2K-Sandwich systems
The 2K sandwich units can – depending on the application and customer requirements –
- be built in a steel intermediate plate
or - directly in the muold half on the nozzle side, referred to as the “hot half”
or - be attached directly to the injection units, referred to as “nozzle or cylinder head”.
The 2K sandwich units are available for all commercially available multi-component injection moulding machines in all sizes and designs and for machines from all manufacturers. They can be used in new machines as well as in machines that are already used in production.
Principle graphics – sandwich
* Due to the poor thermal conductivity of thermoplastics compared to metals, the injected melt only solidifies directly on the wall of the cavity, but continues to flow. The cavity is thus filled in that the melt has to flow through already solidified thermoplastic from the injection point to the end of the flow path.
Advantages and applications of sandwich technology
Sandwich moulded parts with a skin-core structure offer the possibility of combining two different plastics with one another and in this way to achieve technical and economic advantages.
Application | Advantage |
---|---|
Surface (skin) made of new material, recycled material inside |
cost savings |
Surface (skin) compact, inside foamed plastic | Lightweight construction – weight savings, avoidance of sink marks Targeted influencing |
Surface (skin) “soft” plastic, internally “hard” plastic or “hard plastic” for the surface (skin), “soft” plastics for the inside of the moulded part | Targeted influencing of the mechanical, acoustic and thermal properties |
Introducing a “barrier layer” inside the moulded part | Prevention of the penetration of gases and radiation, e.g. UV light |
Use of transparent material for the surface (skin) and coloured core material | Production of molded parts with decorative effects |
Further advantages of the A&E sandwich units:
- Any spray sequences can be implemented, i. e. skin-core and skin-core-skin
- Any number of spray sequences in one cycle are possible
- The integrated shut-off nozzle function results in high process stability with wide processing windows
- Adjusting and control elements release large flow area even with small strokes – thus low pressure losses and low melt shear
- No additional drives required for the standard version, with integrated locking function – use of a core pull of the machine
- Less programming effort for the machine control
The sandwich hot runner nozzles cannot only be built into intermediate plates. For special and large machines in particular, it is recommended that both injection units be firmly connected to the sandwich hot runner nozzles (“nozzle head”).
The sandwich hot runner nozzle can also be installed directly in the injection moulding tool (“hot side”).
Depending on customer requirements, A&E creates a suitable technical solution for the economical use of the sandwich / coinjection process