The production managers at Staud are convinced of this: Those who work in final assembly have an extremely value-adding job and should not be burdened with provisioning tasks. Staud has succeeded in implementing this with an intralogistics solution installed by Knoll, in which the two transport robots Bibi and Tina take on a central task.

Around 100,000 bedroom wardrobes leave the Staud production facility every year in commission-oriented production - with a high degree of variance, as Dirk Schmidtmeier says: "We manufacture different wardrobe systems that allow for more than 40 million variants. To be able to cope with this, we have developed a well thought-out system of identical parts made from elements we manufacture ourselves and those we supply." Staud obtains the chipboard for its furniture in different thicknesses and colors, all of which are already surface-finished.

In the so-called machine lines, equipped with sawing, milling and drilling centers, they are given the required format, edges and individual drill holes. As a bedroom wardrobe consists of units such as carcasses, doors and plinths, production at Staud is structured accordingly. In the "plinth line", the wardrobe bases and shelves as well as the cornice base are assembled. To do this, all the required, finished chipboard panels must be ready on time at the picking stations on the plinth line. The task of the Knoll automation project was to optimize the logistics between the machine line and the base line, including the buffer stations in between.

Previous solution was inflexible and time-consuming

Staud production is already fully automated. After the machine line, there are conveyor belts that transport formatted chipboard stacked on carrier boards. In the past, they were transported at the end of the machine line by elevator to an elevated conveyor with a buffer function. This was an approximately 100 meter long roller conveyor at a height of 3 meters. It contained around 70 carrier boards, which were brought back down at the other end by elevator to the base line.

Dirk Schmidtmeier explains the problem with this transport technology: "Two different production optimizations collided on our elevated conveyor, which led to considerable time losses." This is because the machine line is designed to optimize set-up times. This means that many identical items are produced one after the other, which are stored in four stacks one behind the other on the elevated conveyor. However, as the base line works on an order picking basis, its requirements are different: as a rule, a maximum of two stacks of identical parts are required. "This meant that the sequence on the elevated track never matched," complains Dirk Schmidtmeier. "In practice, this meant that if we wanted to get to the tenth stack, we had to take down nine stacks and put them down somewhere to get to the tenth."

Together with Daniel David, Head of Work Preparation, the Managing Director looked for a solution. In the end, the solution was: "The overhead conveyor has to go. We want to use automated guided vehicles (AGVs) to transport the stacks of chipboard on the carrier boards from the machine line to buffer areas, store them there temporarily and transport them to the picking stations on the base line as required - again using AGVs."

All challenges overcome in a short time

After some searching for a suitable contractor, it turned out that the ideal candidate was right on site: Knoll's automation department. The contract was awarded in May 2022. As Staud already knew exactly what was needed and had prepared perfect data material, the project planning phase only took a few months. During this time, Staud had the elevated track demolished and the entire floor renovated, as it was not suitable for AGVs. In addition, a secure, stable WLAN connection had to be installed, which would later be required as the basis for data exchange.

The installation lasted from Christmas to Epiphany. Since then, the two AGVs, christened Bibi and Tina by the employees, have been transporting the stacks of chipboard. "Of course, we had a few sticking points to overcome up until then," reveals Philipp Miller, Knoll Sales Automation. One challenge, for example, was the connection to Staud's existing conveyor technology. The height of the existing conveyor belts was too low for the AGVs to pass underneath them and pick up the carrier plates. "We developed a customer-specific lifting station for this," explains Philipp Miller. "Directly in front of the lifting station, we also installed a mechanical device that aligns the carrier plates precisely."

Dirk Schmidtmeier is very satisfied with this solution: "This is rock-solid mechanical engineering that not every automation company can offer." This expertise also paid off when it came to designing the buffer stations. Knoll succeeded in arranging 137 stations next to each other in the limited space available. Philipp Miller explains: "These buffer stations have to accommodate panel stacks weighing 800 kg, but without a lower support so that the AGV can drive underneath. We solved this with a type of cantilever rack." The narrow aisle to the buffer stations also influenced the choice of AGV. Christian Spohn explains that a new type X1 AGV developed by Safelog is being used here for the first time, which, among other things, enables space-saving turning on the spot.

Successful communication between AGV, PLC and PPS

One special feature was the networking of the two AGVs with the Knoll PLC and the production planning system from Staud. "Every stack of panels that comes from the machine line has a DMC barcode," says Christian Spohn, describing the process. "We scan it automatically at the transfer station and use it to manage the stack and the respective buffer location in a database. If the picking employee needs certain chipboards, he also requests them via a barcode to be scanned, and the AGV knows exactly which buffer location it has to go to for collection."

As two AGVs are on the move between the pick-up and drop-off stations and buffer areas, there are priority rules and each AGV recognizes where the other AGV is located. "The total volume of data is enormous," confirms Christian Spohn. "In order not to overload the computing power - especially for the AGVs - we have found a practical solution that streamlines the amount of data."