Products intended for use in building services must meet very high quality requirements in terms of both their constituent materials and functionality. A single-cavity mold for a floor grate made by Barku, which appears to be a simple part at first glance, called for a certain level of technical sophistication. This was provided by a moldmaker with the necessary technical understanding and hot-runner manufacturer Witosa who, between them, devised the right solution for what proved nevertheless to be a complex mold.

Sebastian Lotzin, CEO of Barku’s U. S. subsidiary, with floor grate (3250 g) in the 10,000-kN injection molding machine that makes the part

16:9

Sequential Injection with a 6-Fold Valve Gate System for a Floor Grate

Spritzgießen

Kunststoffverarbeitung: Verfahren

Normalien und Heißkanaltechnik

Kunststoffverarbeitung: Maschinen und Komponenten

Komponenten für die Kunststoffverarbeitung

Heißkanalsysteme

A Simple Cascade

Kebo has developed a new needle valve system called MultiValve to specifically address the needs of medical customers.

Kebo will be showing its MultiValve valve gate system in its maximum configuration of eight cavities in Friedrichshafen

Messe Fakuma

kunststoffe-international.com

Medizintechnik

Reinraumsysteme / -technik

Miniaturization is a Megatrend

Jessica Poliner has been appointed President of Barnes Molding Solutions. She replaces Norbert Scheid, who retired from Barnes Group in December 2020.

Jessica Poliner has been appointed President of Barnes Molding Solutions

Spritzgießwerkzeuge

Werkzeuge für die Kunststoffverarbeitung

Werkzeug- und Formenbau

Dienstleistungen

Werkzeug-, Formen- und Modellbau

New Management to Head Barnes Molding Solutions

According to the company, the UltraShot Injection System provides part design freedom, while improving part quality and speed of mold qualification.

The UltraShot Injection System filled the entire part where a conventional injection molding process at 2758 bar could not

Husky introduces the UltraShot Injection System

Kunststoffverarbeitung allgemein

Kunststoffverarbeitung

Spritzgießmaschinen, allgemein

Spritzgießmaschinen

Kunststoffverarbeitungsmaschinen

Next Generation Melt Delivery and Control System

The completion of the transaction is subject to customary regulatory approvals and is expected by the second quarter of 2021.

Oerlikon acquires Italian company INglass S.p.A. and its market-leading HRSflow business unit for hot runner system technologies

Oberflächentechnik

Oerlikon Signs Agreement to Purchase INglass

For the further development of the Streamrunner and also for customer demonstration purposes, Hasco hot runner has developed an innovative 32 cavity injection mold tool.

The special feature of the mold is the 32-cavity Hasco Streamrunner

New Design Possibilities in Moldmaking

With the Streamrunner from Hasco, the first additively manufactured hot runner, now completely new and space-saving options are also available for valve gate systems.

Fully balanced 20-cavity system with valve gate technology with an outer dimension of the 3D-printed manifold of just 124 x 124 mm. 

Additive Fertigung

Heißkanaltechnik

Messtechnik

Messung von Umgebung (Klima)

Additively Manufactured Hot Runner Manifolds with Needle Valve

Aside from offering high mechanical strength, versatility and durability, polymer materials are ideal for applications in the electrical industry because of their ability to isolate electrical current.

For the conduction cooled MicroTCA systems, Harting processes LCP, a material that is flame-resistant, dimensionally stable at high temperatures, chemically resistant, and has only a low thermal expansion

Connectors for Industrial Lifelines: High-Tech Injection Molding at Harting

Hybridtechnik

Polymere, flüssigkristalline

Kunststoff Werkstoffe

Thermoplaste

Stanzen

Verfahren für die spanlose Fertigung

Schneiden

Hybrid-Spritzgießen (Metall / Kunststoff)

Steckverbinder

Elektromechanik

Well-Balanced Hot Runner Technology for LCP Processing

For a cutlery series made of a new biopolymer, three full hot runner molds with digital process monitoring were developed in close cooperation with mold maker Uniform and hot runner specialist Ewikon.

