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Advantages of the Hot Cup Die Casting Process

The Hot Cup Die Casting process is consistent with the use and properties of molten metal, the method of displacing it and the method applying pressure as it solidifies. This ensures that the maximum properties of the high pressure process can be transmitted to the casting itself.

1. No Pre-solidified Alloy

Careful design and process control ensures that the alloy in the cup always remains molten.

Therefore there is no:

  • Premature solidification

  • Cold Flakes

  • Inclusions

2. Oxide Reduction

Where required, a low-cost cover gas (nitrogen) can be maintained in the cup, above the alloy, to replace air and prevent oxides from forming. An appropriate cover gas for Magnesium can also be used.

This enables castings to be made with greater strength and pressure tightness as well as higher integrity and consistency.

3. Reduced Gas Entrapment

There is much less air (or cover gas) in a Hot Cup shot-end compared to a cold chamber machine.

Also, the downward movement of the plunger causes the alloy to move upwards, and sideways into the runner, smoothly displacing any air or cover gas.

This results in less gas porosity and air entrapment in the casting.

4. Reduced Plunger Speed

The diameter of the hot cup is much larger than the diameter of an equivalent cold chamber shot sleeve.


Therefore, the plunger can travel at a much lower speed and still fill the cavity in the same time.

This results in:

• Greatly reduced impact pressure

• Less flash

• Better dimensional accuracy

• Longer die life

• Simpler shot-end hydraulics

5. Reduced Shot-End Friction

The Hot Cup process has been designed so that the plunger smoothly displaces the alloy and is never in direct contact with the hot cup.

At the end of its stroke, the plunger applies the static pressure to a thin shell of molten alloy.

Therefore, there is almost no friction. The temperature profiles are very even, ensuring that there is no distortion or damage to the shot-end components.

Plunger lubrication is no longer required, eliminating residues and reducing operational costs.

The shot-end maintenance costs are therefore greatly reduced.

6. Thin Cup Shells

There is no longer a thick 'slug' or 'biscuit' attached to a Hot Cup casting.

Instead there is a thin shell of alloy inside the cup, which solidifies very quickly. The casting process can be much faster and is determined by the solidification of the cavity.

7. Thinner Castings

The combined reduction of oxides, pre-solidified alloy, inclusions and gas porosity opens up the possibility of making castings which are much thinner than traditional cast parts, but with equivalent strength.

Stiffness requirements can be achieved by adding thin ribs in applicable locations.

By this means, part weight can be reduced, which is of great benefit to manufacturers of products such as automotive, transportation, power tools and other components requiring light weight and strength.

8. Faster Production

A Hot Cup Die Casting machine is able to operate much faster than a traditional cold chamber Die Casting machine. There are several reasons for this as set out below:

Vertical Configuration

A vertical machine is able to operate much faster than a horizontal machine because it working in the same direction as the force of gravity.

Examples of what is possible include large stamping presses and forging presses, where the opening and closing speed is very fast.

The Hot Cup Die Casting machine takes advantage of this by utilizing special hydraulic systems to open and close the dies very quickly, while still maintaining complete control.

No force is needed to close the dies. Instead, it uses the stored gravitational energy from the opening stroke. So, as well as being quick, it uses very little energy, even for very large machines.

No Thick Slugs

The slug, or 'biscuit' is usually the thickest section of a cold chamber Die Cast shot and therefore becomes a limiting factor in the cycle time. Reducing the cycle time often leads to exploding slugs during ejection.

The Hot Cup process eliminates this bottleneck because the slug is replaced by a thin solidified shell as described above.

Fast Alloy Dosing

The Hot Cup process includes special new technology which enables fast dosing of the molten alloy under controlled conditions.

Designed for Speed

The Hot Cup Die Casting Machine has been designed from the ground up to operate at high speed. This includes, the clamping system, the shot-end, the hydraulic system, the fluid cooling system and the ancillary equipment. 

Fast Heat Removal

The Hot Cup process incorporates new technology for the removal of heat from the die at much faster rates than with traditional methods. Consequently, the cycle time of the die can be matched to the high speed capabilities of the machine.

The dies will then run much hotter than traditional cold chamber dies which will reduce heat checking and die deterioration, at the same time improving process consistency. This becomes a win-win scenario.

Fully Automatic

The Hot Cup Die Casting machine, and process, is designed to run fully automatically at fast production rates. Robots and ancillary equipment are all interfaced and optimized for high speed.

9. Lower Casting Costs

Faster production rates transfer directly into lower costs of production.


If the cycle time of a casting can be reduced from 60 seconds to 40 seconds, that reduces its casting cost by 33% - a very significant number!

Reducing it to 20 seconds translates to a massive 66% saving.

Die Casting plants can use this saving in costs in different ways.

  • They can keep all the savings and make substantial improvements in their profitability

  • They can share it with their customers by reducing their selling prices

  • They can improve their competitive position by lowering their quoted prices and winning a lot more work

10. Lower Capital and Maintenance Costs

The Hot Cup Die Casting process can lower the capital investment costings in a business in two different ways.

Increased Capacity

Faster production increases the amount of machine time available in the plant.

If there are 12 Die Casting machines on the factory floor and the cycle time can be improved by 33% on average, that is the equivalent to 4 additional machines.

Even a 10% reduction in cycle time will free up another machine.

For a new plant, that means fewer machines have to be purchased and installed.

For an existing plant, that enables a lot more new work to be taken on without extra investment in machines.

Lower Machine Costs

A Hot Cup Die Casting machine is of simpler construction compared to a horizontal cold chamber Die Casting machine.


The Tie Bars are vertical, in alignment with the force of gravity. So, there is no longer a large sideways force on the platens and dies which works to bend the Tie Bars. Consequently, there is no need for large platen support guides, wear plates and a long rigid machine frame.

There is no toggle mechanism on a Hot Cup Die Casting Machine. This eliminates a complex system of toggle arms, toggle pins, bearings and lubrication components. Certainly the clamp-end hydraulics on a Hot Cup Die Casting machine involve precision high-tech components, but the system as a whole is simplified.

As a consequence of these and other features, at equivalent economies of scale, the manufacturing and maintenance costs of a Hot Cup Die Casting Machine are expected to be less than a similar size cold chamber Die Casting machine.

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