How glass can be injection molded into high-quality optical components.

Injection molding, debinding, sintering – a sustainable path to high-quality optical glass components.

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Kunststoffverarbeitung: Verfahren

Glas

Andere Werkstoffe

Injection Molded Glass Parts

The Kunststoff-Institut Lüdenscheid is currently focusing its development work on combining glass and plastics in an injection molding process. It is forming functional assemblies of flat and shaped glass with plastic. In the last step, researchers are attempting to injection mold the plastic melt between a glass pane and capacitive film, with the aim of generating a functional touchpad in one shot. 

The Plastic-Glass Composite is Reaching Completion with the Integration of  Capacitive Sensors 

Verbundwerkstoffe / Werkstoffverbunde

Folientechnik (IMD, IML, FIM, u.a.)

Inserttechnik

Kapazitive Sensoren

Backmolding Formed Glass 

The particular properties of coated glass previously made it virtually impossible to overmold completely. The material was too inflexible and brittle and frequently led to quite high reject rates, so that mass production rarely seemed sensible. Pentacon GmbH has now developed a process that solves these problems and so opens up a new product field. 

Pentacon Can Now Overmold Coated Glass with Plastic – and Not Just for the  Optics Industry 

Montage-Spritzgießen

Optik

Optics in One Shot 

On 17 October 2022, Vanessa Malena, previously COO of Engel Machinery Inc., took over as President of the North American headquarters of Engel Austria.

Personen

kunststoffe.de

Engel North America with New President

Under the motto “It‘s all Wittmann”, Wittmann Battenfeld is presenting its machines and systems in the new Wittmann design for the first time.

Automation cell with SmartPlus 90 for manufacturing a spirit level.

16:9

Schaumspritzgießen

Messe K-Kunststoffmesse

kunststoffe-international.com

Spritzprägen

Biokunststoffe

Kunststoff Werkstoffe

Energieeffizienz

Industrie 4.0 für die Kunststoffverarbeitung

Industrie 4.0

Spritzgießmaschinen

Kunststoffverarbeitung: Maschinen und Komponenten

Naturmaterialien

Verstärkungsstoffe

Kunststoff-Rezyklat

Green DC Current for the Injection Molding Machine

After the focus was on individual manufacturing and model-supported process set-up in recent years, the Institute for Plastics Processing (IKV) at RWTH Aachen University is linking the two aspects of digitalization and circular economy at K 2022.

The QR code on the PCR component provides project information and process data.

Werkzeuginnendrucksensoren

Messtechnik

Sensoren / Messwertaufnehmer

Digitale Transformation

Wirtschaft

Innovationen und neue Technologie

Kreislaufwirtschaft

Precise Process Control with Injectix

The Bavarian machine manufacturer LWB Steinl, with the multicell, is presenting an unusual method for processing polymer molding compounds.

In the Multicell, the cycle steps are split up between multiple stations.

Industrieroboter

Montagetechnik

Automatisierungstechnik

Cycle Separated into Individual Processes

With Hekutip QC, a quality control assistant for pipette tips, Hekuma and Ziemann & Urban have developed a standalone solution that covers wide-ranging testing requirements fully automatically, as well as being compact and swift to deploy.

Hekutip QC covers wide-ranging testing requirements fully automatically, as well as being compact and swift to deploy.

Medizintechnik (KU)

Kunststoffverarbeitung

Spritzgießwerkzeuge

Werkzeuge für die Kunststoffverarbeitung

Fertigungsautomation

Prozessautomation

A Standalone Measuring Station with a Wide Testing Range

Three solutions for increasing the productivity in the automotive, medical and packaging industries are presented by Tederic at K 2022 with the Neo injection molding machine series. T

The Neo·Ec combines electrical and hydraulic drives.

Mehrkomponenten-Spritzgießen

Polylactid

Thermoplaste

Medizintechnik

Medizinprodukte

Applications in Three Key Sectors

ZF Vigo is now taking compounding into its own hands – with the DCIM process from KraussMaffei.

