|For every manufacturing organisation, breakdowns are a major concern. Not only can they be costly to remedy, they also result in lost production and disappointed customers. Fortunately, there is a convenient and cost-effective way of substantially reducing breakdown risk, says Ian Smith Technical Manager of ERIKS Electro-Mechanical Services.|
Spend a little money on a regular basis and virtually eliminate the risk of equipment failures and breakdowns, the total costs of which can in many cases run into tens, if not hundreds of thousands of pounds. That may sound too good to be true, but it's precisely what well-implemented condition monitoring has to offer.
Essential features of the techniques used in condition monitoring are that they can be employed without the need to shut down the machine that is being monitored. Indeed, most of the techniques rely upon the equipment being in operation while the tests are carried out. In addition, the main techniques are non-invasive, so they will not adversely affect the operation of the equipment in any way.
The forces that produce vibrations are associated with a wide range of types of machine components, each of which usually has its own associated frequency. These so-called forcing frequencies may, for example, relate to rotational shaft speeds, gear meshing, bearing vibrations, oil whirl in plain bearing machines and random vibrations.
Analysis of the data obtained from the vibration transducer can, therefore, be used to give a good indication of its source and, if there is a sudden change in frequency or amplitude, where the investigations into the cause of the change should be focussed.
Closely allied to vibration analysis are modern methods for addressing the problems it reveals. These include laser alignment and on-site balancing of rotating components. Laser alignment is principally used to correct misaligned couplings, and greatly reduces the risk of damage to bearings and seals, as well as minimising energy losses. On-site balancing ensures that machines run smoothly, prolonging their useful life and, once again, reducing power consumption.
Another technique that is starting to be very widely used is thermography - essential looking at images of the equipment that are coloured to show the relative temperatures of the components and, in particular, reveal hot spots. This can be useful, for example, to reveal a bearing that's running hot, or other areas where there is excessive friction in a machine.
Another condition monitoring technique with a very wide range of applications is oil analysis, which is applicable to both mechanical and electrical equipment. Lubrication oils are typically tested for moisture, viscosity change, contamination and component wear particles - the excessive presence of which can signify a component approaching failure.
Specific condition monitoring tests for electrical equipment are many and varied, but among the most useful are insulation tests, especially for high-voltage equipment, where a decline in insulation resistance, even though its current value may still be well within acceptable limits, is a dependable sign that attention is needed.
An innovative and very effective approach to evaluating the condition of the insulation in high voltage motors and generators is partial discharge testing using Rogowski coil technology. This is a completely non-invasive technique that, unlike many of the alternatives, does not stress the insulation. Nevertheless, it yields accurate and reliable results.
Condition monitoring is arguably the best investment a manufacturing company can make in minimising the risk of needing costly plant repairs, and of losing money and customer goodwill because of downtime. Particularly when the condition monitoring service is provided by an expert contractor, the costs are small but the potential benefits are enormous.
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