“The best machines and most sophisticated technologies will not produce the desired result if the material is not right“, says Susanne Schröder, Editor in Chief of Plastics Insights. This is also reflected in this issue.

I am dedicating this editorial to materials – for me the hidden champions in the world of plastics. The best machines and most sophisticated technologies will not produce the desired result if the material is not right. I am always fascinated by how inventive our industry is and how versatile the possible applications are. This is also reflected in this issue.

Starting on page 61, the start-up FibreCoat is experimenting with the coating of fibers, which then provide the often desired EMC shielding while simultaneously dissipating heat. Various innovation awards show how successful the concept is.

The article “Solutions for Laser Welding PPA” starting on page 70 is also innovative: Whereas laser welding of PPA was previously considered problematic or even impossible, two cooperation partners have now developed a solution that even allows laser welding of fiber-reinforced or flame-retardant PPA.

The article from HMS Concept starting on page 64 reports on how the compatibility of plasticizers in PVC can be determined more precisely.

Recycling naturally plays an important role in materials today, and Fraunhofer IVV provides information on the long road to a circular economy starting on p. 67.

These are just some of the stories that await you in this issue. Not to mention that it also contains our extensive Special on Fakuma.

16:9

Editorial Susanne

Schröder, Susanne

Logistics Savings Achieved via 3D Printing

Replique provides an industrial 3D printing platform that helps companies minimize supply chain disruptions and increase parts availability while remaining cost-effective. We feature the start-up as part of our New Plastic Heroes series.

Replique provides an industrial 3D printing platform that helps companies minimize supply chain disruptions.

More and more companies face the common challenges of long lead times, unreliable deliveries and high inventory costs. Compounding this, the costly injection molds required in a traditional manufacturing approach, even when few parts are needed, are equally problematic.

Replique is leveraging digital warehousing and on-demand production to address these issues. Plastics Insights sat down with Dr. Max Siebert, founder and CEO, who shares his insights into the special start-up environment and reveals which customers have already come on board.

Plastics Insights: First of all, what inspired the idea?

Dr. Max Siebert: At the time, I was still with BASF and in the Data-to-Value team, where we wanted to create sustainable business models from data. And 3D printing technology came onto our radar at around the same time, allowing us to invent how we produced any part – or 3D model to be precise – using data alone. But the need to address security and trust issues when using sensitive data for decentralized production was what really triggered the idea for our Replique platform. We wanted to create a secure platform that would allow OEMs to store their data securely and have parts produced for 3D printing by authorized partners over a secure network.

Plastics Insights: What advantages does this offer?

Siebert: Our approach eliminates the need for bulk orders and allows parts to be produced on demand instead. They are stored digitally rather than physically and produced locally as and when needed. Companies can economize and streamline how they use resources as a result. Business models are also more sustainable when spare parts are always available: fewer transportation emissions, less waste and a longer product life. In these times of high interest rates and uncertainty, we offer a way to produce components only when orders are received. This reduces inventory and business risk for our customers.

Plastics Insights: Who is your target audience?

Siebert: We target various industries worldwide, with the current focus on Europe. Our initiative is perfect for companies manufacturing durable products in small quantities or with high variance, meaning a small component series and spare parts are needed. Companies from wide-ranging industries can reap the reward, including transportation, engineering, agriculture and consumer goods.

Plastics Insights: Which specific customer projects stand out?

Siebert: Alstom comes to mind. They use our platform to produce small batches and spare parts for their trains. But companies like Miele and Siena Garden in the B2C sector are also using our platform to supply their customers with 3D printed accessories and spare parts without having to overproduce and store an excessive volume of parts. This means they can be far more responsive to individual customer requests while keeping the whole process straightforward.

Plastics Insights: What have been the greatest successes to date?

Siebert: Right from the start, we have been able to win over well-known customers who have played a key role in helping us to accelerate our efforts to build a business model and reach out to a broader customer base. This has also earned us more trust and recognition from industry. The spin-off from BASF was another milestone, since it paves the way for us to do our own development and business.

Plastics Insights: Now you mention it, what are the advantages to spinning off from an industrial group?

Siebert: One key example is access to resources, expertise and important contacts. We understand what industry needs and the company’s processes and that is the cornerstone. We are also very familiar with industry standards, production processes and certifications – all of which invaluable during customer audits. And the reputation and trust associated with the BASF name are equally helpful. Having BASF and BASF 3D Printing Solutions as one of our many strategic material partners gives us guaranteed ongoing access to the latest materials and technologies. It keeps us ahead of the pack and lets us offer our customers the best possible solutions.

Plastics Insights: Are there any disadvantages?