From the left: Eduardo Casas (ZF, Injection Molding Specialist), Edgar Lopez (ZF, Manufacturing Engineer), Thomas Drogi (KraussMaffei, Process Engineer), Christian Seyferth (KraussMaffei, Global Expert Sales), Achim Härtel (ZF, Core Engineer Plastics), Jacob Seco (ZF, Manufacturing Engineer Specialist), Jose Trasobares (ZF, Manufacturing Engineering Manager), Angel Lemus (Coscollola, Director Post-Venta), Antonio Muñoz (Coscollola, Director Comercial Inyección), Ramazan Baser (Motan-Colortronic, Project Engineer)

Compoundieren

Kunststoff-Aufbereitung

Developing, Testing and Protecting Proprietary Formulations

Last year, nearly 12.9 million t of plastics were processed in Europe using injection molding.

Elastomer-Spritzgießen

Duroplast-Spritzgießen

Ceresana Report on the European Market for Plastic Injection Molding

The new site will shorten delivery times for injection molded components for local customers.

TKW Molding has opened a state-of-the-art plant near Shanghai. 4000 m2 of production and storage space are available there.

Dienstleistungen

Lohnfertigung

Automotive

Fahrzeugbau

Unternehmen

TKW Molding Opens Plant in China

At the end of the K trade fair, Kunststoffe put a few questions to some well-known “industry heads.

Ingemar Bühler, PlasticsEurope: “I sense a strong commitment to the circular economy. These are people on a mission.”

Industry representatives about the positive mood despite the crises and the willingness to cooperate in terms of the circular economy or machine communications.

Closing Thoughts on K 2022

Extrusion

Strategie und Organisation

Schröder, Susanne

“Motivated to the Hilt”

This year, the world’s leading trade show K has succeeded in presenting practical solutions for greater resource efficiency on a broad front. A first foray through the trade show grounds.

K 2022 gave numerous practical examples showing visitors how recyclates can be reliably processed with digital aids.

State-of-the-Art Injection Molding Solutions for Greater Resource Efficiency.

State-of-the-Art Injection Molding Solutions at K 2022

Doriat, Clemens, Dr.

Solar / PV

Energieerzeugung

Erneuerbare Energie

Temperiertechnik

Condition Monitoring / Prozessüberwachung

Instandhaltung

Handling, Handhabungstechnik

Oberflächentechnik

Digitalisierung

Silikonkautschuk

Kautschuk / Elastomere

It Can Be Done!

Bio-Fed and Günther Heisskanaltechnik have performed various trials, which show that even supposedly sensitive bioplastics can be reliably processed in hot runner molds.

Fig. 4. Interchangeable inserts for various test samples can be installed in the two-cavity trial mold.

Bio-Fed and Günther Heisskanaltechnik have performed trials, which show that even supposedly sensitive bioplastics can be reliably processed in hot runner molds.

While Processing Trials Proved Highly Successful, an Intuitive Feeling Is Required

Heißkanalsysteme

Komponenten für die Kunststoffverarbeitung

Processing Bioplastics  in Hot Runners

Glass Parts from an  Injection Molding Machine

Glass is a high-performance material with properties that are indispensable for many industries. High-precision molded parts made of glass are required in the optics, chemical and medical technology industries. However, traditional glass-processing methods impose limits on parts design, especially for tiny structures. Here, injection molding offers an alternative that is also more energy-efficient, more economical and more sustainable. Glassomer and Engel are jointly tapping into this potential.

Glassomer and Engel are rendering high-purity glass parts for optical and medical technology amenable to injection molding for the first time.

The new process developed by Glassomer GmbH makes it possible to process transparent quartz glass on standard plastic injection molding machines that meet very high precision requirements [1]. Both thick-walled and thin-walled parts and complex shapes can be produced from quartz glass in this way (Title figure). This new approach offers huge potential in terms of efficiency and economy. A look at traditional glass-processing technologies shows why (Fig. 1).

Traditionally, glass is cast, ground or etched in accordance with the size and requirements imposed on the intended part. In any event, shaping requires either very high temperatures or the use of toxic chemicals. For casting, the material must be kept permanently at temperatures of around 1500 °C to prevent solidification. After shaping, the part must be cooled very carefully to prevent it from breaking.

