The pressure may not be coming from the street – at least during a pandemic. But from large investor groups. This was most recently apparent at this year’s Amazon annual general meeting: under item 8 on the agenda, a non-profit organization representing shareholders’ interests wanted first to force the group to disclose its own business operations’ annual plastics consumption (in the same way as the retailer Walmart), and then to gradually reduce it. Off the cuff, 35 percent of the voting shares backed this resolution – a thunderbolt, if you consider that Jeff Bezos alone owns 14 percent.

The non-profit foundation “As You Sow,” founded in 1992, which proposed the resolution, had some smart arguments: by using vast amounts of plastic packaging, which endangers marine ecosystems, Amazon runs the medium-term risk of harming its reputation and suffering considerable financial damage. In this context, the self-appointed campaigners for corporate social responsibility (CSR) and sustainability by way of stock corporation law referenced a study by the environmental protection organization Oceana, which asserts that 10,000 of the 210,000 tons of plastics packaging waste that Amazon generated in 2019 ended up in waterways. Although the world’s biggest online trader rejected these figures as inflated, they struck a nerve with the shareholder activists.

True, the demand for a transparent plastic footprint did not prevail. But anyone who thinks these are all just eco-dreamers or cranks is underestimating the growing influence of such factions. They have already made their presence felt with other corporations, too. In a similar vote at DuPont’s annual general meeting, 81 percent supported the motion; Groups such as Unilever and Pepsi consented to drastically reduce their plastics consumption and to increasingly use recycled material for packaging. This may be the plastic industry’s last chance to decisively and proactively design a circular economy – instead of always being driven by public opinion.

16:9

Editorial_Doriat

Doriat, Clemens, Dr.

“Plastics Experts are the Solution –  Not the Problem!”

Educational Work between Political Demands and Corporate Objectives

The plastics industry is currently struggling to raise its profile with positive headlines. The Kunststoffe editorial team discussed the present status of the plastics industry with representatives from industry, universities, and trade associations. Besides topics such as recycling and sustainability, the main focus was on recruiting young talent and the image issue.

Kunststoffe: The politicians are demanding considerably higher recycling quotas over the next few years, especially for plastics packaging. Mr. Weigelt, how actively is your association involved in this?

Michael Weigelt: With GKV/TecPart (German Association of the Plastics Manufacturing Industry/Association of Technical Plastics Products), we are currently represented in 35 different working groups concerned with the plastics tax and the circular economy: in standardization committees, Brussels organizations, national authorities and environment ministries. The discussions are currently very difficult because there are many new actors who just do not understand plastics at all: who do not understand that plastics are energy storers that store carbon provided they are not incinerated; who believe that all post-consumer recyclates can be transformed into a new bumper or a technical component. This is not usually the case, so much educational work is needed.

Kunststoffe: How is the work of the association going at the European level, Mr. Bühler?

Ingemar Bühler: As a trade association, we must be politically active. Today, we are facing our greatest opportunity so far to tackle the acceptance problem in the European political environment. In many areas we have the arguments on our side. To give one example: without high-performance plastics, we will not be able to implement the energy revolution and meet climate targets. Every material needs its own recycling process. European policymakers are exerting tremendous pressure: we must commit to how the future will look in ten or twenty years’ time. There is no single answer – we must develop a compelling vision.

Kunststoffe: Have milestones been defined? What happens if the political demands are not met?

Ingemar Bühler: So far, there have been no clear demands for milestones. If we are only halfway there, this has not worried anyone so far. But we should pursue the matter proactively and not wait until the lawmakers try to profit at the expense of the plastics industry.

Prof. Dr. Thomas Seul: The political demands are one thing – but on the other hand image also plays an important role here. So long as “plastics” is a pejorative word and plastics are seen as a cheap and nasty raw material, nothing will change. If plastics are considered of low worth, they will not be treated as a valuable raw material.

Kunststoffe: Which brings us on to the question of image. Dr. Eggert, how is the VDI (Association of German Engineers) handling this issue?

Dr. Achim Eggert: Over the last few years, our image has been badly damaged by the packaging waste in the world’s oceans. Now we are confronted with widespread hostility. We are trying to tackle this issue at various VDI events, including roundtable discussions with regional and federal politicians. In October of this year we are planning an experts forum that will take up the issue. We are also going to offer a plastics engineering sustainability award in conjunction with the VDI Technical Committee on Injection Molding Technology. This award will be aimed at students who are writing a Bachelor‘s or Master’s thesis on the subject of the circular economy.

Kunststoffe: Mr. Seul, how are you getting across the image issue to your university students?

Prof. Dr. Thomas Seul: We must take this issue very seriously and not talk it down. What I always tell my students is: “You are the solution!” To solve problems arising from the use of plastics, you need plastics experts. This cannot be done by legislators. We must make ourselves aware that we are the solution to the problem. If this gets through to the students, then I feel reassured about the future.

Kunststoffe: What contribution can the trade associations make, Mr. Bühler?

Ingemar Bühler: It is a scientifically measurable fact that if an industry sector has a negative image, this is followed by corresponding political decisions – and regulation greatly increases. Often these knee-jerk political decisions are purely symbolic to show consumers that they are being protected. Here, it doesn’t matter whether there really is a problem or how serious the problem is. The only way we can counteract this is by communicating openly and answering all the questions raised by critics and sceptics.

Kunststoffe: Mr. Hofmann, are image and the environment also important issues in toolmaking?