Siebert: As a digital company, we have to laser-focus on the growth of our business in a fast-moving environment like 3D printing. This is incompatible with a corporate environment involving established processes and long decision paths. With that in mind, spinning off was a crucial move that lets us respond more quickly and flexibly.

Plastics Insights: Finally, what are the next steps for Replique?

Siebert: Going forward, boosting market share and establishing ourselves as a major player in the on-demand manufacturing industry are top of mind. Our focus is to take customers from concept to production as a registered supplier. In the short term, we want to expand our team, further refine our 3D printing platform and provide reliable services to our customers. Long term, we hope to position ourselves as the leading global digital warehouse platform for on-demand parts and a platform for integration and delivery of all the solutions needed in an industrial manufacturing process.

Dr. Max Siebert (CEO and co-founder) and Dr. Henrike Wonneberger (COO and co-founder)

Hauptartikel - Start-up Replique

Replique: Printing Spare Parts On-Demand

<ul><li>Name: Replique GmbH</li><li>Founded: 2020 in Mannheim, Germany (spin-off 2023)</li><li>Number of employees: 14</li><li>Total customers: 50+</li><li>Homepage: <a href="https://replique.io/" target="_blank">www.replique.io</a></li></ul>

Read the German version of the article in our magazine Kunststoffe or at <a href="https://www.kunststoffe.de/a/interview/so-entlastet-der-3d-druck-die-logistik-4964204" target="_blank">www.kunststoffe.de</a>

Logistik

Digitale Transformation

Wirtschaft

Innovationen und neue Technologie

Start up

Unternehmen und Unternehmer

Ehrhardt, Melanie

Additive Fertigung

Beschaffungslogistik

At Fakuma 2023, Rinco will present its solutions for joining and separating plastics. Among other things, the Electrical Motion ultrasonic welding machine will be on display, which now has a software upgrade and additional functions.

Leveraging ultrasonic technology is an easy way to manufacture products in an environmentally friendlier way. Welding ultrasonically also uses far less energy than thermal welding. Enhancing the green credentials further is the fact that solvents or other additives can be dispensed with. In other words, materials can be used with optimal efficiency and single-sort recycling can be facilitated. Applying ultrasonic cutting technology to food allows accurate cuts, with high cleanliness and precision. There is less need to clean the knife and reduced waste.

Recent years have seen soaring amounts of money invested to research renewable resources, biodegradable plastics and the implementation of circular economy and recycling. This is an area where Rinco Ultrasonics goes the extra mile and contributes its extensive expertise in ultrasonic technology to numerous projects. The key focus remains on developing ultrasonic welding and cutting machines for plastics processing.

Test welds on corn starch materials showed unchanged weld seam quality and durability on carrier bags compared to equivalents made of conventional plastics and no extra effort required. The corn starch materials successfully replaced synthetic fibers and the carrier bags were easily compostable after use.

Another example of bioplastic processing is in the production of a functional spice shaker. Here, maintaining the product design when switching from conventional to bio-based plastic is crucial. Test welding on a Rinco Ultrasonics machine showed that an equivalent biomaterial product could meet the same targets as the thermoplastic spice shaker.

Rinco Ultrasonic values ultrasonic welding as an energy-efficient technology and describes a real-world example. A project for a medtech customer saw energy savings of 78 % achieved, according to the manufacturer. The customer uses the welding machine to produce respirator filters. The decisive factor was scope to replace a pneumatic ultrasonic welding machine with a new model – the electrically operated Electrical Motion. The welding cycle was also halved – from two to one second – and the weld quality was improved.

Rinco at Fakuma 2023: hall A4, booth 4130

Electrical Motion series – electrically operated ultrasonic welding machines.

Sustainable shopping bags made of corn starch welded with ultrasound. 

Spice shaker made from bio-based plastic. 

2023-09-20 - Rico

Rinco: Sustainable Plastics Processing

Verbindungstechnik

Schweißmaschinen, Ultraschall

Verbindungstechnik Verfahren

Thermisches Fügeverfahren

Ultraschallschweißen

What force is required to remove a plastic part from the mold surface? To investigate this question, the Institute of Design and Production in Precision Engineering (IKFF) at the University of Stuttgart, Germany, has developed an innovative measurement tool. This permits a practical and cost-effective analysis of the pull-off force components of the plastic/steel surface combination under tensile loading.

A mold developed at the IKFF for investigating adhesive-dependent demolding forces visualizes the influence of process parameters in the injection mold.

