OEE Reports - Automated
Capturing & Recording of Availability Data
Moving Beyond Manual Data
Collection & Manual Data Compilation
Overall Equipment Effectiveness (OEE) continues to gain acceptance as
an effective method to measure production floor performance. Capturing and
recording accurate production floor information is critical for producing
reliable OEE Reports.
A number of production floors are utilizing manual methods of data
collection for producing OEE report. This approach leaves room for both
inconsistencies and inaccuracies. With manual data collection, there is
usually a second step of manually compiling the data. This is most
commonly accomplished by entering in the information into spreadsheets.
This manual compilation step also leaves room for both inconsistencies and
inaccuracies.
Another disadvantage to manually collecting data for your OEE reports,
like with many maintenance and production improvement plans, is
sustainability. The more task intensive an improvement plan is, the more
likely priorities will change and the OEE initiative will fade away. With
an automated data collection system, sustainability is no longer an issue.
Once in place the automated OEE reporting stays in place and you need only
act on the results.
There are cost effective automated data collection alternatives to
manual data collection that significantly improve the accuracy of OEE
reports. Automated capturing and recording of "Availability
Information" will be covered in this article. Future articles will
address the automated data collection of Performance Rate and Quality
Rate.
OEE
OEE = Availability X Performance Rate X Quality
Rate
Availability - Percent of scheduled
production (to measure reliability) or calendar hours 24/7/365 (to
measure equipment utilization) or equipment or line status (to
measure ability to produce), that equipment or a production line is
available for production.
Note: Measures the percent of time that the equipment can be used
(usually total hours of 24-7-365), divided by the equipment uptime
(actual production).
Performance Rate - Percent of parts
produced per time frame, of maximum rate OEM rated production speed at. If
OEM specification is not available, use best known production rate or a
standard production rate can be established.
Note: Performance efficiency is the percentage of available time that
the equipment is producing product at its theoretical speed for
individual products. It measures speed losses. (i.e. inefficient
batching, machine jams)
Quality Rate - Percent of good
sellable parts out of total parts produced per time frame.
Note: Determining the percent of the total output that is good. (i.e.
all products including production, engineering, rework and scrap.)
Example: 50% Availability (0.5) X
70% Performance Rate (0.7) X
20% Quality Reject Rate (results in 80%(0.8) acceptable) =
30%OEE (Please see www.DowntimeCentral.com/OEE_TEEP.htm
for a free online calculator to practice with.)
Defining What Is Availability
One of the first steps in initiating OEE reporting is defining the
parameters for the elements of OEE for the individual piece of equipment,
production line or the entire factory. That is clearly defining,
documenting and communicating why a piece of a piece of equipment or a
production area is unavailable for producing product.
There are three basic approaches to defining availability. The
approaches are the percent of scheduled production, calendar hours, and
equipment or line status. The schedule production approach defines
availability by the production schedule for a piece of equipment, a cell
or an entire production line. The calendar hours defines availability as
the total time available to produce product which is usually 7-24-365. The
equipment or line status approach defines availability in terms that
production line or piece of equipment is in a state to produce product.
All three approaches are valid approaches. The percent of scheduled
production and calendar hours provide a broad view of availability while
the line status approach is a much more defined view.
Some examples to consider as causes for unavailability is power to
piece of equipment or does the production station have personnel in place.
The above two causes may not be enough to define the reason for
unavailability. You may need to add data inputs recording if there was
materials in place or the status of the infrastructure support (such as
air pressure for air driven tools and equipment) as monitoring points
to determine if a piece of equipment, a cell or an production line is
available to produce a product. Availability must be defined for each area
or piece of equipment that will have OEE reports. In some of the instances
there will be more than one element that needs to be monitored to
determine if that piece of equipment or area is considered available.
Setting a goal of capturing availability status information with no
manual data collection or manual compilation for OEE calculations is the
first step in improving both the accuracy of OEE reports as wells as
reducing the cost to produce the reports. Start with defining what affects
availability for various areas of a production facility. Identify the
specific data collection points that will affect availability for a given
area or unit of equipment. In many cases there are data collection points
already in place. For those monitoring points, you need only to retrieve
the existing data. In other instances, a data collection monitoring device
will need to be installed.
For installing new data collection points, there are available a
variety of inexpensive sensors that once installed, can capture the
measurement of numerous parameters. These sensors can detect flow rate,
weight, quantity, motion activity, phases of electrical power as wells as
many other items. The sensors usually come with normally open or normally
closed switch contacts. These switch contacts will serve as the data
collection points for automated data collection.
Using sensors with switch contact outputs for most monitoring
situations are probably the easiest approach for capturing availability
data. To monitor equipment starting with power switches and other
functions of equipment, it is often the case of adding an extra set of
inexpensive contacts to an existing switch on the equipment.
There are other means to capture activity status information including
embedded equipment control software and equipment monitoring software that
can capture the parameters for availability. What must be factored into
the monitoring approach is that each monitoring point must include a time
and date stamp.
The data collected from the monitoring points must be transmitted to a
database for data retention and reporting. The database that captures and
records the status information can be a commonly available P/C database
packages such as Microsoft Access®. It is critical that all data points
recorded must include time, date and location stamps to support the
development of OEE reports. Database report writers can be used to extract
the information to produce OEE reports.
In addition to custom in house database systems, there are available
integrated data collection systems with application software packages with
complete OEE Reports. These systems and reporting can be tailored to each
individual facility's requirements.
The Wireless Connection
The implementation of the wireless LAN or other wireless technologies
to capture and transmit availability data greatly enhances the timeliness,
utilization and flexibility of the data collection system. Hard wired
systems over time, limit the functionality of a data collection system. In
the past wireless technologies did not provide the high level of
reliability that is required for factories, leaving the hard wired systems
as the only alternative. That is no longer true especially with the
introduction of the wireless LAN 802.11g standard and advanced 900 MHz
technology. Wireless data collection and transmission systems provides for
easy reconfigurations of changing production floor layouts or changing
production flow activity. A number of off-the-shelf production floor
wireless data collection systems are available for use on the production
floor.
Cost Justification
The implementation of an automated data collection system with an
integrated database provides immediate financial returns. The labor cost
associated with manual data collection on production lines by production
personnel and the manual compilation of the data to calculate OEE are
eliminated with an automated system. The accuracy and integrity of the
source data is significant improved. With more accurate OEE reports you
will make better financially feasible decisions that will result in even
greater savings. The timeliness of the OEE reports themselves are also
significantly improved with automated data collections. In most cases, the
OEE Reports are available for review the same date as the final element of
information is captured.
About the Author: Bob Giese
is President of VersaCall Technologies Inc. which as been implementing
wireless factory floor monitoring and communications since 1995. To learn
how a wireless system would benefit your location e-mail sales@versacall.com
or visit www.versacall.com.
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