To help manufacturing companies operate as efficiently as possible, many modern firms use what are called manufacturing execution systems (MES.) So, if you thought that ERP and SCM systems were the answer to fully integrated efficiency, then think again

Tuesday, 12 July 2005

Traditionally, MES are used to keep track of production schedules, inventory availability, work in progress and a range of other operations-related information flowing to and from the shop floor.

In most plants there is no lack of raw data about the manufacturing process. SCADA systems (standing for Supervisory Control and Data Acquisition) or similar DCS (Distributed Control Systems) control and monitor plant and equipment hardware and feed data to the MES software layer.

The MES then provide integrated IT support for all factory floor activities, often replacing a fragmented collection of paper schedules, tickets, drawings, routings and so on with electronic equivalents. The Manufacturing Execution Systems Association (MESA) identifies 11 key functions of MES:

Management of all resources and their status - machines, tools, materials etc.
Local scheduling and prioritization of work
Dispatching of work - launching of jobs on resources
Document control - work instructions, drawings etc.
Data collection and acquisition
Labour management - time and attendance and so on
Quality management - quality measurements
Process management - tracking machines etc.
Product tracking
Performance analysis
Maintenance management.

A comprehensive list, I think you'll agree. But one that today's "just-in- time" manufacturing environment requires, i.e. production systems that are more flexible, agile and reliable than ever before, including the manager's ability to monitor plant status in real time and respond quickly to any disruption in output or change in orders.

Until recently, however, there has been little effort to collect and make this kind of plant-floor information available to plant managers and to enterprise management systems such as ERP and SCM tools.

Horses for courses

Analysts go as far as to say that there is a clear dividing line between plant-floor systems and the rest of the enterprise and that ERP vendors simply don't understand plant-automation vendors and vice versa.

For example, much IT in manufacturing companies is about handling large volumes of information that is not usually time or safety critical. An invoice 10 minutes late will not usually damage a business. Real time control is about minute-by-minute control of the manufacturing process. It is often ultra time critical and has plant safety implications. Because of their different needs, these types of computer systems have evolved in very different ways. So have the professionals that run them and there is often quite a gulf of understanding between them.

However, to succeed, MES must not only take information from the IT system, but also minute-by-minute shop floor data from the real time system without compromising it in any way. Only then can it provide the fast, detailed and objective information needed. This analysis is also a two-way street. Once it has taken place and decisions have been made, MES must be able to download instructions to the real-time control system to ensure that the hard won best practice conclusions are locked into the systems that run the manufacturing process itself.

The information gap

Writing in 1998, Richard T. Lilly, founder of Lilly Software Associates was already commenting on the gulf between MES and ERP: "The problem is that most ERP systems don't have a set of screens that show what each machine or department is doing and when they are supposed to be doing it."

He explained further: "Sometimes a given part can be produced in a day. At other times, it takes up to a month. It simply depends on the load in the shop. What about late customer orders? No ERP vendor would dare tell upper management that they don't need to bother themselves with the details of late orders. But they will find it difficult to directly address the question with specific capabilities that can determine why an order is late and how it might be finished earlier, much less how a schedule change in a shop order will affect other orders."

Because there has been little useful information flow between the high level management IT systems and the factory level automation systems, senior managers have had to base strategic decisions on production data that is incomplete, out of date or just plain wrong and there is little evidence that the widespread up-take of ERP has had any positive impact on industrial output. It's only by integrating a plant floor system with the rest of the enterprise that companies are able to get the kind of holistic view that's needed to support a build-to-order model.

(I guess this is why a friend of mine expressed a certain amount of exasperation when having ordered her custom made new car, she was advised of delayed delivery times by a harassed salesman who said that often their computer system told them the car had not yet left the factory when in fact it was already neatly parked at the back of their showroom premises. So much for real time information processing. She asked him to do a very non-technical thing and walk round and take a look to check that this was indeed not the case.)

So under-investment in the connection of the factory floor to the ERP system is still one of the greatest challenges facing manufacturing enterprises.

But that's beginning to change, as reflected by the growing trend among manufacturers to move to an Internet-enabled business that emphasizes low inventories, short cycle times and quick order execution. MES are being viewed as the vital missing link for tying plant-floor information with business management information provided by applications such as ERP and CRM. But not one system and one database for ERP transactions and other separate systems and databases for MES, rather a fully integrated single database system.

Be prepared

Hooking an MES into an enterprise-wide system is still no easy task (but you knew that right?) and requires very tight integration between systems that are as varied as order entry systems, product configurators and planning and control systems, as well as sales force and delivery systems.

Increasingly, ERP systems are including MES modules that fully integrate with the main system and provide the fullest IT support to the factory floor using a single database system, otherwise bridging this gap means integrating software, network capabilities, protocols and languages that often bear little resemblance to each other requiring layers of middleware and connectivity tools.

The proof of the pudding

Richard T. Lilly's advice still seems to hold good. He urged you: " to ask your ERP vendor to show how a customer can get order status and delivery information over the Internet. Or better yet, see if they can demonstrate creating a quote for a new prospect with a scheduled delivery date based on the availability of both materials and resources. Finally, ask if a what-if scenario can be run on a client PC in the space of minutes without shutting down the operational side of the system.

If you are convinced that you can get the entire package at a good price without paying several times the initial cost in additional fees for training, implementation and consulting, then buy it."