The 16-drop family mold on the machine. The removal and packaging of the parts are fully automated

Complete Digital Hot Runner Solution for Automated Biopolymer Processing

Condition Monitoring / Prozessüberwachung

Instandhaltung

Biokunststoffe

Virtual Reality für die Qualitätssicherung

Industrie 4.0

Industrie 4.0 für die Qualitätssicherung

Process Reliability Is Crucial

It is a hot runner nozzle such as had never been seen before Fakuma 2021: with a honeycomb structure on the outside and, in the nozzle interior, integrated insulation gaps manufactured in one part by the additive SLM process, in which even the fastening nut is captively printed on the nozzle body. The pride of the concept is the special algorithmic modification of the nozzles for any application case.

A mold-making job with up to 30 nozzles is processed in the SLM machine in about 24 hours. 

The First Additively Manufactured One-Part Hot Runner Nozzle

Doriat, Clemens, Dr.

Selektives Laserschmelzen von Kunststoff, Metall, Keramik

Verfahren für die additive Fertigung

Pulverbettverfahren

Algorithmically Modified  Inner Workings

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

Leading-Edge Process Control

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

With immediate effect, a new generation of compact linear servo motors is available for Ewikon‘s electric needle valve systems.

Ewikon has now fitted the electric needle valve system with a new generation of compact linear servo motors.

Messe K-Kunststoffmesse

kunststoffe.de

Servo Motors for Needle Valve Technology

Thanks to their outstanding properties, cyclo-olefin polymers and copolymers have become extremely popular over the last few years for the production of pharmaceutical primary packaging. The high demands imposed on the processing of these transparent copolymers can be met with a specially dedicated hot runner system. 

Mold-Making: Reliable and Efficient Processing of COC and COP 

The full range of expertise for processing plastics under clean-room conditions and for the market-oriented packaging of disposables for infusion is represented in the Escholzmatt plant of the globally active medical equipment company, B. Braun. Here the need often arises for a sophisticated mold design – and for a partner with expertise in the technical inner workings of a mold. 

Eightfold Nozzles from Günther Heisskanaltechnik for Application by B. Braun 

Mass Production in Medical Technology Demands Top Precision in Tiny Details 

Looking over the Application  Engineer’s Shoulder

Testing the Processing Limits of Modified POM Copolymer

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.

The coronavirus pandemic has provided a vivid demonstration of the importance of plastics. Protective equipment, syringes, tubes, respirators and test swabs – all these products made with plastic are on everyone’s lips at the moment. Like others, the makers of medical devices have to comply with strict legal regulations which are frequently challenging, such as the special requirements imposed on the raw materials they employ. In this regard, materials manufacturers have for the most part tended to optimize their plastics specifically for use in the healthcare sector, targeting product consistency and conformity, among other things. Before these types of polymers can be used in medical technology applications, numerous approvals have to be obtained, e.g. a listing in Drug Master File No. 11559 is needed where distribution is sought in the USA.

One testing facility in the USA for such materials is operated by the United States Pharmacopeial Convention (also known as USP). The polymers submitted there for testing have to meet various specifications and it is up to the materials manufacturers to find out the details surrounding approvals and test facilities. By contrast, the actual processing of the polymers requires materials manufacturers to share experiences with the mold makers or hot runner manufacturers. That is precisely where the expertise of Günther Heisskanaltechnik application engineers comes in.

VDI 2017 guideline “Medical Grade Plastics” sets out the requirements imposed on medical grade plastics for processing. An important keyword here is consistency, more precisely of formulation, components and manufacturing process. Again, the materials manufacturer is challenged to demonstrate, for example, consistency of formulation, because plastics converters and OEMs must be able to count on long-term deliverability and predictability.

“When you have a material that has been carefully selected and tested and also meets all the complex regulations governing medical grade plastics and the requirements of the intended application, any sudden disruption to deliveries or unannounced changes in production can have devastating consequences,” says Jörg Essinger, Head of Application Technology and Service at Günther Heisskanaltechnik. “As hot runner systems are the predominant choice for the production of certain high-volume medical articles, our application engineers are very often called upon to share their expertise – as is the case now regarding the material tests being conducted for Celanese, a global supplier of specialty materials,” he adds.