The costs for manufacturing injection molded parts, besides the energy costs, are still determined principally by the cycle time and material costs. Demolding, as the final step of an injection molding cycle, plays a crucial role in this, since, if the demolding forces are excessive, this can lead to damage to the injection molded plastic parts. The result can be visible ejector marks or deformation of the parts. This can result in other problems, such as reduced part quality, excessive mold wear and production downtimes, for example as a result of broken ejector pins or stuck parts.

If the demolding forces are high, the part stability must be increased. This is usually achieved by longer cooling times. In addition, the forces must be taken into account during part design, which in turn can mean restrictions in the design of the parts. Consequently, low demolding forces permit more flexibility in part design and shorter cooling and therefore cycle times.

The effects on the demolding forces are extremely complex and consist of several factors:

<ul><li>thermal contraction forces as a result of plastic shrinkage,</li><li> frictional forces, and</li><li>adhesion forces.</li></ul>

The number and weighting of the individual components varies depending on the mold design and part geometry.

Various methods of surface treatment and coating have long been introduced into production to keep the demolding forces in check. Nevertheless, the effects occurring during demolding are still not completely understood. To determine the effectiveness and influences of coatings, specialists have already developed various measurement tools. However, the focus of these measurement tools is on measuring friction forces and the adhesion-dependent shear forces that occur. If, however, the release behavior of the part on planar surfaces in the tensile direction is to be considered, this has not been possible in this form until now.

Reproducible Characteristic Values  for Adhesive Bonding

To obtain reproducible characteristics for the adhesive bonding of plastic parts, it is important that the contact surface to be measured is intact before the actual measurement is made. This is particularly challenging under practical conditions due to the machine and mold movements. To meet these circumstances, a new measurement tool was developed at the IKFF, which makes use of multiple mechanisms to ensure a contact surface that is as intact as possible. This allows reproducible characteristic values for adhesive bonding to be determined.

The basic measurement principle consists in pulling off a flat mold surface from a freshly molded test molding in a perpendicular direction. To be able to rapidly investigate different mold surfaces, interchangeable blanks are used, which can be easily manufactured and suitably coated (Fig. 1). The blanks have a diameter of 27 mm and correspond to the contact surface to be investigated. The circular test molding is molded onto the blank and has several shoulders, which are designed to minimize detachment of the contact surface by shrinkage and warpage. The test molding has an overall diameter of 45 mm and a molded-part thickness of 2 mm.

Practical Measurement of the Demolding Force

The construction of the overall mold, due to its design as a 3-platen mold, also minimizes undesirable early detachment of the contact surface (Fig. 2). A roller puller makes the desired movement of the intermediate plate possible. After the plastic melt has solidified, the mold opens. First, the intermediate plate lifts from the mounting plate – the cavity is still closed at first. This reduces the loading of the contact surface during opening. Only in the next step does the ejector half separate from the intermediate plate and open the cavity. The test molding remains on the ejector half.

The mold is now open and allows the integrated camera to view the contact surface. In the case of transparent plastics, this allows wetting to be optically identified. Thus, the presence of an intact measurement surface is ensured before the measurement. Then the actual measurement takes place, but separately from the actual ejection: Driven by two motors, the test platen with the entire test package (Fig. 2, blue) first moves backwards away from the test block. The blank is pulled off the test molding. The necessary force is registered by a piezo force transducer, which can receive forces up to 3 kN. A sampling rate of 9000 Hz ensures reliable recording of the peak force (Fig. 3).

The test plate then returns to the starting position. Only after this process step is the test molding ejected by the ejector pins. To obtain meaningful results, as soon as the mold is in thermal equilibrium, 15 successive measurements are performed and the values of the peak force are averaged.

The measurement tool can now be very easily used to determine the influence of various factors, such as process parameters, plastic type and surfaces on the adhesive forces during demolding. This shows huge potential for considering individual coatings. For example, for the use of a CrN coating at a mold temperature of 60 °C, a reduction of the demolding forces of over 98 % for PET could be demonstrated compared to an uncoated blank of 1.2343 hot-work steel (Fig. 4).

Earlier studies already revealed the influence of roughness in the case of demolding with shear-loading [1]. For comparison of the somewhat rougher surface (Sq = 33.3 nm) due to the CrN coating, a blank with comparable roughness (Sq = 29.7 nm) was also used in addition to a highly polished blank (Sq = 2.7 nm). However, the surface roughness showed a significantly lower influence on the demolding force than the coating used in tensile tests.

