Bi-injection – simultaneous or sequenced injection of two components into one cavity

Core-back technique – injection of two components into one cavity one after the other, the space for the second component being accessed by shifting a valve

Transfer technique – the preform is transferred manually or by means of a robot into the second cavity or second machine

Rotary technique – transfer is by axial or vertical rotation with the rotary function provided for in the machine or in the mould

Sandwich technique – different plastics are laminated together to produce a skin-and-core structure.

However different they may be, most multi-component techniques offer similar advantages

Cycle times are signifi cantly shorter

Setting-up of the machine is simpler and faster compared to two “mono material” machines

Operations are simplified

Assembly effort is reduced

Quality assurance and reproducibility are enhanced

Less floor space is required

Energy consumption is lower

The term “multi-component technology” denotes a variety of methods employing specially designed mould and machine features. Basically, they all use two or more injection units to inject two or more materials onto each other or in between each other. If injected onto each other, the components will either form an integral moulding (say an automotive taillight) or a split moulding (say, a closure with a seal ring). If injection is with a shot in between the other shots, referred to as the sandwich technique, a “laminated” structure is obtained, for instance, with a soft skin and a hard core (typically, regrind may be used for the core and virgin material to provide a high-quality surface).