Once again, the K 2019 in Düsseldorf, Germany, lived up to its claim to be the leading trade show for plastics technology. At least in the field of injection molding, there were exciting global innovations to see – if you looked closely.

Injection Molding Trends at K 2019

Spritzgießen

Kunststoffverarbeitung: Verfahren

Schaumspritzgießen

Smart Factory

Energieeffizienz

Mikrospritzgießen

Mehrkomponenten-Spritzgießen

Spritzgießmaschinen, allgemein

Kunststoffverarbeitung: Maschinen und Komponenten

Spritzgießmaschinen

Spritzgießwerkzeuge

Werkzeuge für die Kunststoffverarbeitung

Fließpressen

Handling, Handhabungstechnik für die spanende Fertigung

Automatisierungstechnik

Handling, Handhabungstechnik

Spritzgieß-Sonderverfahren

Spritzgießsimulation

Software

Simulation

Elastomer-Spritzgießen

Linearroboter für die Kunststoffverarbeitung

Industrieroboter

Montagetechnik

Industrie 4.0 für die Kunststoffverarbeitung

Industrie 4.0

Montage-Spritzgießen

Knickarmroboter

Co-Injektion (Barriere-/Sandwich-Spritzgießen)

Hybrid-Spritzgießen (Metall / Kunststoff)

Ressourcenmanagement

Produktion

Technical Excellence thanks  to Digital Assistance

The required screw diameter can be ascertained on the basis of the shot volume. The formula for the average residence time can be used to estimate the degree of utilization and the thermal load on the material.

Part 1 of the Series Discusses the Basic Design of a Plasticizing Unit and the Correct Choice of Injection Unit

Schnecken und Plastifiziersysteme

All about Plasticizing Screws

To be able to carry out the practical test in a resource-saving manner, the designers use simulation tools to assess the screw geometry. What is important here is explained using a 3-zone screw as an example.

Part 2 of the Series Deals with Basic Methods for Evaluating a Screw Geometry

iQ process observer, the new process monitoring platform from Engel monitors hundreds of parameters from the injection molding cell in the background.

A Process Monitoring Platform Monitors Several Hundred Parameters Simultaneously

Steuerungen (Hardware und Software)

Industrie 4.0 für die Qualitätssicherung

Prozessvisualisierung

Condition Monitoring / Prozessüberwachung

Instandhaltung

IoT-Plattformen für die Kunststoffverarbeitung

An Eye on the Process –  a Handle on Quality

Over past months, many in-house workflows and development processes have slowed down and also changed. Nevertheless, time has not stood still, also not in injection molding technology. The debate and development have been shaped by two themes: digitalization and the circular economy. Below are some examples of developments and projects that underpin this trend.

Innovative Injection Molding in Times of Pandemic

Künstliche Intelligenz für die Qualitätssicherung

Steuern, Regeln

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

Digitale Transformation

Wirtschaft

Innovationen und neue Technologie

Biokunststoffe

Kunststoff Werkstoffe

Nachhaltigkeit

Umweltmanagement

Machine Learning / Künstliche Intelligenz für die spanende Fertigung

Industrie 4.0 für die spanende Fertigung

Kunststoff-Recycling

Kunststoff-Aufbereitung

Lasermarkieren

Oberflächentechnik

Laserbearbeitungen

Inline- / Online-Messsysteme

Qualitätssicherung

Qualitätssicherung Kunststoff

Kreislaufwirtschaft

There Is More beyond the Horizon

Which injection molding machine is the right one for which application? Below we will demonstrate why performance is not always performance, but physics is always physics.

How Feed Rate, Injection Volume and Filling Time Correlate with Injection Unit Performance

Kugelgewindetriebe

Maschinenelemente

Getriebe

Elektrische Antriebe für Spritzgießmaschinen

Antriebe

Elektrische Antriebe

Elektromechanische Maschinen

A Question of Class

In cars, LEDs are taking over ever more applications and are increasingly used as differentiating design elements. In order to ensure a high luminous efficiency even with complex geometries and elongated structures, Engel has developed a new plasticizing process for manufacturing light guides.

The Principle of Starve Feeding: Injection Molding Ultrahigh Purity Light Guides

Farbmessgeräte

Messtechnik

Optische Mess- und Prüftechnik

LED / OLED-Systeme und Faseroptik

Lichttechnik

Less Granules  Stock Means More Quality

A year to forget is nearing its completion. To brighten up this dreary fall season without a major event like Fakuma, injection molding machine builders have concocted various strategies.