The Influence of  the Demolding Temperature

However, the necessary demolding force depends strongly on the demolding temperature. It is therefore necessary to investigate the influence of coatings at different temperatures. Coatings can obtain different results depending on the mold temperature [1, 2]. For example, the use of an rPET grade in the studies of the tensile force for particular temperature ranges showed the advantages of different coatings (Fig. 5). While, with the uncoated and DLC-coated blank, the determined demolding force increases noticeably with increasing mold temperature, the influence of the temperature for CrN and XLC coatings is significantly lower – even with an overall lower force level as well.

When TiN is used, on the other hand, a more volatile influence of the mold temperature on the demolding can be observed. This shows that the underlying adhesion is not only dependent on the temperature, but also on the chemical affinity of two materials coming into contact and their individual thermal properties. Under certain conditions, this can lead to deposits that significantly increase the demolding force.

Whether a coating offers advantages for demolding depends crucially on the plastic to be processed. Thus, with PMMA, a completely different picture is found than with rPET (Fig. 6). At the low mold temperatures of up to 50 °C used for PMMA, none of the surfaces investigated showed demolding forces. However, at temperatures of 70 °C, the measurements showed clear differences in the coatings. The uncoated, as well as the XLC and TiN-coated blanks proved advantageous. In the case of PMMA, on the other hand, both a DLC coating and the CrN coating, which is advantageous for rPET, significantly increased the required demolding force.

The mold developed at the IKFF for investigating adhesive-dependent demolding forces, by making reproducible measurements, can reveal potentials for the use of coatings in injection molds. Different surfaces, as well as the influences of process parameters, can be rapidly investigated. The new approach extends existing measurement tools by providing the ability to investigate the demolding purely according to tensile loading.

[1] Schönherr, M; Gundelsweiler, B.: Charakterisierung von Entformungskräften beim Spritzgiessen: Neuer Ansatz zur Ermittlung der adhäsionsbedingten Zugkräfte zwischen Werkzeugoberfläche und Kunststoff. 27. Stuttgarter Kunststoffkolloquium, Stuttgart 2021

[2] Schönherr, M.; Rühl, H.; Günther, T.; Zimmermann, A.; Gundelsweiler, B.: Adhesion-Induced Demolding Forces of Hard Coated Microstructures Measured with a Novel Injection Molding Tool. Polymers 15 (2023) 5, S. 1285. URL: <a href="https://doi.org/10.3390/polym15051285" target="_blank">https://doi.org/10.3390/polym15051285</a>

Injection mold for measuring adhesive demolding forces in the tensile direction.

Fig. 1. Different mold coatings can be investigated with the aid of rapidly interchangeable blanks.

Fig. 2. Construction of the new measurement tool. When the test plate with the entire test package (blue) moves backwards from the test block, the blank is pulled off the test molding.

Fig. 3. The force profile in the tensile force measurement is recorded by a piezo force transducer. The sampling rate is high enough to capture the force peak.

Fig. 4. A CrN coating considerably reduces the demolding force for a PET part compared to an uncoated blank (mold temperature: 60 °C).

Fig. 5. The effect of the mold temperature on the demolding force of an rPET part is significantly lower in the case of CrN and XLC coatings.

Fig. 6. Comparison of the demolding force for a PMMA part. At higher temperatures, the uncoated and the XLC and TiN-coated edges showed the best results.

Hauptartikel

Measuring Tool for Investigating the Adhesion Force during the Demolding of Injection-Molded Parts

<ul><li>Dipl.-Ing. Maximilian Schönherr is a doctoral student at the Institute of Design and Production in Precision Engineering (IKFF) at the University of Stuttgart in the field of demolding force studies during injection molding;</li><li><a href="mailto:maximilian.schoenherr@ikff.uni-stuttgart.de">maximilian.schoenherr@ikff.uni-stuttgart.de</a></li><li>Prof. Dr.-Ing. Bernd Gundelsweiler is Institute Head of the IKFF.</li></ul>

Read the German version of the article in our magazine Kunststoffe or at <a href="https://www.kunststoffe.de/a/fachartikel/die-entformung-besser-verstehen-5049310" target="_blank">www.kunststoffe.de</a>

Spritzgießen

Kunststoffverarbeitung: Verfahren

Spritzgießwerkzeuge

Kunststoffverarbeitung: Maschinen und Komponenten

Werkzeuge für die Kunststoffverarbeitung

Messtechnik

Zug-und Druckfestigkeitsprüfgeräte

Werkstoffprüfung

Druck- / Kraftsensoren

Sensoren / Messwertaufnehmer

Werkzeugbeschichten

Dienstleistungen

Dienstleistungen in der Metallbearbeitung

Intelligent Assistance Relieves the Strain on Production Staff

The plastics industry has been hard hit by the shortage of skilled staff, as fewer and fewer young people are choosing to enter the profession in this industry. Measures are available to increase the attractiveness of the plastics industry as an employer, but until they have an appreciable effect, the efficient deployment of the available human resources is becoming a survival issue for many companies. Here, digitalization opens up opportunities for supporting the well-trained technical staff and reducing the pressure on them.

