So says David Manning-Ohren, a condition monitoring guru at MRO (maintenance, repair and overhaul) specialist Eriks UK, who is now offering 10 rules to get condition monitoring working for you, not against you.
"Effective maintenance management depends on the accurate forecasting and diagnosis of problems – but using the wrong technique can waste time, money and resources with no effect on uptime," he warns.
Rule 1 – Never use condition monitoring on its own, or as a trending tool. For monitoring to work best it must be implemented with a strong maintenance strategy and repair feedback from the maintenance team or outside suppliers. A sound maintenance programme needs to take into account multiple factors, not just trends.
Rule 2 - Spend your money on the most valuable asset: the key to improving uptime is assessing which plant is critical and devising a schedule that takes into account its failure or repair history and cost to a business when it is unproductive. A small motor gearbox with a replacement cost of a few hundred pounds, which can be sourced quickly and easily from a distributor, is not critical equipment.
Rule 3 – Get close to your key plant and machinery: "The best condition monitoring device ever invented is man," quips Manning-Ohren. "Tap into the people using the machine every day, and who notice the rattles, smells, squeaks, drips, bumps that are out of the ordinary. Every one of these will help you predict failure." Over time the operator is the one person who will detect changes in cycle times, efficiency or vibration that offer clues to what is going on.
Rule 4 – There is no ideal condition monitoring frequency: "I'm often asked, 'How often should we monitor the condition of machinery?'. The answer is 'I don't know', because it depends on many variables – from the maintenance regime to the quality and age of the equipment and its criticality." Frequency can only be determined once you understand the plant and equipment, and its role in production.
Rule 5 - Keep a vibration database. Since vibration is a key to a strong condition monitoring regime, a good database is essential and this should include trends, spectra and time waveform. "Trend records the overall vibration parameter value, and details the date and time of the reading. Spectrum measures the amplitude of the vibration parameter with respect to its frequency. And the time waveform measures the raw vibration signature without filtering or processing. Vibration checks every four to eight weeks is a good starting point."
Rule 6 – Understand the plant and understand the operating conditions. "Always walk around a site before taking any readings. Switch on any machinery to ensure that it is warmed up and fully operational." A reading when a piece of plant is cold could be very different from that on a machine that has been running flat out for two hours, explains Manning-Ohren. "Also the speed of plant can change, causing vibrations and temperatures to alter non-linearly. Base-lining with respect to speed and operating load is excellent practice."
Rule 7 – Certification is better than qualification. Condition monitoring is constantly evolving, advises Manning-Ohren, so any qualification has an expiry date as techniques are updated. "Certification that requires updating every five years is infinitely preferable to any qualification. If you are condition monitoring in-house, you need to ensure that your people are up-to-speed, and aware of new technologies and practises."
Rule 8 – If you outsource condition monitoring, insist on seeing some paperwork. "There are sound reasons for [outsourcing] but, before employing anyone, ask to see some paperwork to ensure you are only employing the best condition monitoring experts," suggests Manning-Ohren. "Plant users should insist that all engineers sent by a service provider are qualified to ISO 18436 and abide by the BINDT [British Institute of Non-Destructive Testing] code of ethics".
Rule 9 - Judge a condition monitoring provider on more than the day-rate. "Typically, the cost of condition monitoring is based on the number of machines that require monitoring multiplied by the expert's day rate. Unfortunately, this takes no account of the type of data being taken, software being used or basic competence," explains Manning-Ohren. "Also, consider the support that an organisation can offer: expertise on bearings, gearboxes, pumps and motors is essential to any condition monitoring service provider."
Rule 10 – Delay failure with good maintenance. "Be sure you are taking appropriate measures to delay the failure as long as possible by doing the little things – like appropriate lubrication, dusting down cooling fans on motors, running a vacuum over the distribution board and cleaning the pool of oil under the machine so any new drips are noticeable. Some people call this preventive maintenance. It's just common sense."