Engel's Clearmelt process is used for wood veneer trim.
The Schuster demonstrator uses non-visible capacitive inks.
This Plastics News Europe feature looks at in-mould labelling used for functional surfaces in car interiors.
At Fakuma 2015, Schuster Kunststofftechnik exhibited a demonstrator which could point the way to how capacitive surfaces will evolve in car interiors.
The company, based in Waltershausen, Germany, is an injection moulder which has become a specialist in the in-mould labelling (IML) process. While IML was initially developed for packaging, then adapted for decorative automotive surfaces, Schuster has also been developing IML functional surfaces. In these, printed circuitry replaces the decorative layer on a hard-coated film, which is back moulded to create a finished surface with electronic functions like displays and keys.
At Fakuma, Roland Beil, managing director at Schuster Kunststofftechnik, said: “Automotive companies want a completely closed surface, like on smartphones.”
In North America, Tesla’s electric cars have printed electronics on a flat substrate, but European carmakers want curved functional surfaces, he said.Injection moulding using IML is suitable for 3D geometries, but there are challenges. During the film preforming stage, the possibility of breaking open the capacitive ink must be avoided. Then when back moulding the preformed film, the company has to be careful that heat from the process does not wash out the ink layer.
“We have overcome these challenges,” said Beil.
Recent work with its ink partner has led to development of non-visible capacitive inks, as shown in the demonstrator part at Fakuma. Normally, capacitive inks show through from the back of a display, so printed electronic keys are positioned outside the edge of the display. But with the new non-visible inks for IML, Beil said keys can be positioned anywhere in the display area.
Holding up a conventional car display module with buttons, switches and dials, he said: “This has 16 keys which have all got to be painted, laser etched, and so on. With IML, you completely do away with these keys.”
IML keys lead to weight reduction and compare very favourably in a cost comparison with traditional keys, according to Beil. The scratch resistance of surfaces created with IML is another attribute in its favour.
“We see this as the future in the industry,” he said.
And the future for Shuster does not mean just keys for car interiors. He said there is potential for the IML process to be used for any electronic feature that can be printed: for example, non-visible heating circuits in screen covers on parking sensors, which currently are affected by frost. In consumer electronics, there is potential for IML in smartphone antennae.
Schuster Group has been experiencing good growth, with turnover rising from €23m in 2008 to nearly €40m in 2014 – including Schuster Kunststofftechnik’s sister companies Werkzeugbau Ruhla (mould and tool making), Back Stickers Industrial Labels (printing) and Sur-Tech Surface Technologies (surface lasering, painting and printing).
Schuster Kunststofftechnik has been investing in new injection moulding machines. Beil said a new Arburg machine was due to be installed in January 2016, following on from two new Arburg machines in 2015 and three new machines in 2014.
Many of Schuster’s opportunities are in the automotive sector, which accounts for 70% of its turnover. But other markets are becoming important, such as medical technology, which has a 10% share of turnover. Beil referred to a medical device part that the company recently started producing, using IML to create both high gloss and soft touch surfaces.
While Shuster highlighted functional surfaces at Fakuma, KraussMaffei and RocTool showcased a decorative development in surfaces that does not need film at all. The injection moulding process involves dynamic mould heating (DMH) in combination with laser-structured microsurfaces on the mould to achieve gloss and textured surfaces.
On a CX 160 machine, KraussMaffei moulded a black polycarbonate demonstrator part with a variety of surface effects, such as high gloss, matt and even holograms. It was developed as an alternative to IML in partnership with RocTool of France, whose dynamically inductive mould temperature control system is used in the process.
Hans Ulrich Golz, managing director of KraussMaffei, said at the company’s Fakuma press conference that the process reduces costs by 20-30% versus back injection of foils in the IML process.
“You get very good surface quality without using IML,” said Peter Wentzel, RocTool’s manager for Germany and Benelux, who spoke with Plastics News Europe on KraussMaffei’s stand. “The process gives a lot of design freedom. You can put anything on the surface you like. And it comes straight out of the mould with no finishing steps.”
According to Wentzel, the post-moulding steps in IML cost money and increase reject rates.
The RocTool DMH technology helps the precise replication of the microstructures laser etched onto the mould, enabling the effects such as holograms that the mircostructures create. Wentzel also paid tribute to other partners in the project, such as GF Machining Solutions of Switzerland, which developed the laser technology for etching the mould microstructures. He said a mould coating from Oerlikon Balzers of Liechtenstein adds to the part quality and makes the mould durable for high volume production.
The project’s partners also include Sch?fer of Austria (mould), Incoe of the USA (hot runners), Motan-Colortronic of Germany (materials handling), ONI Temperiertechnik Rhytemper of Germany (temperature control) and Sabic of Saudi Arabia (Lexan PC material).
Automotive surfaces using wood veneer were the focus of one of Engel’s demonstrations at Fakuma. The process involves Engel’s Clearmelt method, back injection of the wood veneer with thermoplastic and coating with transparent polyurethane to protect the surface.
Engel said the process provides economical manufacturing of decor elements with genuine wood veneers. Each step takes place in a manufacturing cell, at the centre of which is an Engel duo 3550/650 combi M injection moulding machine with a rotary platen that supports high-volume production with short cycle times.
“On one side of the mould, the wood veneers are back-injected with PC/ABS, while at the same time on the other side, the base elements produced immediately prior to this are flooded with PUR,” said Engel.
Cavity surfaces usually need to be sprayed with separating agent before processing PUR, but the PUR used at Fakuma already included a separating agent, which saves an entire process step, said Engel.
The first serial application is set to start soon with production at HIB Trim Part Solutions in Bruchsal, Germany. Other partners in the project include Hennecke (PUR technology).
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