Ultrasound-based detection of flow fronts in injection molds

Ultrasound-based detection of flow fronts in injection molds

In this paper, we describe a new method for dynamic detection of flow fronts in injection molds using ultrasonic sensors.
The Injection molding is a widely used process for manufacturing plastic parts. In this process, liquid plastic is injected into a mold (the injection mold) and transformed into a solid form by cooling and solidification.

The quality of the injection molding process depends largely on the filling process and on the ability to create a uniform flow front of the plastic within the mold.

An uneven flow front can lead to weak spots in the material, undesirable weld lines and rejected parts, which in turn reduces the profit when selling the end product.

MoldFront with cable

Challenges in flow front detection:

Detecting flow fronts in injection molds is a complex task.

An uneven flow front can be caused by these various factors:

  • Changes in material properties
  • Tool design
  • Changes in the injection molding process

To date, there have been a wide variety of approaches to flow front detection, such as optical sensors, pressure sensors, and temperature sensors. However, these methods have certain drawbacks, such as sensitivity to abrasive materials or limited dynamic range.

A promising alternative to this isnon-contact measurement using ultrasonic sensors.

How ultrasonic flow front detection works:

Ultrasonic flow front detection relies on the continuous transmission of ultrasonic pulses toward the cavity during the injection molding process.

With an empty cavity, 100 % of the ultrasonic energy is reflected at the steel/air interface. If the plastic now hits the measuring point, part of the ultrasonic energy is coupled into the plastic and precisely this difference is subsequently detected by the MoldFront sensor system.

Moldfront Assembly Machine Tool

MoldFront electronic unit mounted on an injection molding machine

Click here to view the sensor product mentioned:

Advantages of ultrasonic flow front detection

Ultrasonic flow front detection offers several advantages over other methods:

  • Die Methode erfasst dynamisch und in Echtzeit Veränderungen der Fließfront, was eine schnelle Reaktionszeit im Bereich von < 5 Millisekunden ermöglicht.
  • The method is resistant to external factors such as abrasive media, high spray pressures, or humidity.
  • The method is independent of the material and tool design and can therefore be applied to a wide range of applications.
  • This method allows for non-contact measurement at many different points on the tool, resulting in a high degree of design freedom.

Comparison of MoldFront flow front detection and pressure sensors

The use of pressure sensors is a common method for measuring pressure and detecting flow fronts in industry.

The MoldFront ultrasonic sensor technology can be used analogously. While the pressure sensor system measures the increase in pressure in the cavity in order to detect the flow front, the MoldFront ultrasonic sensor system uses density changes in the cavity. This accurately detects whether the steel/air or steel/plastic interface exists at the measurement point. This works equally well for other metals, such as aluminum or copper.

Comparison MoldFront Pressure Sensor Tool
From the measurement data in the graph shown, it is clear that the Flow front detected cyclically, reliably and dynamically will.

The major advantage of ultrasonic flow front detection is therefore that it allows the flow front to be measured independently of the pressure conditions in the cavity. This means that no response pressure is required, and there is no longer any need to limit the pressure to a specified maximum.

In addition, due to the non-invasive or non-contact measurement, ultrasonic flow front detection can also be used with abrasive media or vacuum applications without any problems.

Click here to view the sensor product mentioned:

Is anything unclear, or do you need more information?

Difference between structure-borne sound and directly measuring ultrasonic sensor technology

Difference between structure-borne sound and directly measuring ultrasonic sensor technology

In this article you will learn what exactly is the difference between structure-borne sound systems and directly measuring ultrasonic sensor technology.

Injection molds are essential for the production of plastic parts. This is a process in which plastic granules are injected into a mold, which is then formed under high pressure and temperature. To ensure that the process works properly, sensors are required to measure important quality parameters during the filling process.

In the injection molding industry, there are two main types of sound sensors: Structure-borne sound sensors and direct-measurement ultrasonic sensors. Although both are used for monitoring the injection molding process, they differ in their operation and application.

In this article, the difference between structure-borne sound sensors and direct-measurement ultrasonic sensors in injection molds will be explained in more detail.