Stefan Hofmann: For toolmaking, the raw materials are not an issue. But for us as a company, sustainability has great importance and so we meet high requirements through environmental and quality certification, e. g. for energy management and environmental protection. I think it is very important, however, that we in the plastics industry are ourselves all prepared with sufficient arguments. We should be best informed about which regulations apply.

Kunststoffe: Dr. Glück, what approach does a chemical company take with regard to the image issue?

Dr. Guiscard Glück: As a chemicals company and plastics producer, we hear the concerns and take our responsibility here very seriously. For example, as part of the Alliance to End Plastic Waste, we are committed to stopping plastics waste entering the environment. If we broaden the discussion somewhat and talk about the great human concern of climate change, it is clear that plastics can help reduce CO2 emissions in the transport, construction, and consumer sectors. We are continually striving to increase the value of plastics over their entire lifecycle and minimize their CO2 footprint. So we are concentrating, for example, on the efficient use of raw materials and the purchase of renewable energy for manufacture. BASF has set itself tough targets in this respect. Our CEO, Martin Brudermüller, who is a member of the Economic Advisory Committee of the German Green Party parliamentary group, makes himself very clear on this issue both within the company and outside. Just recently he announced a tightening of our sustainability targets, committing the company to a 25 % cut in its CO2 emissions by 2030 and worldwide CO2-neutral production from 2050. These are very ambitious targets and also apply to the production of our plastics.

Kunststoffe: Another topic much discussed at present is the recruitment of young talent. What ideas does the trade association have on this, Mr. Bühler?

Ingemar Bühler: We need many clever minds to overcome the upcoming challenges. If our industry does not attract young people, we have got a problem. We must move away from just defending ourselves against political pressure. We must work towards a goal. And that consists not in defending the status quo but transforming a whole industry. If we explain that boldly and with vision, then we can also inspire people.

Dr. Guiscard Glück: I completely agree with Mr. Bühler. Change can only be brought about by people. And we need young people!

Kunststoffe: Can the industry persuade people if the set recycling targets are achieved? In the case of plastics packaging this means doubling the previous recycling target to 50 % by 2025 and even 55 % by 2030.

Ingemar Bühler: We are losing the educated middle class and young people – we currently have a large acceptance problem with both groups. They will not be won back with some recycling target to be reached in ten years’ time. We have to participate in this debate in a whole different way.

Kunststoffe: What framework conditions can tackle the recycling issue better than quotas, Dr. Bürkle?

Dr. Erwin Bürkle: The currently high global volume of waste from vaccination equipment such as syringes, vials, and packaging is forcing the plastics industry in particular to launch initiatives for material recycling as soon as possible. Of course, in so doing, the specific regulatory requirements should be heeded and the entire value chain taken into consideration. That means new framework conditions must be created. Ultimately, however, our plastics products should be recycled in a closed loop. This recycling potential of valuable raw materials must be realized and translated into new material streams and recycling chains. I think that a whole range of recycling methods have already been developed that can be used, albeit in modified and expanded form. We should not just accept these valuable materials being incinerated with the household waste.

Kunststoffe: Prof. Hopmann, what part does the subject of the circular economy play in student education?

Prof. Dr. Christian Hopmann: Recycling is not really a new subject. The IKV (Institute for Plastics Processing) was concerned with this subject way back in the 1980s. For years there has been a separate lecture on plastics recycling. But in recent times, students have been asking a lot of questions about it. The subject has developed in an evolutionary way over the last few years. That is why, in the early semesters, we now deal with the subject in depth to show that plastics are indispensable in many sectors. Without plastics, there would be no face masks and to a large extent no food packaging today. Nevertheless, plastics present us with great challenges. We have many exposed flanks when it comes to sustainability.

Kunststoffe: Mr. Bühler, how do you as a trade association deal with the “exposed flanks”?

Ingemar Bühler: It feels like a stretch. We have many members who take the subject very seriously. But on the other hand, there is the practical business perspective. Ideally, through strategic objectives, we would usher in the new era of the circular economy. Without a raw material shortage and with good-quality recyclates at an acceptable price, we would have one problem less, namely our dependence on fossil fuel-based raw materials. But from a business viewpoint, this is not easy. It must remain financially feasible.

Kunststoffe: Does the plastics industry feel it is taken seriously by politicians?

Michael Weigelt: More and more. At least technical interest is increasing, since we have to get across the fact that recycling for technical parts is not as easy as for PET bottles. Contaminated parts that do not comply with present chemicals legislation cannot simply be recycled. We now have a huge opportunity with products that are used everywhere in the pandemic such as syringes, masks or other personal protective equipment.

Kunststoffe: What role does machinery manufacture play in environmental protection matters?

Martin Würtele: We need to differentiate between climate protection and environmental protection. We have a great opportunity to create a circular economy for plastics and achieve the energy revolution. But for machinery manufacture, ecology is not the only important topic. Our aim is to think holistically and also take into account social concerns. The efforts made as part of corporate social responsibility address both areas. And here we can play a leading role in Europe – I see this as an opportunity to distinguish ourselves from the competition. In low-wage countries, a manufacturer perhaps does not know exactly how, for example, the liquids from the pickling tank of his electroplating plant are disposed of. We are in a position to determine that. I am sure that we will find ways and means to solve environmental problems. We must bring recycling technologies to where the waste is so that waste can be returned back into the loop on the spot.

Kunststoffe: Is recycling the solution to the problem? What is your view, Mr. Weigelt?

Michael Weigelt: It must be made clear that recycling is not the all-embracing solution. But every ecologically and economically sensible recycling operation contributes to eliminating the problem.

Kunststoffe: Ecology is an enduring issue. Mr. Würtele, in conclusion, look into the future for us. How will this problem develop?

