The new high-performance CNC machining centre for the production of wooden parts ought to be highly productive, but a closer look at the situation shows that the high-tech machine cannot fully utilise its performance.

The reason for this could be that far too much of the available operating time is wasted in the process of changing the workpieces, i.e. the positioning and clamping of the raw part and the unclamping and removal of the finished part. In companies which started as artisan's workshops, it frequently occurs that the new machines are loaded and unloaded with the old methods and aids, just because they are already there. In general, very little attention is paid to the handling of the workpieces, but this is not true at Messrs. Ernst Stöhr Möbel- und Innenausbau GmbH, in 72221 Beihingen in the Black Forest, who use a very modern CNC woodworking centre for such work as the machining of high-quality doors.

In for a penny, in for a pound …

When the new machine was ordered, the company also invested in a material handling and loading system for the heavy sheets of wood from which doors are created on the machining centre. For this, Stöhr commissioned the vacuum specialists J. Schmalz GmbH in 72293 Glatten with the planning and implementation of a vacuum handling system for the safe and careful handling of the doors.

Since the raw materials are delivered either standing or lying on transport trolleys to the machining centre, some of them must be turned from the vertical to the horizontal position before they are placed on the machine. For this reason, the Schmalz engineers equipped a vacuum-tube lifter of the type JumboErgo 110 with a pneumatic swivelling unit PSE. Depending on the machining task, the workpieces are then swivelled with the PSE or left in the original orientation. This provides the workers Stöhr with the necessary flexibility they wanted.

Flexible gripping, lifting and swivelling
of flat wooden parts

The vacuum handling system installed at Stöhr thus consists of a standard slewing column crane SKJ for loads of up to 140 kg, a vacuum-tube lifter JumboErgo 110 for loads of up to 110 kg, a quadruple vacuum head with flexible positioning of the suction cups and the pneumatic swivelling unit PSE.

Due to its weight, the PSE reduces the maximum load the handling system can lift to about 90 kg, but this is still more than enough, since the doors generally weigh between 25 and 30 kg. The slewing column crane has a jib length of 4,500 mm, providing enough free space for the handling of the sheets of wood, which are about 2,100 x 1,000 mm in size.

In the past, two persons were frequently needed to handle the materials; today, the machine operator can do everything alone. At the same time, the ergonomical handling reduces the physical effort needed for handling the doors and also the risk of working accidents. This is even more true for the larger furniture panels which are also machined on the same CNC system.

Easier handling and more productivity!

The handling of the doors and furniture panels is today far easier and causes less damage to the parts, regardless of the orientation in which they are delivered, since the PSE executes the swivelling action precisely and safely, as necessary.

Both the vacuum-tube lifter and the swivelling unit are controlled from the same operator handle, which also permits precise positioning of the parts being moved. The large suction pads and the safety elements which prevent incorrect operation ensure a high level of operating safety, particularly as the size of the suction pads by far exceeds the value demanded by the applicable safety regulations.

Equipping the vacuum-tube lifter at Stöhr with the swivelling unit PSE thus offers the operators the desired amount of flexibility in the vertical/horizontal handling of the doors and panels and the resulting fast changing of the workpieces on the machining centre keeps the standstill times to a minimum.