Stacked mold

Energy Savings via Stack Molding and Double Shot Holding C7.S)... 

Husky Newsletter, (Feb. 1978), "Stack Mold Developments", Husky Injection Molding Limited, P.0. Box 1000, Bolton, Ontario, Canada LOP 1A0. 

The principal types are two-plate, three-plate, and stack molds. Others include the family mold that has multiple cavities of different shapes in one mold.3, 324 A further distinction concerns the feed system that can be either the cold or hot type. These classifications overlap. Three-plate molds will usually have a cold runner feed system, and a stack mold will have a hot runner system. Two-plate molds can have either feed system. 

Stack mold also features two or more daylights in the open position. Two daylights are the normal form (Figure 17.5) but up to four are also used more could be used. The purpose of the stack mold is to increase the number of cavities in the mold without increasing the projected area so the clamp force required from the IMM remains the same. Similar cavities and cores between each of the daylights are normally used. 

Patent Number US 6155811 A1 20001205 STACK MOLD CARRIER MOUNTED ON LINEAR BEARINGS... 

Most molds for injection molding are unique in design, which depends on application, fluoroelastomer compound, and feed system (hot or cold runners). Standard systems are distinguished as two plate, three plate, or stack molds [58],... 

Strauch, R. Development and construction of a stack mold. Kunststoffe German Plastics 1988, 78, 15-16. 

Other developments have not been as dramatic, but they have nevertheless contributed significantly to the process efficiency. The electric screw drives were replaced by hydraulic motors with a gear box on the reciprocating screw unit. In the future the hydraulic motor may in turn be replaced by a direct hydraulic drive (19). The Introduction of stack molds has also increased productivity. In a stack mold, two cavity plates are placed on top of each other so that the projected area is the same and twice as many parts can be formed with the same clamping tonnage. This technique works best with thin wall, flat parts with short cycle times. 

The section of the mold containing the convex core is usually the piece that moves back and forth to open and close the mold, and is referred to as the moving platen. In some designs, especially in stack molds, the mold cavity is mounted on an intermediate section called the floating platen, rather than directly on the injection molding machine. 

A stripper plate mold is a two-plate mold in which the core and ejector plates are combined into a stripper plate. It is used for thin wall parts and parts with symmetry and no undercuts. A three-plate mold has two parting Unes, thereby providing automatic separation of the parts and runner system. This does not work with all materials brittle materials tend to fracture on ejection. It also limits the selection of gate locations and does not eliminate scrap. A stack mold is used to mold two layers of parts without increasing clamp force. Because stack molds are not as precise as two-plate molds, they are used for low-tolerance parts such as polystyrene drinking cups. 

In this type of mold, production can be theoretically doubled providing that the machine capacity is high enough to flU both sets of cavities. The stacked mold consists of two sets of cavities, one on top of another. In this way high clamping pressure, which would normally be required with a mold having an increased number of cavities, is also minimized. 

The hotrunner system is located in the middle plate of the stack mold. It is centrally fed by a heated runner pipe which is also called snorkel . 

Stack molds are built up to 4 stacks. In this case though, a customized machine has to be provided (Figure 1.63). 

Also unequal molded parts can be produced in a stack mold for better utilization of injection and plasticizing capacity. The option tandem mold (Figure 1.64) is in this case preferred. The both parting lines of the cavities are sequentially locked and filled. 

FIGURE 1.60 Stack mold with rack and pinion mechanism for synchronous opening in both parting lines [33]... 

FIGURE 1.62 Middle plate of a stack mold a Centrally located snorkel [24]... 

Slider mold Stack mold Three plate mold H... 

The use of the hot runner technology allows only certain component geometries and mold concepts. With hot runner systems, gating positions are achieved that cannot be reached conventionally the active movement or complete avoidance of fill lines can be implemented by sequential injection multi-component injection molding can be performed with up to five materials in a mold high-speed stack molds can be built film and fabric can be back injected gas and water injection technology can be implemented multi-cavity molds can be realized clean room production can be optimized and the co-injection technique can be enabled. 

Plank,H., Horizontal Turntable and Stack Mold technologies-Innovative Technologies in Multicomponent Injection Molding , ANTEC Proceedings (2002), w/p. 

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