Structure-borne sound sensors

Structure-borne sound sensors are used to measure vibrations in the injection mold. They are usually attached to the mold frame or other structural elements of the mold and detect vibrations that occur during the injection molding process. These vibrations are an indicator of the functioning of the mold and can thus be used, for example, for the

  • Condition-based maintenance of tools
  • Tool damage detection
  • or the tool qualification

be used.

This means that the structure-borne sound waves, which change as a function of the tool vibrations that occur, are interpreted and assigned to specific damage categories.

Structure-borne sound sensors can operate in several ways, including piezoelectric sensors, accelerometers, and laser Doppler vibrometers. Piezoelectric sensors convert vibrations into electrical signals, while accelerometers measure acceleration caused by tool vibrations. Laser Doppler vibrometers, on the other hand, measure the speed of tool vibrations by observing laser light, directing a laser beam at the surface and then analyzing the reflected radiation.

Direct measuring ultrasonic sensors (Moldsonics Sensorik)

Direct-measurement ultrasonic sensors are used to measure quality parameters directly on the injection molded part, i.e. directly on the resulting product.

They are usually placed at critical and quality-relevant positions in the injection mold and record a characteristic ultrasonic response curve of the injection and holding pressure process.

Curve-MoldUni-Comparison-Koerperschall-en

Characteristic ultrasonic response curve when using directly measuring ultrasonic sensor technology

Curve-MoldUni-Comparison-Koerperschall-en

Characteristic ultrasonic response curve when using directly measuring ultrasonic sensor technology

The mode of operation is based on the permanent emission of ultrasonic waves and the analysis of the reflected waves. These sensors use the piezoelectric effect to generate electrical signals when they are loaded by electrical voltage and, conversely, to generate sound waves when they receive electrical current.

The ultrasonic waves emitted by the sensors are reflected by the cavity wall and the plastic melt to be measured and return to the sensor. Based on the time it takes for the ultrasonic waves to return and the intensity of the reflected ultrasonic pulse, the sensor can determine a wide variety of quality-related parameters. These include:

  • The flow front detection, i.e. when the melt front reaches the sensor position
  • The velocity of the melt flowing by
  • The solidification rate of the cooling plastic material
  • The shrinkage of the plastic component from the cavity wall
  • The thermal equilibrium of the injection mold

The use of this direct measuring ultrasonic sensor technology in the injection molding industry is completely new. To date, the measurement of a characteristic ultrasonic response curve can only be achieved with Moldsonics' sensor technology and is therefore unique.

The use of this sensor technology is not limited to individual industries and is currently already being used in a wide variety of industries, including the medical industry, the automotive industry, the food industry and the toy industry, to name just a few.

Is anything unclear, or do you need more information?

Application example Haidlmair and Moldsonics

Application example Haidlmair and Moldsonics

Haidlmair mold and Moldsonics sensors - a perfect match.

This application example illustrates how you can use the MoldUni sensor system in practice.

Moldsonics MoldUni on Haidlmair Mold at K2022

At this year's K2022 in Düsseldorf, Haidlmair and Moldsonics presented their latest innovation: the Sixpack mold, which uses ultrasonic sensor technology to continuously monitor the quality of its components.

One of the most important features of this mold is the use of the FDU (Flat Die Unit) as a hot runner system. This enables high-precision temperature control and faster cycle times, resulting in higher quality components.

An additional highlight is the integration of MoldUni sensor technology. The integration of ultrasonic sensors allows users to monitor and document the production process in real time without having contact with the melt, making sensor marks or leaks a thing of the past. This allows manufacturers to quickly identify problems and take corrective action to ensure each part meets the highest quality standards.

"Moldsonics' ultrasound-based sensor technology offers us completely new possibilities for analyzing processes in our filling operations and thus improving our tools."

Lukas WAGNER

Head of Advanced Simulations,HAIDLMAIR GmbH

In addition to advanced sensor technology, the mold is also a mix of conventional and 3D-printed components. This allows greater design flexibility in the construction and shorter cycle times as well as higher efficiency in the injection molding process.

Overall, the Sixpack mold is an innovative example of how sensor technology and advanced manufacturing techniques can be combined to create high-quality components with improved monitoring and shorter production times.

We are excited to see in which exciting projects these two innovations can still be combined and are looking forward to the applications still to come.

