Dolphin

Injection moulding solution for softtouch surfaces in the automotive interior

Dolphin is a process for the manufacture of soft-touch car interior components using a combination of injection moulding and foam moulding in just one machine.

The Dolphin process is an interesting alternative process for the production of many of the sandwich components and polyurethane (PUR) foam components currently produced for passenger car interiors.  Most of ENGEL's customer projects are focused on dashboard panels, centre console components, glove compartment flaps and inside door trim parts.

ENGEL and its system partners also address other target groups besides the automotive industry. A typical example are manufacturers of seating furniture, for whom the integration of injection moulding and foam moulding in one single production cycle opens up countless possibilities.

Sample-parts manufactured with the Dolphin process.

Das Verfahren

The first injection unit for the conventionally injection moulded core is mounted – as is usual in such applications – behind the stationary platen.  The second injection unit, for the overmoulded foam, is mounted on, and moves with, the rear side of the moving platen where the ejector is normally fitted.  Thus the melt for the second component can be injected into the cavity via the shortest route and the bypass hot runner normally required in a double-daylight mould can be waived. The second component is mechanically foamed by means of the MuCell process. To this end, the plasticizing unit on the moving platen is equipped with the necessary gas injectors in the melt cylinder and a plasticizing screw with a downstream gas mixing section. Transfer of the core component from the first to the second injection station is performed with the aid of the central block, which is coupled with the moving mould half and rotates around its vertical axis.  Depending on the actual application, this rotating central block can be arranged to index either through an angle of 90° or – as in the case of this Dolphin application – through an angle of 180°.

Compared with conventional processes for the production of multilayered foam-moulded parts, the Dolphin process offers a great many advantages. It is considerably faster and more economical, less complex and clearly advantageous from both a space-saving and a logistical aspect.  A dashboard panel, for example, can be efficiently produced in one single operation. The conventional process involves the separate production of the core component and the foamed soft-touch outer skin and the subsequent lamination of the core component with the outer skin – all in different machines and with a not inconsiderable scrap rate.

Cross-section of a Dolphin component