In the northwest of Germany, a medium-sized concrete block plant is taking a big leap forward - the goal is digitally traceable and controllable production. Highly automated plant and conveying technology was installed in one go. In addition, all relevant data arising during the manufacture of the concrete products are gradually being recorded and evaluated, from the mixing plant to the block making machine, and from the drying chamber to the cuber.

Christian Jahn, CPI worldwide, Germany

Rarely does a company provide an insight into a still ongoing conversion project. It is more usual for the completed project to be presented. At Kortmann Beton, things are different - the CPI editor was allowed to visit the concrete block plant in Schüttorf twice within a year.
The reconstruction is progressing at a rapid pace: the old circulation plant was completely replaced by a new, highly automated system. In addition, a new pallet warehouse with pallet feed has been built and put into operation.

Inventory recorded, target defined

Talking to Managing Director Henning Kortmann, it becomes clear that the replacement of the system technology is not enough. In fact, the exchange is only the visible part of a much more profound upheaval that is taking place everywhere in the company, from the very top to the very bottom of the company roots.
At the same time, nobody could represent this profound change more credibly than the 31-year-old, self-confident and energetic Henning Kortmann. The trained wholesale and foreign trade merchant with additional training in concrete technology joined the company management in 2012 and gradually took over the tasks of his father as managing director in the third generation.

"Traceability of production is now standard in many industries. In our concrete world, on the other hand, this is not yet the case, for various reasons," says Kortmann. Although there are partial solutions, when individual machines use their own operating data to increase process efficiency and product quality, he has not yet seen holistic solutions that utilize all the machine data of a cycle for this purpose. "But our goal is exactly that: we want to record all relevant machine and plant data for the circulation so that production can be tracked and better controlled," says Kortmann.
So the management first took stock. Kortmann visited numerous concrete block plants in Europe that are similarly positioned to his company. He looked at what the plants were doing and how. Subsequently, he and his colleagues from the company management drew up a plan for the restructuring of the company. This "master plan", as Kortmann calls it, comprised well over a hundred individual projects, all with the single goal of making production as a whole traceable and easier to control.

The production control system of the block making machine as the data hub

The new Hess Multimat RH 1.500-3 with MAC-8 controller is now the heart of production in two respects: First, it forms the products from the fresh concrete and compacts them. The big board machine with the maximum board size of 1,400 x 1,100 mm in the standard version was developed for the high performance range. Depending on the machine settings, the concrete recipe and other factors, the cycle times are around 10.5 s for a standard paving block with the dimensions 10 x 20 x 6 cm without facing layer and around 12.5 s for a standard paving block with the same dimensions with facing layer; accordingly, 2,517 m2 or 2,114 m2 can be produced in an 8-hour shift. The Multimat produces hollow blocks measuring 20 x 40 x 20 cm in 14.5 s; that makes a total of 20,258 pieces in an 8-hour shift.

"In three-shift operation, the new Hess block making machine is now producing more concrete products than the two old block making machines previously did together," says Kortmann with satisfaction.

Secondly, and much more decisively for the great goal of traceability, Kortmann Beton has made the plant's production control system the central hub - where all the data for the individual circulation components converge. The production controller not only collects and evaluates the operating data from the Multimat block making machine; it also receives, merges and evaluates the data from quality inspection facilities on the wet and dry sides.

The quality testing facilities on the wet side include R&W's laser-based stone height measurement system and the Quaver for testing the compaction of the face and core, surface permeability, product height and weight, fresh bulk density and possible differences in compaction across the entire production board.
The wet side is insofar technically up to date; the conversion is largely completed there and only minor corrections of the conveyor systems still remain to be implemented, which will happen soon.

Automated quality control on the dry side

The actual "plant engineering revolution" is taking place at Kortmann Beton on the dry side. The company has automated the entire quality control of the concrete products, which are returned from the drying chamber to the circulation for further processing.