Martin Würtele: I recently read a report about the German Ruhr area from the 1970s. At that time the sky there was a sulphurous yellow and it was obvious to everyone that things could not continue in this way. In fact, a change of thinking then took place. Now you can breathe fresh air in the Ruhr area and swim in the rivers. In exactly the same way, we will get to grips with the problem of plastics waste. We must face this task. We are all challenged to take responsibility for this. If we show the public positive examples, we will also raise political awareness of our issues.

The Kunststoffe advisory committee: top Erwin Bürkle, Thomas Seul, and Martin Würtele; center Guiscard Glück, Stefan Hofmann, and Ingemar Bühler; bottom Christian Hopmann, Achim Eggert, and Michael Weigelt (from left to right in each case)

Name - Hauptartikel

<ul><li>Ingemar Bühler, PlasticsEurope Germany</li><li>Dr.-Ing. Erwin Bürkle, Innovation mentor, Benediktbeuern, Germany</li><li>Dr. Achim P. Eggert, VDI – The Association of German Engineers, Plastics Engineering Section, Düsseldorf, Germany</li><li>Dr. Guiscard Glück, R&D Engineering Plastics, Performance Materials Europe, BASF SE, Ludwigshafen, Germany</li><li>Dipl.-Ing. Stefan Hofmann, Siegfried Hofmann GmbH, Lichtenfels, Germany</li><li>Prof. Dr.-Ing. Christian Hopmann, Institute for Plastics Processing at RWTH Aachen University, Germany</li><li>Prof. Dr.-Ing. Thomas Seul, Applied Plastics Engineering Department at Schmalkalden University of Applied Sciences, Germany and VDWF (Association of German Tool and Moldmakers) e. V. Schwendi, Germany</li><li>Dipl.-Ing. Michael Weigelt, GKV/TecPart (German Association of the Plastics Manufacturing Industry/Association of Technical Plastics Products), Frankfurt am Main, Germany</li><li>Dipl.-Ing. Martin Würtele, KraussMaffei Technologies GmbH, Munich, Germany</li></ul>

All the participants belong to the advisory committee of Kunststoffe.

“We must bring recycling technologies to where the waste is.”

“We are losing the educated middle class and young people. Recycling targets alone will not be enough to win them back.”

“The aim is to reform industry not to defend the status quo.”

Ingemar Bühler, PlasticsEurope Deutschland

Strategie und Organisation

Wirtschaft

Schröder, Susanne

Streifinger, Florian

Kunststoff-Recycling

Kunststoffverarbeitung: Verfahren

Kunststoff-Aufbereitung

How the Stiff Requirements for Sustainable Injection Molding Can Be Mastered

Those in charge at Engel are convinced: Digitalization is not just a technical issue, it is also a mental hurdle, and sustainability is a lot more than hype. At the live e-symposium 2021 from June 22nd to 24th, 2021, the supplier of injection molding systems bridged the gap between the two megatrends of our time. And showed how the one can help jump-start the other.

Digitalization helps us to leverage the full potential of the injection molding machine, and to make production more efficient by doing so”, as Engel Group CEO, Dr. Stefan Engleder, said in his opening keynote at their three-day in-house show that was flanked by a specialist conference.

A current study undertaken by business consultant Accenture in behalf of bitkom – the Bundesverband Informationswirtschaft, Telekommunikation und neue Medien, e.  V. – prognosticates that the use of digitalization could cut current CO2 emissions from German operations by as much as 58 %. Quite a high share of that, 23 %, is contributed by production plant. “If we genuinely make use of digitalization, the CO2 reduction targets set by politicians will suddenly no longer seem impossible,” said Engleder.

It is in the industry’s own interest to put this topic on its agenda, said the CEO, since the consequences could, for example, affect company refinancing. Engleder continued, “There is a wide spectrum of proven digital solutions available to us. Now it is up to injection molding producers to put these decarbonization enablers to use.” Engel envisions the entire product life cycle: from concept to design and production all the way to recycling – the symposium made that clear, too.

The example of a three-part vehicle door module visualized the process by which part design can pave the way to resource-saving manufacturing and subsequent recycling. Using sim link software, Engel connects simulation with production. The settings determined in the simulation are transferred to the injection molding machine control. This significantly accelerates the patterning of the mold as well as further optimization of the processing parameters. Conversely, processing parameters and measurement results can be easily transferred from machine to simulation. “The mold filling study already gives us the correct setting parameters for the machine without having to intervene manually,” as Dr. Gerhard Dimmler, Vice President of Research & Development at Engel, said in his talk.

Machine connectivity as well as constant data flow and exchange along the entire value chain are prerequisites for reducing CO2 emissions in an energy efficient injection molding plant that produces few rejects, on the one hand, and, on the other hand, as Dimmler pointed out, for establishing pure, high-quality recycling. Meanwhile, 30 % of all newly shipped Engel machine are online, and several hundred “edge devices” on the market. Engel has made good here on its promise to develop a kind of FritzBox for injection molding machines. As it turns out, other machine manufacturers have also adopted the edge device as a benchmark.

However, Dimmler also found words of self-criticism. Addressing the connected customers directly, he said: “Seen in retrospect, we incorrectly assumed that we should not get involved in your processing issues. You have set us straight on that.” In fact, the “iQ process observer”, a live data-based assistance system introduced at the K 2019, has met with considerable interest. On the other hand, we have been disillusioned regarding the platform economy we had initially prioritized. This will remain so until “we can merge horizontal and vertical platforms for you as a customer.”

