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Plastic injection molding with robot-based injection molding machine
Plastics processing by injection molding is the ultimate challenge in the field of injection molding techniques. The family-owned company Hauff has fully automated the production of rollers for the upper baskets of dishwashers. This is made possible by a KUKA robot and a multi-functional production cube.
Injection molding process with plastic and great expertise in Pforzheim
When Jörg Vetter drives up to the industrial park in Pforzheim in southern Germany, he gazes up at the building’s windows. “I enjoy watching it in operation every time.” The cell bringing a smile to the face of the Technical Manager at the injection molding company Hermann Hauff GmbH & Co. KG is an Arburg Allrounder Cube 2900 injection molding machine. Since 2019, it has been producing rollers for the upper baskets of dishwashers at Hauff. These plastic elements consist of two interconnected parts, a freely movable wheel and a fixed bushing. The rollers, which are essential for easy loading and unloading of dishwashers, are molded in the injection molding machine. Molding and assembly take place here in a fully automated process that Hauff set up jointly with injection molding machine manufacturer Arburg.
KR QUANTEC PA brings plastic into perfect form with the injection molding machine.
Unique large-scale system with injection molding machines
“Our system and all the associated processes are unrivaled worldwide,” says Jörg Vetter. “It saves us four to five injection molding machines and relieves our employees of monotonous production tasks.” Every year, Hauff produces around 60 million components for BSH Hausgeräte GmbH alone using the Cube. In the next three years, production is to be ramped up to 75 million units. The family-owned company was founded by Hermann Hauff in Pforzheim, Germany in 1966 and today produces high-quality precision injection moldings as well as injection molds under the direction of his daughters, Andrea Hauff and Carmen Hauff-Bischoff. Hauff’s customers come from the domestic appliance (white goods) sector, from the automotive industry and from the field of medical technology.
Hidden champion with the highest standards in plastic injection molding
“In plastics processing, we start where others stop,” notes Jörg Vetter in describing the corporate philosophy. After 20 years with the company, he knows that “ice cream spoons can be produced easily and cheaply. But when it comes to sophisticated and intricate high-tech components with a shot weight of 0.0004 to 400 grams, you have to be able to rely on quality – and not just anyone can deliver that.” One factor helping to meet this goal every day here in Pforzheim is robomotion GmbH.
The technology developer specializes in the design and construction of customized automation solutions – with a particular focus on the plastics sector. This is why the robotics experts are sought-after and valued development partners for Hauff in the creation of automated production processes.
An autonomous process based on one-piece flow
“Our task was to redesign the production and assembly of the rollers for upper baskets of dishwashers with the aim of achieving greater quantities and high efficiency while at the same time making optimal use of the limited production space,” explains robomotion Managing Director Andreas Wolf. “It was about leaving manual operations and setting up autonomous production from the injection molding machine to the pallet – and doing this in a one-piece flow, in other words as a continuous, uninterrupted process.” Together with Jörg Vetter and his team, robomotion analyzed the entire process in order to develop a system integrating the injection molding machine, the tool and the associated robot cells as well as the required grippers and the palletizer.
A customized machine for plastic injection molding
“The development of the complete system took more than two years; the software alone accounting for one year,” reports Jörg Vetter. “It was a constant process of weighing options and reconceptualizing.” To meet Hauff’s specific requirements, the machine builder Arburg configured the “Cube” – a tool uniting the production of two components with their assembly. The name “Reverse Cube 2900” of the injection molding machines says it all. The steel cube can be counter-rotated about its central axis in the reverse direction, enabling the parts molded here to be assembled in two work steps with the aid of a special gripper before being transported via a conveyor belt to the packaging and palletizing cell. “This is unique in the world and can only be found at our company,” Vetter states proudly.
Bringing plastic into perfect shape with injection molding robots
“To be able to operate with maximum efficiency and operational reliability in the confined space, we put the process in the ‘hands’ of KUKA robots. That gave us a lot of design options,” explains Andreas Wolf. The injection molding machine thus works together with a six-axis KR QUANTEC, which achieves maximum repeatability and continuous precision. Simultaneously with the injection molding cycle, it removes the rollers from the lower part of the Cube, inserts them into the bushings and then unloads the finished plastic elements, placing them on the conveyor belt to the packaging operation. In this way, 24 high-quality rollers for upper baskets are produced every 9.5 seconds.
Plastics processing with the KR QUANTEC PA
The conveyor connects the production cell to the packaging and palletizing cell, where a KR QUANTEC PA robot – one of the fastest palletizers on the market – carries out its work. “The slim palletizing robot is extremely versatile and dynamic, with a very small interference contour,” says Andreas Wolf. At Hauff, the robot folds the shipping cartons, places them under the conveyor belt, seals them when they have been filled and then stacks them on a europallet. Three pallets, each containing 45 cartons and 70,200 plastic rollers, leave the plant every day.
“The system runs completely autonomously, without the need for any further support,” says Andreas Wolf. “We have planned a buffer time of eight hours. An employee then has to remove the fully loaded pallets from the system. This means that the injection molding machine is able to handle a full shift on its own just fine.”
Error avoidance through simulation during planning
To be able to introduce this complex production step into an ongoing manufacturing operation, it is essential to plan as precisely as possible. This is why Andreas Wolf integrated KUKA.Sim – a smart planning software package for the offline programming of KUKA robots – into the system development. “Precisely because the space in the production hall is so limited, it was important to try out the system and its functionalities before actually realizing them. For example, we were able to perform a cycle time analysis as early as the engineering phase and include it in the layout and design. It was 'learning by doing' in a virtual space,” Wolf says. “Without KUKA.Sim, the system configuration would certainly have been much more time-consuming and costly – or perhaps even have gone wrong. Particularly for a medium-sized company, that is just not an option.”
Automation of plastics processing with a spark of enthusiasm
The accompanying in-depth understanding of the Cube system and its possibilities helps Jörg Vetter to get Hauff’s employees excited about the automation. “There is always a bit of convincing required to show that the new technology is not directed against people, but serves them and makes their work easier and more varied,” the technical manager explains. He also notes that this is a particularly important factor in times with an increasing shortage of skilled workers. “We are always optimizing. I’m already thinking a few steps ahead and am in consultation with our management and our technology partners as to how we can produce as many products as possible on one machine. If we see new opportunities that pay off, we will take advantage of them.”
With its extreme speed, the robot reduces the cycle times in production and increases manufacturing quality, without ever getting out of step.