How to make prefabrication efficient

Whoever says "share of timber construction" also says "prefabricated housing industry". In all German-speaking countries, the proportion of prefabricated single and multi-family houses is on the rise. Almost all the building material used there is wood, be it in timber frame or in the growing sector of solid wood construction. There are three reasons which make prefabricated houses so competitive: Firstly, they are cheap. Secondly, they are built in no time and thirdly, owing to the secure environment of the production hall, their manufacture quality is much higher than could ever be achieved out on the construction site.
And in a causal way, all of this has to do with systems designer Weinmann Holzbausystemtechnik, St. Johann in Württemberg/DE. The Homag daughter company describes itself as a world leader in machinery for the prefabricated building industry. Why this is so and which Weinmann systems are still running despite their often "biblical age", were among the things CEO Hans Bert Ott's presentation touched upon at the "Weinmann Fair" on 7 November at the company's headquarters in the Swabian Alb.

Strong performance as a group

More than 140 carpenters and industrial manufacturers of prefabricated houses visited the factory in St. Johann that day. There they found a large part of the range on display - including some resourceful innovations. It is Weinmann's ambition to cover the complete scope of hardware for the prefabricated house industry. For the Weinmann engineers, this starts at joinery and ends with finished walls or roofs. Internally, the machines and tools are divided into "joinery and cutting", "panel processing", "element design" and "handling and storage". Within the group, Weinmann can also rely on Homag's product range and sales structure which is benefitial for the customers. The standardized machines interact smoothly. And there just is no project is too big for Germany's largest group for wooden mechanical engineering.At the same time, Weinmann does not dodge the special needs of small-scale manufacturers. The first system which was shown on the tour through the workshops was a DIY solution for small carpenters. In this case, Weinmann supplies the components of the assembly table WTV 100. In order to save costs, the device is to be mounted by the customer himself. Waiting right next to it, the assembly table WTZ 110 showcased the first innovation on that day in November. It allows for the manufacture of angle- and dimensionally precise wall, ceiling and gable elements in wood frame construction.

The novelty is an integrated position sensor system. The installer sets the table precisely at the desired angle. Sensors measure its position and if desired show it on the display. If the table is adjusted, say, to the roof pitch, dormers can easily be install with a spirit level. As incoming orders increase and order books fill, the master carpenter may want to extend the modular assembly table. The tilting mechanism is such that it is possible to extend it to serve as a butterfly turning table or a three table solution at any given time.

A bridge with twelve tools

The multifunctional bridge WMS 120 really is Weinmann's step towards more automation. On its work surface, components are planked. What would be tiresome for mechanics, the WMS 120 does automatically. A tool changer brings flexibility to all procedures. Twelve sawing, milling, drilling or marking tools can be accommodated in the exchange unit. This minimizes set-up times. The multifunctional bridge can even place slats on the planking and attach them there. Time-consuming calibration is thus a thing of the past. What is more, operability has been improved. On the "Weinmann Fair", the WMS 120 was for the first time presented with the ergonomic touch screen "Power Touch" developed by Homag.

Combined timber frame and planking

Especially if workshop space is limited, the Weinmann WEK 100 is worth a consideration. This type name stands for a compact combination of framing station and a multifunctional bridge. The whole unit is barely bigger than a work table which makes it ideal for timber house builders.
The WEK 100 manufactures wall panels stationary on a single workstation. The manufacture of ceiling and gable elements is also possible. This is cheaper and more space-saving than two separate units and one additional operator would be, argues Weinmann.
It all starts with the placement of the timber frame. Moving catchers help the operator to position studs simple but precise. Spacing and nailing positions can be freely selected. Step by step, the CAD plans materialize into complete wall systems without the hassle of having to re-measure all the time. The completion of the timber frame is followed by positioning of the planks. The WEK 100 can automatically attach and modify the cladding. As a novelty, the combination system even has a tiltable saw unit. Bevel cuts, as they often occur on the top floor, can now be done without manual set-up.

Space-saving joinery all-rounder

Also the joining unit designed by Weinmann is really compact. The WBS 140 is only 19 m long (good for a 6 m-workpieces) and 4.2 m wide. With its height of 2.9 m, it fits in almost every assembly hall – and that without a hole in the ground. Cuts and joinery work are done with a a fivefold spindle and an eightfold tool changer. The machine handles workpieces with cross sections of between 2 by 5 cm and 20 by 45.5 cm. According to Weinmann, the WBS 140 is geared towards customers with a low joining volume, but with high demands for machining flexibility – that is, the classic carpenters. Two NC-controlled grippers with a high-resolution positioning system and precise guides position the workpieces. Thus, each cut and each milling is done with absolute precision. Marking and labeling units provide extra comfort during assembly later on.
For this year's model, the WBS 140 was also equipped with the innovative "Power Touch" operating concept. The Weinmann engineers also optimized the automatic timber infeed. Stainless steel chains improve the durability and are beneficial for handling sight timber, they say.

Processing center for CLT 5.6 m wide

For two-dimensional joinery tasks, Weinmann is offering portal machining center WMP 240. It can machine elements up to 5.6 m width and up to 35 cm thickness. Theoretically, length is unlimited. Usually the WMP 240 processes cross-laminated and large glue-laminated timber. But also it masters sandwich elements effortlessly.
Once the workpiece is placed in the workspace it is automatically measured. Then 30-kW aggregates come into play – a five-axis main spindle with a tool changer and one saw unit. The required precision is achieved by a high-load rail system with a rack and pinion drive. The WMP 240 can also be hooked on to the Lignocam program for automatic data transfer.
For visually sensitive connections the system can apply concealed slots with a mortising machine. This is complemented by a new deep hole drilling system for holes of up to 1.25 m. In order to machine the backside of the component automatically, Weinmann has integrated an under-floor processing unit. Right now, a WMP 240 is being installed on the other side of the world: CLT producer Timberlab of New Zealand will start working with it next December.

In operation for 20 years

Weinmann machinery is built to withstand the heavy-duty use in industries, CEO Ott emphasizes. As a proof, he referred to a joinery machine that was installed at Lux-Haus ten years ago having processed some 2.5 million rm of construction timber since then. On the premises of Schwoerer-Haus, a CNC prefab house line has been well-tried even after 20 years of operation which for industrial installation is almost a biblical age.

Annual meeting with lectures

As is usual with a company of the Homag-group, Weinmann enhances its in-house exhibition with interesting lectures. The whole event is then called Weinmann Fair ("Weinmann-Treff"). On 6 November, Gerhard Lutz of the Kompetenzzentrum Holzbau und Ausbau (competence center for timber construction and interior) from Biberach/DE gave a presentation on the future of timber construction. And he generally presented a positive outlook. As building ground becoming more and more scarce and with the densification of housing space, timber can fully exploit its strengths. "Problem areas" are sound insulation, fire protection and ceiling structures. The Weinmann Fair was attended by 140 guests from Germany and neighboring countries.