The Goal: Re- and Upcycling  instead of Downcycling

A vertical platform means a digitally imaged system or production cell within a single link of the value chain. Such a “digital twin” describes the system and its behavior based on data, thus laying the foundation for optimization. One example of an application is the “Engel e-connect.24” digital service solution which, when docked to the e-connect customer portal, includes remote maintenance and online support – issues that have come more into focus for manufacturing companies, due not in the least to the Covid 19 pandemic. Many companies are now giving thought to how they can secure their productivity and ability to deliver in the event of future crises.

According to Gerhard Dimmler, vertical platforms have become established, but horizontal ones are just getting started. By shifting to horizontal platforms, as Engel and other companies in the plastics industry are vigorously pursuing, the entire value chain comes into focus. Applications and companies network themselves along this chain in order to exchange information and data. This benefits the circular economy as well. “It is our goal to replace the dominant downsizing of materials with re- or even upcycling,” says Stefan Engleder. This can work only if data is shared throughout the lifetime of the product and, thus, all along the value chain.

A digital watermark is such an example. Applied invisibly to packaging, it could enable more effective sorting of plastics wastes, in short: pure, high-quality recycling. The material, the manufacturer of the packaging, and the processing method then are identified by the watermark. These data are open to all participants and users of the horizontal platform. In this way, the recycling process as well as downstream recyclate processing can be controlled and attuned to each other in the sense of maximal resource efficiency.

In the virtual exhibition for experts, the several thousand participants in the symposium could discover solutions aimed at simplifying and intensifying recyclate use: in addition to Engel’s iQ Assistance Systems for maintaining process stability, procedural approaches, such as a new co-injection process that enables high recyclate content (over 30 %) to be completely enclosed in new material, or a new, twin-step process with which plastics wastes can be processed by injection molding immediately after being ground into flakes. In the first instance, the switchover from recyclate to new material takes place near the cavity, directly at the injection point, with the aid of a needle valve system. In the second instance, a melt filter and a degassing unit are installed between the plasticizing screw and the injection screw (or ram unit).

In closing, Engleder appealed to the branch to be open for digital solutions. “To do so, we need to change our mindsets. Find the courage to apply our inject 4.0 solutions and give connectivity a chance!” Only if by working together can we make the plastics industry sustainable.

What is needed is the courage to be open for digital solutions: Dr. Stefan Engleder 

30 percent of all recently shipped Engel machines are already online: Dr. Gerhard Dimmler

To make high recyclate content visible, a transparent skin made from new material is combined with a black core

Those who could not participate live in Engel’s e-symposium 2021 can still register and visit the machine showroom, undertake a virtual plant tour with an Engel contact person, and view all the keynotes and business talks (discussion groups on the topics packaging, medical, automotive, and technical molding. The entire program is available all year long and around the clock to customers, partners, and anyone interested.

<a href="http://www.engelglobal.com/e-symposium">www.engelglobal.com/e-symposium</a>

Spritzgießen

Kreislaufwirtschaft

Thermoset Injection Molding of Packages for Electronic Devices

Thermosets are being increasingly used for packaging electronic devices, and offer good properties for this application. Direct overmolding of the components is particularly interesting here. However, achieving a successful product requires striking a balance between processability, thermal conductivity and reproducibility.

Thermoset materials have a track record of industrial use dating back to 1908 [1]. That makes them the oldest synthetic polymers. Even now, these materials are continually finding new applications. Thermosets reached a peak in the second half of the 20th century, when their good thermal and chemical resistance played a major role in most areas of application. However, they have diminished in importance in recent decades. Nevertheless, developments in the electronics and automotive industries have given thermoset components a new lease of life in recent years. A focus here is the protection of sensitive electronic devices, such as sensors. At Robert Bosch GmbH, too, ever more electronic devices are being provided with thermoset packages, often by means of direct packaging.

In direct packaging, an electronic device, for example a control unit or sensor, is directly overmolded with a thermoset molding compound. The thermoset forms at least an adhesive bond with the packaged components and, at the same time, often also forms the subsequent device package. The thermomechanical properties of thermosets are a special advantage here, especially the low thermal expansion and virtually isotropic properties in the plane. Seen quantitatively, thermoset molding compounds typically have a thermal expansion of the order of copper (17  ·  10–6  K-1 or aluminum (23  ·  10–6  K-1). The thermal expansion of the circuit board is similar to that of the molding compounds used. The nearer the coefficient of expansions are to one another, the lower the mechanical stresses are under cyclic thermal loads. Thermoset molding compounds therefore offer ideal prerequisites for use as encapsulating materials. A typical temperature application range for direct packaging is between –40 and 150 °C.

More Gentle Processing Compared  to Thermoplastics

The processing properties of thermosets also favor their use for packaging sensitive devices. During filling, i. e. when the degree of curing is low, thermosets show the lowest viscosity (mold temperature > material temperature). The encapsulation can therefore be done especially gently. With thermoplastics, the viscosity in the mold (mold temperature &lt; material temperature) increases rapidly and consequently the components to be encapsulated are subject to greater stress. In addition, very low-viscosity thermoset formulations exist for both transfer molding and injection molding, which allow very low cavity pressures to be realized [2]. A disadvantage of the materials is the curing that occurs during processing, the influence of which should always be taken into account in considerations about process reliability.

The advantages of direct packaging that should be particularly stressed are, among others, its high functional integration, reduced number of assembly steps and the improved reliability, for example regarding soldered connections [3, 4]. On the other hand, a significant challenge for direct packaging of electronic devices is the dissipation of excess heat, which may reach a considerable level especially in automotive applications. In a conventional housing, heat dissipation is often achieved by connecting to a cooling structure. Since plastics are generally thermally insulating materials, corresponding functionalization is necessary, for example by adding thermally conductive particles.

