NPE2018 New Technology Focus: LSR in the Spotlight
LSR remains a popular topic, visible at numerous molding demos at the show.
Undiminished interest in liquid silicone rubber (LSR) will be evident in molding demonstrations by at least nine injection machine builders.
Arburg (Booth W1325) will show two examples of two-shot LSR/LSR molding—one producing a watch strap in two colors and durometers, and another making a dual-durometer membrane for valves used in medical and automotive applications. The latter will use Arburg’s 0.1-oz micro-injection unit with a 0.3-in. screw diam. to produce one shot of 0.0018 oz, followed by a second shot from a servo-electric injector from Kipe Molds.
Engel (Booth W3303) is showing for the first time a particularly complex LSR application—automotive headlight lenses with light guides. They will run on a 120-ton, tiebarless, all-electric e-victory machine with a metering/pumping system and two-cavity mold, both from ACH solution in Austria. The mold uses a new ServoShot cold-runner valve-gate system with valves that are pneumatically actuated but the pin strokes are set electrically. All the valve gates open together, but varying the pins’ open positions adjusts the flow through each valve gate. Parts will be checked via integrated camera inspection and will be weighed individually. The ServoShot software then will adjust the pin openings to balance the fill and equalize the weights in the cavities. The entire cell, including LSR dosing, is handled by the Engel CC300 controller.
KraussMaffei (Booth W403) will mold LSR medical dosing caps, or “duckbills,” on its PX 51-55 SilcoSet all-electric machine.
Maruka (Booths W1103, W911) will mold LSR magnifiers on a Toyo Si-110-6.
Milacron (Booth W2703) will run LSR on a Milacron-Fanuc Roboshot 140. The retrofittable LSR package includes a special Milacron screw and barrel with water jackets, vacuum pump, and water regulator.
Negri Bossi (Booth W363) is operating a 180-m.t. press in its relatively new Canbio ST servo-hydraulic toggle line, molding a ping pong paddle from PBT, TPU and both foamed and solid LSR.
Nissei (Booth W923) will team up two presses to mold a magnifier. The thermoplastic casing is made in a new NEX-IV all-electric press (121 tons), and then a robot passes the part to a FNX-II hybrid (121 tons) to overmold the LSR lens.
CAE simulation software provider Sigma Plastic Services (Booth S30023) will demonstrate an unusual two-color LSR molding application and compare the actual results with its “Virtual Molding” prediction.
One of the more prominent trends in processing is the need for higher plastic pressures to mold parts.
Modifications to the common core pin can be a simple solution, but don’t expect all resins to behave the same. Gas assist is also worth a try.
The reason you dry certain plastics is to get the moisture out. But why does the moisture have to be taken out before processing?