OEE key to improving plant performance

London — Process companies can benefit from adopting a new consolidated approach to performance improvement based upon the use of a KPI (key performance indicator) known as Overall Equipment Effectiveness (OEE).

While not a new concept, OEE is only now being widely recognised in industries away from its historical roots in automotive and pure manufacturing. This trend is being supported by the emergence of well-defined and broadly accepted methods of measuring plant performance.

OEE is a key measurement of efficiency in manufacturing processes at machine, manufacturing cell or assembly line levels. The concept had its roots in the Total Productive Maintenance (TPM) concept first conceived and used in the Japanese automotive industry in the 1960s and 70s.

In its simplest form OEE is encompasses three factors – availability, performance and quality. These can be defined as follows:

· Availability = Actual Production time / Planned Production time

· Performance = Current Run rate / Ideal Run rate

· Quality = Good Product / Total Product

· OEE = Availability x Performance x Quality

Using OEE as an analysis tool, businesses can benchmark their operations against world-class performance in their operating sectors. However, a simplistic comparison can be misleading if the sector specific variations — based on factors such as industry, type of equipment, level of customer demand are not considered.

As an aid in this area, the following OEE benchmarks are widely quoted as being “best practice” scores for a continuous manufacturing process:

Figure 1 “Best Practice” OEE Scores

OEE Factor World-class Score

OEE FACTOR	WORLD-CLASS SCORE
Availability	90%
Performance	95%
Quality	99.9%
OEE	85%

While the above scores are best practice, experience shows that most production operations typically operate with OEE scores in the range of 60-70%, indicating that most organisations have significant scope for improvement in the way that their manufacturing operations are run.

The key to achieving effective OEE is capturing and analysing data in real-time — or close to real-time — from production equipment, and presenting the data to plant operators and manufacturing management in a format that enables the data to be understood. These operations are generally performed by MES (manufacturing execution software) packages provided by companies such as Citect, which generally interface with existing SCADA/HMI,

These packages provide information and insight to everyone from corporate level executives and plant managers to maintenance and process engineers. The systems use a variety of graphs and charts that can be tailored for the individual’s particular information needs and preferences.

Implementation of an OEE package, typically takes between one and three months depending on the level and scale of adoption. Most of this time is devoted to planning rather than actual implementation.

The planning process attempts to address the key needs and concerns of the business within the context of its actual operations. It asks key questions such as: what ‘causes’ impact on production the most? What cause-based data points need to be measured? What definitions need input from the shop floor? What is the time-usage model adopted? What outputs does the business require at shop floor level, at corporate level and by department? What KPIs need to be displayed?

At all stages of the planning and implementation phases, OEE solutions should be regarded as an investment, not as a cost, Why? Because they bring significant benefits to organisations through improved profitability, better asset utilisation and virtually immediate ROI.

The OEE solution provides these economic benefits in a number of ways:

• It identifies “lost production”- the hidden potential in a machine or a cell that can deliver

additional throughput to improve overall plant performance

• It provides fast identification of the actual causes of problems that have a detrimental

effect on production; whether through human input (process/operator issues) or

machine/material issues.

• It facilitates more predictable production, allowing for better planning, quicker decision

making and execution and lower time to market for new products

• It provides the key to improvements in product quality, leading to lower product costs

and higher customer satisfaction.

• It delivers cost savings through increased production consistency and reduced waste

• It allows organisations to move from reactive approach repair and maintenance to a

more proactive approach

Once a system that captures data in real time is implemented, then the power of analysis can be unleased, revealing real “cause based” issues that can be resolved through various improvement initiatives. A good OEE will improve the production of the operation but consistent application of OEE will go further by rewarding the bottom line of a business.

Process Engineering article based on edited report by Citect, a supplier of industrial automation, real-time intelligence and MES systems