Filling in the case of thermosets is normally described by a so-called block-shear flow. This filling behavior is triggered, for example, by the thermal conditions and resulting viscosity profile: while the material in direct contact with the mold is heated very rapidly and the viscosity is reduced correspondingly, the viscosity in the interior is higher because of the lower temperature. Correspondingly, the material is strongly sheared, particularly in the peripheral region, resulting in a filler orientation induced by the flow. In the interior, a statistical orientation of the fillers is assumed. Based on studies with magnetic and thermally conductive fillers, it was possible to demonstrate this behavior for different sheet thicknesses (Fig. 1) [5, 6]. Thermally conductive fillers with a platelet shape, such as hexagonal boron nitride, also show a similar behavior. Small platelet thicknesses, in particular, show a pronounced orientation of the fillers in the flow direction, while with large platelet thicknesses, the thermal conductivity is highly pronounced in the z-direction.

There is only a limited range of thermally conductive materials available for use in thermoset molding compounds. Nevertheless, some commercial materials are available. The thermal conductivity of thermoset molding compounds extends from values in the range from 0.5 W/m·K (standard material) to 8 W/m·K (thermally conductive polymer). However, the measurement method used plays an important role. For the measurements in the present case, the test unit NanoFlash LFA447 from Netzsch-Gerätebau GmbH was used. A special sample preparation allows the thermal conductivity to be recorded in all spatial directions, which is of great importance for thermal simulations and for part design.

Power Loss and Thermal Conductivity not Proportional

In addition, the materials were checked for heat dissipation under free and forced convection, and special heat removal structures, such as pins and ribs were molded on directly in the injection molding process [7]. It was found that the recordable power loss does not rise in proportion to the thermal conductivity (Fig. 2). A high dosage of the fillers, which generally leads to a strong price rise of the materials, does not inevitably result in an improvement of the thermal conditions in the packaged device.

The process of direct packaging is normally included at the end of the value-creation chain. The requirements on feasibility and reproducibility of the process are therefore correspondingly high. An error occurring in the process, for example due to a pressure spike during filling as a result of fluctuations in the material or process, can damage the electronic components. Since, in addition, the molds are often multicavity for cost reasons, the monetary damage can very quickly become very high. Due to the absence of a non-return valve, special attention is therefore paid to reproducibility particularly during thermoset injection molding. Besides the use of materials with low viscosities to minimize the cavity pressures as far as possible, precise process control is also necessary.

To permit this, the cavity pressure was investigated at Bosch during packaging with various materials. Whereas standard material shows very low cavity pressures of about 10 bar, they are already significantly higher for the thermally conductive material (Fig. 3). The filling behavior is also very different. With standard material there is virtually no difference between the pressure measured close to and distant from the gate. Only a small pressure increase close to the gate during filling is noticeable. With the thermally conductive material, on the other hand, the pressure close to the gate increases strongly during filling, which is another sign of the material’s higher velocity. Although a slight improvement regarding thermal conductivity can be achieved by increasing the temperature of the insert, the mentioned pressure rise can already be clearly seen.

The effect of the cavity pressures and filling behavior can be very readily assessed from microsections of the packaged electronics. In the investigated case, the sensitive devices were represented by an SMD (surface-mounted device) and a THT (through-hole technology) electrolytic capacitor. Both components show signs of failure at cavity pressures over 50 bar. While in the case of the SMD electrolytic capacitor, a slight indentation of the housing can be seen, with the THT electrolytic capacitor, predominantly the rubber cap is pressed in. At even higher cavity pressures, complete failure of the device eventually occurs (Fig. 4).

Another fault pattern is caused by the viscosity of the materials and the resulting stresses during filling. This may result in displacement of the capacitor in the flow path direction (Fig. 5). The contacts are bent and the rubber cap is also pressed in. The filling step can thus lead to failure of the device. In addition, the mounting and connecting technology also includes even more sensitive devices such as bond wires, for which the permissible stresses are even lower.

Besides the difficulties in encapsulating electronic devices described above, there are also other challenges. They include, e. g., air inclusions in the component, delaminations between molding compound and device, deformations of the circuit board and solder point damage, as well as the necessary underfilling of components. Depending on the device and components, this list can be further extended. Good process control is therefore all the more important. However, a suitable method for designing the part and process is required.

The reproducibility of the material and process play a key role in the packaging of electronic devices. As mentioned above, electronic packaging is the last stage in a long process chain and the financial risks in the event of rejects are correspondingly high. Even minor changes in the processing properties or boundary conditions can have an influence on the process quality. It is essential to have a suitable strategy for material qualification as well as process control.

Differences between Simulation  and Reality

Besides real influences on the process and devices, virtual product development at Bosch is increasingly moving into the spotlight. To be able to minimize the above-described problems in advance, a correspondingly reliable process and structure simulation is necessary. Although filling simulation already provides very good results, e. g. as regards the filling behavior and occurrence of air inclusions and weld seams, quantitative evaluation still has room for improvement. Particularly as regards predicting process pressures during thermoset injection molding, some programs show clear differences between the measured values (Fig. 6). In addition, obtaining reliable material data is often a challenge for process simulation with thermosets.

In the example shown in Figure 6, the required pressure (specific hydraulic pressure) during mold filling has been underestimated for a good decade. The cavity pressure is also not correctly modeled by the simulation. Perfect pressure transmission appears to be present, which is not the case in reality. Other focuses in improving thermoset injection molding can be found in the area of the loads to be expected for fitted components and in predicting the lifetime of the packaged electronic components.