The algorithms for identifying faults and optimization possibilities stored in assistance systems of injection molding machines are continually being expanded.

With the development of the iQ product family, the injection molding machine manufacturer and system supplier Engel Austria has been pursuing the goal for over ten years of equipping injection molding machines with a steadily growing number of assistance systems. It is thereby giving the users tools that will relieve them of time-consuming activities and help them to perform their work more efficiently. Software-aided assistance now spans the curve from the initial setting of the machine, through the elimination of process fluctuations, through to continuous monitoring and analysis of the production process.

Automatic Adjustment, Control  and Analysis

The process setting for a new mold, besides technical expertise, principally takes time. After all, machine operators often proceed by trial and error. The quality and robustness of the operating point determined in this way lay the cornerstone for making production as trouble-free and therefore economical as possible. The disadvantage of this established method is that unfavorable process settings often only become apparent later in the current process in the form of frequent interruptions or the production of rejects.

Intelligent assistance systems, on the other hand, automatically determine the optimum process settings within the limits set by the user, such as clamping force or holding time. If the production process runs with the objectively determined optimum process parameters, the energy input, and often the raw material consumption, too, can be reduced, the cycle time shortened and thereby money saved. That is particularly true when the assistance systems not only determine the appropriate setpoint values, but also keep the process parameters relevant to quality and efficiency constant even during the production process. Digital process controllers automatically adjust the setpoint values determined for the cycle, such as the changeover point and the holding pressure level, to the current conditions. In this way, for example, the injected melt volume remains constant, even if the material properties change or the ambient conditions fluctuate. This actively prevents rejects.

Controlled conditions are also advantageous for mold temperature control. High-end cooling water manifolds optionally control either the flow rate or the temperature difference between the feed and return, and thereby ensure a constant cooling process irrespective of fluctuations in the water supply. Combining these water manifolds with temperature-control units operating with a speed-regulated pump even allows the pump speed to be controlled according to demand. This leads to energy savings of up to 85 %.

Last but not least, it is worthwhile keeping an eye on the process during production. For this, too, the iQ product family has a digital helper. The software analyzes the process data shot by shot and recognizes independently occurring changes, deviations and current improvement potential.

The machine assistants for the injection molder, if used consistently, prove to be a comprehensive carefree package: They support the optimization of setpoint values and automatically adjust process settings to compensate for fluctuations. All the user has to do is to decide how and in what sequence the now diverse assistance systems are used to obtain an optimum result (see Box). The new process check list in the Engel control system helps with this.

Process Check List Supports the Use of Smart Assistance Systems

The process check list shows the user what potential can be unleashed by means of the assistance systems in the Engel injection molding machine. It gives injection molders greater reliability in the selection and use of smart assistance systems. It will be presented for the first time at Fakuma 2023, and from then on will be the cornerstone for the use of digital assistants. Integrated into the injection molding machine control, it supports the user with a simple, clear display (Fig. 1). The user learns

<ul><li> which assistance systems are available in the machine or can be easily tested by means of a preinstalled trial version,</li><li>in which sequence they must be activated for an optimum result, and</li><li>whether an action is necessary at the current time.</li></ul>

The process check list thus makes the available optimization potential transparent. The user can immediately see with a notification icon how many optimization possibilities the process check list currently holds for him. It supports the technical staff in rapidly and efficiently saving both energy and valuable working hours.

The production of 4-pin plugs for automotive electronics (Fig. 2) on an Engel e-mac 100 injection molding machine, which is equipped with all available iQ systems, makes clear the great benefit of the process check list. Before process optimization, the cycle time was 13 s, and the production cell required 0.8 kWh to process 1 kg of raw material. After all the optimization steps recommended in the process check list had been implemented, the cycle time was only 12.5 s and the energy consumption of the production cell was 15 % lower. In addition, the clamping force could be reduced by 50 %.

iQ hold control reduced the holding time from 4 to 3.5 s. As a result, the energy consumption could be reduced by 5 %. iQ flow control saved a further 10 % energy by reducing the speed in the temperature control unit and automatically adjusting the flow rates based on the temperature difference. Last but not least, iQ clamp control was able to reduce the clamping force from 500 to 250 kN.

With the activation of the iQ weight control, the machine automatically performs process adaptations in the event of fluctuations and relieves the pressure on the technical staff during process adjustment – for example during the night shift or on batch exchange.

