Robot-based plastic injection molding

Plastics processing by injection molding is the ultimate challenge among injection molding techniques. Hauff, a family-owned company in southern Germany, fully automated the production of rollers for the upper racks of dishwashers. A KUKA robot and a multi-functional production cube made this achievement possible.

Injection molding process with plastic and great expertise in Pforzheim

When Jörg Vetter, Technical Manager at the injection molding company Hermann Hauff GmbH & Co. KG, drives up to the industrial park in Pforzheim in southern Germany, he gazes up at the building’s windows. “I enjoy watching that cell in operation every time,” Vetter said. At Hauff, the cell in question is an Arburg Allrounder Cube 2900 injection molding machine that has produced rollers for the upper racks of dishwashers since 2019. Molded in an injection molding machine, these plastic elements consist of two interconnected parts – a freely movable wheel and a fixed bushing – and are essential for easy loading and unloading of dishwashers. Molding and assembly take place here in a fully automated process that Hauff set up jointly with Arburg, an injection molding machine manufacturer.

Unique large-scale system with injection molding machines

“Our system and all its associated processes are unrivaled worldwide,” said Jörg Vetter. “It saves us four to five injection molding machines and relieves our employees of monotonous production tasks.” Every year, Hauff uses the Cube to produce about 60 million components for BSH Hausgeräte GmbH alone. Over the next three years, production will ramp up to 75 million units.

Hermann Hauff founded the company in Pforzheim, Germany, in 1966. Today, still family owned, the company that bears his name 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, 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 molding

“In plastics processing, we start where others stop,” noted Jörg Vetter in describing the Hauff corporate philosophy. After 20 years with the company, he knows that “you can produce ice cream spoons easily and cheaply. But for sophisticated, intricate high-tech components with a shot weight of 0.0004 to 400 grams, you have to rely on quality – and not just anyone can deliver that.” Along with Arburg, another partner that helps Hauff meet this goal every day in Pforzheim is robomotion GmbH.

High-quality plastic production processed with the right tools

This technology developer specializes in the design and construction of customized automation solutions, with a particular focus on the plastics sector. That's what makes these robotics experts such sought-after, 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 rollers for upper racks of dishwashers to achieve greater quantities and high efficiency, and also make optimal use of limited production space. Arburg made this possible with the integrated Reverse Cube from Foboha. “This was about breaking with manual operations, setting up autonomous production from the injection molding machine to the pallet and doing it in a one-piece flow: in other words, as a continuous, uninterrupted process,” explained robomotion Managing Director Andreas Wolf. Together with Jörg Vetter and his team, Arburg scrutinized the entire process to develop a system that integrated the injection molding machine, the Cube from Foboha, the associated robot cells, 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 molding

“The development of the complete system took more than two years, with one year for the software alone,” reported Jörg Vetter. “It was a matter of constantly weighing things and reconsidering them.” To meet Hauff’s specific requirements, Foboha configured the “Cube” – a tool that unites the production of two components with their assembly. The injection molding machines' name – “Reverse Cube 2900” – says it all. The steel cube can be counter-rotated around its central axis in the reverse direction, so the parts molded here can 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 stated proudly.

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

Bringing plastic into perfect shape with injection molding robots

“To operate with maximum efficiency and operational reliability in a confined space, machine builder Arburg and we put the process in the ‘hands’ of KUKA robots. That gave us a lot of design options,” explained 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 rollers from the lower part of the Cube, inserts them into bushings and then unloads the finished plastic elements, placing them on the conveyor belt to the packaging operation. This system produces 24 high-quality dishwasher rollers 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 robomotion packaging and palletizing cell, where a KR QUANTEC PA robot – one of the fastest palletizers on the market – gets to work. “The slim palletizing robot is extremely versatile and dynamic, with a very small interference contour,” said 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 introduce this complex production step into an ongoing manufacturing operation required precise planning, so Arburg and robomotion integrated KUKA.Sim – a smart planning software package for offline programming of KUKA robots – into the system development. “Precisely because space in the production hall is so limited, it was important to try out the system and its functionalities before we actually set them up. For example, we performed a cycle time analysis as early as the engineering phase and included it in the layout and design. It was 'learning by doing' in a virtual space,” Wolf said. “Without KUKA.Sim, the system configuration certainly would have been much more time consuming and costly – or perhaps even would 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 Jörg Vetter get Hauff’s employees excited about the automation. “There is always a bit of convincing required to show that new technology is not directed against people, that instead, it serves them and makes their work easier and more varied,” the technical manager explained. He also notes that this is a particularly important because of 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 about 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 production cycle times and increases manufacturing quality, without ever getting out of step.

Andreas Wolf, Managing Director of robomotion GmbH