Joint development of a moulding cell for testing with high performance polymers

Creating tomorrow’s polymer innovations starts with understanding the chemical and mechanical performance and processing conditions of materials. At the Injection Moulding & Extrusion Pilot Plant of Basf in Ludwigshafen, Germany, the newest all-electric fully-automated injection moulding cell from Sumitomo (SHI) Demag is delivering pioneering and repeatable results on over 4,000 test settings a year.

Pooling their engineering competences and technological resources, Basf’s Performance Materials division in collaboration with Sumitomo (SHI) Demag and H + S Automatisierung have created an innovative manufacturing cell to produce a wide range of different test specimens for the product development and research activities of thermoplastic polymers and compounds.

Taking centre stage in the cell is Sumitomo (SHI) Demag’s ultra-precise IntElect 1000 kN injection moulding machine. Selected for its compact design, energy efficiency and repeatability, the team of 30 research operatives at the facility have also welcomed the IntElect’s enhanced welfare and safety features. Among them progressive solutions to automate mould changes and low noise emissions combined with fully-digitised robotic processing solutions.

For operative safety and efficiency, a linear SDR 5-35S robot serves two purposes. A new feature is fully automating the selection and placement one of 12 interchangeable mould inserts from a magazine located within the cell. After the part is moulded, the same robot fitted with a multifunctional gripper, gently extracts the test specimen from the mould and passes it to the small six-axis articulated-arm Yaskawa GP8 robot for precise cut of the specimens from the gate using a servo spindle drive punching machine.

Integrating Basf’s existing mould insert concept and special features into the injection unit, the installation also includes an existing thermal temperature control unit and a new digital Manufacturing Execution System (MES) to map each test sequence. Reinhard Jakobi, Head of Performance Materials Processing at BASF, describes the project as an achievement of advanced engineering combining mature technology with state-of-the-art automation and moulding precision. He credits the dedication, flexibility and solutions orientated approach of the entire team to the delivery of such a pioneering project.

Angelika Homes, Senior Project Engineer at Basf expands: “Although we have extensive experience collaborating with the Sumitomo (SHI) Demag team producing standard test parts, from the outset all of the partners had the courage to deviate from previous concepts and break new ground. Despite the complexity of the project, Sumitomo (SHI) Demag and H + S delivered an innovative production cell design in a much smaller energy and spatial footprint.”

Too hot to handle

Many of the specimens processed at Basf’s technical centre are high temperature thermoplastics, fibre reinforced and often flame retardant. Consequently, melt temperatures can reach up to 400°C with mould temperatures hitting up to 180°C.

At any time, up to 12 interchangeable inserts can be loaded to the side magazine and then swapped automatically into the injection moulding machine. By integrating a HB-Therm temperature control system with Sumitomo (SHI) Demag’s machine control, automated mould insert changes can be completed safely and efficiently, even when running the process at high mould temperatures.

Automation Systems Senior Engineer at Sumitomo (SHI) Demag Markus Hausmann explains: “In order to lower the temperature to 80°C and depressurize the insert to guarantee that the SDR robot could remove the mould insert safely, our machine control has to talk and interact seamlessly with Basf’s MES.

Basf’s MES informs the cell when the current produced sample setting is about to end, lining up the next mould application. Immediately after the injection process stops, cooling of the mould insert is directed by the integrated temperature control unit interface.

Then, the change of the mould inserts is synchronised to the cell control via output and input signals with transmission of the new mould data record via the robot interface. After the change of the mould insert, the temperature control units are heated up again. Automatic operation resumes and a new mould data record is initiated as soon as the target temperature is reached.

Punching with precision

For Basf, solving the punch challenge was one of the greatest engineering accomplishments. Due to its extensive application profile, BASF tests a wide range of materials - from soft and tough to stiff and brittle polymers. There are also many different sample geometries, including thicknesses varying from 0.8 mm to 4 mm. All Basf test specimens are manufactured in accordance with the ISO 294 standard. This specifies the precision of the sprue system and specific requirements each sample geometry must fulfil. “Removal by punch is a pre-requisite, as it does not change the material properties and eliminates dust particles,” explains Markus Hausmann.

The multifunctional gripper ensures all sample geometries are placed with exacting precision onto the punch plate. This is complex in itself due to many of the materials BASF works with having high fibre glass content which can cause warpage. Describing how the servo driven parallel punch gripper overcomes the challenge of placing parts securely onto the punch plate, Markus Hausmann notes: “If the test specimens are not held sufficiently well in place the punchings could be crooked or not conform to specified quality standards.”

Digital integration

Being a pilot centre, the BASF research team typically sets up 20 test settings daily on this machine. That means the control program of the cell has to be adapted to different materials, sample geometries, temperatures and processing parameters. Every single setting that runs is recorded and documented digitally.

Angelika Homes comments: “Unlike our former MES systems, this one logs every single aspect of a trial and the results, giving us insight for every single shot. This data is extremely valuable as it represents the entire processing sequence and enables us to draw deeper conclusions about how materials perform under certain conditions and how a customer might later process it.”