Finally, the current operating point is determined as a reference for a subsequent process analysis. For the plug housings, the time required for optimization was a total of 30 minutes. Without the assistance systems and without the guidance provided by the check list, this would have occupied a skilled staff member for an entire working day.

Is software the better injection molder? Some experienced injection molders worry about this question. The situation is comparable to the early days of automation. Then, too, it was feared that robots could rob people of their jobs. Today, hardly any machine operator in injection molding would want to do the work of the removal robots again. But it is correct to say that we have reached the point in injection molding technology where the machines can perform not only manual but also analytical activities, such as process data analysis.

Injection molders often face the following questions: The machine produces more rejects than yesterday – what is different now? When will my process be stable again after a production interruption? What undesirable side effects are there if I change the speed during metering?

Can the machines really answer all these questions?

The fact is that, until now, a large number of measurement values have been available in daily injection molding practice, but only a handful of selected parameters are usually used for monitoring and analyzing processes. This is partly because it is laborious to choose suitable parameters and determine suitable warning or monitoring limits. On the other hand, with increasing numbers of analyzed process parameters, it is increasingly difficult to keep track of what is essential at the moment. Against this background, many injection molders are content with a restricted view of the process.

The software shows its strengths in identifying deviations arising from hundreds of process data. But humans have a clear advantage when it comes to finding the cause.

But regarding this point, too, there have been pioneering developments in recent years. The iQ process observer from Engel goes two steps beyond monitoring and recognizing deviations (Fig. 3). The first step consists in the fact that the process as a whole is considered and, instead of some selected process data, hundreds of them are now automatically processed so that they can be read by the expert user like a story in pictures. This picture story narrates the sequence of changes over time (Fig. 4). The trigger for the deviations can often be quickly read from this (Fig. 5). With data processing, the software relieves the user of the complicated task of searching for deviations, filtering the relevant data and presenting the data in a form that makes interpretation possible in the first place.

The second step consists in the assistant also taking over the interpretation of the data. For this, Engel has packaged a large number of known error and optimization scenarios in smart algorithms. Using the setpoint and actual values, they check for each cycle whether one of the known errors is present or there is optimization potential. If this is the case, the system gives indications of the problem, the possible cause and the specific solution.

The Data Network Is Becoming  Ever Tighter

The iQ process observer is a living system. That means the stored algorithms for identifying faults and optimization possibilities are continually being expanded and developed. Since the know-how is not held locally on the machine, but is made available via the cloud, the system is always up to date. This makes the net with which the iQ process observer fishes in the sea of data for optimization possibilities ever tighter.

Intelligent assistance systems in the injection molding machine control help the machine operator to perform the work more efficiently.

Fig. 1. In the process check list, a brief explanation, a recommendation for the next necessary step, an icon for jumping directly to the respective screen page and a status icon can be found for each assistance system.

Fig. 2. The production of plugs illustrates the benefit of the check list.

Fig. 3. Unlike conventional data analysis tools, the iQ process observer is not only capable of gathering data. Rather, it also prepares the data so that the user recognizes weaknesses in the process. The software automatically recognizes a large number of typical errors and optimization possibilities.

Fig. 4. In this example, the iQ process observer lists the incidents within 100 cycles. The yellow region in the timeline shows process changes. The pencil symbol at the beginning of this phase also provides the reason for this: settings have been changed. In the still-collapsed detail range below, it can be seen that the changes affected the process steps “plasticizing” and “injection.” 

Fig. 5. Further information can be found by expanding the detail range: A user has changed the metering rate (recognizable by the pencil symbol). The desired effect was the change of metering time (marked yellow in the “time” line). However, the assistant also indicates a different consequence of this change: The melt cushion, i.e. the screw position at the end of the injection operation, has also changed (marked yellow in the corresponding line). This may indicate that, from this point on, a different amount of material was injected. All the other process parameters analyzed are unchanged.

Injection Molding: Digital Assistance Systems Relieve the Strain on Production Staff

DI Josef Giessauf is the team leader of the Process Engineering department at Engel Austria GmbH, Schwertberg, Austria; <a href="mailto:josef.giessauf@engel.at">josef.giessauf@engel.at</a>

DI Karlheinz Mayr is head of smart machine at Engel; <a href="mailto:karlheinz.mayr@engel.at">karlheinz.mayr@engel.at</a>

Dr. Johannes Kilian is head of Global Application Technology at Engel; <a href="mailto:johannes.kilian@engel.at">johannes.kilian@engel.at</a>

Read the German version of the article in our magazine Kunststoffe or at <a href="https://www.kunststoffe.de/a/fachartikel/intelligente-assistenz-entlastet-das-pro-5049305" target="_blank">www.kunststoffe.de</a>

Assistance systems provide support for a large number of tasks: in setting, controlling and analyzing quality and efficiency-determining process parameters.

