Anyone who keeps his eyes open when walking through the production departments of companies of all sizes which produce wooden and plastic products will in many cases see that there is still a considerable potential for further rationalisation. Although many companies already have modern, high-performance CNC machining centres with quick-change tool systems, the handling and clamping of the workpieces is still done conventionally and often very laboriously, and the companies concerned do not seem to realise that the time taken for this task cancels out any time-savings which may result from the modern machines and hinders further productivity increases.

What is the point of investing in CNC machine technology if the material flow and the workpiece handling are not simultaneously organised to take advantage of this technology?

Without such reorganisation, the CNC machining centre will never be able to run at its full efficiency and will thus pay for itself more slowly, if at all. It is not sufficient to change tool quickly: if the changing of workpieces is not done precisely and reproducibly, it will not be possible to reduce the absolutely unproductive waiting times and to ensure that more of the running time of the machine is productive machining time.

This may seem obvious, but a glance in many workshops will show that this is not true. Anyone who invests in a CNC machining centre must also ensure that the machine is loaded efficiently with the raw parts and that the finished parts are removed equally quickly. The same also applies, of course, the clamping and unclamping of the raw parts, since only precisely clamped parts permit the CNC machining program to be started immediately. The periphery of the CNC machining centre is thus of decisive importance. While the loading of raw parts and the removal of the finished parts on newly installed or existing CNC woodworking centres can be achieved relatively easily with, for example, a flexible vacuum handling system. Selection of a universal clamping system for rational fixing of the workpieces is rather more difficult. The reasons for this are that there are many different tables on many different machines and that the requirements of the woodworking and plastic-machining companies vary widely. Depending on the type of table, manually or pneumatically actuated clamping systems or vacuum clamping systems may be suitable.

The all-rounder: vacuum clamping technology

It is also necessary to decide whether or not it is worthwhile to upgrade an existing woodworking centre, since the prerequisites here are different from those for a new machining centre already equipped with clamping technology. Finally, it is necessary to consider the types of workpieces to be clamped, because mechanical or pneumatic clamping with the aid of claws or lugs is unsuitable for workpieces with easily damaged surfaces or workpieces which have to be machined on all edges. Only one workpiece clamping technology can provide a convincing solution to all of the above problems, namely clamping with vacuum – a method which the specialist J. Schmalz GmbH in D-72293 Glatten has been developing and selling for many years. Many of the company's innovations are protected by patents. With five different clamping systems, a wide range of components for installation on many different types of woodworking centres and a high level of competence in designing system and detailed solutions, Schmalz is the accepted world leader in this sector. The five different clamping concepts permit the rapid and economical implementation of individual clamping systems for all imaginable applications. Each clamping-system family is based on standardised components and modules from which universal or very specific clamping devices can be built.

Vacuum clamping systems from Schmalz are already fitted as original equipment on many machines and are also ideal for retrofitting on existing machining centres. Due to the wide range of components, the vacuum clamping systems can be mounted on the tables of machines made by almost all companies (such as Homag, IMA, Weeke, HolzHer, Masterwood, SCM/Morbidelli, Biesse, Busellato, Anderson, etc.) without costly and time-consuming modifications. It is also worth mentioning that the product range includes spare and replacement suction blocks and plates, not only for the Schmalz systems but also all common clamping systems made by other manufacturers.

The world of vacuum clamping technology

The five different vacuum clamping systems mentioned above differ from each other as follows:

Innospann is the vacuum clamping system for simple upgrading of woodworking centres.
Its modular design permits the simple, rapid and economical construction of clamping devices for the production of one-off jobs and small batches and is also ideal for flexible adaptation and quick conversion with only very short machine downtimes.

Innospann systems are available for mounting on slotted tables, smooth tables and console tables. In the case of slotted tables, the so-called Steel-Plates, Steel-Plates-T or slotted-table suction elements form the basis on which the actual clamping elements, the Quad-Base or Mono-Base and the replaceable suction cups are mounted. For smooth tables, an intermediate plate with a Steel-Plate or Steel-Plate-T forms the basis on which the same clamping elements are positioned. For console tables, either intermediate plates or adapter plates with, if necessary, special steel-plate parts are used, again with the same actual clamping elements. All of these solution are hose-free, i.e. the suction pads are supplied with vacuum without the need for vacuum hoses in the working area. On the Steel-Plate the vacuum is distributed to the suction pads through vacuum apertures which can be sealed manually with magnetic plugs when not needed. On the Steel-Plate-T, solenoid valves distribute the vacuum automatically.

The second system is the version VC-G, a universal vacuum clamping system with hose connections for use on smooth tables. A wide range of different suction blocks with high holding forces makes it possible to build, extend and convert all types of clamping devices.

The third system, VC-T, is a hose-free vacuum clamping system with even better flexibility with respect to the arrangement and use of the clamping elements. The suction blocks can be positioned freely on the smooth aluminium table to suit the size and shape of the workpiece to be clamped. VC-T is thus ideal for the production of individual parts, since new clamping configurations can be set up very quickly without the need for tools.

The comprehensive range of
OEM, conversion and spare parts

The fourth system, the VC-K1/VC-K2, provides rational vacuum clamping solutions for console machines with Schmalz clamping technology. The suction blocks can be positioned and removed quickly, providing a high degree of flexibility with respect to the use of the machine and thus very low machine downtimes for conversion. In addition to this working flexibility, the VC-K1/VC-K2 system is characterised by extremely good precision and repeatability, making it very suitable for batch production tasks where a large number of identical parts have to be produced. Standardised suction blocks for special solutions, such as clamping narrow parts, door and window frames and curved parts round off this comprehensive modular system. The difference between the versions K1 and K2 is that K1 is a single-circuit system while K2 has two vacuum circuits.

Finally, there is the fifth system, the VC-B/VC-S, which contains mounting parts and spare parts for the systems made by other manufacturers. The suction pads of this program are absolutely compatible with the original suction blocks and thus fit precisely into the existing mountings on the widely used Italian CNC machining centres made such companies as SCM/Morbidelli and Biesse. The five vacuum clamping systems described here make CNC woodworking machines more productive, which means that they pay for themselves more quickly. Neutral examinations have shown that the use of optimised vacuum clamping systems can eliminate up to 80% of the set-up times, permitting these to be used for more production. If one also considers the time savings which result from the faster handling and clamping, it is clear that an investment in vacuum clamping technology will quickly pay for itself, even without considering the other benefits such as careful handling and damage-free clamping, the ability to machine the parts from five sides without reclamping or the significantly reduced costs for clamping devices and spare parts.