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

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

Spritzgießen

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 

The aim of this joint project is to develop a production cell in which a rear license plate light can be manufactured with hybrid processes without any additional steps such as bonding. Some of the necessary analyses and pre-testing of the material combinations resulting from the structure of the product – plastic housing and optics plus metal conductive tracks – are presented in this article.

Lighting  solutions on various products. 

16:9

Manufacture of a Rear License Plate Light in a Highly Integrated Production Cell

LED / OLED-Systeme und Faseroptik

Lichttechnik

Polymethylmethacrylat

Kunststoff Werkstoffe

Thermoplaste

Hybrid-Spritzgießen (Metall / Kunststoff)

Polycarbonat

What Is the Most Suitable  Material Combination?

Family molds belong to the state-of-the-art in injection molding – at least when wall thicknesses and volumes of individual components vary considerably. Using a trial mold soon ready for series production, Synventive demonstrates that – though demanding – optimal process control can be achieved using the right technology. The filling of each mold cavity is controlled individually and in real time. The Kunststoffe editorial team were among the first guests at the new Tech Center.

View into the mold space of the Engel Duo 2700 at the Tech Center. In the background, a 6-axis robot with 180 kg load-bearing capacity which removes the components.

Single-Shot Injection Molding of Heterogeneous Components

Schröder, Susanne

Spritzgießwerkzeuge

Kunststoffverarbeitung: Maschinen und Komponenten

Werkzeuge für die Kunststoffverarbeitung

Heißkanalsysteme

Komponenten für die Kunststoffverarbeitung

Leading-Edge Process Control

The plastics processor TKW Molding, which specializes in safety-related automotive components, is responding to the increasing requirements of its tier 1 and OEM customers by extensively automating its injection molding production. This also encompasses downstream process steps, such as integrated component testing, traceable part deposition and packaging. The company has been working closely with Arburg in this field since 2020.

A robotic system removes the parts from TKW’s 8+8-cavity mold.

Fully Automated In-Mold Assembly Process at TKW Molding

Optische Mess- und Prüftechnik

Messtechnik

KFZ-Zulieferer

Dienstleistungen

Safely Belted in

Arburg presents a total of four Allrounder exhibits and two Freeformers on show. All machines will be connected live to the Arburg host computer system ALS for demonstration purposes and to the arburgXworld customer portal, another focus of the trade fair display. Detailed information on the arburgGreenworld environmental and recycling program will round off Arburg‘s involvement in Chinaplas.

Arburg will be demonstrating the potential of freeformers for additive manufacturing on two exhibits at Chinaplas 2022.

Spritzgießmaschinen

Arburg Kunststoff Freiformen

Verfahren für die additive Fertigung

Freiraumverfahren

High-End Wherever You Look

The new “Heat-Inject” product from Incoe International Europe stands out in that it uses the hot runner system as a carrier platform, but instead of melt, it brings heat into the cavity.

The heat pulse from heat-inject ensures good surface quality where a weld line may otherwise be visible due to the part geometry and gating.

Targeted Heat Pulses in the Cavity

At the presentation of The Economic Times’ brand awards, Hasco’s Indian subsidiary received the award for “Best Plastics & Polymers Brand 2022”.

Sandeep KP, Technical Sales Engineer and Rajnikant Patel, Business Development Manager / Hasco India (from left)

Special Honor for Hasco India

Pharmaceutical crimp caps generally consist of a thin aluminum sheet and a plastic component, and are used to seal medical vials, for example for vaccines. Through a combined deep-drawing and backmolding process with previous inline laser treatment of the thin aluminum sheet, the process can be significantly shortened. The media-proof joining together of the two materials is carried out through a mechanically interlocking connection.

A crimp cap for injection vials is manufactured in a two-step process.

Combined Deep-Drawing and Backmolding Process with Mechanically Interlocking Joint

Hybridtechnik

Aluminiumlegierungen

Metall Werkstoffe

NE-Metalle

Laserbearbeitungen

Oberflächentechnik

Tiefziehen

Verfahren für die spanlose Fertigung

Spritzgieß-Sonderverfahren

Simulation Stanzen / Umformen

Software

Simulation

Laserstrukturieren

Medizintechnik

Medizinprodukte

Process Chain for the Production of Hybrid Medical Products

Nowhere are the demands imposed on materials higher than in the area of medical technology. That is understandable because, after all, what is ultimately at stake here is the patient’s health. But any materials manufacturers seeking to use hot runner technology to process polymers in compliance with strict directives and differentiated legal regulations also need the expertise possessed by the hot runner manufacturer’s application engineers.

Günther has recently installed two new injection-molding machines for customer trials in its technical center.

Testing the Processing Limits of Modified POM Copolymer

Polyoxymethylen

Normalien und Heißkanaltechnik

Looking over the Application  Engineer’s Shoulder

Pipette tips are small and relatively simple components that are now in high demand. One might think  producing large quantities of these products is a simple task. It is not. The requested high quality can only be reached by using complex automation. To meet these challenging requirements, MA micro automation has developed a modular solution: Centauri IVD.

The Centauri IVD production system can be adapted to meet specific pipette tip manufacturing requirements.

Automated High Volume Consumables Production

Handling, Handhabungstechnik

Automatisierungstechnik

Prozessautomation

From Tool to Blister

Anybrid GmbH has succeeded in transforming the usually rigid injection molding machine into a mobile machine that can move freely in the room and can be used to overmold profiles, etc. The company is thus serving a steadily growing market for the production of hybrid components. For the first time, the advantages of plastics processing are combined directly with the flexibility of robotics. In close cooperation with Rehau, extensive studies on an extrusion line were recently successfully completed.

The Robin injection molding system can be swiveled freely on the arm of a six-axis robot to the particular application points.

Automated Lightweight Module for Functionalization and Hybridization of Components

Mikrospritzgießen

Rohr- und Profilextrusion

Extrusion

Industrieroboter

Montagetechnik

Injection Molding on the Fly

Injection, holding pressure, cooling phase – injection molding is a sequential process with individual steps that are usually optimized. Therefore, they offer little more potential for improving the cycle time. But what about the automation system?

With the synchronous motion function, the gripper of the robot starts faster, saving valuable cycle time.

Lucrative Early Start

Multiaxialroboter für die Kunststoffverarbeitung

Synchronous Motion Shortens Demolding Time up to 35 %

Thin wall packaging manufacturers think in terms of efficiency gains in tenths of a second. Every cycle time reduction leads to increased productivity. Another factor influencing part costs is the energy efficiency of the production equipment. In these two key dimensions, Netstal was able to optimize the smallest model in the Elios series with 4500 kN clamping force.

The optimized Elios 4500 with electrically operated toggle levers enables users to achieve cycle time reductions and savings in power consumption (the photo shows the previous variant).

Higher Output and Reduced Energy Consumption

Energieeffizienz

Elektrische Antriebe für Spritzgießmaschinen

Antriebe

Elektrische Antriebe

Clamping Unit of the Elios 4500 with Fully Electric Drive Concept

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>