We have summarized everything in detail in one article:

Any questions?

That was K2022!

That was K2022!

K2022 in Düsseldorf, the leading trade fair for the plastics and rubber industry, was a major success for the sector this year. More than 176,000 trade visitors from every continent traveled to the event, which took place at the Düsseldorf Exhibition Center. The trade visitors came from 157 different countries, and the trade show was a great opportunity for companies in the plastics and rubber industry to showcase their latest products and innovations.

Moldsonics to Exhibit at K for the First Time

We at Moldsonics were one of the many exhibitors at K2022 and were pleased to present our latest ultrasonic sensor systems, MoldFront and MoldUni, which were developed to improve the accuracy and efficiency of manufacturing processes in the plastics and rubber industries. The sensor system is capable of detecting even the slightest fluctuations in the manufacturing process, enabling better control and more consistent results. All parameters—far beyond just pressure and temperature—can be measured without coming into contact with the melt.

To demonstrate the many capabilities of our sensor system, we set up a measurement kit at our booth. Visitors to the trade show were able to see the system in action, and many of them were impressed by its resolution accuracy and the new measurement capabilities. In addition to our own booth, our sensor system was also in operation at three partner booths, allowing even more visitors to see it in action.

K2022 Demonstrator
IMG 5190 scaled Moldsonics K2022
IMG 5192 scaled Moldsonics K2022

The K2022 trade show was an excellent opportunity for us to establish valuable contacts in the plastics and rubber industry. We had many interesting conversations with potential customers, were able to network with other companies, and learned about the latest developments in the industry. We are confident that the contacts we made at the trade show will be of great benefit to our company in the future, and we are very much looking forward to the upcoming collaborations.

Overall, the K2022 trade show was a fantastic experience for our company. We were able to showcase our new sensor system to a large and diverse audience and made many valuable connections within the plastics and rubber industry. We are already looking forward to the next trade show and hope to continue being part of this important and innovative industry event in the future.

K2022 – Official Press Release

K2022 – Official Press Release

K2022 – Trade fair results exceed all expectations

A driver of innovation for the global plastics and rubber industry

A wide range of concrete solutions, machines, and products to support the transition to a circular economy

A new life for plastic. Because we care.

The excitement within the plastics and rubber industry at finally being able to exchange ideas in person on a global scale again after three years defined K2022 Düsseldorf and created a positive atmosphere among the 3,037 exhibitors. Companies reported an exceptionally high volume of leads and a strong willingness to invest among trade visitors, noting promising new customer relationships and the conclusion of numerous business deals, some of which were made on the spot.

“K in Düsseldorf has once again exceeded the highest expectations. It remains the most international, comprehensive, and innovative trade fair for the global plastics and rubber industry,” says Erhard Wienkamp, Managing Director at Messe Düsseldorf, expressing his delight at the strong results and adding: “The trade fair has impressively demonstrated just how valuable in-person networking, chance encounters, and hands-on brand and product experiences are. We are very pleased to see that K2022 succeeded in sending out strong signals as a driver of innovation in the industry and that our exhibitors did business with a large number of international customers with significant decision-making authority.”

176,000 trade visitors from every continent traveled to their most relevant industry event in Düsseldorf. At over 70%, the proportion of international guests at K2022 remained consistently high.

Ulrich Reifenhäuser, Chairman of the Exhibitor Advisory Board at K2022, also offers a very positive assessment: “With virtually no trade fairs taking place worldwide—including at the national level—over the past three years, K2022 was all the more eagerly anticipated as the world’s leading trade fair for the plastics and rubber industry, and it succeeded in providing fresh momentum across all sectors of our industry. The many—and in some cases unexpected—concrete contract negotiations held at the trade fair speak for themselves!”  

“The current unpredictability and uncertainty surrounding events have certainly created a challenging situation for the sector as a whole, but this did not dampen exhibitor enthusiasm or visitor interest—quite the opposite: ‘Especially now, in these turbulent times and as the plastics industry undergoes a transformation toward the circular economy, K2022 was the ideal place to work together and actively chart a course for the future,’ summarizes Ulrich Reifenhäuser.”

