Special equipment of CNC machining centers for nesting.
Equipment suitable for nesting usually requires a particularly strong vacuum pump as well as a matrix table or another special table, which is suitable for high vacuum capacities. Most often, it is necessary to use special nesting software, to make this technical method effective.
Some machines are also equipped with with periphery for automatic feed and unloading, which was especially designed for use in nesting (e.g. automatic unloading devices, devices for automatic positioning of the protection board, automatic feed).
Nesting technology in furniture manufacturing
The nesting technology has its origin in the leather industry, which was confronted with the problem of having to nest as many cutting patterns as possible onto irregularly shaped raw materials (animal skin).
In wood processing, with the trend to have ever more individualized furniture and thus, ever smaller batch sizes of up to size 1, the demand for individual solutions grew. A beamsaw is used very efficiently if packets with the same stipe widths can be cut.
If the formats of the single parts to be produced are very different and even irregularly shaped, panel sizing is only possible with lots of wastage and therefore, very inefficient.
With nesting technology the single parts to be produced are nested into each other on a large-format plate in a way that there is almost no wastage. However, this is only efficient with computer programs. Such a pattern can no longer be created with a beamsaw, but has to be milled on a stationary machine.
Problems of this process
- When dividing, the tool has to go down to the very bottom edge of the workpiece to separate it completely. If the workpiece rested directly on the machine table, the table would be destroyed after some time. Today´s most common solution is a so-called protection board, usually a thin MDF board. Through this a vacuum is sucked. The milling tool now cuts about 0.2 - 0.5 mm deep into this board, which therefore has to be replaced after a few work cycles. Because of the stronger vacuum and the additional material costs that are necessary, not insignificant costs are caused. Other nesting technologies are based on putting the large-format plate to be divided directly onto the machine table, but not to cut through completely. After this, the plate is automatically turned around and cut through from the other side. However, the turning around an repositioning of the plate has to be absolutely precise, so that no reworking on the narrow side is necessary. Because of the high technical expenditure, this solution has not yet succeeded. Another solution is cutting the plates up to a few tenths of a millimeter and to polish off the small bridge on a wide belt sander. This solution also has not succeeded since the process´s security is not sufficiently high.
- Due to the system, workpieces cannot be edited on their narrow sides (particularly dowel holes). Therefore, additional steps and thus machines are necessary. The introduction of so-called nesting cells should optimize the corresponding work processes. Here, a drilling machine and often even an edgebander is in direct proximity of the CNC-machining center. The whole group of machines is operated be only one person which edits the parts immediately after their removal with the drilling machine and possibly coats it with the edgebander. Here, the parts are usually marked with bar codes or other means, so that the appropriate program is run automatically on each machine.