Injection Molding Machine Builders Are Discovering New Ways to Reach Their Customers

Vernetzung / Cloudlösung für die Kunststoffverarbeitung

Schneidmühlen

Silikonkautschuk

Kautschuk / Elastomere

What Can You Do at Fall Fairtime,  When There Aren’t Any?

Infrared heating technology has become established as the standard in the processing of thermoplastic composite materials. The focus is on process control. On the one hand, it is important that the heating process is fast, on the other hand, the material must not be overheated. It is also important to achieve excellent temperature homogeneity. Simultaneous processing of blanks with different thicknesses is a particular challenge.

Efficient and Precise Heating up of Thermoplastic Composites

Infrarotstrahler

Verbundwerkstoffe / Werkstoffverbunde

Organobleche (gewebeverstärkte Thermoplast-Halbzeuge)

Halbzeuge und Zwischenprodukte

Kunststoff-Halbzeuge

Software-Based Control of IR Ovens

ENGEL, headquartered in Schwertberg, Austria, is one of the globally leading companies in plastics processing machines. From individual injection moulding machines to integrated and automated production cells, ENGEL offers customised solutions for thermoplastic, thermoset and elastomer processing from a single source. ENGEL injection moulding solutions are used, for example, to manufacture automotive components, housings and other parts for electrical and electronic products, household goods, toys and leisure articles, packaging, and products for medical technology and health care. ENGEL‘s leading market position is founded on two cornerstones: on the one hand, high-technology business that initiates permanent further development and on the other hand, large-scale production to make our cost-intensive development work financially affordable. With nine production plants in Europe, North America and Asia, as well as subsidiaries and representatives in more than 85 countries, ENGEL has a global presence. From its foundation in 1945 to the present day, ENGEL has always been 100 percent family-owned.

Engel Austria GmbH  

https://www.engelglobal.com

The new injection-molding machine Engel duo speed combines productivity and efficiency with short cycle times in a high clamping force range. The two-platen machine is thus making inroads into a range of packaging applications that were formerly the domain of toggle machines.

Engel Duo Speed Expands the Machine Portfolio for Packaging Applications

High-Speed Machine with a  Small Footprint

The fifth broadcast by arburgXvision was all about the exciting question of how productivity can be optimized by bringing together technology, organization and digitalization in the ideal manner.

5. arburgXvision: „Savings through Hidden Benefits!“

The area of application of cube molds has expanded to take in the production of technical parts. The new Allrounder Cube 1800 from Arburg with a clamping force of 1800 kN is providing the response to this trend. With its compact cube, this machine completes the portfolio of products at the lower end of the range.

Arburg Expands Hybrid Cube Series

After a year’s forced break of Fakuma, Wittmann Battenfeld is announcing the new servohydraulic SmartPlus machine as the highlight of this year’s trade show. It is claimed to be characterized by high economic and energy efficiency and repeat accuracy.

Messe Fakuma

kunststoffe-international.com

Spritzprägen

Injection Molding Innovations In-House, Live and in Color

Emilio López has been appointed as the new managing director of Engel de Mexico SA de CV. He succeeds Peter Auinger, who retired on 1st September 2021.

New Managing Director in Mexico

Part 3 of the Series Deals with the Tests to Optimize the Screw Geometry

In the second part of the series, calculations were carried out on the throughput behaviour, pressure build-up capacity and the melting process on the basis of an exemplary geometry. These results are now to be examined in more detail and subsequently optimized. For this purpose, the effects of adjusting some selected geometry parameters have to be investigated and interpreted.

In the second part of the series, calculations were carried out on the throughput behaviour, pressure build-up capacity and the melting process on the basis of an exemplary geometry. These results are now to be examined in more detail and subsequently optimized.

The main task of a plasticizing unit is to melt the plastic granulate and homogenize the molding compound. Plasticizing units in which the heated barrel is combined with a three-zone screw are widely used. In the feed zone, the granules are fed from the hopper into the plasticizing unit. In the compression zone, the screw flight narrows so that the molding compound is compressed and melts due to the interaction between the frictional heat generated and the heated cylinder. In the metering zone, the viscous melt is mixed to distribute additives and fillers as well as heat evenly.

In part 1 and part 2 of the series (Kunststoffe international 10/2020 and 1/2021), the basic principles of plasticizing unit design and screw geometry calculation were discussed. Calculations concerning throughput behavior, pressure build-up capacity and the melting process were demonstrated on an exemplary screw geometry. In our example the average metering performance was about 12.49 g/s with a back pressure of 80 bar and a circumferential screw speed of 300 mm/s – a value which can be improved by appropriate geometry optimizations.