Identifying and Implementing Optimization Potential

The application engineers at Günther Heisskanaltechnik are generally process mechanics who have received training in plastics and rubber technology, and have specialized in injection molding. “Some of our colleagues have then gone on to complete their training as industrial foremen or technicians,” says Essinger, stressing the skill levels on hand. “Our applications engineers are expected not only to know about injection molding and the processing specifics of all kinds of thermoplastics, but also to be well versed in mold technology and, of course, hot runner technology.”

To the same extent that customers’ application areas are diverse, molds and hot runner systems differ in their design. In addition, the applications engineer must also know how to process liquid silicone (LSR) using cold runner systems. Essinger continues, “And then there are requirements relating to the closed-loop technology for controlling the hot runner system and the open-loop technology for operating the electric valve gate systems, for example.” Experience shows that, by comparison, the work of applications engineers in injection molding shops is more focused on the field of application, namely the selection of polymers, the types of applications and thus also the design of the molds and hot runner systems used by the customer.

“We are also often called in to identify and implement the optimization potential residing in materials, tools and processes,” says Essinger, rounding off the activity areas of the applications engineers at Günther. “Naturally, there are customers who know all about the polymer they want processed and about the processes themselves and who have experience of optimizing their own processing methods. But there are also companies, for example, who come to us with new applications that require new types of polymer that they have little experience of or who up to now have only ever used open hot runner systems and now have to take a mold featuring valve gate technology and ready it for series production. It’s no surprise that they don’t have the necessary experience.”

The fact that materials manufacturers often only have a limited number of proving molds featuring hot runner nozzles enables Günther to bring its technical center into play. After all, if you want to test out a wide range of different hot runner designs, it makes sense to conduct a series of trials. Just early last year, Günther maintained its position at the forefront of technology by investing in two new injection molding machines (Title figure): an Allrounder 370 A with a clamping force of 600 kN and an injection unit 100 (as per Euromap) for processing thermoplastics and silicone and an Allrounder 520 A with a clamping force of 1500 kN and an injection unit 400 (manufacturer in each case: Arburg).

Since the special regulations governing the medical technology sector have to be taken into account by the part designer and manufacturer in particular, but above all by the materials manufacturer, Celanese wanted to know how using different hot runner nozzles (valve gate or open nozzle with heat-conducting tip) to process a material would affect the quality of the molded part. “Hostaform POM Slidex is a tribologically modified POM copolymer that is available in an industrial and a medical grade. This is a highly shear sensitive POM. In other words, delamination can occur during processing,” says Essinger, explaining the rationale for the test series (Fig. 1). “Celanese’s experience was that both melt compounding – especially as regards temperature, screw speed and back pressure – and injection time exert a substantial influence on the delamination effect.” The tribologically modified POM copolymer was being considered for a medical article to be produced in high volumes.

Agreement on how the trials would be conducted was reached in advance with the materials manufacturer. This largely concerned points that are a standard feature of material sampling, such as maximum and minimum hot runner temperature, pressure losses in the hot runners and corresponding filling studies, along with a determination of the maximum holding-pressure time for valve gate systems. The aim of the tests was to explore the limits of processing this grade of Hostaform using different hot runner nozzles. The resulting insights would subsequently form the basis of a processing recommendation. The optimal parameter settings would then be used to process the polymer for a defined period of time and so to assess its process capability.

The Goal: Robust Parameters Worthy of Discussion

Agreement having been reached on which hot runner nozzles (with valve gate or open) and test specimen to use, the test mold was mounted and set up on the injection-molding machine. In this case, it was a 2-cavity test mold with a disc-like test specimen having an injection volume of 1 cm³ and a wall thickness of 2 mm. Günther supplied 6NHF50LA hot runner valve gate nozzles (Fig. 2) and 5SHF80 open hot runner nozzles for the tests. “These nozzles feature a thick-film heating element which ensures a homogeneous temperature curve in the nozzle and provides adequate power concentration in the gating area. To test whether the size of the gating point in the valve gate nozzles influences the process, a needle guide with a gating point diameter of 1.0 mm was selected for one test variant and a needle guide with a diameter of 1.6 mm for the other,” says Essinger, explaining the experimental setup.

