Boxes on a conveyor belt

Engineering time

When production lines are under pressure, time needed for process improvements is one of the first casualties. But, as E&T discovers, there are ways to avoid postponing necessary downtime.

At potato processor Solanum, planned maintenance once tended to be more of an aspiration than a reality.

“We were completely reactive,” recalls Darren Mortimer, operations director of the Spalding, Lincolnshire-based business, which supplies potatoes to a number of UK supermarket chains. “When pieces of equipment broke, we’d repair them - with the engineers under pressure to give them back to production as quickly as possible.”

Solanum’s conveyor-based sponge drier roller tables, for instance, handle 57,000t of potatoes each year, with the bearing races on each table being prone to water and grit ingress, which dramatically shortens their lives. In theory, a twice-yearly bearing rebuild would significantly cut unplanned downtime. In practice, says Mortimer, temporary repairs were more usually the order of the day.

Such stories are commonplace. While machinery always runs better when regularly maintained, it’s not always convenient for the manufacturing function to release it for maintenance. Planning regular maintenance is one thing; working to that plan quite another.

The all-too-common result is maintenance deferred - often again and again, until a breakdown occurs. Worse, when planned maintenance does take place, it often does so at weekends, prompting premium payments in overtime to maintenance staff.

It’s a similar story with engineering improvements - even though the machinery in question, when handed back to production, will have improved yield, cycle-time and quality performances.

Third-party servicing

Yet it doesn’t have to be like that. Solanum is one of a growing number of UK manufacturing companies to have found practical solutions to the problem. The bottom line: there isn’t a one-size-fits-all solution - but there are several proven time-tested tactics that are worth trying.

At Exeter-based precision engineering subcontractor UK Precision, for instance, the maintenance of the company’s extensive range of CNC and manual turning and milling machines has been outsourced to third-party specialists, says managing director Andrew Warren.

The business tries extremely hard to make machines available on the day that an annual service has been booked, he explains. “It might cause us pain to release it, but we’ll try hard to do it,” he stresses. “If you keep postponing maintenance, you don’t get the reliability you need - and we need that reliability.”

The sting in the tail: a cancellation fee is payable if planned maintenance is cancelled at short notice. “It’s around 50 per cent of the cost of the maintenance - big enough to give us pause for thought,” concedes Warren.

At GKN Wheels in Telford, meanwhile, an IT application called Shopware helps to initiate planned maintenance by a combination of ‘trigger-based’ maintenance intervals - such as the number of strokes on a press, or the number of hours of production - and condition monitoring, supplemented by Overall Equipment Effectiveness (OEE) measures that point to adverse impacts on yield, uptime, scrap or rework.

As such, the business is better equipped than many to identify emerging maintenance issues early - and do so in time for remedial action to be taken. “Generally speaking, if the production guys have a good handle on OEE, you’ll see the quality and yield components start to deteriorate - which will encourage them to release it,” says Dennis McCarthy, director of DAK Consulting of Henley-on-Thames, a manufacturing improvement consultancy with a specialism in Total Productive Maintenance. 

“It’s education and awareness: many manufacturers focus on downtime, which disguises the need for maintenance until the deterioration is advanced,” he adds. “A growing number of small stoppages are also often a sign of emerging unreliability - and again, the effect of these usually shows up better in the OEE measure, due to start-up losses and lower output.”

Certainly, an awareness that diminishing equipment effectiveness is hampering production’s task serves to emphasise to GKN Wheels’ manufacturing management the need for maintenance, confirms Steve Burgess, continuous improvement project engineer within GKN Wheels’ central engineering function. With hard metrics highlighting just what is happening to a machine’s performance, he notes, it’s much easier to make a compelling case for maintenance.

That said, though, plant engineering teams at GKN Wheels try hard to minimise the impact on production by carrying out maintenance tasks while equipment is down for tooling set-ups.

“Changeovers can take six hours - and on older equipment, up to 12 hours,” notes Burgess. “So we try to carry out planned improvement work, or small maintenance jobs, while the equipment is down for a changeover. That way, we get the work done without affecting output.”

But not every business is so fortunate. For many, maintenance invariably equates to output loss. Even so, examples of best practice suggest ways of minimising the impact.

At Alcoa Fastening Systems - coincidentally, also based in Telford - maintenance manager Lee Johnson each year sets out a ‘shopping list’ for that year’s proposed maintenance, and then meets with production management and the plant’s production planner to consider the implications of what is proposed.

An agreed schedule is worked out, and committed to paper - or, more accurately, committed to a combination of a visual planning board in the engineering workshop, and an asset management system. The system, explains Johnson, generates the relevant engineering works orders to initiate maintenance, and also helps order the relevant spare parts - belts, filters, bearings and so on.

