Technical article: Soft touch for the price of two-component injection molding


One of the key differentiating features of modern cars is the interior. In addition to the overall design, special attention is being paid to the quality of the surfaces. A variety of manufacturing processes have been created to give interior grained surfaces a soft feel. The Dolphin process, which is unrivalled in cost effectiveness, is set to join the ranks.

Methods for manufacturing parts with a soft-touch surface must strike a balance between high quality requirements, technical feasibility and cost. Conventional processes used to generate a pleasant tactile feel - such as the laminating of compact injection molded thermoplastic parts or in-mold foaming with polyurethane or slush processes -have one thing in common; they are multistage processes, which inevitably involve trimming, folding or bending after the last shaping stage. The linking of the individual process steps and the secondary finishing processes are time consuming, increase the investment costs for the production line, require a logistical effort for conveying the semi-finished products that is considerable in many cases, and - like the production of PVC slush skins - are often very energy intensive.

For those reasons, the aim of developing the Dolphin process1 was to use thermoplastic injection molding to achieve soft-touch surfaces with a good level of softness, acceptable density and foam heights, with no secondary process required apart from sprue cutting. That is to say the soft surface should be applied (created) directly in the injection molding machine to (on) the hard support material. Also, the trend toward greater flexibility of manufacturing technology was taken into account. An injection molding machine that is suitable for this complex process can be used for different injection molds and processes and adapted to future product generations.
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