Jeremy Salisbury, Brammer UK

As competitive pressures on manufacturers in all industry sectors increase, any means of maintaining or improving production efficiency and business profitability is something to be welcomed.

The area of maintenance is one which has come under increasing focus in recent years, with maintenance often considered amongst the largest controllable costs for many manufacturing companies. As maintenance is increasingly seen as an aid to productivity rather than just a costly breakdown service, many companies are seeking to take a proactive and planned approach, rather than simply waiting for things to go wrong.

Before maintenance was considered as having the potential to add value to production, most companies based their approach on ‘run to failure’ or breakdown maintenance, meaning damaged or failed components were only replaced just before or when machinery came to a complete stop. While one advantage is that maximum life is extracted from each component, this is significantly outweighed by the potential impact on operational effectiveness and overall machine performance. Today, this approach is only really viable if shutdowns do not affect production and where labour and material costs are not a major factor – meaning it is rarely seen in large production facilities.

A more common approach is preventive or time-based maintenance, with maintenance scheduled at predetermined time intervals based on the production schedule rather than the machine’s true condition. This allows damaged or failing components to be repaired or replaced before obvious problems occur. However, one disadvantage to this approach is that it can result in key maintenance tasks being performed too early – with parts being replaced while they still have useful life in them – or too late.

For those companies more determined to extract the maximum service life from components while minimising downtime, predictive or condition-based maintenance is the usual way forward. This approach consists of scheduling maintenance activities based on the detection of mechanical and operational conditions as an early warning of potential failure. It enables machines to be shut down at a time most convenient to the owner, but does require upfront investment in condition monitoring equipment for factors such as vibration. Furthermore, this approach is only as effective as the information received and how it is interpreted – indeed, an incorrect assessment of deterioration in machine performance may actually result in an increase in maintenance work as well as in greater expenditure on replacement components.

An approach which negates the problems associated with all three of these maintenance methods is proactive or condition-based maintenance. While preventive and predictive maintenance seek to detect and prevent symptoms before they result in breakdown, proactive maintenance programmes seek to lessen or eliminate problems through root cause analysis (RCA).

RCA is based on the premise that problems are best solved by attempting to correct or eliminate root causes rather than by addressing immediate symptoms, with corrective measures then directed at these root causes to minimise the likelihood of problem recurrence.  Six main root cause categories are typically identified as encompassing all areas of failure – these are faulty design, materials defects, manufacturing errors, assembly or installation errors, off-design operation and maintenance errors.

The scope of proactive maintenance tools for RCA includes laser alignment, vibration analysis, infrared thermography and oil analysis, with the data from this analysis then able to be used to optimise equipment, programmes and schedules.

To be effective, RCA must be performed systematically, with causes and conclusions backed up by documented evidence. It comprises seven main steps – defining the problem; gathering data and evidence; asking why the problem is occurring and identifying the causal relationships associated with it; identifying how these  causes should be removed or altered to prevent recurrence of the problem; establishing whether solutions that prevent recurrence are within control, meet objectives and do not cause other problems; implementation of the proposed solutions; and finally monitoring of these solutions to assess their effectiveness.

While such as systematic and detailed approach marks a major departure in maintenance strategy for many manufacturers, its impact is being widely proven in terms of safeguarding production schedules, adding new efficiencies to operations and reducing maintenance costs, and proactive maintenance is likely to become the norm among forward-thinking manufacturers in all sectors within the next decade.