Die casting is quite complicated, especially if you do not have a background in the process. Two main techniques are commonly used, which are the hot chamber and the cold chamber die casting processes. The technique used for products depends on the specifications and the results that you are after. 

In this article, we will be discussing how hot chamber casting works, what metals are commonly used, and the benefits of choosing this technique over its counterpart the cold chamber die casting. 

Hot Chamber Die Casting

Die casting is a manufacturing process that uses a permanent mold that liquefied metal is poured into to make a new shape. It then uses pressure to push the metal into a mold. A significant amount of pressure is required to create metal castings with different surfaces, accurate dimensions, and stable thin walls — some castings can even be as thick as a half millimeter.  

The use of this process started in the early 20th century, making it a relatively old process. Metal die castings vary in size, which can range from extremely small to up to fifty-pound casts. Die-cast parts are created using tools, machine components, motors, housings, etc. 

During the hot chamber die casting process, metal will heat up in the attached casting machine. Casting machines, which are also called gooseneck machines may include a built-in furnace that will warm up the metal until it reaches its melting point and becomes liquefied. Different metals have different melting points so the process can vary, especially when it comes to the period of melting the metal. 

A hydraulic-powered piston will be used to push the liquefied metal from the furnace into the die. The die casting process is relatively fast and it is commonly used for high-productivity applications that will need a large output of products. 

The cold chamber casting differs from the hot chamber die casting process because the machines do not heat and melt the metal. The process only uses a liquefied metal where it will be spilled into the chamber manually using ladles or an automatic machine. When the liquefied metal has been poured into the chamber, the hydraulic piston will push the liquefied metal into the die using the specified pressure. 

What Are The Materials Used In The Hot Chamber Die Casting?

The hot chamber die casting uses an internal melting pot; metals with low melting points are used as per the advice of the manufacturer. One important aspect of the hot chamber die casting process is the metals that will be used will not melt or erode the machine’s melting pot when it is heated or placed under high pressure.

 For example, machine parts like the metal plunger are constantly submerged within the liquefied metal. If the metal used has a high melting point, it can cause the plunger to erode or dissolve, which can affect its integrity and functionality. This can lead to the need for constant costly repairs and replacements which is not sustainable in the long run for any business.

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Metals like aluminum and zinc are commonly used in the die casting process. aluminum has a higher melting point; it melts at 1,220 degrees Fahrenheit. On the other hand, zinc melts at 786 degrees Fahrenheit. Because of its high melting point, aluminum is not advised for use in the hot chamber die casting process; it is used in the cold chamber die casting process. The metals that are recommended for use in hot chamber die casting are zinc and magnesium alloy. 

Zinc 

Zinc is a metal that has impressive strength and hardness. It is commonly used for applications that require that metals are pressed, machined, fabricated, and stamped components. Zinc is also known for having good structural integrity and resists wear and tear, which makes it an ideal metal for complex-shaped metal products that are used for electronics and automotive industries. 

What Are The Benefits Of Using Zinc Alloy?

  • Low-cost raw material
  • Allows stable and accurate dimensions
  • Hard, durable, and strong
  • Good electrical conductivity
  • Great thermal conductivity
  • Can be used for creating die-cast metals with thin walls and different shapes and sizes
  • Can be used for creating cold chamber die cast products
  • Great resistance against rust and corrosion
  • Recyclable and reusable
  • High-quality finishing properties

Magnesium

Magnesium is one of the most lightweight die-cast alloys that come with an excellent strength versus weight ratio. It is a great metal to use for applications that require radiofrequency interference and electromagnetic interference shielding. It is known to be used as connectors and electrical housings. It is commonly used for medical and laboratory instruments and paraphernalia because it can help prevent interfering signals.

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What Are The Benefits Of Using Magnesium?

  • Can withstand high temperatures
  • Can conduct heat and electricity
  • Can be used for creating die-cast metals with thin walls
  • High resistance against rust and corrosion
  • Can be recycled
  • Allows stable and accurate dimensions
  • High-quality finishing properties

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What Is The Hot Chamber Die Casting Process?

The hot chamber die casting process is performed by connecting the liquefied metal supply to the die casting machine, which serves as an important part of the operation. Check out the step-by-step process below. 

  1. The hot chamber is filled up by the liquefied metal and the shot cylinder that powers the injection stroke is placed above the liquefied metal supply. The shot cylinder is attached to the plunger rod, which then will be connected to the metal plunger.  The plunger then makes contact with the liquefied metal, and because it is the start of the casting process, the plunger will be located at the top part of the hot chamber. While the liquefied metal is in this position, the liquid metal will then enter the chamber through the intake ports which will then be filled inside.
  2. The plunger goes down as the die casting cycle starts. The shot cylinder will push the plunger downwards, which will cause it to travel over the intake ports which then prevents the liquefied metal from going inside the hot chamber. During this point, the correct amount of the liquefied metal will be seen inside the hot chamber for the shot, so it will fill the mold and then make the die casting accordingly. 
  3. The plunger will go down further when the plunger is pushed down. This will then force the liquefied metal into the die. In the hot chamber die casting process, the pressure that will be exerted on the liquefied metal to fill the die normally ranges from 700-5,000 pounds per square inch. The pressure will be held for a long time until the casting becomes solid. 
  4. The plunger goes back to its original position. To prepare for the upcoming die casting cycle, the plunger will reverse and revert to its original position which is in the top part of the hot chamber. This will then expose the intake port which allows the liquefied metal to enter inside and fill the chamber of the die casting machine. 

What Are The Benefits Of The Hot Chamber Die Casting Process?

The hot chamber die casting process has a lot of benefits compared to its cold counterpart. The most important benefit is a much quicker cycle time. This will allow die casting companies to manufacture more products faster which will then help improve their productivity and efficiency, resulting in customer satisfaction. Check out the other benefits of hot chamber die casting below:

  • The hot chamber die casting process is faster and more convenient compared to cold chamber die casting. It has approximately 15 cycles per minute, which significantly decreases the production cycle time and makes it a cost-effective manufacturing process. 
  • The metal alloys used in the hot chamber die casting process do not easily dissolve or erode during the process. This leads to a decrease in the porosity, and, more importantly, leads to a longer life. The die design is effective and efficient, so it results in less wasted raw materials during the die casting process. 
  • The hot chamber die casting process is a more environmentally friendly process because it produces less metal waste. 
  • This is an overall more efficient process because it uses an internal melting pot. 
  • The machine lasts longer because raw materials like zinc have a low melting point, so higher temperatures are less likely to wear down the internal mechanisms of the machine. 

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If you need a company that offers die casting products made from zinc and aluminum, then make sure to check out SEI Castings, you can request a quote here. Feel free to contact us by filling up this contact form here. We offer standard and custom products, so please let us know if you want custom-made die-cast products for your company.

Are you looking for a company that manufacturers aluminum and zinc die-cast products? SEI Castings is the perfect solution for you. We are a company that offers standard and custom die-cast products made from zinc and aluminum.

 If you want to learn more about our company or the services and products that we are currently offering please do not hesitate to contact us or check out our website for our full range of products and services. You can reach out to us emailing us at sales@seimw.com. What are you waiting for? Contact us today! Make sure to choose a reliable company for all your die cast product needs. We are looking forward to catering to your requests.