[1]  DRP 23 3803: Verfahren zur Herstellung von Kondensationsprodukten aus Phenolen und Formaldehyd (1908) Baekeland, L.H.

[2] J. Cederstrom und M. Walcher: Elko, Microcontroller & MOSFET – Prototypen und Lösungen für Serienumhüllungen, 10. Internationale Duroplasttagung, Iserlohn, 2019

[3]  M. Walcher: Duroplastisches Umspritzen von elektrischen Bauteilen mit Epoxid-Formmassen. Fuse Box meets dryer – Kunststoffe in E&E Anwendungen, Würzburg, 2018

[4]  H. Kawaguchi: Total SB solutions for lightweights in automotive. Lightweight composite solutions in Automotive (ICE, EV & Brakes) and other industries, Ghent, 2018

[5]  T. Maenz: Spritzgiesstechnische Herstellung duroplastgebundener Dauermagnete. Dissertation, TU Chemnitz, 2018

[6] T. Maenz, A. Jakobinski, G. Hülder, M. Gehde: On the filler orientation of functionalized thermoset molding compounds during injection molding. ANTEC, Anaheim, 2017

[7]  A. Jakobinski: Empirische Untersuchungen der Material- und Prozesseinflüsse beim Spritzgiessen wärmeleitfähiger Epoxidharze auf die Bauteileigenschaften. Masterarbeit, Hochschule Niederrhein, 2016

In direct packaging,  the electronic devices or components are directly overmolded with the molding compound 

Fig. 1. Thermal conductivity depending on the flow direction for different sheet thicknesses: with increasing sheet thickness, the thermal conductivity decreases in the x-direction and increases in the  z-direction 

Source: Robert Bosch GmbH; graphic: © Hanser

Fig. 2. Thermal conductivity (left) and power consumption (right; with/without convection) for 2 mm thick sheets of different thermoset molding compounds: the thermal conductivity and power consumption of the materials increase disproportionately to one another

Fig. 3. Comparison of the cavity pressures for materials with lower (left) and higher (right) viscosity: at lower viscosity, the cavity pressure is significantly lower 

Fig. 4. Fault patterns in SMD and THT electrolytic capacitors: higher cavity pressures can lead to damage of the devices

Fig. 5. High-viscosity materials may result in displacement of the capacitor and consequent damage during filling  (PCB = printed circuit board) 

Source: Robert Bosch GmbH;  graphic: © Hanser

Fig. 6. The comparison of real (left) and simulated (right) process pressures during thermoset injection molding discloses significant deviations in the simulation

KU 8-21_Bosch - Hauptartikel

<ul><li> Dr.-Ing. Torsten Maenz is project manager at B. Braun Melsungen AG in the field of assembly and injection molding at the Braun Technology Center in Melsungen, Germany; <a href="mailto:torsten.maenz@bbraun.com">torsten.maenz@bbraun.com</a></li><li>Dr.-Ing. Martin Giersbeck is director at Robert Bosch GmbH in the field of Applied Mathematics and Engineering for Future Components within the Corporate Sector Research and Advance Engineering in Renningen, Germany; <a href="mailto:martin.giersbeck@de.bosch.com">martin.giersbeck@de.bosch.com</a></li><li>Dr.-Ing. Gerrit Hülder is senior manager at Robert Bosch in the field of Materials and Manufacturing Technologies Polymers within the Corporate Sector Research and Advance Engineering in Renningen; <a href="mailto:gerrit.huelder@de.bosch.com">gerrit.huelder@de.bosch.com</a></li><li>Dipl.-Ing. Armin Kech is research engineer at Robert Bosch in the department of Design and Dimensioning of Components, Prediction of Lifetime, Process Simulation within the Corporate Sector Research and Advance Engineering in Renningen; <a href="mailto:armin.kech@de.bosch.com">armin.kech@de.bosch.com</a></li></ul>

Elektronik

Kunststoff

Bauwesen

Baustoffe

Duroplastische Werkstoffe

Kunststoff Werkstoffe

Duroplaste

Duroplast-Spritzgießen

A Machine Strategy with  Extra Automation

At Goerlich, a Turnkey Plant Replaces Two Machines with a Vertical Clamping Unit

The aim of the project was clear: a highly automated turnkey system must replace several decentralized, operator-guided machines in order to be able to mass produce enclosures for a vacuum sensor with three inserted pins in a way that is smooth, automated and therefore faster than before in large-scale production, and error-free. The plastics processor Goerlich chose the machine manufacturer Arburg as a partner in its goal of achieving greater production efficiency.

From electronic components to housings: the potential applications of plastics technology in the electrical industry cover a wide range of shapes, sizes and applications. They also include many electrical components in automotive production, which are produced by injection molding. In its involvement in the electrical industry, Goerlich Kunststofftechnik GmbH, Wilsdruff, Germany, relies on its precision, experience with different materials and state-of-the-art technologies.

Many Subprocesses Implemented  in a Confined Space

The housing for a vacuum sensor consists of a polybutylene terephthalate (PBT-GF30) reinforced with 30 % glass fibers and integrating three metal pins. The fully automated plant, which the injection-molding machine manufacturer Arburg has conceived together with Goerlich, and in which the housings are produced, will in the future be able to manufacture three versions by exchanging the corresponding mold inserts. The plant replaces two decentralized operator-controlled machines with a vertical clamping unit (type: Allrounder 320 C), including testing technology, which were previously necessary for series production.

