In industries that rely on complex manufacturing, there is a common misperception that all manufacturing execution systems (MES) have a common intent, purpose, and function. Gartner defines MES as systems that do the following:
Manage, monitor and synchronize the execution of real-time, physical processes involved in transforming raw materials into intermediate and/or finished goods. They coordinate this execution of work orders with production scheduling and enterprise-level systems. MES applications also provide feedback on process performance, and support component-level and material-level traceability, genealogy, and integration with process history, where required.
While this is a very good general definition, the fact is that MES is not a general solution, but rather one very specific to the industry in which it is being applied. Contrary to those vendors that present MES as a “one size fits all” tool that can be applied to any market, MES solutions are industry-specific tools. Selling one into a market it wasn’t designed for is an expensive gambit for the company that buys it, because it will require time- and capital-intensive customization to make the round peg fit into the square hole.
Five Main Types of MES
Five principal types of MES have been developed to serve different industrial markets: continuous process (e.g., oil and gas), pharmaceutical; automotive, consumer electronics, and complex discrete (e.g., aerospace, defense, nuclear, medical devices, industrial equipment). Consider the key functionalities they deliver in each instance, and how they differ from one another in core functionality:
Continuous Process MES
- Multiple monitoring tools that track on a per-second basis
- Intimate linkage to machines; importance of the SCADA layer
- Lot traceability only
- Minimal instructions
- Highly controlled software development, testing, and validation processes
- Built-in oversight functionality
- Built-in quality tools (receiving and in process)
- Lot and sub-lot traceability
Consumer Electronics MES
- Designed around the circuit card assembly process
- Close integration to machine inputs and outputs
- A highly efficient debug and repair process
- Little process deviation allowance
- Emphasis on front-end simulation and validation of processes and tools
- Closely scripted routing and materials control paths
- Built-in line balancing technology
- Automated lot and serial traceability
- Engineering around a repeatable and predictable process
Complex Discrete MES
In light of the remarkable degree of differences among these MES tools, it sounds impossible that an MES designed for one market would be sold into another. Yet it happens often. Unscrupulous or opportunistic vendors are at fault, but so, too, are MES users who have fallen prey to generalization – the belief that MES is MES is MES – and who fail to understand that their MES tool must be focused on the intricacies of the shop floor they operate.
A Closer Look at MES for Complex Discrete Manufacturing
In complex discrete manufacturing, technicians are involved in 30 to 60 percent of the assembly, and that assembly is a quantity of one. That one unit, through its build, may go through 30, 40, or 50 engineering changes from the time it is started to when it gets released. That doesn’t happen in any other industry.
One example is in building aircraft carriers for the U.S. military. When any aircraft carrier is built, it has already been completely redesigned by the time it gets delivered to the Navy. On average, one ship has gone through seven complete rebuilds. It takes three years to deliver one of these assets, and technology grows faster than the build process, so things can get completely re-engineered.
One might ask, “Why don’t you just design the command and control at the end and do it once?” The reality is it takes so long to figure out how all the electronics and devices interact with command and control that there is no choice but to do it up front, even though it will evolve enormously throughout the build process. It’s understood that these rebuilds and evolutions will have to happen.
Re-Routing in Complex Discrete Manufacturing
Re-routing has to be extremely flexible, because it is being written on a part-by-part basis, and not on a part-number-by-part-number basis, but on a unit-by-unit basis. So, for example, every satellite will have multiple iterations of a work instruction. Even though 26 satellites will be built in the next two years, each one may have work instructions written four and five times individually. No other environment has that kind of rewrite.
Non-Conformance and Deviation in Complex Discrete Manufacturing
The non-conformance and deviation process must be ironclad and completely linked to the unit, because that unit history shows a lot more about what went wrong than about what went right. All the details about what went wrong – how it was dealt with and how it was fixed, as well as the process through which the customer agreed to accept the new specifications – must be included in the delivery of that unit.
Serial Tracking and Delivering the Digital Twin
Every unit has to be delivered with its digital twin, but very few MES systems can actually deliver the digital packet. In fact, the earlier paper-based documentation often weighed more than the actual unit itself, be it a helicopter or tank!
Finally, serial tracking must go all the way into the supply chain, pre-assigning serial numbers into the unit and pre-testing those units before they even get to receive the instructions. No other industry requires this level of involvement. Complex discrete does this as a matter of course.
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