Dolphin
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. Two factors are critical in automotive part design: cost and time-to-market, particularly important when multistep processes are involved. 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 - a two-component molding technology that makes soft-touch parts on one press in less time than with conventional techniques, and at less cost.
The first injection unit for the conventionally injection moulded core is mounted ? as is usual in such applications ? behind the stationary platen. The alloy is metered through an injection unit on the fixed platen. The mold rotates horizontally. A nitrogen-foamed Pibiflex 2567 copolyester grade from P-Group, injected by a unit on the moving platen, is molded onto the substrate. The mold opens slightly to permit a preset expansion of the foam. Thicknesses range from 2 to 12 mm. The soft-skin layer forms after expansion and the part is demolded. During foam molding, another substrate is fabricated on the opposite side of the mold. Molding cycles range from 80 to 120 seconds, based on foam thickness.
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.
The finished part is a multilayer construction of substrate, microcellular foam core, and soft-touch skin. Textured inserts can be used to give the surface a look of grained leather. Engel says the Dolphin process competes with traditional soft-touch fabrication methods for automotive interiors that use solid substrates, polyurethane foam, and slush-molded vinyl skins, each fabricated in a separate process prior to assembly.
Called "Dolphin," the process is the result of several years of collaboration involving Engel, Swiss moldmaker Georg Kaufmann Formenbau, resin producers BASF in Germany and P-Group of Italy , and US-based Trexel Inc., which supplies the MuCell microcellular foam process. Target parts include instrument panels, door panels, interior trim, consoles, and armrests.
The most obvious of these are reduced capital investments in molds and machinery, since only one molding cell is required to fabricate parts. Single-cell manufacturing also means simplified process control, fewer workers, reduced floor-space requirements, no secondary processes like trimming and assembly, and more efficient supply and handling of raw materials.
Recycling, in-plant and at the end of vehicle life, is facilitated by the use of a mostly polyester resin structure and elimination of thermoset polyurethane foam, a common component of slush-molded parts. The ability of a vehicle to meet end-of-life recycling rules is a growing design requirement in Europe , and this requirement is expected to increase elsewhere.
The technology makes other soft-touch processes obsolete by giving molders the means to produce finished parts on one machine. The initial investment is sizable- about €1.5-1.7 mln (US$2.3-2.6 mln, as of May 2008). A mold is €800,000-1 mln (US$1.24-1.55 mln, as of May 2008). There are also investments for the MuCell foaming system, automation, and related equipment. |
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