For each phase of board cut-to-size, such as infeed, alignment, trimming, cutting to size and stacking the cut material, special solutions have been developed for thin boards. The manufacturer of the world-renowned thin, smooth-faced MDF/HDF HOMADUR wood fiber boards, the German company Homanit GmbH, already relies on a total of eight Schelling cut-to-size plants in its factories in Losheim / Germany and in Karlino / Poland for cutting thin boards to size.
The Schelling cut-to-size plant in action at MDF/HDF wood fiber board producer Homanit in the Karlino factory in Poland.
Special infeed solution
Schelling has developed a special thin board infeed that has already been used with excellent results in numerous plants. This solution uses two vacuum infeed carriages and a nip roller. Here boards are lifted one at a time by the vacuum carriage and transferred to the nip roller. Due to the two alternately operating vacuum carriages, very high cycle times of more than 25 cycles per minute can be achieved. The technical availability of this infeed system is more than 99%. Ernst Keider, General Manager of Homanit GmbH, describes the advantages of this type of feed:
"While one infeed cycle is running, the other is already being prepared – the systems are interleaved without hindering each other. As a result we were able to double the speed during infeed. The infeed concept on the new plants impressed us so much that we have even had older saws upgraded."
Schelling has developed several infeed options depending on the required weighting between capacity and protection of the surface finish: a combination of "nip roller system & pusher" or "nip roller system & vacuum feeding rails", as well as the "dual vacuum system" in case of the need for maximum protection of the surface finish.
Minimum trim waste
A crucial stage in the thin board cut-to-size process is the alignment system. If the cutting books are precisely aligned, unnecessary trim waste can be avoided. The alignment tables on the cut-to-size plants in Homanit's Losheim and Karlino factories have electronically positioned, adjustable aligning devices that make it possible to align even the thinnest boards without damage within the necessary cycle time. To ensure the small trim waste does not fall through the saw gap on the sawing machine and cause soiling or malfunctions there, Schelling Anlagenbau developed a special saw gap closing device that only opens briefly in the area of the saw blade and then closes again. The waste that is produced during trimming or "dust cuts" is ejected through automatic waste flaps to a conveyor system below. The waste is transferred via a central outlet to the guillotines where it is chopped up and transported away.
Using a turntable in front of the rip saw, it is also possible to cut complex cutting patterns with head cuts in the Karlino factory.
Cutting to size on a cushion of air
Another aspect that impressed the wood fiber board manufacturer Homanit is the method used to protect the material during the cutting to size phase. For this purpose the steel saw machine tables have a hard chromium-plated work surface that, at Schelling Anlagenbau, is also equipped with air nozzles to provide "floating" transport. The saw carriage is based on a concept developed and patented by Schelling. In this case the saw motor remains stationary, only the saw blade is raised for the cutting process. As a consequence it is possible to use more powerful saw motors, resulting in turn in higher cutting speeds.
Flexible sorting and stacking solutions
The stacking solution has a major impact on the overall capacity of the plant. If, after cutting to size, the boards are not removed at the same speed as during the infeed and cutting to size phase, a typical "bottleneck situation" is produced that slows down the whole process. Schelling can offer a very diverse range of solutions for this task, starting with simple, manually assisted material stacking to fully automatic sorting and stacking. Homanit decided for a combination of automatic stacking devices and manually operated stacking places. A software program developed by Schelling is used to indicate precisely to the operators at the manual stacking places which format is to be placed in which stacking place using color coding on a monitor.
Due to two alternately operating vacuum carriages, very high cycle times can be achieved in the infeed.
Easy to operate
"So that we can manufacture flexibly and efficiently, with both large and also small batch sizes, we need plants that are as uncomplicated as possible", explains the General Manager of Homanit. "As Homanit produces seven days a week around the clock, we need cut-to-size plants with user interfaces that are easy to use", he reports, "even if no programmers or software specialists are available." This requirement was rigorously implemented during development at Schelling.
Furthermore, quick, un-bureaucratic decisions, short communication channels and a quick response are also important criteria for him. "Even on the best plants there are sometimes technical defects. If need be, companies with a flat hierarchy can help quicker than those in which it is necessary to first fight your way through several layers. Here we have had a very positive experience with Schelling."
Schelling Anlagenbau GmbH is a specialist in custom solutions for cut-to-size plants for the board and furniture industry as well as for the circuit board industry, metal industry and plastics industry. The 90-year-old company now trades worldwide – with subsidiaries or representatives in almost all parts of the world.
Fact box
Information on Schelling cut-to-size plants
- Cut length: 3300 mm - 7800 mm
- Width: 1300 mm - 3300 mm
- Height: 120 mm - 210 mm
- Saw motor power: 27-75 Kw/50 Hz
- Infeed, cutting to size and stacking solution to suit customer requirements
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