“The process works well,” he says. “And good communication with production is the key to it: they understand the importance of maintenance, and we understand that sometimes they are under even more pressure than usual to achieve planned output levels - so flexibility is required as well.”

This year, for example, there have been instances when maintenance activities have started later than originally planned. “Demand has been down, and the business has taken on work at short notice - so we’ve had to be flexible,” says Johnson.

And, in another example of good practice, he adds that an element of contingency is deliberately built into maintenance planning, to avoid disrupting production schedules by handing back equipment later than planned.

“The idea is that we hand the machine back when we said we would,” he says. “So if we’re running late, having an element of contingency built in allows us to avoid impacting production. Better still, it also gives us the opportunity to tackle anything unexpected that we might find when we start to work on a machine. If all goes well, we hand the machine back to production early. But we very rarely hand it back late.”

Finite-capacity planning

Yet, however clear the communication between maintenance and production, the fact remains that a piece of equipment is being taken off-line - and that while it is out of action, customer orders aren’t being worked upon. While it’s a rare plant in which a piece of equipment is unique and not duplicated or buffered by ‘back-up’ capabilities, the fact remains that off-loading a piece of equipment’s workload onto other items of plant invariably causes stresses and strains.

This is why potato processor Solanum chose to use finite capacity planning solution Preactor, from Chippenham-based Preactor International, to build maintenance and improvement activities into its factory production schedule.

Both preventative maintenance and ‘5-S’ workplace improvement initiatives are formally planned, with the Preactor system taking care not to disrupt deliveries to customers - even if, as was the case recently, a whole production line was taken down for three days.

Through a combination of inventory building and diverting work onto alternative lines, any impact on output is avoided, enthuses operations director Mortimer. “We’d never have been able to do that before,” he says. “The pressure to keep up production would have been just too great.” The Preactor system even takes into account which lines are the most efficient substitutes for lines taken out of production, he reports, and reallocates work in a strict order of preference.

Yet, ironically, although finite capacity scheduling systems have become more prevalent in recent years - even to the extent, as is the case with Preactor, of being available in desktop-based versions capable of running on a reasonably personal computer - relatively few manufacturing businesses use them to actually plan planned maintenance.

It’s something of a missed opportunity, reckons Preactor’s technical director Graham Hackwell. “It’s something that many prospective customers often ask about, but subsequently don’t go on to put into practice,” he notes. “Yet the reality - as at Solanum - is that they’d almost certainly do better if they did.”

Role models do exist, he reports - notably in the food and pharmaceutical industries, where strict regulations require certain types of maintenance, such as in-line cleaning and sterilisation, to be both carried out and logged. Building such activities into the schedule, says Hackwell, makes sure that they don’t get over-ridden by shopfloor management keen to keep lines going, and also provides part of the required audit trail to demonstrate compliance.

Working time management

Yet ironically, it’s two such manufacturers that provide an example of another best-practice approach to maintenance: working time management.

At Barnsley-based Manor Bakeries - producer of cakes bearing the Mr Kipling, Lyons and Cadbury brands - some 60 engineering craftsmen provided 24 hour Monday to Friday coverage on a variety of shift patterns. Work on a Saturday or Sunday was at the company’s discretion, was voluntary, and paid on an overtime basis.

But this increasingly became an issue when the business decided to introduce a formal preventive maintenance programme based on weekend working to avoid disrupting production. The voluntary nature of the weekend overtime, it turned out, couldn’t guarantee either the level of coverage, or that the coverage would be by engineers with the appropriate skills. Plus, of course, weekend working was at overtime rates.

The solution was a move to a different shift pattern for maintenance engineers, following an analysis and recommendation from Manchester-based working time specialist consultants Working Time Solutions.

“It’s something we see a lot: maintenance engineers working Monday to Friday, and fighting to gain access to plant and equipment for maintenance, yet that same machinery lying idle at weekends - when maintenance engineering staff aren’t contracted to work on it,” says Martin Gee, the firm’s director of consulting.

Similarly, he notes, Working Time Solutions recently helped the Ware, Hertfordshire plant of pharmaceutical giant GlaxoSmithKline move to new working arrangements - arrangements that provided built‑in flexibility to both the company and its workforce. While maintenance wasn’t the sole factor behind the move, says Gee, it was certainly very much part of the picture.

“All too often, people are employed on working patterns that are traditional, but which turn out to be no longer appropriate for the needs of the modern business,” he adds. Changing the shift patterns of the entire workforce can sometimes seem a bridge too far - and not only is changing the working arrangements of maintenance staff a more manageable challenge, but the benefits extend beyond the wage bill, into improved equipment reliability as well.

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