Modular Prefab

Automatic Google-Translation from the German Original:

The large timber builder from the Ulm area is mainly active in building construction and produces around 130,000 m2 of elements per year, i.e. the equivalent of around 300 single-family houses. A volume that they wanted to double with the new production hall.

Modularity already tried and tested

A modular facility has already proven its worth in the old halls. In addition to the previous panel cutting using the SPM-3 from Hundegger, two element construction tables from the Swiss supplier woodtec Fankhauser GmbH are at the heart of the process.

“80% of our elements are between 3 and 3.6 m high,” explains Managing Director Reinhold Müller, which is why we have combined the modular element tables to form a 4.5 x 12 m work surface. “Since only a few elements can have the full length Two workstations can be set up on the left and right of each table with little effort. “If the size of the element makes it possible, we will of course add a third element in the middle,” says Müller.

The element construction table is used for modular production – the new concept for element construction production facilities mainly for the assembly of the wooden frame and the initial planking. Then the elements are dimensionally stable, are turned with the hall crane and processed on simple trestles at a second station. Depending on the degree of production, they are set up vertically again for the attachment of windows or facades before they are loaded directly onto interchangeable flatbed platforms (Flad`s).

A look into the hall in everyday operation clearly shows the contrast to an industrial street: Here, several teams work alongside and with one another in parallel. At Müllerblaustein you have z. B. also consciously decided against components of industrial production such as butterfly turning tables for handing over the elements. “A second table is too expensive for further processing, since the element is already dimensionally stable. It also takes up a lot of space in the hall because it is a fixed installation and you are no longer modular, ”explains Müller, adding that the production process would have been too restricted and that there were expensive waiting times when coordinating the handover of the elements would be.

All types of elements are manufactured on the system, from inside and outside walls to roofs and ceilings, and produced as far as possible in the order in which they are erected on site. “With us everything is totally project-dependent and has to be produced that way,” explains the managing director. “We look for an optimal production process for each property and set up the hall accordingly.”

That should be even better possible in the new hall.

New hall with 24 m element production

The layout of the new 24 m wide and 120 m long hall shows that it has been designed for maximum modularity and flexibility, far from conventional industrial thinking. Once again, two 4.5 x 12 m long element construction tables from woodtec were used there.

“The element construction tables are very robust, can be modulated for large areas, the hole pattern is extremely flexible for clamping the elements with the pneumatic cylinders, the continuous edge stop is very precise, thanks to the additional adjustable stops also suitable for very thick elements and you can preset the overhang” , Müller explains some of the advantages of choosing the Swiss machine manufacturer internally. He also emphasizes that the low working height was a very important advantage. Müllerblaustein even uses a special substructure so that the table is even lower than in the standard version. “This makes it easy to walk on and you can also work on thick elements,” says Müller, explaining the design required by the employees.

The tables can in turn be divided into several workstations and put together very flexibly. Either in rows along one side of the hall, together as a 24 m long table, on opposite sides of the hall or even across one end of the hall, depending on the project.

Handling and material flows are an important issue

This time, special attention was paid to handling. In addition to the two bridge cranes, each with two 12.5 t trolleys, a wall bracket crane with a 10 m cantilever and a load of 3.2 t was mounted on each hall wall. “With this second crane level, the teams have to wait much less for each other to finally have a load device available,” explains Müller.

The hook height of 11.5 m for the first level and 9 m for the second level has also been chosen so that it is easier to pass each other, elements can be lifted on top of each other and modules can be stacked on top of each other.

In terms of material flows in particular, Müller sees significant opportunities for increasing efficiency. “Where is the material stored? How can transport routes in the infeed and outfeed be shortened? Is it possible to inject more efficient insulation throughout the entire process, including material storage? And certain parts have to be pre-assembled, ”says Müller, raising the questions that are to be examined more closely in the new production facility and optimized for each order.

From the modular production hall to the production of modules

Müller sees another important step towards improving productivity in modular wood construction, for which the new hall is specially designed. Not only should your own production be modular, but the objects themselves should be built that way.

“The higher the degree of prefabrication, the lower the construction effort, the lower the construction costs,” is how Müller sums up the new company strategy. In the new hall, from plumbing to interior fitters, as many professions as possible should do their work in a dry place, always have materials and tools to hand and be able to shorten stair climbing and other travel times. “Especially when the shortage of skilled workers is worsening, it is important not only to use them optimally, but also to enable more pleasant working conditions,” says Müller. “The construction site belongs to the factory. That creates more interesting jobs and better quality assurance. “

At Müllerblaustein Holzbau GmbH, cross-laminated timber is also used in multi-storey timber construction. In terms of the degree of prefabrication, direct delivery to the construction site is not the solution there either. Especially since the waiting times are long for tailor-made deliveries and this method is very prone to the smallest discrepancies. The panels are to be bought raw and then formatted on the new, approx. 42 m long PBA-3 cutting portal from Hundegger. Then insulation, façades, windows, gypsum fiber boards, etc. are added and are then partly assembled into modules in combination with conventional wooden frame elements.

More added value through organization and innovative products

On the one hand, Müller sees future added value in timber construction from an organizational perspective. That timber builders are increasingly acting as general contractors and that the production method can already be taken into account during the design, optimized and the coordination of the various professional categories better coordinated.

And of course with the products themselves. Everything that is not standard. Be it in timber engineering, with glued products such as box elements and so on. “But for that you need a flexible and modular production hall”.

Modular Prefab Layout: the new trend in timber construction

At woodtec Fankhauser GmbH, the trend towards modular operating equipment has been observed for several years. “Our table was originally intended for the traditional timber house builder who had to produce very individually and flexibly,” says Managing Director Thomas Fankhauser, explaining the reasons for the conception of a very flexible system. “Thanks to the timber construction boom of recent years and often also a diversification into multi-storey timber construction, these companies have grown considerably and now had to deal with much larger order volumes. Instead of the traditional motto ‘one table = one workplace’, the tables, which are highly valued by the employees, were not replaced by a complete automation of the production, but logically simply extended and thus created several, very flexibly modular workstations.

At the same time, there are now more and more large companies that take the advantages of this way of working and the competitiveness of the originally smaller companies seriously. “Twenty years ago nobody would have believed in this development,” says the trained carpenter and engineer FH. “At that time, the idea prevailed that larger manufacturers should invest in industrial systems and that houses would soon be delivered from the assembly line like cars.”

However, the fact remains that the batch size is not in the thousands, as in industry, but is always ‘1’. “Even if you make the same object again, you can never produce the same elements one after the other in terms of organization and transport,” says Fankhauser. That in addition to Müllerblaustein also prefabricated house manufacturers such as Lehner Holzhaus GmbH is switching from production lines to a modular facility with tables from woodtec, is evidence of a clear structural change in timber construction for the latter.

Team size ‘one’ – gain another 20% in efficiency

For the further development in timber construction, woodtec sees new products such as glued box elements, for which the manufacturer has also designed machines that are compatible with the element construction table. Additional opportunities for higher productivity would clearly also lie in reducing the team size. “At the moment, two or even three people work on an element,” explains Fankhauser. “But studies show that you are not twice as fast as a single worker, but only about 1.6 times.”

If you can achieve team size ‘one’, that means a possible increase in productivity of 20%. This would make timber construction even more competitive and gain even more market shares. New machines that enable this decisive step towards team size ‘one’ should come onto the market in mid-2019. “And of course they will be compatible with the existing element construction table,” says Fankhauser in conclusion.