Monday, September 24, 2012

Stack Molding: Don’t Blow Your Stack!

Plastic injection molding may be the most utilized industrial process in the world. And no matter what the end product – whether a drug vial or a car door handle – the plastic injection molding process is more or less the same. Plastic, in the form of granules or pellets, is fed into a hopper, heated, China CC Composite Heat Shield Manufacturers than “injected” or rammed into a mold containing a cavity which is the exact shape of the part to be made.

Similarly to other plastic injection molding companies the world over, Illinois plastic injection molding companies discovered many years ago that if you assemble several molds in a line on the same press, you can turbo-charge your efficiency by adding more cavities. China CC Composite Electrode Bolt Manufacturers This series of connected face molds is known collectively as a “stack mold.” Each mold in the stack has the same shape and mass as the one next to it, so they all fit within the same tie bar assembly.

Although it depends on many factors, productivity usually goes up in proportion to the number of molds in the stack. For instance, a manufacturer can double output per run by doubling the number of cavities on the same press.

There are many different types of stack molds but some commonalities include:

* Very high production runs on fewer machines

* Multiple cores and cavites

* Indexable cores, to injection-mold multiple materials

* Have the ability to perform multiple operations in the same molding cycle

Generally speaking, a stack mold has a stationary “A” half, and at least two “B”, or moveable halves. They are similar to rotary molds that have been in use for many years, but in many cases are vertical rather than horizontal. This means that the moveable cores rotate about a vertical axis, rather than a horizontal. Also, the stack mold is very compact and has a much smaller footprint than other types of molds.

Stack molds can be expensive. So a high volume is necessary to compensate for their price. But no worries; the return-on-investment is also high. Car and healthcare products are also typically made with stack mold technology.

Just think about the amazing amount of engineering and mold-making required, China CC Composite Electrode Sheath Manufacturers the money is understandable. Designing and making a stack mold is not for every company, or molders who just want to make quick buck. China CC Composite Cover Plate Manufacturers Plastic injection molding is not a breeze at any time but stack molding is a whole new dimension of competence in our industry.

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