Bonna Sabla counts on “Magic” manufaccturing

Located in Lamotte in Northern France, the plant of the precast producer Bonna Sabla is one of the major production sites of the civil works division of Consolis Group, which has an Europe-wide presence. As a result of the recent commissioning of a new production line for round and square-shaped manhole elements, the company has elevated its industrial equipment to the state of the art by installing a stand-alone production system forming part of a sophisticated automation design that is even more user-friendly whilst enabling short cycle times and a higher level of occupational safety.

For almost 20 years, an Exact line supplied by Schlüsselbauer, the Austrian equipment manufacturer, has been in service at the Lamotte plant in Trosly Breuil operated by Bonna Sabla. This line is used to produce well shafts with and without drain holes, manhole rings and square- or round-shaped manhole top sections. In response to high demand existing, in particular, for circular elements, the Paris-based management board of Bonna Sabla decided to invest in a latest-generation production line, a Magic 1500 system supplied by Schlüsselbauer.
This choice was driven by the desire to add a significant degree of flexibility to the processes involved in the production of the various precast elements, and, as a matter of course, to increase the production capacity of the Lamotte operation. “Not only can the Magic system be controlled by only one operator – it also enables high production outputs of 30 precast units per hour. Making use of this advantage, we can produce about 2,000 elements in two seven-hour shifts, working Mondays to Fridays,” explains Yoann Kermin, production engineer at the Lamotte plant. The greater flexibility of the new production line makes it possible to avoid interruptions due to stock shortages. For example, the production setup of the system can be converted quickly and easily from circular manholes to rectangular elements. Even custom products in unique shapes can be manufactured effortlessly. “The producer can reuse the existing Exact line molds, which further optimizes the investment. This has made the commissioning of the new system much easier,” says Sophie Joan-Grangé, who is taking care of the French market for Schlüsselbauer.

Modern times
The Magic production line provides a high degree of automation. This enables both a high production output and a consistently high finished product quality, as well as resulting in a significantly enhanced ease of operation. The operator merely supervises the production process while manual interventions are required only on very rare occasions. Only a few work steps still need to be done manually, such as the cleaning of the press at the end of the shift.
The line also achieves extremely short cycle times in the production of the precast elements. Once the steel base ring has been centered at the level of the press, the system requires less than 45 seconds for concrete placement, compaction and output of a 200 kg manhole section. “In order to enable quick demolding, no-slump concretes with an average water/cement ratio of 0.33 are processed. Both the vibration speed and the contact pressure are designed for highest production speeds,” the production engineer responsible for the Magic line goes on to comment.
One of the particular features of the Schlüsselbauer systems is their sturdy machine frame, which has been designed to take up all loads and stresses created by vibratory compaction throughout the service life of the line. “We have been using the Exact line for almost 20 years now, and have never had any major problems. By investing in a similar system, we want to ensure the same quality standard,” says the Lamotte plant manager.

Improvement in every respect
The Austrian manufacturer developed an absolutely reliable, sophisticated equipment design in order to respond to the requirements at the precast plant, in particular with regard to quality assurance, high production speed, easy operation and maintenance, and occupational safety. “The programming of the automated control unit has been tailored to the specific needs of our production setup, which includes all precast element manufacturing steps. This way, we get both the quality standard and the quantities required. The traveling path of the cylinder to press on the steel base rings, the control of the stroke and contact pressure of the hydraulic press cylinder, the demolding time – all these processes have been fine-tuned to each other to the very last millimeter and second,” the production engineer comments.
Another big advantage of the system is its option to design and manufacture custom products. For example, step rungs on the manhole inside, grilles for drainage lines or anchors can be included in the design right from the start. Regarding these options, Sophie Joan-Grangé says: “What we offer is actually a standard line that the customer can complement by further options responding to specific needs, in particular when it comes to producing units in custom shapes and tailor-made drainage openings.”
In addition, Schlüsselbauer has again gone a long way to make servicing and maintenance easier. The remote data transmission options available today enable technical interventions to update the plant or to get systems up and running again also from a long distance – at a very low cost and in virtually no time. For precast plant operators, these and many more points are compelling arguments in favor of such systems, especially if they wish to ensure continuous production and a consistently high product quality. This also applies to the Lamotte plant – most of its products carry the French NF quality label. 

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