A Comparison of the Hot-Chamber and Cold-Chamber Processes

Examining the Differences Between Hot-Chamber and Cold-Chamber Die Casting

What is Die Casting?

In the most basic terms, die casting is the process that involves the use of high pressure to force molten metal into a mold cavity to produce metal parts; these mold cavities are made of two hardened tool steel dies that are machined to conform to the specifications of the respective part or product.  For optimum results, most die castings are manufactured from non-ferrous metals i.e., metals that do not contain iron to any appreciable amount.

There are essentially two types of die casting processes – hot-chamber and cold-chamber:

What is Hot-Chamber Die Casting?

Hot-Chamber Die Casting Process – a pool of molten metal is forced into the mold cavity via pressure applied by a pneumatic-powered or hydraulic-powered piston.  The advantages of hot-chamber die casting include fast cycle times (up to 15 cycles per minute on average) and the convenience of melting the metal directly in the chamber/machine; a drawback to this process is its limitation to metals with low melting points only.

What is Cold-Chamber Die Casting?

Cold-Chamber Die Casting Process – use of this method requires the metal to be melted in a separate furnace then transported in precise amounts to the cold-chamber machine; this molten metal is then injected or shot into the mold by hydraulic or mechanical pistons.  Use of the cold-chamber die casting process is ideal metals with high melting temperatures; its primary disadvantage is longer cycle times, due to the additional step of transferring the molten metal from a separate furnace to the machine.

As intimated above, the metal point or metal temperature of the respective metal dictates the type of die casting process that must be applied; a synopsis of the common metals most often used in each method would include:

• Hot-Chamber Die Casting
  • Low melting-point metals/alloys – zinc, lead, magnesium 
• Cold-Chamber Die Casting
  • High melting-point metals/alloys – brass, copper, aluminum

In general, die casting is one of the most versatile metalworking processes; consequently, the use of die casting is common across a wide range of industries for the manufacturing of parts, components, and finished products in a variety of shapes and sizes.

Some examples of its application would include:

It is important to note that few metalworking/manufacturing methods can be applied for all products or with all types of materials, and this relates to die casting as well; some of the limitations of the hot-chamber and cold-chamber die casting processes are the lack of cost-effectiveness for low-volume production runs and its diminished efficiency when the weight of a part or product exceeds 75 pounds.

Precision Molds for Optimal Results in Hot-Chamber and Cold-Chamber Die Casting

Many of the production efficiencies/benefits associated with either method of die casting are directly dependent on the accuracy and quality of the molds used in the specific processes.  And while manufacturers might have the financial assets to invest in die casting equipment that can be used on a repeat basis, this may not be applicable to the one-time development of the actual mold or molds.

In order to achieve optimal benefits from their use of die casting, manufacturers might want to engage the mold-making expertise of the team at Noble Precision; these capabilities are supported by Noble Precision’s investment in state-of-the-art technology, specifically the latest in 5-axis simultaneous CNC machines and CAD/CAM software.

For further insight on the die casting services offered by Noble Precision, including precision mold making, see our die casting process page.

Call the precision mold making specialists from Noble Precision at 647-499-7569 today or contact us to request a complimentary consultation on our cutting-edge technologies and services and how we can support your hot-chamber and cold-chamber die casting needs.