The BT Master SC unit with integrated 2D line scan camera and integrated 3D laser as well as the subsequent Kuka sorting robot (see also CPi 06/2019), developed by the specialized Hamburg engineering office ibea, are central. The unit detects unwanted colour differences, bugholes or fine cracks on the surface of a concrete product as well as geometric deviations from the desired shape. The Kuka sorting robot, which Kortmann Beton named "WALL E" after the Disney film hero of the same name, replaces the defective concrete products with faultless ones.

The 2D line scan camera is attached to a portal that spans the conveyor belt orthogonally to the conveying direction - the conveyor belt thus transports the production boards with the concrete products underneath the portal. The camera captures the concrete products line by line and forwards this data to the computer of the evaluation unit.
The 3D laser of the BT Master SC is also mounted above the conveyor section. The laser beam strikes the conveyor belt from above, orthogonally to the conveying direction, over its entire width. On the conveyor belt, the production boards with the concrete products lying on them pass through this "laser curtain", where the geometric outlines are visible in the laser light. A high-resolution 3D camera, which is attached to the top of the scanner unit's portal slightly behind the laser unit in the direction of travel of the conveyor belt, records this process in the image. The width and height, e.g. of a paving stone, can thus be precisely determined over its entire length. The 3D measuring module detects product widths, heights, angles and lengths with an accuracy of 0.1 mm or 0.5° - any product winginess or bending is reliably detected. The unit passes this information on to the computer of the evaluation unit.

The computer evaluates the information from the 2D line scan camera and the 3D laser and informs the Kuka robot which concrete product in which exact position on the currently inspected production board deviates too much from the specified parameters, is therefore considered faulty and must be replaced.
The transfer and evaluation of the information are extremely fast. Hence, the Kuka robot has already received its sorting instructions when the conveyor belt moves the production board with the defective concrete products within its radius of action.

KBH lifting tables for uninterrupted production

Since the robot requires time for the actual exchange process, two lifting tables had to be integrated into the conveyor system within its radius of action. The first lifting table raises the production board containing the defective concrete products. The second lifting table, which follows the first in the conveying direction, raises a production board containing only faultless concrete products.

In step one, the robot uses a vacuum gripper to remove a defective concrete product from the production board of lifting table one and dispose of it into an adjacent container. In a further modernization project, Kortmann Beton plans to replace the container with a further conveyor belt that departs orthogonally from the conveyor belt of the circulation. The robot places the defective concrete products it has sorted out onto this new conveyor belt, which then ejects them from the robot cage and finally from the hall.

"At the moment, employees have to remove the container from the robot cage when it is full. In the future, when the additional conveyor belt removes the faulty blocks, the robot will be an autonomous workstation," says Kortmann.

Once the defective concrete product has been sorted out, step two follows. The robot removes a faultless concrete product from the production board of lifting table two and inserts it precisely into the gap on the production board on lifting table one.

"We have defined the exchange process in such a way that a maximum of three blocks is exchanged on the board. If there are more than three defective blocks on a board, the entire layer is removed. Sorting out more than three stones is simply not economical", says Kortmann.

The subsequent production boards are moved further under the two lifting tables by the conveyor belt during the entire exchange process. "This ensures a continuous, undisturbed production flow. Congestion would only occur if defective concrete products were found on several successive production boards. That would be bad, but it's just a worst-case scenario," says Kortmann.

Labels with Package ID

The empty pallet warehouse in the outdoor area next to the production hall has also already been implemented. The conveying technology comes from Rekers. The empty pallets are fed into the hall and moved on a conveyor belt installed parallel to the conveyor belt on the dry side, in the opposite direction to the production direction. A KBH transfer device removes the block layers from the production boards on the dry side conveyor belt and places them on the pallet on the parallel conveyor belt. This is followed by a film applicator and the horizontal and vertical strapping from Cyklop.

"At the end, labels with the respective package ID are automatically affixed to the crossing points of the horizontal and vertical strapping. The labels provide information about the layers that make up a package. And for each layer, I have all the information from the mixer, from the block making machine, from the drying chamber and so on," says Kortmann. From the final product, the paver, Kortmann can trace the entire production process back to the components of the concrete mix. Quality can be continuously monitored and also adjusted.

