Stack Molding and Tandem Moulding?

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 conventional plastic injection mould.

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

Stack and Tandem moulding is capable of molding different number of cavities and part geometries on their respective parting lines.

Advantages of Stack Molding
Increases Output
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.