Mitsubishi Heavy Industries Plastics Technology Co., Ltd. (MHIPT) of Japan specializes in the development and construction of injection molding machines. These solutions are primarily used in the automotive industry, as well as the home appliance and PC industries. For its latest MEIII machine series, the company selected Beckhoff's PC-based control technology, believing that the openness of the control architecture is forward-looking and provides everything needed for the connected production facilities. In addition to improving repeatability and production flexibility, MHIPT also considered simplifying the integration of condition monitoring functions and implementing predictive maintenance, which would be a significant step forward.
An injection molding machine essentially combines an injection unit and a clamping unit. The injection unit heats and plasticizes the material, then injects it into the mold through a high-pressure nozzle. The clamping unit opens and closes the mold, keeping it locked during injection. The clamping force is an indicator of machine size and power. MHIPT offers machines with clamping forces ranging from 350 to 3500 tons.
Open automation platforms bring competitive advantages
The MEIII is MHIPT's latest medium-sized injection molding machine, with clamping forces ranging from 550 to 850 tons. While most injection molding machines are equipped with hydraulic drives, the MEIII uses servo motors for drive control. "This improves production efficiency while reducing power consumption," said Takashi Mizuno, Director of Engineering and CEO of MHIPT. "In terms of automation, MHIPT has changed its previous development approach for the MEIII machine series. We now use PC-based control systems across our entire product line. Previously, we developed our controllers entirely in-house; using PC control systems allows us to focus entirely on software development. Our goal is to integrate all the expertise our company has accumulated in injection molding machines into the injection molding process software, enabling us to stand out in the competitive market."
Like the previous MEII series, the MEIII series is equipped with MHIPT's proprietary DD (direct drive) motors. These motors eliminate the need for a gearbox because they can generate significant force at low speeds; this provides the advantages of dynamic injection drive, making maintenance easier as pulleys, conveyor belts, and other consumables are eliminated. A key design feature of the MEIII series is its replacement of the mechanical connection system between the two direct drive motors with high-precision software synchronization. "The speed, reliability, and accuracy of the servo electric control system directly determine the quality of the product," emphasizes Takashi Mizuno.
Open control technology: independent of supplier-specific standards and specifications
Takashi Takiiad, Design Director of Engineering at MHIPT and Project Manager for MEIII Development, explained: “The biggest advantage of an open control architecture is that we and our customers can operate independently of supplier-specific standards or specifications. PC-based control systems are highly efficient, open control systems that offer high flexibility and versatility, providing us with the reliability and quality we need.”
High efficiency in machine development
Thanks to the high flexibility and scalability of its PC control platform, MHIPT can offer its customers approximately 200 optional specifications to achieve the geometry of the plastic workpieces to be produced using different tools or molds. “This is roughly three times the number of options available with traditional control systems. Specifications that previously required additional costs are now available to our customers at standard prices and delivery times. Furthermore, the use of open standards provides us with sufficient flexibility to meet our customers’ requirements regarding sensors and servo motors. By using EtherCAT and TwinCAT as a common communication system and a common software platform, respectively, a unified data flow is achieved, greatly improving the repeatability of machine operations,” explains Takashi Takii.
“In short, the use of a PC platform has greatly improved machine engineering efficiency,” said Takashi Takii. “The use of distributed I/O stations for communication via EtherCAT simplifies the modular design of the control cabinet, thereby not only improving flexibility—such as the ability to make temporary modifications—but also reducing the time required for machine manufacturing, disassembly, transportation, and installation. The high scalability of the PC control platform ultimately allows multiple injection molding machines of varying sizes and applications to be controlled using a single PC-based central control system.”
MHIPT's machine software needs to manage over 30,000 data points to enable the versatility and flexibility of injection molding applications. MHIPT uses an Oracle database for critical software design and configuration. "The tight connectivity required for the database cannot be achieved with tools offered by traditional control system vendors," explains Takashi Takii. "For us, the seamless connectivity of TwinCAT is a huge step towards fully or semi-automated software configuration. In addition, in-circuit debugging tools, oscilloscope software, and other development tools provide valuable functionality."
Open control architecture helps realize new business models
Takashi Takii also saw the potential business advantages of a PC-based control architecture. “Large injection molding machines are a typical example of small-batch and high-volume production, almost equivalent to specialized machine manufacturing. Our ideal solution is to meet every customer requirement. Traditional control technologies often limit us, while the controller used in the MEIII enables efficient and flexible software development. Different options for the injection molding process can be automatically generated using software, without programming. I can confidently say that the software design has improved customer satisfaction. The magic triangle of quality, cost, and time has made a leap forward.”
Preparing for Industry 4.0
Takashi Takii also sees the advantages of open control architecture in the current manufacturing trend. “The open, flexible control data flow enabled by EtherCAT and TwinCAT is not limited to individual injection molding machines, but also achieves modularity and uniformity of data flow throughout the entire factory. This allows us to provide highly responsive support for the technological goals set by Germany’s Industry 4.0 and the US’s Industrial Internet of Things (IIoT). I believe this will be about leveraging big data to extend the Mean Time Between Failures (MTBF) and shorten the Mean Time To Repair (MTTR). We must position ourselves to be able to collect, store, and analyze large volumes of data in order to determine how our machines change over time, how we use them, and how we can standardize and compare data collected in different production environments,” Takashi Takii concluded when outlining the future strategy.