To obtain robust parameters worthy of discussion in respect of the above-mentioned test goals, the tests were conducted at different melt, hot runner and mold temperatures as well as different injection times and injection points. Before each change, the parameters were reset to the default setting as doing so would enable the influence of each parameter on the quality of the component to be determined. The dwell time of the melt in the hot runner and especially in the injection molding machine unit was also determined.

The background to this is that very often the dwell time of the melt in the injection unit is too short, thereby preventing homogeneous preparation in conjunction with sufficient heat transfer to the melt. The consequence is that the melt may have different viscosity ranges, even to the extent of containing unmelted pellet particles. That, of course, has a substantial impact on process stability and part quality. “Although these are rather complex test parameters, they did provide insights into what constitutes a stable injection molding process as well as into the process capability over a specified period, usually of three hours, for Hostaform POM Slidex,” says Essinger in summary.

The evaluation of the tests conducted with the valve gate nozzle reveals, for example, one case of an inhomogeneous structure in the form of a cold plug near the injection point. This occurs because the holding pressure time is too long and the mold wall temperature is too low when the needle closes (Fig. 3). After the process control was optimized, a homogeneous structure was seen in this area (Fig. 4). The holding pressure time and the mold or melt temperature exert more of an influence on this behavior than the size of the gating point.

The specialists from Günther then discussed the results with Rochus Hiekisch, who is an expert on injection molding processing and hot runner technology at Celanese. Says Essinger, “You can think of it as a mutual exchange of experience in which the polymer manufacturer contributes his knowledge of materials while the applications engineer from Günther contributes his decades of experience in hot runner systems and process technology.”

Polymer Know-How and Contextual Expertise Combined

The applications engineers at Günther possess the requisite contextual expertise – i.e. the ability to find and make connections. Because only those who are able to open up contexts and make them accessible to others will find solutions. “You don’t acquire such contextual expertise simply as you go along,” explains Jörg Essinger. “Our applications engineers draw not only on a wealth of knowledge about machine and process technology, but also on comprehensive expertise surrounding the physical and chemical properties of polymers. And above all, they are in a position to comment on the interactions between material, design and processing. Many have been with us for decades, and some of them did their training here.”

Managing Director Siegrid Sommer sums up the position of the applications engineers at Günther: “The world of polymers is not unambiguous; rather, it is diverse and ambiguous. That’s why it’s important for the material developer and the product developer to get together and for the downstream user or processor to meet up with the toolmaker. And, this should be done in a setting that is conducive to a genuine exchange of knowledge. Questions are not only permitted but are also heard and taken seriously. Because all progress comes from critiquing things.”

Celanese Services Germany GmbH  

https://www.celanese.com

Günther Heisskanaltechnik GmbH  

https://www.guenther-heisskanal.de

Ausgabenartikel

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

Fig. 1. Example of delamination near the gating point in the case of Hostaform POM Slidex. 

Fig. 2. Cross-sectional view of hot runner valve gate nozzle 6NHF50LA with BlueFlow thick-film heating element.

Fig. 3. The microtome section of the test specimen made of POM (Hostaform) reveals an inhomogeneous microstructure in the form of a cold plug near the gating point after closing of the needle.

Fig. 4. The microtome section of the specimen reveals a homogeneous microstructure near the gating point after closing of the needle following optimized process control. 

Name - Hauptartikel

Delamination is the term used to describe the splicing or flaking of surface layers on injection-molded parts. The cause of this poor bonding between the polymer layers is a combination of excessive shearing of the relatively cold compound and mold cooling. In the case of semi-crystalline thermoplastics, this can lead to the formation of layers having different crystal structures, and in the case of amorphous thermoplastics to segregation in the melt/additive/pigment mixture.

<b> Dipl.-Ing. Horst-Werner Bremmer</b> is head of application technology consulting and sales at Günther Heisskanaltechnik GmbH; <a href="mailto:bremmer@guenther-heisskanal.de">bremmer@guenther-heisskanal.de</a>