Casting is useful for fabricating precision structures in the millimeter range. Finer structures in the sub-millimeter range are mostly produced by etching and lasering, with compression methods being employed for certain types of glass. Precision glass molding (PGM) is deemed to be a modern molding method. For this, small glass blanks are heated, liquefied and pressed directly between two molds. One of its disadvantages is long cycle times. Another is that it requires expensive precision molds that are capable of withstanding the high temperatures.

Etching with a chemical entails the use of lithography to coat parts of a solid glass blank to selectively create structures. The etching process is preceded by laser pre-processing. However, etching can only produce certain profiles and shapes and yields rough surfaces.

Novel Granulate Made from  High-Purity Quartz Glass

Compared with conventionally formed glass parts, thermoplastics can be injection molded into almost any shape in a very short time and at relatively low temperatures. It is this versatility that has provided the motivation to injection-mold glass. The use of injection molding to shape glass not only promotes design freedom, but also improves the energy balance of glass production.

The injection molding process for shaping transparent glass is based on a new type of granulate that has a high content of glass particles. The particles originate from the fabrication of moldings for glass fiber production and are therefore particularly pure. However, it is also possible to use glass particles sourced from cosmetics production, where they serve, for example, as thickeners. The granulate is produced by mixing the high-purity glass powder with a resin, followed by extrusion and granulation. The granulate can be injection-molded like a filled polymer, i.e. at temperatures in the region of 130 °C and with cycle times lasting less than 20 s.

Targeted Control over  Surface Properties

The material has deliberately been developed for low-abrasion processing. All of the granulate’s ingredients are non-toxic and contain regular polymer resins. Most of the resin in the green body produced in the injection molding process is removed in a water bath and the remainder is burned out in an oven at 600 °C. This yields a compacted “brown” powder part that is stable due to the large overall surface area of the glass particles. The “brown” part is then sintered to yield high-purity glass (Fig. 2).

The glass is sintered to full density in the process. When this is done properly, no air pockets remain. Shrinkage during sintering amounts to about 16 %, but can be controlled via the quantity of powder used. Since the part shrinks isotropically, the shrinkage can be calculated readily and with precision during the planning stage, and the parts produced are dimensionally accurate, e.g. holes are completely spherical (Fig. 3).

The surface finish can be controlled directly via the nature of the mold-cavity surfaces. The parts can be milky or transparent. Suitably high-quality optical molds yield optical-grade surfaces that do not require post-treatment.

Processing of the Glassomer material may sound simple, but it requires a high-precision injection molding machine, because even the slightest defect in the injection-molded green part would be visible in the sintered glass part. Glassomer has therefore opted for machines from Engel’s e-motion TL series (Fig. 4). These all-electric, tie-bar-less machines are so precise that they are also used to produce smartphone camera lenses made of polycarbonate and cycloolefin copolymers.

The e-motion TL has a specially designed frame for ensuring particularly high platen parallelism throughout the molding process, combined with uniform clamping force distribution over the entire mold fixing platen. All principal movements are servo-electrically controlled, which allows the parallel movements to be synchronized.

Parts of the Highest Purity and  Optical Quality

The Engel injection molding machines transform the Glassomer materials into high-precision, transparent parts of high-purity silica. These include not only thick-walled and thin-walled parts, but also complex shapes. The medical technology part shown (Fig. 5) is proof that molds designed for processing thermoplastics can also be used for glass injection molding without modification. Structures and wall thicknesses larger than those depicted are also feasible.

The quartz glass employed is characterized by high thermal stability, coupled with a vanishingly small coefficient of thermal expansion. Even large temperature differences give rise to only slight expansion or contraction. For example, treatment at 800 °C can be followed by quenching with cold water, without any problems. This is a property needed in the field of optics, and others, where the fabrication of ever-smaller light sources for generating increasingly higher energy densities requires fine lens structures in a glass that is chemically and thermally highly stable. Other applications lie in sensor technology, where, again, the operating temperatures and ambient conditions often fluctuate extensively.

In many applications, Glassomer’s injection-moldable materials even outperform conventional quartz glass. The quality of quartz glass depends on the content of hydroxyl groups, the impurities it contains in the form of positively charged ions and the associated negative charges in the glass framework. A high content of metal impurities, for example, reduces transparency in the lower UV range, whereas a large quantity of hydroxyl groups gives rise to significant absorption in the infrared range. In contrast, because Glassomer’s quartz glass for optical applications is sintered under vacuum, it contains only small quantities of hydroxyl groups. The Glassomer materials are highly transparent, having transmission values of >92 % in the 300 to 1000 nm range, 84 % at 200 nm, and >90 % in the infrared range between 1000 and 3400 nm.

