pressure die casting that produces hundreds or thousands of components per hour. Although cold chamber high pressure die casting is a slower process, it still can produce between 15 and 250 castings per hour.

The popularity of high pressure die casting is directly related to the speed at which castings are produced. Other forms of casting are labor intensive and time consuming. In the modern era, speed of production has become a major and critical issue, which is the reason that high pressure die casting is constantly being improved and perfected.

Cycle Times

Cycle times are directly related to the volume of castings produced per hour. The rapid cycle times of high pressure die casting is due to the speed at which the molten metal is forced into the die cavity. In essence, with hot chamber high pressure die casting, the molten metal is drawn from the melting pot, forced under pressure into the mold, solidifies, and is ejected. It's almost as fast as a punch press.

Precision control of the injection process decreases cycle times and part production. As cycle times rise, more parts are produced per hour. This particular factor offsets the high cost of high pressure die casting.

Wall Thicknesses

The precision of high pressure die casting makes it possible to produce intricate and delicate parts with the thinnest of wall thicknesses. This is especially true for cold chamber high pressure die casting, which is noted for producing intricate detailed casting with high tolerances and thin part walls.

The key to wall thicknesses is the pressure placed on the molten metal that forces it into every crevice, corner, and indentation of the die cavity. The continued and constant pressure makes it nearly impossible for the molten metal to withdraw from any portion of the cavity. Although other injection casting methods can produce thin walls, none of them can match the quality of the thicknesses of high pressure die casting.

The ability to manufacture castings with significantly thinner walls makes the process ideal for producing components for assemblies that require lightweight. It is important to understand that the presence of thin walls does not mean that a metal loses its strength. Even though the walls may be thinner, the castings retain the same durability, strength, and resilience of the base metal.

Tolerances

High tolerances are a necessity for modern components. Dimensional tolerances ensure that components for a product for which they are designed will be in compliance with a product’s parameters. The high-quality tolerances of high pressure die casting is one of the main reasons for its popularity.

The dies for high pressure die casting are made from H13 tooled steel and are machined to the micron level to produce casting dies with exceptional tolerances. The dimensional accuracy of the tolerances varies between metals but are between a ±0.001 in and ±0.004 in.

Porosity

A concern for all types of casting is porosity, which is holes or pores created in a casting by trapped gases and air pockets. In metal components, pores weaken components and cause malfunctions and breakage. The turbulence created during the injection process of high pressure die casting leads to fast solidification, which minimizes porosity.

In addition to the five benefits of high pressure die casting listed above, other benefits include the solid microstructure of castings, exceptional surface finish, ability to cast any size component, and castings being heat treatable. Although the cost of high pressure die casting is a glaring problem, the outstanding quality of finished components and parts compensates for the higher cost. High tolerance and dimensionally accurate castings ensure the quality of products and their longevity.