Personal well-being and plant profitability have some things in common. The more we know ourselves, the easier we find our way in life.

When we have a handle on our financial obligation in the near future, we sleep easily. At work, the same element of understanding applies. But too often, a lack of knowledge and control leads to lost profits. In the plant maintenance arena, we frequently see companies with no game plan. In an economic climate of flexible manufacturing reliable equipment performance is vital.

Predictive maintenance helps businesses know themselves. Armed with knowledge about their equipment, they can control cost, quality, and delivery.

A sound reliability-based maintenance plan not only detects and confirms machinery problems, but diagnoses their root cause to correct it once and for all. That translates into millions of dollars in savings for discrete manufacturing industries.

Machines run more efficiently with tighter tolerances, for instance. The result is less scrap and waste and better quality. Rough-running machinery often produces an inconsistent product, whether in size or finish variations. There's more at stake than money. For components that are manufactured for power aircraft or automobiles, quality becomes an issue of safety and reputation.

As the first step, discrete manufactures need a system and equipment reliability and prioritization plan.

Predictive programs
The predictive maintenance programs at many discrete batch plants, particularly smaller ones, run on a catch-as-catch-can basis--when budget and time permits. A number of companies use their equipment for troubleshooting rather than organized trend-monitoring. Understandably, at a small company the cost of equipment and training may not be justified so an outside contractor comes in periodically to monitor the health of the machinery.

Whomever is responsible, whether in-house staff or consulting team, wants to determine where deterioration may occur well in advance and appropriately plan for repairs that actually will be needed.

Some plants tear down and inspect every 30, 60, or 90 days. However, that practice does not take into account the individual nature of an operation, such as the percent of the time machines are running or other operating conditions. It's like changing the car oil every three months because the manufacturer says to do so, not because of the conditions the vehicle has endured.

System and equipment reliability plan

As the first step, discrete manufacturers need a system and equipment reliability and prioritization plan. This is a way to rank the importance of different pieces of machinery in the plant to achieve maximum reliability.

The significance of systems and equipment to the overall process is based on function, cost, production, safety, quality, and other concerns. If a main transformer went down, for example, that would be critical. But if a bathroom fan blew, well, who would care?

Among the benefits of such a survey is the tailoring of preventive maintenance activities to ensure an appropriate level of service. The goal, of course, is to keep machinery in excellent condition, but not to overmaintain it. The results of such a system and equipment reliability plan include:
 

•  system definition and ranking of systems by element,
•  equipment assignment and ranking,
•  critical equipment list,
•  maintenance priority for critical equipment,
•  failure modes and effects analysis for critical equipment,
•  maintenance task analysis for critical equipment,
•  maintenance priority for noncritical equipment, and
•  maintenance task reviews for noncritical equipment.

What happens most often? Are the common problems misalignment, imbalance and bearing wear or gear-tooth grinding and rotor rub?

Then they look at plausible functional failures: the possible modes, underlying causes, and the consequences. After checking the equipment, failure modes, and effects the next step is drawing a defense plan. This encompasses the most cost-effective mix of maintenance tools and services. The goal is to assign tasks that mitigate, warn, or defend against failure in appropriate ways.

Our philosophy is to use nonintrusive techniques and technologies wherever possible. We try to keep preventive maintenance to a minimum. This helps reduce lost production and associated costs. A business ideally knows in advance when major maintenance is needed. This is especially important in the era of just-in-time production, when precious dollars ride on every minute of available production time.

Finally, continue system and equipment reliability planning with noncritical machines. To make the process more manageable, try taking the equipment list in bits--say, 20 percent at a time--until all systems are go.

Just in time
Until recently, companies often stocked large inventories, but tying up capital that way is no longer common. Instead, businesses depend on just-in-time inventory. Companies that can respond command the road.

They dispatch products to customers just in time to meet their needs. If the shipment arrives late, a whole factory of people may not have anything to do. That's where predictive maintenance comes in.

Many automobile manufacturers require their vendors to have predictive maintenance plans in place. They gain a feeling of comfort that supply needs will be met just in time. For those who can pull it off, just-in-time delivery saves untold millions. But the time constraints leave little room for failure. For instance, for a car to be manufactured at noon, the parts need to arrive at a certain time just before that.

Dependable equipment allows vendors to hit the right delivery hour. If the machinery isn't running properly and the product doesn't come through on time, an angry customer may have a few words to say about reliability.

Manufacturers that use predictive maintenance to stay on track often have smart monitors that serve as the first defense against machine problems. The monitors, that track the operating and cumulative effects of parameters such as load, number of starts, temperature, and vibration, act as burglar alarms. They warn against potential hazards and help maintenance professionals decide where to investigate further with a full diagnostic analysis. Smart monitors help just-in-time manufacturers in many ways, including:
 

•  extending motor life.
•  estimating motor aging.
•  providing accurate motor condition assessment.

Selecting the best equipment
What is the right monitoring technology to buy? How much data to collect? The answer to both questions is the same: It depends.

Refer back to the system equipment reliability prioritization plan. Which are the most critical pieces of machinery to the operation? How much work do you expect from your equipment? What are the failure rates and modes?

After ranking equipment in priority of its effect on production and understanding what can go wrong, learn what practices can help prevent failure. Then find a supplier that can meet as many of those needs as possible.

The mix may include vibration analysis, oil analysis, infrared thermography, motor diagnostics, and laser alignment and balancing. It's a good idea to seek multiple technologies from a common supplier to help ensure continuity in product, service and training. quality assurance

As the name implies, predictive maintenance helps predict when and where deterioration will occur. Advance knowledge can head off problems which cause waste and cost time.

It costs considerably less time and money to ensure that a pump or gearbox is properly lubricated than it does to replace the lubricant. Ideally your company will strike a good balance of predictive, preventive, and proactive maintenance to ensure the highest quality possible in the end product. These are not programs, but rather, a style of maintenance that spells care and concern for the customer and marketplace.