Engel Austria GmbH supplied its X-Melt technology — which blasts melted resin into the mold — to HTP High Tech Plastics AG of NeudÃ¶rfl, Austria, for molding the lens holder for the laser head on a DVD player.
Engel, based in Schwertberg, Austria, said there is no other way to mold the part, which is liquid crystal polymer containing 30 percent chopped-strand reinforcement to produce the two-minute, yet complex, parts for the laser head. HTP molds the upper and lower parts separately, in a four-cavity mold.
To mold the complicated parts precisely — especially their very thin webs and projections — the injection press has to operate within an extremely narrow processing window. That would not be possible with classic micromolding, according to Engel.
X-Melt has allowed HTP to turn out 5 million of the lens holders.
Under X-Melt, the screw precompresses the melt to a high pressure, with the shut-off nozzle in the closed position. For injection, the nozzle opens and the plastic explodes into the mold all at once. The mold cavity is filled in a fraction of a second.
HTP used an Engel E-motion all-electric injection press with a clamping force of 60 tons, instead of a micromolding machine, which would have been limited to that one job.
According to Engel, the repeatability is superior to conventional molding because X-Melt harnesses the physical properties of the compressed plastic melt. That's important for the DVD player lens head, because the part's complex geometry does not permit in-line quality control with monitoring systems — HTP is banking on the repeatability of the machine itself.
Engel officials described the X-Melt application during a pre-K show news conference in Schwertberg.
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