By Kathie Poindexter
What is the di;erence between enterprise resource planning (ERP) and a manu- facturing execution system (MES)? Ultimately, it matters less what you call it. Infinitely
more important is this: Can the system support
your manufacturing operation?
How MES Came to Be
Some ERP systems include some or all of the functionality usually expected in an MES, while other
ERP platforms may contain only a subset and need
an added MES to support the manufacturing operation fully.
Early material requirements planning (MRP) systems evolved into MRP II, manufacturing resource
planning, which accounted for the resources, like
people and machines, needed to produce a product. It then expanded further to what is now known
ERP typically recorded transactional data and
reported it daily, weekly, or monthly. This did not
meet the needs of shop management, who wanted
a platform to be able to record and report every
transaction on the floor instantaneously. So;ware
applications needed to record and report trans-
actions as they occur, in real time. This demand
spurred the development of so;ware applications
to support real-time data collection, which evolved
to become what we know today as MES.
In the late 1980s MES for the job shop started to
become available. They o;ered operations scheduling, data collection, and machine maintenance
scheduling. By the early 1990s we saw these basic
scheduling and data collection so;ware applications being transformed into the MES applications
of the modern era.
The term manufacturing execution system was
first used in 1992 by AMR Research, now part of
Gartner, and in that same year MESA, or the Manu-
facturing Enterprise Solutions Association, came
into existence. MESA defined MES as “a dynamic in-
formation system that drives e;ective execution of
manufacturing operations. Using current and accu-
rate data, MES guides, triggers, and reports on plant
activities as events occur. The MES set of functions
manages production operations from the point of
order release into manufacturing to the point of
product delivery into finished goods. MES provides
mission-critical information about production ac-
tivities to others across the organization and supply
chain via bidirectional channels.”
MES capabilities have improved greatly since
1992 thanks in part to MESA, which has acted as a
global forum for manufacturers and so;ware ven-
dors alike. The organization also has helped the
growth and adoption of the ANSI/ISA- 95 standard,
which serves as the basis of MES development.
From the 1990s until today, MES has continued
to evolve. Early applications were deployed on-site and modeled on the current manufacturing
processes. They o;en required a high initial capital
investment, and they also were not very adaptable.
It was di;icult for manufacturers to implement
changes, and any change required a lot of e;ort and
specialized resources. Those changes also required
someone to be very well-versed with the system.
These factors also have made some organizations
reluctant to replace legacy MES with more modern,
flexible, and robust systems.
These early systems also did not eliminate manual data entry—a significant frustration for managers
and shop floor personnel alike. It was not unusual
to see operators spend time walking over to a computer terminal to key in job information. If the shop
didn’t have enough terminals, operators sometimes
had to stand in line to enter data into the system.
Moreover, manually keying in data opened the door
for errors. The result: An e;ort to track productivity
sometimes made an operation less productive.
In the mid-2000s MES started becoming more
flexible and web-based. Eventually cloud-deployed
applications became popular, which allowed more
investment in the application itself rather than the
hardware to support it.
The MES also moved from being one monolithic
system to being modular, which meant that organizations could choose which function was most
critical to their success and pay only for the features
required. As long as internet access was available,
manufacturers could use an MES from anywhere,
from any device (laptop, phone, tablet), and for any
plant or production line around the world.
Some may describe MES as either a module or
an extension of ERP. Today you will find both stand-alone MES packages that can be integrated into an
ERP system as well as ERP systems that have the
MES functionality embedded within the application.
Human and Machine
Whether considered independent or a module of
ERP, every MES has two distinct points of interaction: human and machine. The human MES, a common component of most modern ERP systems,
provides accurate labor reporting, a vital concern in
job-costing and job-status reporting. Online transaction tracking gives management a current picture
of what is occurring on the plant floor by employee
and by job.
Embedded within ERP, human MES provides one
holistic flow of information for job management,
scheduling, quality assurance, and material management; eliminates dual entry; and provides online, real-time views of the latest plant floor scheduling priorities.
Embedded document management allows plant
floor access to needed documentation, including
product drawings, process documents, and even
The name doesn’t matter—but its effectiveness does