Today’s manufacturing environment is driven by competition like never before. Customers are demanding more product more quickly, and if your company cannot keep up, they will find one that can. So when the word comes down from upstairs that production goals are being raised, you had better be prepared to meet demand, especially if you are in the maintenance department.
Maintenance's responsibility is to sustain all of the production capacity in any manufacturing facility. That is quite a responsibility. And because business is getting more complex and more competitive, the importance of maintenance is increasing proportionately and has required the evolution of strategies to cope.
"Most people think that the biggest production losses would be those big, catastrophic equipment failures where the plant is out of commission for hours or days, but in reality, it is the smaller interruptions that rob production," says Futuristix-Wonderware MD, Mike le Plastrier. "These can be caused through start-ups that are not as prompt as they should be or running a piece of equipment not quite up to its full capability. It is those daily, chronic and smaller production losses that really add up as a sum to be greater than any big outages."
Here are four things that can be done to alleviate some of these smaller blips that stand in the way of increasing production
Measure overall equipment effectiveness
Overall equipment effectiveness (OEE) is a way of measuring production on a line or on a piece of equipment. Three factors are used in an equation to calculate OEE:
* Availability, which is the measure of how long the line or equipment ran compared to its planned run time. To determine availability, operating time is divided by the total available time. Some companies also subtract planned downtime from this figure.
* Performance efficiency, which measures the number of units (or tonnage, etc) that were produced compared with how many could have been produced during that same time period if a piece of machinery could be run at its maximum sustainable rate.
* Quality rate, which is the percent of product that is first-run quality. This is simply the total number of parts or quantity run minus any rejected product or rework that may be necessary during that same run.
OEE is determined by multiplying the above three factors when expressed as percentages: OEE = Availability x Performance Efficiency x Quality Rate
Usually, a world-class facility has an 85% OEE, with availability at about 90%, performance efficiency at about 95% and quality usually at around 99%. Substituting these values in the above equation we get: OEE = 0,90 x 0,95 x 0,99 = 0,8465 (85%)
But it does not take much to drop OEE significantly. Assuming that availability drops to 80% because of unplanned maintenance or forced planned maintenance and that performance efficiency drops to 85% because of operational delays (re-tooling, poor changeovers, etc) while quality drops to 90% because of inadequately maintained machining centres or other equipment running outside their tolerances, we end up with an OEE of 61%.
"Wonderware's Down Time Analyst and Avantis solutions are designed to help manufacturers drastically improve OEE," continues le Plastrier. "DT Analyst is a scalable solution that is designed to provide insight into the events that cause production systems or their components to stop functioning. Armed with detail cause and effect scenarios, operators, engineers and managers can quickly identify problem areas and take remedial action. Avantis is a realtime condition-based maintenance and procurement solution that works as an additional layer to the InTouch scada HMI (Human Machine Interface) application. Condition-based maintenance means that maintenance is only performed as and when necessary thereby reducing plant down times. This can only be done with realtime monitoring of the equipment and that is why Avantis is linked to InTouch."
Improve set-up times
Sloppy changeovers often rob production time. But there are a few simple things that can be done to improve this considerably. The goal of improving set-up times is to reduce the time it takes to get from the last good part produced for the previous product run to the first good part made for the next product run. For many companies this takes one to two hours, but it can often be reduced to about 10 minutes.
"The first step is to be prepared for the next set-up," says le Plastrier, "and DT Analyst, through its history of what went wrong in the past, can help considerably with this by producing activity and equipment availability schedules that will improve incrementally each time the set-up is performed."
Be a better housekeeper
For these types of improvements to take place, a clean operating environment is a must. The five Japanese words - Seiri, Seiton, Seiso, Seiketsu and Shitsuke - mean: clearing the work area, arrangement, housekeeping, standardisation and ingraining.
Eliminating clutter creates space for the materials that the operator needs to perform his or her job. It also frees up room to create staging areas for items needed for the next changeover. Keeping everything in its proper place eliminates a huge waste of a worker's time: the scavenger hunt. Knowing the locations of tools, gauges, supplies, auxiliary equipment and other key items saves operators tremendous amounts of time by eliminating the search. This time-saving applies to the regular operations of the process, as well as when changing over the process from one product to another.
A clean environment also helps. If equipment is normally clean, the appearance of metal shavings or hydraulic fluid is an indication that trouble is looming and that action should be taken proactively rather than reactively when it is too late. All this, of course, has to be ingrained into the culture of the operators otherwise the benefits soon disappear.
Maintain communication
All of these associated practices involve communication between all departments, according to the experts. "The visual workplace is a buzzword which implies that if you do not share your information with all levels, including managers, supervisors and core employees, then how do you expect everyone to know where you stand now and where you are going?" says le Plastrier. The visual aspect refers to the need to go a step beyond traditional methods of communications such as memos and procedure manuals that lack the ability to inspire or, sometimes, even to inform accurately.
"Today, we have at our disposal a vast array of graphical analysis, visualisation and reporting tools that allow anyone at any level of the enterprise access to realtime and historical production and maintenance information," continues le Plastrier. "From Avantis which is as realtime as scada can get to web-enabled analysis tools such as SuiteVoyager and ActiveFactory which allow for the sharing of information worldwide."
SuiteVoyager provides management with the information portal they need to view their production and other processes and ActiveFactory is a web-enabled, plant-wide database management system that allows for the analysis of trends on selected tag groups while also making effective use of MS Excel for analysis and MS Word for reporting.
These steps can be applied to any industry to make improvements that will help eliminate the smaller, time-consuming maintenance hiccups that eat away at valuable production time and profits.
Futuristix
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