How do you shape up?09 December 2014
A quarter of factory management teams lack a formal maintenance strategy, while a third are oblivious to the costs of downtime, according to research. Time for a wake-up call, says Max Gosney
Too many factory management teams, it would seem, are adopting the ostrich approach to maintenance. Up to 30% don't know how much downtime costs their business, according to Plant Engineer's recent Maintenance Report. Factory leaders simply bury their heads deep and assume that all is well. Only all too often, it isn't. In this fragile world, it's a case of what you can't see may well hurt you.
Against this backdrop, the virtues of predictive maintenance – such as ensuring more cost-effective, efficient and safer plant – have been much espoused. That said, convincing senior management of its transformative power remains the challenge. The starting point is to make sure they understand what exactly predictive maintenance brings to the boardroom and, by contrast, where preventive maintenance can fall short.
"Preventive maintenance is work that is done according to a predetermined schedule," comments Reliable Manufacturing's managing director Andrew Fraser. "For example, every three months we tighten these belts; every six months we calibrate an instrument; or every three years we overhaul this machine."
By contrast, predictive or condition-based maintenance is work done on equipment that has been determined by a measured change in its health or performance. "It [predictive maintenance] allows us to understand the degradation process, so we can avoid a failure or minimise the consequence of the failure," Fraser explains. "It is critical to understand that most equipment failures are random, meaning that doing time-based replacement will not help manage most failures. So, having a good condition monitoring programme is essential."
Predictive maintenance, Fraser adds, is consistent with TPM (total productive maintenance). "This demands operator care and involvement in maintaining equipment, avoiding failure modes and monitoring them." In other words, operators must be trained in understanding how their equipment and processes work, and what to look out for to detect changes in the process and equipment performance.
"It is also an integral part of RCM [reliability centred maintenance], whose primary objective is to preserve system function. RCM identifies failure modes and then selects the most appropriate action to prevent or mitigate each failure mode, depending on criticality. Condition monitoring of failure modes is one of the key strategies for implementing the results of an RCM analysis."
It's also essential to understand that operators are a critical element in condition monitoring, looking at process and equipment performance for any signs of deterioration, he advises. "You can detect some 40% of your equipment problems by doing simple 'look, listen, feel and smell'. Benefits from instilling a predictive maintenance strategy should come almost immediately, through failure and/or cost avoidance," asserts Fraser.
Defects should be tracked and notional estimates of cost avoidance recorded, he advises, conceding that cost avoidance can be difficult to 'take to the bank'. That said, "you should begin to see lower maintenance costs within the first year or two of implementation of your programme", he reckons.
Meanwhile, thermal imaging is playing an increasingly vital role in predictive maintenance, providing a snapshot of the health of a system, suggests Andrew Baker, sales manager for Flir Systems. "It allows the maintenance teams to gather more information on the problem that has been flagged up by continuous monitoring. It enables engineers to see the fault in context, repair and then verify its elimination, once remedial action has been taken."
Historically the preserve of larger companies with big budgets, thermal imaging is now affordable for use in any engineering discipline – the price having been driven down by the increasingly widespread use of thermography across industry. With cost no longer a barrier, users are looking for the features that make thermal inspection both more cost effective and accurate. Flir's patented MSX, for example, takes elements of the visual image, overlaying them on its thermal counterpart, so that even the writing on a fuse board can be clearly visible on the thermal image.
"Several technologies can be used alongside thermal imaging, such as ultrasound, motor current and vibration analysis," Baker continues. "Each has its merits and none of them directly competes with thermal imaging. It is widely regarded as the ideal method for instantly indicating the health of a system, both electrical and mechanical. No other method can match it for flexibility.
"For example, the camera you use for checking an electrical circuit can equally be applied to underfloor pipework, spotting an overheating bearing or detecting missing wall insulation. Another benefit of thermal imaging is that it puts the problem in context. Not only does it show the hotspot, but also its relationship with other components, which greatly assists in diagnosing the fault."
There is a very real driver for preventive maintenance beyond cost saving. As Martin Robinson, chief exec at IRISS, says, it's about loss avoidance. "A production process may be optimally designed but, if it is frequently interrupted by the failure of electrical systems, the result can be catastrophic," he points out. "Total operation costs increase, personnel safety is compromised and fire risk escalates. Indeed, it is estimated that around 35% of all industrial fires are caused by electrical faults." In response, thermal imaging windows have been rapidly gathering ground as a safe method of inspecting both electrical systems and mechanical systems.
"And now there is an increasing trend towards the incorporation of other electrical maintenance safety devices (EMSDs) into basic systems designs, too," states Robinson. "This is a move supported by safety organisations, such as the IEEE, with its 'Safer by Design Initiative'. It encourages the inclusion of EMSDs into enclosures and panels at the point of manufacture. The clear benefit is that they allow maintenance tasks to be completed while the system remains closed, and in a safe and guarded condition."
In this way, the inspector is never exposed to the dangers of arc flash or electrocution, and inspection can be completed in a fraction of the time, compared with opening up panels. "The inclusion of EMSDs, either when the system is specified or when it's in the field, is proving an excellent way to minimise risks. They avert electrical fires, minimise loss of production and safeguard maintenance engineers. They are a win-win for any plant."
FLIR Systems Ltd
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