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Robot-based plastic injection molding

Plastics processing with injection molding is the supreme discipline of injection molding processes. The Hauff company has completely automated the production of upper basket rollers for dishwashers. This is made possible by a KUKA robot and a multifunctional production cube.

When Jörg Vetter drives up to Robert-Bosch-Strasse 3 in Pforzheim’s Büchenbronn industrial park at seven in the morning, he always gazes up at the windows of the building’s second floor first. “I enjoy watching it in operation every time.” The huge cell bringing a smile to the face of the Technical Manager at the injection molding company Hermann Hauff GmbH & Co. KG every morning is an Arburg Allrounder Cube 2900 injection molding machine. Since 2019, it has been in service at Hauff, producing rollers for the upper baskets of dishwashers.
These small, gray plastic elements consist of two interconnected parts, a freely movable wheel and a fixed bushing. Essential for easy loading and unloading of dishwashers, the parts of the rollers are molded in the Cube and then immediately assembled using a counter-rotating tool. Molding and assembly thus take place in a fully automated, two-stage process that Hauff set up jointly with injection molding machine manufacturer Arburg.
The KR QUANTEC operating with injection molding machines.

Unique system with large dimensions

“Our system and all the associated processes are unrivaled worldwide,” says Jörg Vetter proudly. “It saves us four to five injection molding machines and relieves our employees of monotonous production tasks.” A look at the figures helps to gauge the dimension of this innovation. 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 Hauff family business thus remains fully on course for the future. 
The Hermann Hauff company in Pforzheim manufactures plastic parts with injection molding machines.
The 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. In 2000, the mold making division was strengthened by the subsidiary ProForm Formenbau GmbH and since that time has been driving new technologies forward in the production of injection molds completely in 3D. Hauff’s customers come from a wide variety of industrial sectors: from domestic appliance manufacturers with their “white goods”, from the automotive industry and from the field of medical technology.

Hidden champion with aspirations

“In plastics processing, we start where others stop,” notes Jörg Vetter in describing the hidden champion’s corporate philosophy. After 20 years with the company, he knows its ins and outs along with its potential. He thus knows that “ice cream spoons can be easily and cheaply produced anywhere in the world. 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.”

70,200 plastic rollers leave the Hauff plant every day.
One factor helping to meet this goal every day here in Pforzheim is robomotion GmbH. The technology developer from Leinfelden-Echterdingen in Germany specializes in the design and construction of customized automation solutions for the food, pharmaceutical and packaging industries – with a particular focus on the plastics sector. This is why the robotics experts from the neighboring Stuttgart metropolitan region are also sought-after and valued development partners for Hauff in the creation of customized, automated production processes.

A fully 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 breaking with 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,” says Andreas Wolf.
Precision and pace in plastic injection molding
Andreas Wolf also notes that, together with Jörg Vetter and his team, robomotion intensively scrutinized the entire process in order to develop and configure a system integrating the injection molding machine, the assembly tool and the associated robot cells as well as the required grippers and the palletizer. “That was extremely challenging,” recalls the robomotion Managing Director.

A tailor-made cube solution

“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.” Vetter further explains that expertise flowed into the project from various directions. First among these sources of expertise: the experienced machine builder Arburg. To meet Hauff’s specific requirements, Arburg configured the “Cube” – a tool uniting the production of two components with their assembly. The name “Reverse Cube 2900” 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 directly 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.
From manufacturing to packaging: in a short time, the robots get the job done

Right in step with KUKA robotics

This production innovation, however, was not just about building the actual machine, but rather the entire manufacturing process – from handling the Cube to packaging and palletizing the finished products. To achieve this, Jörg Vetter and the robomotion experts had to delve deep into the operational details.
“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.
With the support of KR QUANTEC PA, upper basket rollers for dishwashers are manufactured
The Cube thus works together with a six-axis KR QUANTEC, which achieves maximum repeatability and continuous precision thanks to its robust design. Using a special gripper, it removes the rollers from the lower part of the Cube simultaneously with the injection molding cycle. It then inserts the rollers into the bushings located in the upper half, unloads the finished elements and places them on the conveyor belt to the packaging operation. “With its extreme speed, the robot reduces the cycle times in production and increases manufacturing quality, without ever getting out of step,” states Wolf. He also stresses that this is a key requirement for Hauff. This results in the production of 24 high-quality upper basket rollers every 9.5 seconds – as if from a single mold.

Plastics processing with a KR QUANTEC PA

The conveyor connects the production cell to the packaging and palletizing cell, where a KUKA KR QUANTEC PA – 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 in explaining the choice of equipment. At Hauff, the KR QUANTEC PA independently folds the shipping cartons, places them under the conveyor belt, seals them when they have been filled with exactly 1,560 rollers and then stacks them on a europallet. 
From plastic injection molding to palletizing with robots
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 Cube is able to handle a full shift on its own just fine.”

Error avoidance through simulation

To be able to introduce this complex new production step into an ongoing manufacturing operation, it is essential to plan as precisely as possible. Jörg Vetter, also a passionate golfer, thus approaches automation tasks with a clear commitment to perfection and a forward-looking tactical approach. At his side, he has a congenial partner in Andreas Wolf, who integrated KUKA.Sim – a smart planning software package for the offline programming of KUKA robots – into the system development right from the beginning. “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.”
With KUKA.Sim, the KUKA robot with a new injection molding machine was easily integrated into the system

Automation with a spark of enthusiasm

Even today, 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. Given the way his face shines and his eyes light up, it is easy to see how he spreads his spark of enthusiasm for automation. “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.” So it seems the excitement here in Pforzheim will continue.

With its extreme speed, this robot reduces cycle times in production while increasing manufacturing quality without ever getting out of sync.

Andreas Wolf, Managing Director robomotion GmbH

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