Revolutionary molding technology
The first ultrasonic molding machine is geared up to revolutionize the concept of polymer transformation. Ultrasion has developed a new technology called ultrasonic molding to produce plastic parts by melting raw material in a process that relies solely on ultrasonic waves. This is a totally new approach, and B&R products played a key role in its implementation.
Ultrasion SL is the first company in the world dedicated to designing, manufacturing and commercializing industrial solutions based on high-powered ultrasonic waves. The company, founded in 2010, is the result of years of applied research into the advantages of ultrasonic waves as a clean and highly efficient source of energy for processing polymers.
Ultrasonic energy savings
The first machine that Ultrasion has put onto the market is called Sonorus, and utilizes USM (ultrasonic molding) technology to produce plastic parts using ultrasonic waves. Replacing the conventional resistor-based plasticizing unit with an innovative ultrasonic system drastically increases the energy efficiency of the process. In addition, the dramatic effect of the ultrasonic waves on the fluidity of the plastic allows for highly precise replication of the details in the mold cavity without forcing the injection conditions. Moderate injection pressure, regardless of the material being injected, makes it possible to build a compact and fully electric machine that is well-suited to applications with high accuracy requirements.
The energy needed to melt the thermoplastic polymer molecules and cause the material to flow is transmitted from an acoustic unit. Plastic pellets are dosed into the mold, completely melted and then injected during each cycle, which minimizes the residence time of the molten plastic. This is an advantage over the conventional injection process where extended residence times can cause material degradation or necessitate high temperatures not otherwise required by the application. This advantage gives Sonorus the ability to quickly implement color and material changes, often without having to purge the machine. Since the molten material remains in contact with the ultrasonic transducer for only a few tenths of a second, the amount of energy consumed is approximately one percent of that consumed by conventional injection molding machines.
Setting up and controlling the machine required operators to adapt their understanding of the process itself. Several new terms such as amplitude and frequency now play an important role in controlling the process. However, after the initial learning curve operation is quite simple, because only a few parameters are needed to control the machine and the process.
Ultrasion has tested a wide range of semi-crystalline and amorphous materials with settings relevant to the machine parameters, and the overall results have been positive. The first version of Sonorus is designed for the production of mini- and micro-scale pieces, but it is also currently being evaluated for potential applications with larger injection volumes. Overall, Sonorus and USM technology have high commercial potential because of their technical input, return of investment and the wide range of new applications.
From pneumatic to electrical axes
The main component of Sonorus is a special ultrasonic unit that operates at 30 kHz using no more than 1 kW of power. Only a fraction of this power is used for the USM process itself, however. The ultrasonic wave is produced with a transducer and then amplified enough to be applied to the polymer through a special tip called a sonotrode. It is absolutely essential to control the pressure applied to the plastic and the axis position with a high level of accuracy during injection; otherwise, the ultrasonic waves will not work properly. Initial USM tests started on a prototype machine based on pneumatic cylinders for linear movements. For Ultrasion it soon became clear, however that they would need a totally new approach for the process in order to control pressure and displacement of the ultrasonic unit with sufficient accuracy. Moving to electric servo motors and precise ball screws meant redesigning the control strategy in order to take advantage of the new concept and ensure process repeatability and produce high-quality molded parts. In addition, Ultrasion introduced special sensors to monitor the process in a feedback loop. At this point, B&R products played a key role in the project, providing excellent support and assistance with its advanced Automation Studio software and its extended libraries and auto-tuning tools. Throughout this process, Ultrasion's engineers focused not only on the process, but also on visualization and operation. Since then, the USM process has evolved from an initial concept into a full-fledged new technology ready for the market.
"When we started this new project, we had very few points of reference to follow. It was a huge advantage to be able to rely on flexible hardware and a high-performance development environment like Automation Studio, with its integrated debugging tools," says Ultrasion's sales director Enric Sirera.
Not only did Ultrasion have design the control strategy, they also needed to create various microelectromechanical systems to integrate in the final machine. One of these is the feeding system that provides the precise pellet doses for every cycle. Integrating them into the Automation PC used by Sonorus was no problem at all.
"The combination of reduced development times and exceptional flexibility is a key aspect when designing a new high-performance machine concept like Sonorus," explains Sirera. "It was a challenge to quickly implement the process settings for every polymer, but Automation Studio turned out to be a great tool for analyzing issues related to debugging and the process itself."
"B&R components were selected for several reasons, but mainly because of the excellent local support," concludes Sirera.
Automation Studio fulfills several important goals at once: keeping quality high, engineering costs low and time to market short. These were the main reasons why Ultrasion chose Automation Studio for their high-performance machine concept Sonorus – it offers great possibilities for analyzing issues related to debugging and the process itself.