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Weiss chooses Yaskawa jointed-arm robots

Flexible automation in plastics processing

Installed housing for gripper valve terminals on robot arm (Source: Weiss Kunststoffverarbeitung GmbH & Co. KG)

A new automation concept is increasing production flexibility in plastics processing for Weiss Kunstoffverarbeitung GmbH & Co. KG. The company has decided to use Yaskawa jointed-arm robots in its injection moulding and assembly. The first robots are already in use.

Weiss develops and manufactures high-quality functional plastics components at two production facilities in Illertissen, Germany and Győr, Hungary. Its customers include automotive and mechanical engineering companies. To meet their demanding standards for component quality, functionality and accuracy, Weiss always uses very high-quality plant technology – from injection moulding and automated assembly to testing systems.

Until recently, Weiss used automated linear handling systems to remove injection moulding parts from the machine. The linear axes were purchased externally and the sequence programmes written internally. The company generally does many tasks in house, in order to stay flexible and ensure a high level of quality. For this reason, the gripper is also developed and manufactured in house.

 

New jointed-arm robot concept

Although the existing handling concept had proved its worth, more complex motion sequences and greater flexibility were increasingly needed for the injection moulding stage, and particularly for subsequent assembly processes. So the managers decided to develop a new concept using jointed-arm robots. Robert Heller, automation facilities construction manager, says, “We weren’t looking for ready-made solutions. We wanted a platform that we could use universally and throughout the entire automated handling process, from component removal through a wide variety of assembly tasks right up to packaging.”

On this basis, the managers began to survey the market and researched manufacturers and users. They did not just consider flexibility and investment costs, but also life cycle costs and reliability. This market research resulted in the decision to use Yaskawa: “Several respondents stated that these robots are built to last and require little maintenance. It was already clear to us that they are easy to operate and that the price is ‘right’.”

 

Motoman HP20D as standard

Weiss opted for the six-axle Motoman HP20D model, which many users have found excellent for handling of small to medium-sized components at a high operating speed. This universal robot requires minimal installation space and provides the largest workspace in its class: 1,717 mm. To move heavier loads or cover larger distances, Weiss uses the larger model, the Motoman UP50/MH50.

The first robot that Weiss ordered from Yaskawa was integrated into an assembly and packaging line. Its tasks include putting polyamide chain tensioners in special trays. The sensors integrated in the gripper check that the parts are complete and ensure that the sprue parts are removed. Parts that are identified as sub-standard, for example because the snap-fit hooks are incorrectly positioned, are removed.

The robot also stacks the full trays on a pallet and supplies the empty trays. For these different tasks, it needs a relatively long range and a greater degree of freedom than the portal robots that were used previously.

 

Optimal production and information flow integration

Since Weiss prefers to control plant engineering internally, easy programmability was an important selection criterion for a new standard robot. Robert Heller says, “The robot has to adapt to machine cycle times and therefore communicate with machine control. The robots are also involved in the CAQ quality assurance system. This means that a stand-alone solution is out of the question for us.” Two Weiss employees therefore completed programming training at the Yaskawa academy to gain the knowledge needed to write basic programmes that can be easily adjusted by the operator.

The first system was successfully installed within a short time. Heller says, “We had to rethink a bit, because a jointed-arm robot has completely different motion sequences. But with control engineering experience and technical knowledge it’s easy to address these teething problems. Getting the devices up and running is really straightforward.”

Weiss has taken on systems integration for the robot stations, integrating the moulding machine with the jointed-arm robot and safety technology. One key advantage of this is that Weiss can respond quickly to changes and new projects without having to rely on external assistance.

 

Transferring the concept to injection moulding

Following all-round positive experience with the first robot in assembly and packaging, the project managers transferred the handling concept to the injection moulding machines, where the robots remove the newly manufactured parts.

The advantage of jointed-arm robots in this process is that they can drop the extracted parts directly into the shipping units, such as mesh pallet cages. This simplifies and speeds up processes and saves space, because a conveyor belt is not required to transfer the parts. The direct connection to the machine controls and QA software also ensures that rejects are recognised and weeded out straight away for separate disposal.

 

A basic factory standard for all applications

Once the advantages of this application had been demonstrated, the Weiss managers developed a factory standard for using jointed-arm robots. In both applications – injection moulding and assembly/packaging – the same programmes are used. Robert Heller says, “We have determined a standard naming convention for programming and standardised the control link to the assembly line. Building on this basic development, each operator can customise the programme to the individual application.”

This concept has now been implemented in five other injection moulding systems. Here, and on the assembly line, it has more than proved itself in practice. So, over the next few months, Weiss will not only equip new plants with Yaskawa industrial robots, but also gradually replace older linear handling technology systems with jointed-arm robots.