Trade visitors were particularly impressed by the wealth of new technological developments presented by raw material producers, machinery manufacturers, and plastics processors for implementing the circular economy, conserving resources, and protecting the climate. Commenting on this, Ulrich Reifenhäuser says: “It is clear that all companies have embraced the need to take on social responsibility and think about plastics in a sustainable way from the very beginning of the process chain. The variety of solutions, machinery, and products for the transition to a circular economy presented at K2022 was incredible.”

Trade visitors at this year’s K traveled to the Rhine from 157 countries. In addition to Germany, the European countries with the strongest representation among visitors included the Netherlands, Italy, Turkey, France, Belgium, Poland, and Spain. With 42% of visitors coming from overseas, K’s reach among the international trade audience remains as high as ever. While visitors from the East Asian region, in particular, were less well represented than at K three years ago due to the currently more difficult conditions in those countries resulting from quarantine regulations, numerous visitors from the USA, Brazil, and India were welcomed at K2022.

For about two-thirds of all visitors surveyed, machinery and plant construction ranked first in terms of interest. Fifty-seven percent—5% more than at K 2019—said they were interested in raw and auxiliary materials, with recyclates and bioplastics being particularly popular. For 28%, semi-finished products and technical parts made of plastics and rubber were the main reason for attending (multiple responses allowed). Over 70% of all visitors are from top and middle management.

Visitors to K2022 gave top marks for the comprehensiveness of the product ranges and the event’s coverage of the entire supply chain. 98% of all professionals reported that they had fully achieved the goals they had set for their visit.

Over the course of the eight-day trade fair, it became clear that this year’s K had hit the mark with its selection of key topics: the circular economy, climate protection, and digitalization. In terms of investment plans, machinery and equipment for processing and recycling stood out, accounting for 43%. The focus was particularly on sustainability, but also on the circular economy and energy and resource efficiency in production. Around 40% of decision-makers said they were exploring the topic of decarbonization.

The K specials, which also focused on the three key topics, were very well received. The official special show, “Plastics Shape the Future,” addressed the economic, social, and ecological challenges and potential solutions related to the K guiding topics through high-caliber discussions and lectures, and this show was well attended throughout.  The Circular Economy Forum, where the VDMA and 13 of its member companies impressively demonstrated the importance of technology in implementing the circular economy in the plastics industry, won over the international audience with live demonstrations, a wealth of expert knowledge, and detailed information on the topic.

At this year’s K in Düsseldorf, there was also a great deal of discussion about the global industrial standard, OPC UA. This standard enables the operating parameters of the machinery and equipment involved to be coordinated more precisely and in a more targeted manner. This, in turn, is considered an important prerequisite for optimized circular management. Forty companies from eight countries participated in an OPC UA demonstration project at the trade fair.

At the Science Campus, both exhibitors and visitors at K2022 were given a concise overview of scientific activities and findings in the plastics and rubber sector. Numerous universities, research institutes, and funding agencies provided opportunities for direct dialogue there.

Many students, trainees, and college students took advantage of the Plastics Training Initiative (KAI) to learn about job profiles and career opportunities in the plastics industry.

The next K Düsseldorf will take place from October 8 to 15, 2025.

Moldsonics at K2022

Moldsonics at K2022

Photo of the founders of Moldsonics GmbH with the three founders

70 years of K in Düsseldorf—a reason to celebrate! We’re marking this anniversary by having our own Moldsonics booth at the trade show for the first time.

K is regarded as the world’s leading trade fair for the plastics and rubber industry. The developments and innovations showcased there set the course for a sustainable future in which plastics play a key role. The three key themes of K 2022 are the circular economy, climate protection, and digitalization.

We at Moldsonics will be showcasing our new products at the anniversary trade show. Among other things, we will be introducing our newly released product,MoldFront, as well as our upcoming solutions.

Click here for an overview of our current product offerings:

Visit us at booth 12D36-05 in Hall 12 and talk to us about the latest developments in ultrasonic sensor technology!

We look forward to seeing you!

K2022 Trade Fair in Düsseldorf

Date: October 19–26, 2022

Location: 40474 Düsseldorf, Am Staad (Stockumer Höfe)

Location:Hall 12 / D36-05

 

General information on how to get there can be found here: Getting to K2022

 

k2022 Moldsonics Plan