Robot-based plastic injection moulding

Plastics processing by injection moulding is the ultimate challenge in the field of injection moulding 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 moulding process with plastic and great expertise in Pforzheim

When J?rg 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 moulding company Hermann Hauff GmbH & Co. KG is an Arburg Allrounder Cube 2900 injection moulding 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 moulded in the injection moulding machine. Moulding and assembly take place here in a fully automated process that Hauff set up jointly with injection moulding machine manufacturer Arburg.

Unique large-scale system with injection moulding machines

“Our system and all the associated processes are unrivaled worldwide,” says J?rg Vetter. “It saves us four to five injection moulding machines and relieves our employees of monotonous production tasks.” Every year, Hauff produces around 60 million components for BSH Hausger?te 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 mouldings as well as injection moulds under the direction of his daughters, Andrea Hauff and Carmen Hauff-Bischoff. Hauff’s customers come from the domestic appliance (white goods) sector, the automotive industry and the field of medical technology.

The Hauff company in Pforzheim manufactures plastic parts with injection molding machines

Hidden champion with the highest standards in plastic injection moulding

“In plastics processing, we start where others stop,” notes J?rg 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.” Apart from Arburg, one factor helping to meet this goal every day here in Pforzheim is robomotion GmbH.

Plastics processed in high quality with the right tools

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

The 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. Arburg made this possible with the integrated Reverse Cube from Foboha. “It was about breaking with manual operations and setting up autonomous production from the injection moulding machine to the pallet – and doing this in a one-piece flow – in other words as a continuous, uninterrupted process,” explains robomotion Managing Director Andreas Wolf. Together with J?rg Vetter and his team, Arburg scrutinized the entire process in order to develop a system integrating the injection moulding machine and the Cube from Foboha, the associated robot cells as well as the required grippers and, together with robomotion, the palletizer.

Precision and speed in the field of plastic injection molding

A customized machine for plastic injection moulding

“The development of the complete system took more than two years; the software alone accounting for one year,” reports J?rg Vetter. “It was a matter of constantly weighing things up and reconsidering them.” To meet Hauff’s specific requirements, Foboha configured the “Cube” – a tool uniting the production of two components with their assembly. The name “Reverse Cube 2900” of the injection moulding machines says it all. The steel cube can be counter-rotated about its central axis in the reverse direction, enabling the parts moulded 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.

From manufacturing to packaging: robots take care of the work in a short time

Bringing plastic into perfect shape with injection moulding robots

“To be able to operate with maximum efficiency and operational reliability in the confined space, machine builder Arburg and we put the process in the ‘hands’ of KUKA robots. That gave us a lot of design options,” explains Andreas Wolf. The injection moulding machine thus works together with a six-axis KR QUANTEC, which achieves maximum repeatability and continuous precision. Simultaneously with the injection moulding 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.

Upper basket rollers for dishwashers are manufactured with the aid of the KR QUANTEC PA

Plastics processing with the KR QUANTEC PA

The conveyor connects the production cell to the packaging and palletizing cell from robomotion, 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.

From plastic injection molding to palletizing with robots

“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 moulding 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 Arburg und robomotion integrated KUKA.Sim?– a smart planning software package for 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.”

With KUKA.Sim, the KUKA robot with new injection molding machine was easily integrated into the system

Automation of plastics processing with a spark of enthusiasm

The accompanying in-depth understanding of the Cube system and its possibilities helps J?rg 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.

Andreas Wolf, Managing Director of robomotion GmbH