Glassomer and Engel have already implemented the first glass injection molding applications on an industrial scale. Glassomer’s new production facilities in Freiburg im Breisgau, Germany, are injection-molded glass parts at high throughput levels.

The collaboration is benefiting from Engel’s know-how and longstanding expertise in the areas of optics and micro injection molding on one hand and its experience with high-volume series production on the other. The aim of the collaborative development work is to lower the barriers to entry for this new technology through the use of highly efficient, economical processes and machines, thus paving the way for the mass production of glass parts on injection molding machines.

Fine structuring of glass in particular will play an increasingly important role in coming years, with one area of application being that of chemical and pharmaceutical synthesis. The future here lies, for example, in the parallel production of active ingredients in lab-on-a-chip systems. Fine channels, reactors and mixer structures can optimize the synthesis and open up new ways to screen active ingredients (Fig. 6).

Medical technology offers further potential. Minimally invasive procedures require optically transparent, sterilizable and durable material that will not release undesirable substances. While ions are very easily leached out of traditional borosilicate and soda lime glass, this is not the case for high-purity quartz glass.

[1] Mader, M.; Schlatter, O.; Heck, B.; Warmbold, A.; Dorn, A.; Zappe, H.; Risch, P.; Helmer, D.; Kotz, F.; Rapp, B.: High-throughput injection molding of transparent fused silica glass. Science 372 (2021) 6538, pp. 182–186

Engel Austria GmbH  

https://www.engelglobal.com

Glassomer GmbH  

https://www.glassomer.com

Ausgabenartikel

Fig. 1. Traditional glass-manufacturing methods compared with the Glassomer process (A): grinding, polishing and lapping (B), precision glass molding (C), conventional lithography and etching processes for fabricating glass structures at wafer level (D), laser-assisted structuring and downstream etching and polishing (E).

Fig. 3. The multi-stage manufacturing process can produce different surface finishes. As shrinkage can be calculated, a high degree of dimensional accuracy is achieved.

From micro to macro: High-precision structures can be created by glass injection molding.

Fig. 2. The various process steps from granulate to injection-molded “green” part to ready-to-use glass part, as exemplified by a perforated plate.

Fig. 4. The e-motion TL all-electric, tie-bar-less injection molding machine produces high-precision camera lenses from thermoplastics – and now also glass parts.

Fig. 5. Different sample parts were produced at Glassomer. The medical technology part (top right) here served as a feasibility study. It showed that the new quartz glass material could also be processed in molds originally designed for thermoplastic injection molding.

Fig 6. Fine structuring of glass is becoming increasingly important, for example in the field of chemical and pharmaceutical synthesis. High-precision channels can already be produced by the new process.

Hauptartikel

Novel Material Made of High-Purity Quartz Glass Can Be Processed with Injection Molding Machines like a Thermoplastic

Dr. Dorothea Helmer is CEO of Glassomer GmbH in Freiburg, Germany; <a href="mailto:dorothea.helmer@glassomer.com">dorothea.helmer@glassomer.com</a>

Dr. Clemens Kastner is Product Manager Technologies at Engel Austria GmbH, Schwertberg, Austria; <a href="mailto:clemens.kastner@engel.at">clemens.kastner@engel.at</a>

Glassomer GmbH was founded as a start-up in 2018 and has already received numerous awards, including the Lothar Späth Award 2021, the Freiburg Innovation Award 2019 and the Neuland Transfer Award 2019. The company founders have also been been honored with the MIT Technology Review Innovators Under 35 Europe, the German Study Award, the Südwestmetall Promotion Award and the Gips-Schüle Young Talent Award.

<a href="http://www.glassomer.com" target="_blank">www.glassomer.com</a>

Read the German version of the article in our magazine Kunststoffe or at <a href="https://www.kunststoffe.de/a/fachartikel/glasbauteile-aus-der-spritzgiessmaschine-3590716" target="_blank">www.kunststoffe.de</a>