As shown in the second part of the series, the screw showed a considerable overcapacity for pressure build-up. With a back pressure of 80 bar, the screw was able to reach a peak pressure of just under 160 bar. But in the interest of gentle plasticizing to protect the material, this peak pressure should be reduced to below 120 bar in practice.

However, the melting process developed very positively, as the material was already completely liquefied after traveling about L/D = 8 in conveying direction. In the course of further optimization, it is now necessary to prevent solid material from traveling too far into the metering zone, since in extreme cases this could lead to excessive wear of the screw, the barrel and the check valve. Ultimately, this is also why the dwell time of the melt should not be allowed to fall below the minimum dwell time recommended by the manufacturer of the material.

Step 1 of Optimizing the Geometry: Shortening the Metering Zone

As a first step, the length of the metering zone should be reduced. The idea behind this is that the metering zone with its low flight depth and considerable length produces a corresponding blockage effect on the preceding screw zones. This is also shown by the closeness of the peak pressure point to the end of the compression zone prior to the optimization attempt. In this first test, the metering zone is shortened from 5.5 D to 3.5 D. To keep the total screw length of 22 D unchanged, the compression zone is lengthened (from 5.5 D to 7.5 D) accordingly (Table 1).

The effect on the peak pressure is negligible. However, the pressure gradient in the metering zone has now become steeper, since the pressure peak has moved closer to the check valve (Fig. 1). For the sake of completeness, it should also be mentioned that the change has a similarly minor effect on the melting process and throughput. Liquefication is now completed at L/D = 8.9, and the average metering performance is about 13.02 g/s.

Step 2 of Optimizing the Geometry: Increasing the Metering Zone Depth

Since the effect achieved by shortening the metering zone is only minor, the flight depth is now examined as a second step. The individual zones are returned to their original lengths (feed zone 50 % of the total length, metering and compression zone 25 % each). The flight depth ratio of 2 zones remains unchanged, but that of the metering zone is increased by between 25 and 30 %. In rounded figures, a flight depth of roughly 3.2 mm is calculated for the metering zone (Table 2).

After carrying out this optimization attempt, the pressure curve shows that the original pressure of 158 bar has been reduced to 129 bar (Fig. 2). It is interesting to see how a 28 % increase in the flight depth reduces the blockage effect much more strongly than a shortening of the metering zone by some 36 %.

Other points worth mentioning here are the average metering performance of 15.23 g/s reached by this move, and the shift of complete liquefication to L/D = 10.4. Moreover, it is basically possible to vary the compression ratio, the zone length ratios, etc., in a similar way in order to optimize their influence on the processing parameters.

Where these tests are carried out for many different materials and harmonized accordingly, a universally applicable screw geometry emerges as a result. At Wittmann Battenfeld GmbH, Kottingbrunn, Austria, multi-purpose screws of this kind are sold under the name of Unimelt. They stand out by their extremely wide range of possible applications in thermoplastics processing. In combination with a suitable anti-wear package, they offer a long-lasting plasticizing system. Wherever special challenges in injection molding must be mastered, the Wittmann Battenfeld team of engineers stand ready to help their customers in a joint search for the optimal plasticizing solution to fit every individual purpose.

Empirical tests and simulation-supported test series allow the design of a screw tailored to the specific application (for example, low pressure build-up or high plasticizing flow). Outside this application, however, such a screw cannot reach its full potential. It is also possible to generate a universal screw by means of comprehensive test variations, which can be used for a wide variety of materials and process parameters.

Wittmann Battenfeld GmbH  

https://www.wittmann-group.com

Ausgabenartikel

Through empirical tests and simulation-supported test series, a screw can be designed in a tailor-made manner for the respective application 

Table 1. Geometry optimization, test 1: Metering zone shortened, compression zone lengthened

Table 2. Geometry optimization, test 2: Screw with increased flight depth

Fig. 1. First test for geometry optimization: Pressure curve along the screw at stroke position 50 mm

Fig. 2. Second test for geometry optimization: Pressure curve after the increase of flight depth by approx. 28 %

Name - Hauptartikel

<b>Filipp Pühringer</b> heads the Process Engineering Development Department at Wittmann Battenfeld GmbH in Kottingbrunn, Austria.

The first two parts of this three-part series were devoted to the basics of designing a plasticizing unit and first steps towards optimizing the screw geometry. They have been published in Kunststoffe international, issue 10/2020, pp. 27–29, and 1/2021, pp. 14–16.