Stack And Tandem Molds

Stack and Tandem Moulds

Kore is one of the pioneers in Asia to manufacture and test successful tandem moulds

To date, we have built multiple tandem moulds which are already in production in America and Europe. Tandem moulds are often difficult to test or run production on-site in China. However, we are equipped with the appropriate injection moulding machine and auxiliary equipment to run the moulds.

Our Experience

What is a Stack Mold?

Stack molds are two or more moulding surfaces ‘stacked’ together. This multi-layer plastic injection mould doubles the moulding capacity as compared to a normal plastic injection mould.

Contrary to the common perception, stack mold does not require additional clamping force in spite of having double the moulding surface.

It is also possible to set different number of cavities in each mould parting surface. Stack moulding can also be used for multi-material injection.

Advantages of Stack Molding

  • Increases Output
  • Flexible for multi-materials or different number cavities per layer
  • Requires less number of machines
  • Reduces the overall cost by increasing the number of parts without increase in press size or clamp force.

What are Tandem Moulds?

Tandem moulding is very similar to stack moulding. Like stack moulding, tandem moulding also has two parting lines. However, the difference lies in the material injection process.

Unlike stack moulding where injection takes place concurrently on multiple moulding surfaces; the melt in tandem moulds happens  in an alternating surfaces at one time.

Tandem moulding also optimizes processing costs by utilizing cooling time of one moulding surface to injection sequence of the other moulding surface.

Benefits of Tandem Moulding

  • Saves Time -  Each side is processed separately resulting in more optimized process window
  • Optimizes Output
  • Compatible with many injection moulding machines

Differences between Stack and Tandem Moulds

  • Stack moulds technology is purely mechanical racks/pinions and Tandem moulds is electronically controlled with magnetic locks.
  • Stack moulds opens its dual parting lines and ejects all its moulded parts in one single cycle, whereas Tandem moulds ejects only moulded parts in one parting line at a time.

Why Use Stack and Tandem Moulds?

Key Advantages

  • They help solve width and length limitations of the injection moulding press.
  • They potentially doubles the output of the available injection moulding equipment and labor.

For instance, a conventional 4-cavity automotive bracket mould with 700 grams shot weight would require 55 seconds cycle time on a 400 ton injection moulding machine that moulds about 260 parts per hour.

  • Stack Mould - there will be an 58% increase in output with the same injection moulding equipment and labour.
  • Tandem mould - there will be a staggering 480 parts per hour representing an 85% increase in output with the same injection moulding equipment and labor, if any.

If the economics of Stack or Tandem injection moulding technology justifies its adoption. The moulder need to perceive the Stack or Tandem injection mould as two injection moulds instead of just one mould and allocate resources and schedule lead time accordingly to avoid unnecessary frustrations.

When to consider Stack and Tandem Moulds as options?

We will consider tandem or stack mould solutions when:

  1. our plastic injection moulds are at the maximum number of cavities for the largest available injection moulding machines sizes;
  2. our largest injection moulding machines running your maxed-out-cavities moulds are running at full or near full loading
  3. we have limited room in the shop floor for more large injection moulding machines
  4. we are having a hard time finding operators for current injection moulding stations, let alone adding more stations.

For more interesting mould and moulding technologies, please check out our case studies here.

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