Lean Automation
Sunday, January 29th, 2012Most people are familiar with the term Lean Manufacturing: the elimination of waste from manufacturing processes and, in the process, simplifying and adding efficiency to those processes. Lean automation borrows those principles and applies them to automation.
Furthermore, lean automation allows owners to easily improve the performance of their systems and to introduce scalability to them. They can also use the data transparency that lean automation gives them to, e.g. generate, performance reports, assess the impact of changes or to gauge the effectiveness of cost reducing measures.
So, if lean automation is such a dramatic measure, how is it achieved? The answer is a combination of two technologies. Bus-based control wiring systems in control panels is one of these technologies; the other being the integrated HMI/PLC.
Bus-based wiring replaces the traditional “spaghetti” of wiring found in older control panels and replaces it with just one bus cable that runs around the components in the panel. Indicator lights, switchgear, motor starters and inverters are examples of parts that can be wired into this single loop. Now, instead of a jumble of wiring linking to the PLC or smart relay at the heart of the control system, the bus cable acts as the single link and almost removes the need for conventional inputs and outputs to the system.
In addition, should you later wish to expand or modify your system, all you need to do is plug or unplug components into the central bus cable. Scalability comes as standard and the bus cable technology allows you to plug modules into the system instead of having to rewire or “plumb in” a new component group.
Being a bus cable, it not only carries control signals to the various components, but it also transmits data. Every action carried out by the system can be carried to logging systems or …. Theoretically at least, total data transparency can be achieved.
So, that’s how bus cable technology can transform control wiring, but how does the integrated HMI/PLC help? The very existence of such devices depends on bus-based control wiring systems, meaning that only minimal provision needs to be made for conventional inputs and outputs. The formerly separate HMI and PLC functions can now be combined in just one unit. At a stroke, cost and space savings are made, but, crucially, programming is greatly simplified.
Choose your HMI/PLC product carefully, and you’ll have the ability to exchange data with external systems. What was once a very clever, but isolated piece of automated machinery can now be brought into the data fold of large-scale production plants. Communication with other IT systems is possible, so you can link to systems responsible for, e.g. quality control and order scheduling.
Lean automation is already having repercussions in the design of automation systems. “Traditional” automation systems have an architecture that includes a core PLC and a standalone HMI with a spaghetti of wiring both in the control panel itself and in the field. An obvious disadvantage of this architecture is the amount of time it physically takes to wire up. Less obvious is the fact that modifying or upgrading such systems is complicated and thus costly. In nearly all such systems, data transparency is, at best, at a poor level, because the control wiring is not capable of, nor designed to, transmit data to the PLC.
Acknowledging these shortcomings, designers started to use fieldbus systems, instead of the more commonplace field wiring, in conjunction with remote input/output modules. Clearly, this reduces the amount of field wiring and builds in greater flexibility and fieldbus systems can offer data transparency. However, there is still the “spaghetti” in the control panel to consider. The complexity of this wiring makes system modifications complex and although individual components within the control panel offer data transparency, in practise harnessing these data is often difficult, because the sheer amount of wiring renders the components inaccessible.
The implementation of lean automation has been made easier today, by using bus-based control wiring and integrated HMI/PLC devices within control panels. Combine this with the fieldbus systems and remote input/output devices mentioned above – all now commercially available – and nearly all the prerequisites for lean automation, i.e. data transparency have been achieved.
Control wiring is greatly reduced within control panels, so less space is needed inside them. Less wiring means less cost and system flexibility is greatly enhanced. Key automation components are now linked to the PLC via the bus-based wiring, so data transparency and exchange are now a given. This makes it possible to implement actions such as complicated product changeovers on a machine automatically and remotely, thus doing away with costly manual resets.
Looking to the future, it will soon be possible to further enhance lean automation. Single bus-based systems will appear to eliminate the need for a separate fieldbus. When this is achieved, the holy grails of total lean automation and complete data transparency will be upon us. Cost savings will be significant, as will increases in system flexibility. Once this stage is reached, designers will have all the tools at their disposal that they have identified as essential for future automation systems.
The lure of lean automation means that designers are already integrating the concept into their products. As time goes by, there will be further improvements and developments, but there is nothing to stop earlier adopters from benefitting now from the gains to be made. Components and technologies are on the market now to deliver almost totally lean automation. By building them into new systems, companies will be buying themselves a competitive edge and gaining industry market share, which can only be to their benefit.
Barcode picking has been around for some years now to direct a warehouse picker and to integrate each picker with the materials handling system. The barcode scanners themselves have developed into an entire range to choose from.