Andreas Armbruster from Arburg’s Turnkey Project Planning team explains the extensive specifications that the system had to meet: “The biggest challenge was implementing the various production steps within the required short cycle time. Above all, the feeding of the 24 very delicate pins from the punching strip to their insertion into the 8-cavity mold is correspondingly demanding.” According to Armbruster, what is special about the system is that the many sub-processes can be implemented in a very confined space with straightforward technology (Title figure). Without this automation solution, the annual production volume would only be achievable by deploying considerably more staff.

Automated Parts Testing in  Multiple Steps

The injection mold was developed and constructed in Goerlich’s mold shop. Besides a hot runner with cold sub-distributor, it is also equipped with hydraulically operated slides for precise receiving of the pins. The gold-plated plug contacts are fed on the conveyor from upstream and separated out. A Scara robot places these on a loading plate with rotary drive in the correct position for pickup by a Multilift V robotic system (Fig. 1). The pins are inserted into the mold slides without force, as is the removal of the eight finished parts on the ejector side of the mold.

After the contacts have been overmolded, the four sprue sub-distributors are first demolded and ejected into the machine stand. The robotic system places the eight connectors on a testing device with slide and NC axis for exact positioning. By moving the slide to different positions, a continuity and high-voltage test with 1000 V and a light test are carried out in succession, followed by the marking of the OK parts. Finally, a turntable distribution system that rotates back and forth through 180° ensures that parts are ejected into PE bags using separated cavities.

A hybrid Allrounder 470 H with a clamping force of 1000 kN and size 290 injection unit is used in the turnkey system (Fig. 2), which is equipped with several core pullers and special signals. The combination of an electric toggle-type clamping unit and a dynamic injection unit enables simultaneous movements. This results in time advantages in series production. The Selogica control system is highly valued because it supports communication between the various plant control systems, thereby ensuring fully coordinated production processes.

Thomas Ehrlich (Fig. 3), operations manager at Goerlich, is very satisfied with Arburg as a system supplier: “With this turnkey system in particular, Arburg’s project management team ensured that there was thorough and rapid communication and coordination between the suppliers, and hence a solution-oriented approach to the project.” Goerlich relies exclusively on Arburg for its injection molding production. The 34 Allrounders, including two-component and vertical machines, process special plastics such as PEEK, PSU, PEI, and LCP.

When asked why the company was pursuing this one-machine strategy, operations manager Thomas Ehrlich answered: “The Allrounders are reliable machines with which we can produce our portfolio for our customers in excellent, high-quality continuous operation. There is no reason for us to change or add anything, quite simply because we have been very satisfied with Arburg, its range of machines, and its service since the beginning of our working relationship in the 1980s. The smooth implementation of the turnkey system has once again confirmed our strategy.”

All upstream process steps are integrated in a very small space: after the pins have been  punched out (right), a Scara robot places them in the correct position on a loading plate (left) so that the Multilift V robotic system can pick up 24 pins and insert them into the mold

Fig. 1. The tasks of the gripper at the Multilift V are extremely varied and demanding in this application

Fig. 2. Goerlich manufactures enclosures for vacuum sensors efficiently and flexibly with its compact turnkey system

Fig. 3. Thomas Ehrlich, operations manager at Goerlich, is delighted with the increase in efficiency that the turnkey system brings to his injection molding production

 Susanne Palm works in corporate communications at Arburg GmbH + Co KG, Lossburg, Germany.

Goerlich Kunststofftechnik GmbH, Wilsdruff, Germany, manufactures switches, plug connectors and technical components for the automotive, telecommunications and electrical industries by injection molding. The company was founded in 1978 by Rudolf Görlich in Leingarten near Heilbronn, Germany, and today has its sole headquarters near Dresden, Germany. In 2019, before the beginning of the Corona crisis, Goerlich achieved sales of EUR 10.3 million with about 100 employees.

<a href="http://www.goerlich-verbindet.de">www.goerlich-verbindet.de</a>

Automatisierungszellen

Automatisierungstechnik

Spritzgießwerkzeuge

Kunststoffverarbeitung: Maschinen und Komponenten

Werkzeuge für die Kunststoffverarbeitung

Linearroboter für die Kunststoffverarbeitung

Handling, Handhabungstechnik

Hybrid-Spritzgießen (Metall / Kunststoff)

Injection Molds for Insulating  Stators and Rotors

Overmolding as a Prerequisite for Cost-Efficient, High-Quality Electric Motors

Electrical components are made from conductive and nonconductive materials. Pressure of competition makes it necessary to reduce the number of components and work steps and to streamline assembly. The moldmaker Mühlbeyer uses a hybrid technology for manufacturing stators and rotors, in which the contact material and plastic are permanently bonded in one production step.

In our modern world, if something is caused to rotate or move at the push of a button, electrical drives are usually involved. Electric motors make manufacturing processes effective and efficient in many industries – e. g. machinery, apparatus, material processing, chemicals, plastics, paper, textile, foods, stone/earths. Electric motors are also indispensable in transport (rail, automotive, marine, air), household appliances, agriculture and consumer goods. In the mass production of electric drives, too, electric motors permit highly efficient manufacturing, enabling a very good price-performance ratio.

