Batch size 1 production of kitchen units
02 February 2017
Cooking today is a popular leisure activity for which the kitchen is becoming the focal point of the home. This is reflected in the way kitchens are being custom designed for much more than functionality.
Manufacturers are following this development, changing from mass-production to one-off jobs with series production characteristics. An example is a new saw centre designed by Schelling for the production of kitchen units. This Austrian company brought Lenze on-board as a technology partner for the motion centric automation of the saws.
The requirements for modern built-in kitchens are high: they must be of the right quality, be functional, have a long useful life and, of course, be attractively designed. Anyone buying a new kitchen is faced with a sometimes bewildering array of surfaces, colours, shapes, dimensions and fittings. Today, because of the increasing number and complexity of the parts involved, more individually customised kitchens are being made instead of standard modules. Thomas Gsellmann, head of marketing at Schelling, says batch size one is a very hot topic at the moment.
Individual job production with series-production characteristics is now in demand. In order to ensure that this trend does not excessively detract from productivity and economic efficiency, flexible production plants are needed that interact with the inventory control system directly as envisaged by Industry 4.0. One such solution is Schelling's new saw centre, the "Is1". Thanks to a circulating materials handling system with two gantry units, the "Is1" saw line can work without interruption. Board manipulators were created in close collaboration with Lenze and the heart of the motion control solution is the new Lenze FAST technology software module for robot applications, "Pick & Place".
Cutting panel boards to size
Digitised kitchen plans are translated into parts lists and cutting diagrams. Each part is individually sawn by the Schelling "Is1" with full automation. This involves continually changing expensive panel boards with their different colours and surfaces. Another challenge is to cut the boards with as little waste as possible and with efficient utilisation of saw power. Material waste is a big issue at the moment. Optimisation of cutting diagrams and integrated temporary storage of residual boards are therefore essential. In addition, the new "Is1" is directly connected to an automated storage system also made by Schelling. Dietmar Nußbaumer, head of technical systems and installation at Schelling explains that the saw is integrated into a higher-level master system, whereby it is the element that sets the pace in the production line.
The core principle of the circulating materials handling system is based on gantries which turn the boards after the first longitudinal cut and then transport them via sliding tables onto the next sawing section. The concept on which the circulating system is based makes it possible to optimise cutting diagrams on several levels. Once the parts are finished, a gantry discharges them for further processing. When designing the gantries, Schelling and Lenze made use of the new FAST software technology. This contains a fully-fledged robotics core that offers everything the design engineer needs for fast and flexible handling tasks, even without any special knowledge of robotics. The target is to quickly supply the saw with the right boards and then to speedily transport them for further processing, all in the most efficient way possible.
Adapting path profiles the easy way
Lenze FAST software creates coordinated multiple-axis path profiles with advantages compared to sequence-controlled single-axis movements of XYZ gantries. The coordinated movements in three dimensional space make the gantries faster and the accelerations of the boards considerably gentler. The consequence is a higher number of cycles because the gantry moves along an optimised pathway; the gantry can travel slower but arrives at its destination in the same time. It follows from this that the drives need less power and can therefore be designed to be smaller, lighter and less expensive.
One special requirement for the Schelling solution was to bypass obstacles in the working area as quickly as possible. This is achieved by means of flexible path planning that is independent of the workpiece. For horizontal transport, the tables are fitted with brushes on which the boards can slide without being scratched. This avoids the need for expensive vacuum systems that lift the heavy boards with suction pads.
Motion control with the standard "Pick & Place" FAST technology module for gantry robots has clear advantages. The software controls most of the functions of this application. The paths a gantry robot has to move along can be set with the "Pick & Place" technology module or with the standardised motion commands of PLCopen Part 4. The benefits are time and cost savings because more complex motion control programming is unnecessary, and improved software quality due to structured programming.
Efficient multi-axis system
The board paths are processed by the Lenze 3200C Motion Controller, which communicates with Lenze i700 servo inverters via EtherCAT. These products are specially designed for coordinated multi-axis movements with a central power supply module supplying power via a DC-bus. An exchange of energy between the individual inverters improves efficiency and, at the same time, enables a compact control cabinet layout. The Lenze Motion Controller 3200C is not only responsible for motion control but simultaneously serves as an interface to the higher-level plant control system where the cutting geometry is created. Schelling is thus ensuring progression towards the goals of Industry 4.0 by implementing a networked mode of production that can be optimised holistically. Dietmar Nußbaumer, when describing his company's collaboration with Lenze, said Schelling is increasingly thinking in terms of mechatronic modules consisting of mechanical parts, electronics and software that it can re-use for other projects. It therefore needs full-range suppliers that can also help it to develop software
Lenze FAST technology generates efficiency gains over the entire product life-cycle - from the design of a machine, through development and programming, to commissioning and operation. As FAST technology modules are tested and software products are well documented, less time is spent on complex software development of machine functions. Moreover, the extensive libraries of prepared basic functions and the overall easy use of complex technologies such as "Pick & Place" for varied robot kinematics make the work much easier.
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