<ul><li>iQ clamp control automatically determines the optimum clamping force. Effect: no burn marks, no flashing, good venting, reduced mold wear and often also a lower energy demand, since the optimum clamping force is usually lower than the one set manually.</li><li>iQ hold control is the automatic and rapid alternative to complicated sealing point determination to determine the optimum holding time.</li><li>iQ melt control reduces the screw speed during metering if possible, so that the available cooling time is optimally utilized. This reduces screw wear.</li><li>iQ motion control optimizes the acceleration phases of movement sequences, such as the opening and closing of the clamping unit or the movement of the robot arm, and thereby shortens the cycle time.</li></ul>

<ul><li>iQ weight control individually adapts the injection profile, the changeover point and the holding pressure to the current conditions for each cycle. This ensures consistently high product quality even in the event of fluctuations in the ambient conditions and raw material.</li><li>iQ flow control, based on the measured values of the e-flomo temperature-control manifold, ensures uniform temperature-control conditions in the mold and high energy efficiency by actively controlling the temperature difference in all individual temperature-control circuits. In addition, iQ flow control regulates the speed of the Engel e-temp temperature control units according to demand, which further reduces the energy demand of the production cell.</li></ul>

<ul><li>iQ process observer continually analyzes hundreds of process data, recognizes changes and deviations, and provides information about optimization possibilities. The software automatically determines the warning limits for all parameters.</li></ul>

Steuerungen (Hardware und Software)

Automatisierungstechnik

Industrie 4.0 für die Kunststoffverarbeitung

Industrie 4.0

Digitalisierung

Spritzgießmaschinen

Goodbye Hot Spots – with No Extra Energy Expenditure

Molds with integrated heat pipe technology can be cooled with less energy input and thus significantly more efficiently than previous systems. The superiority of structurally integrated heat pipe molds has been successfully demonstrated in practical tests: The cavity temperature in the area of a hot spot can be reduced by 50 °C compared to conventional cooling systems – without additional system peripherals. A win-win situation in injection molding.

A study demonstrates the superiority of heat pipes integrated into the mold core – lower temperatures were achieved in the injection mold.

In order to achieve a high article quality with an economic cycle time, an exact and uniform cavity temperature is necessary, which is usually set by an oversized water temperature control [1, 2]. This sub-process is very energy-intensive. Temperature control, with 37 %, makes up the largest share of the total energy consumption in the injection molding of engineering plastics and thus also of CO2 emissions [3]. This has consequences, because energy costs are the key problem today: the industrial electricity price in Germany has risen from 17.8 cents/kWh (2020) to 54.4  cents/kWh (2022) [4]. The margin and thus the competitiveness of many companies is falling or tending towards zero.

Local heat accumulations (hot spots) are particularly cycle-critical. Due to the engineering realities of moldmaking, uniform cooling is often not possible. This can have various reasons:

<ul><li> In long, narrow areas, water has a predominantly laminar flow with less heat dissipation.</li><li>Water-carrying standard elements only run in straight lines and thus offer limited design freedom. The water is guided to hot spots and led away within the same space. This further narrows the already thermally critical areas.</li><li> Expensive additively manufactured molded elements are increasingly being used [5]. However, small cooling cross-sections and branches lead to a high pressure loss. Furthermore, insulating impurities can form in the cooling channels.</li><li>The position and number of ejectors are often specified by the customer, which restricts the contour of the temperature control channels.</li></ul>

The simple but costly solution in each case outlined here is a higher flow rate – which increases energy consumption as well as CO2 emissions all the more.

In order to reduce the temperatures in the hot spot area, several temperature control units for different circuits and temperatures are often used to keep the mold at production temperature. Due to the different temperatures, the channels thermally influence each other, which results in a high energy loss.

This effect is particularly noticeable when using copper for hot spot cooling. Thus, copper inserts are cooled with cold water for a high temperature difference and thus good heat dissipation. Although copper conducts heat very well, this solution is not optimal. Heat is conducted most effectively in the case of large cross-sections and short lengths – which is in conflict with the design challenges of moldmaking.

Heat Pipes Offer Superior Heat Transfer Performance

Heat pipes have a much higher heat transfer performance than copper or water with the same contours. To illustrate this fact, a heat pipe and a copper rod of the same size were placed in boiling water (Fig. 1). After approx. one minute, the heat pipe had reached its steady state of approx. 75 °C. The temperature difference with respect to the heat pipe was lower than the temperature difference with respect to water. A lower temperature difference with respect to the heat source was not achievable due to heat losses. The copper rod only showed a slight color change after about one minute and had reached a steady state of approx. 50 °C after just under eight minutes.