The key elements of a simple electric motor are:

<ul><li>rotor (rotating electromagnet),</li><li> stator,</li><li>commutator (only for d. c. motors),</li><li> brushes,</li><li>coil, and</li><li> shaft.</li></ul>

The rotor (Fig. 1) is the moving part of the motor and moves between the two poles of the stator (Fig. 2). Depending on the type of electric drive and electrical winding, there are two types of electric motor, depending on how power is generated:

<ul><li> The laminated core serves for guiding and locally concentrating the magnetic field lines.</li><li>The electrical winding generates the magnetic field.</li></ul>

The laminated core of an electric motor consists of thin sheets of a soft magnetic material, with thicknesses from about 0.1 to 1.2 mm, depending on the type and size of the machine. The two dimensional form of the rotor or stator is punched out of these sheets with punching tools. The sheets are stacked in the axial direction and are insulated from one another to minimize the effect of eddy currents.

The winding of an electric motor consists of copper wire of various types: stranded, flat, profile, fine, drill, braided, baked varnish or standard wire, insulated and, in some cases, with a lubricant coating. Irrespective of the type of winding (distributed or concentrated), the wires are electrically insulated from one another and with respect to the laminated core.

The winding insulation is the electric motor’s Achilles’ heel as regards heat resistance. Thermal materials have service temperatures up to 250 °C. At the same time, the copper conductors form the largest heat source by far due to current heat losses. That means that the power density is dependent on the thermal loading capacity of the insulation and on the possibility of dissipating the heat loss. For conducting the current, the insulating materials are just as important as the conductor materials.

The Insulating Materials Are as Important as the Conductor Materials

The large number of available insulating materials makes selection and a summary presentation very difficult. There are various requirements, such as high dielectric strength, high tracking resistance, good thermal conductivity, high thermal resistance, good chemical resistance, high mechanical strength and low costs. Since these goals are difficult to reconcile with one another, specially modified insulating materials are selected depending on the priority. The insulating materials used have a direct influence on the thermal conductivity, the voltage tolerance and in particular the geometrical design of the motor. The thicknesses of the insulating layer and creepage paths should thus be provided according to design criteria.

Here it should be considered how the insulating system of the electric motor can be designed according to the load. Among other things, the voltage distribution must be analyzed under different operating states and various insulation materials characterized. This function is generally performed by plastics.

During overmolding of the laminated core, plastic-coated stators/stator segments must include, in addition to the slot insulation and the base plate for fitting the laminated core, also technical functions such as track ribs for wire bonds, pole-pocket insulation, plug shafts for contact parts, deflection pins, passages for wire guides, pole-piece inner flanges, clearances for screw heads, inlet and outlet slots (Fig. 3).

At the beginning of the injection cycle, the laminated core is inserted into the mold manually or automatically by grippers, and positioned via a center core. As the mold closes, it is held in position by slides and subsequently overmolded with plastic, e. g. a PPS-GF40, to form the final part. Finally, a camera performs automatic optical quality inspection of the parts. Such molds are one of the specialties of Mühlbeyer Werkzeug- und Formenbau GmbH.

Mold Components Are More Expensive at High Mold Temperatures

The plastic selected for insulating the stator segments, the stator, rotor or fan impeller crucially influences the costs of the injection mold. Polyamide (PA), which requires a mold temperature of 80 to 100 °C, causes far lower costs than a plastic such as polyphenylene sulfide (PPS), which requires a mold temperature of approx. 150 °C, polyetherketone (PEK) or polyetheretherketone (PEEK), which require a mold temperature as high as 240 °C or more.

At high mold temperatures, standards such as sensors, actuators, magnets for inserts, complete all-round insulation of the injection mold, the hot runner system, or more complex slides (flash formation), become significantly more expensive. The dimensional tolerances of the mold components are smaller and may require a machining accuracy of 2 µm. Furthermore, the corrections for the high-performance plastics PPS, PEEK and PEK are much more complex, since the viscosity (flash formation on the spotting surfaces) is higher than for PA. In high-voltage insulating bodies, the flash formation can lead to partial discharges or even damage wires or winding errors.

There is a negative influence on the flow behavior of plastic compounds containing glass fiber reinforcement or mica. Therefore, an injection molding simulation (mold flow analysis) should be performed if possible to avoid a faulty design due to wrong assumptions. Possible error patterns of the injection molded part could be: incomplete injection, weld line defects, etc. In the simulation, additional flow aids, multiple gates, etc. can be introduced and simulated if necessary – or else an overflow cavity in which the excess plastic is automatically separated off as the mold is opened.

Flow Guides Assist Filling in  Thin-Walled Regions

Flow aids are additionally installed at places that do not affect the function of the electric motor. This may be, e. g., at the slot insulation surface, toward the inner-central region of the yoke ring, which is not in contact with the winding. Flow guides can also be implemented by means of holes through the laminated core of the rotor or stator with diameters of a few millimeters. These flow guides support the material flow of thermoplastics and promote complete filling of thin-walled sections.

Such injection molds must always incorporate compensation of the laminated core tolerances (up to 0.8 mm) to ensure a stable process. Because of the winding technique, extremely small geometries (e. g. 0.1 mm radius) are necessary for placing the winding wire. For inclined winding in grooves, a certain surface roughness is necessary to prevent slipping of the winding. Of course this presupposes that the polymer insulating material can also perform this.

There Are Consequences to How Precisely the Inserts Are Positioned

Inserts such as permanent magnets, laminated core or others must be precisely positioned in the injection mold; their position must be clearly defined during injection molding. This is possible with various Mühlbeyer clamping systems in the injection mold. The greater the positioning accuracy of the inserts, the lower is the motor imbalance. That means that the asymmetric distribution of the rotor mass is advantageously reduced. A lower imbalance in turn has a positive effect on the efficiency of the electrical drive and at the same time reduces the noise and component wear. Furthermore, due to precise positioning of the laminated core or basic body in the injection mold, the tolerance chain is improved in the radial, circumferential and longitudinal directions.