The printing device for the labels is currently being developed by Kortmann Beton itself because it is not intended that additional printing software will be used. In fact, it is intended that the ERP system from Softbauware, which has also just been introduced, will give the instructions directly to the printer. "Providing data is not a problem. Currently, however, we are looking for a thermal transfer printer that can also be moved vertically and can thus move to the crossing points of the strapping and apply the labels," says Kortmann.

Autonomous fork-lifters in an open-air warehouse

Many individual projects on the long list for corporate restructuring have already been ticked off by Kortmann and his staff. In the medium term, it is planned to demolish the existing mixing tower, where two Teka mixers and a Pemat mixer have been mixing the core concrete very reliably for a long time and a new Haarup mixer has very recently begun mixing the facing concrete. A completely new mixing tower with a large linear dosing system is to be built in the same place.

Another project seems fantastic: Kortmann Beton plans to use autonomous fork-lifters in the open-air storage area in the future. The company is participating in a corresponding research and development project in which the Fraunhofer Institute among others is playing a leading role.

"We'll have room for about 350 stone packets in the open-air storage area. A crane will set each individual stone package down exactly in a predetermined place. This is a basic prerequisite for the use of autonomous fork-lifters, which can only then find and pick up the stone packages," says Kortmann. Other basic prerequisites are that the fork-lifters operate regardless of the weather conditions and that they avoid collisions with people who have strayed into the open-air storage area. "In the indoor area, the use of autonomous fork-lifters is already working. We will also implement this in the outdoor area," says Kortmann as a matter of course. For the manager, the autonomous fork-lifters are ultimately just one project on the list of measures to be implemented on the way to digital, traceable concrete product manufacturing.

Kortmann Beton - company history

At least once in the company's history, Kortmann Beton has been at the forefront of machine and plant technology. In the 1980s, one of the first automated circulation plants in Germany was in operation at the concrete block plant in Schüttorf, Lower Saxony, not far from the German border with the Netherlands, with a block making machine from Henke. In a sense, history seems to be repeating itself as Henning Kortmann, the third-generation managing director, brings the company up to date with the very latest in automated and digitally traceable production.

The origins of Kortmann Beton date back to the 1950s. At that time, during the reconstruction years in destroyed post-war Germany, the building materials haulage trade served the great demand for building materials.

In the 1970s, the company acquired a stake in a concrete plant in Gronau, around 25 km as the crow flies from today's Kortmann Beton site in Schüttorf. A mobile block machine was used to produce pavers and stones for the drainage of courtyards and roads.

From self-compacting concrete to digital production

The company moved to its new location in 1983, and the Henke circulation plant mentioned at the beginning soon went into operation. Six years later, a second block making machine from Schlosser was added (this block making machine is still running today, but is to be shut down as soon as all 200 existing block moulds have been run in on the new, recently commissioned Hess block making machine).

The company experienced its next burst of development when self-compacting concrete (SCC) became popular in the 1990s and Kortmann Beton added precast elements made of SCC to its portfolio. The company then imported polycarboxylates itself directly from Japan. At Kortmann Beton, many systems are still a combination of earth-moist products and wetcast products.

"I joined the company in 2012. First of all, I took care of marketing, sales and purchasing," says 31-year-old Henning Kortmann, who completed a bachelor's degree in business administration in a dual education system. "I've been a member of the management board since 2014 and been in charge of production for four years."

Kortmann first recorded the current situation and then very quickly developed his vision for the concrete block plant, which is set up in such a way that people "will want to work in it for the next thirty years". "It was clear that we wanted to implement everything here that is technically possible today," says Kortmann resolutely.

Other topics that are high on the agenda for the management of Kortmann Beton are the generation and storage of solar energy for the company's own needs and the recycling of concrete rubble.

Kortmann Beton already has several thousand square meters of solar panels on the hall roofs and a further 10,000 m2 are being planned in several steps; the management is also interested in its own batteries for energy storage.

With our own processing technology, sorted concrete rubble is processed and reused in production as aggregate. In addition, Kortmann Beton carries out test sieving of unsorted material in order to test its medium-term usability.

Kortmann Beton today has 140 employees and an annual turnover of about 20 million euros.