A heat pipe is a closed hollow body that contains some water under a slight negative pressure (Fig. 2). At a hot side (heat source: cavity), the transition from water to steam takes place. In the process, a large amount of heat is absorbed and extracted from the mold. The steam flows to a remote location and condenses (heat sink). The water flows back to the heat source [6, 7]. Gravity-assisted condensate return flow is recommended and leads to significantly higher outputs.

The high heat transport rates, even over long distances, make it possible to mitigate hot spots and thus save energy and CO2. However, instead of assembling commercially available standard elements, Bielefeld University of Applied Sciences and Arts, Germany, builds entire cores or slide systems directly as a structurally integrated heat pipe – so the mold itself functions directly as a heat pipe. The great potential of heat pipes has already been demonstrated [8 – 11]. Since then, the performance has again been significantly increased compared to the previous experiments.

A test article in the form of a sleeve (length 85 mm, outer diameter 14 mm, wall thickness 1.1 mm) is made of ABS (type: Sitralac 8E-IM / C94150; manufacturer: Sitraplas GmbH; melt temperature: 220 °C). The sleeve is formed by two exchangeable cores. This allows different cooling methods to be compared directly with each other (Fig. 3).

The investigations focus on different mold cores:

<ul><li>heat pipe cores with natural roughness on the interior (smooth),</li><li> heat pipe cores with groove structure on the interior,</li><li>core with copper center,</li><li>conventional core with water flow.</li></ul>

The core interior has a diameter of 7 mm in each case. In the heat pipe variants, an air gap between the phase transition areas (adiabatic zone) forms the thermal separation [12 – 14].

The tests were carried out on an Allrounder 370 E injection molding machine (manufacturer: Arburg). The mold is cooled to approx. 16 °C with a temperature control unit (Thermo-5, HB-Therm). The cycle time is 8.3 s, with a cooling time of 2 s and a holding pressure time of 1.4 s. The cycle time results from a visual quality assessment of the part produced with conventional water cooling and is intended to represent the benchmark in the system comparison.

A thermography system is used to determine the article temperature (type: PIR uc 180, software Irbis 3; manufacturer: InfraTec). The mold cores are not measured directly because reflection influences from the environment are to be expected due to the cylindrical core contour. Therefore, the temperature was determined via the inner surface of the plastic part directly after demolding. The camera looks into the article from above (Fig. 3). The recordings were started after 20 cycles in a quasi-steady state.

The measured article temperatures and the formula of the contact temperature are used to calculate the cavity temperature. The difference between the temperatures of the heat pipe cooling and of conventional methods such as water cooling or copper core is clearly visible (Fig. 4). The article temperatures of the heat pipe cores are between approx. 52 °C and 74 °C, which corresponds to calculated core temperatures of approx. 41 °C and 64 °C respectively. The articles with water- or copper-cooled cores show temperatures of approx. 100 °C and core temperatures of approx. 93 and 94 °C, respectively. This results in temperature differences between heat pipe and water cooling of about 30 to 53 K and an average of 41.5 K.

The heat pipe cores are below the recommended cavity temperature of 60 °C in three out of four cases. However, with the water and copper cooling systems, the required mold temperature of maximum 70 °C cannot be achieved. The quality is probably satisfactory due to the rotationally symmetrical contour. Flatter contours would require lower temperatures, otherwise there is a risk of warpage and deformation. The respective physical and material-specific effects for heat dissipation can be demonstrated as expected and shown in their respective effectiveness. This shows that the evaporation processes in the two-phase heat transfer of a heat pipe are significantly more effective than heat conduction or water cooling.

Application for Low-Energy  Hot Spot Reduction

The superiority of structurally integrated heat pipe cores has been proven – significantly lower temperatures could be achieved compared to conventional systems. Thus, a loss of power can be accepted. This results in opportunities:

<ul><li> The performance of the heat pipe core is higher than that of its counterparts with copper and water cooling. Thus, longer and narrower contours can be cooled and hot spots can be mitigated.</li><li> The performance of the heat pipe decreases with smaller temperature differences. Therefore, the heat sink can be cooled with an existing temperature control system. Initial tests on the presented mold with a heat sink temperature of approx. 50 °C were successful. Extra cooling circuits and temperature control peripherals are saved.</li><li> The heat sink can also be cooled in pulses and thus the temperature at the heat source can be adjusted.</li></ul>