Skilled Trades are Machine Surgeons
Mining is a capital intensive industry filled with extensive investments in physical assets that all operate under arduous conditions, and keeping those assets productive requires maintenance, an activity that chews up a big part of operating budgets.
And, while it is likely that this state of affairs will endure, costs can be reduced while gaining a few other benefits you might not have considered.
Machinery does not last forever – it gets used and used up. It wears out, and it breaks down for other reasons – randomly. Why does it fail?
First of all, machinery is not designed to last forever, and while computer-aided designs and the use of stronger materials helps develop equipment that is lighter and stronger (without wasting excessive amounts of material on “over capacity”), machines do fail.
Engineers build in some safety factors to allow for material variability, manufacturing tolerances, safety factors, and to allow for their own uncertainty, but users of the equipment don’t know how much extra has been designed in, so they tend to push it a bit.
Not surprisingly, our assets actually do more for us than their nameplates suggest. But how much more? And, for how long? We just don’t know except by experience.
We could choose more robust designs for longer life, but we might be more tempted to operate them beyond their stated operating range. Even if we resist that temptation and we do have more robust and longer lasting designs, they still don’t last forever, and likely not for life of mine.
If they did, their cost would be astronomical. Let’s consider that we do make well-informed asset choices, but accept the fact that they will ultimately fail.
Every physical asset has a design “envelop” – a range of performance that it is capable of achieving. Push the asset beyond that range and we overstress it. Consider a shovel being used to break rock – we damage its bucket, hydraulics and structure. It is designed to dig and transfer rock, not break it – that’s what blasting and rock breakers are for. To the operator, breaking the occasional rock with the shovel may seem expedient. We get away with it for a while, but each time it’s done, the shovel weakens, eventually it breaks down.
To be “safe,” keep the asset within the stated capability, not the stretch capability that you’ve just discovered by breaking it. Once repaired, it is likely to be weaker than it was when it was new.
In fact, all assets deteriorate with age due to factors we can only sometimes see. We can see erosion by slurries, wear on belts, chutes, truck buckets, shovel teeth, corrosion from caustics, acids and even water. But we can’t see fatigue – that gradual weakening of the metal from continued cyclical use.
Materials can take a lot of cycles at low stress, or fewer at high stress. If we overload our equipment we put it through more of those high stress cycles, leaving less resistance to the more common and more frequent lower stresses.
We can see how engineering and operations have their roles to play in keeping our maintenance costs down. Now let’s look at the maintenance function.
Maintenance spends money on labour, materials and support equipment (tools). Sometimes that goes through contractor hands but it is still for the same things. Maintenance can spend less, but that means doing less work. There are two ways to do less work. Both entail working smarter.
We can become more efficient at what we are doing. Waste less time. We spend a lot of time getting parts and materials, traveling, finding drawings and manuals, finding instructions, getting special tools and support equipment, getting permits signed, waiting for operations to make systems ready for work and then release them to care.
In a process plant environment, the average maintainer spends so much time on those activities, plus lunch and breaks that he’s left with only 30% of his day on the tools. Shop environments are usually a bit better and mobile work crews much worse. They are not lazy or avoiding work either – they are usually very busy and even overstressed trying to keep up with demands.
We are paying our trades for much more, so how much is reasonable to expect? After all, we know he needs all those things to be done or he can’t get to his tools. Plant – up to 60% of his time can spent on the tools; shops – up to 80%; mobile – highly variable with all the factors to consider but let’s say about double what they achieve today.
How do we get there? Efficiency. We get better at what we do and specifically we get better at preparing for the work. Work should be planned in sufficient detail that nothing is left to doubt when the job starts. That includes identification of tools, parts, materials, consumables and even the work instructions. After planning comes staging – making sure that everything that is needed is actually there. Some mines go so far as to “kit” the parts into boxes or on pallets. This means less time wasted at stores. Going further, some mines even deliver those packages to the job site – a designated area in the shop beside the work bay or a drop off point in the process plant.
Imagine the preparation that goes into getting an operating room in a hospital ready for any specific surgery. The surgeon doesn’t commence work until everything is ready, including allowance for foreseeable contingencies. If we consider the planning activity, together with the needed co-ordination and co-operation from supply chain and production to be the equivalent of what is needed to make that operating room ready, then you get a good idea of what excellent planning will look like. Your skilled trades are your machine surgeons. Don’t make them look for their tools and parts, etc. while they are performing their “surgery”. That’s how you minimize the time they are forced to waste.
To do that you need planners and schedulers – sometimes the same person does both. You need to have your planning and materials processes tightly integrated with sharing of information and co-operation. You need a supply chain that can provide the needed materials without delay. Better still, you need the right inventory in stores – and that requires a lot more than following manufacturers’ recommendations. Maintenance needs to forecast much better than it does today. You want to achieve much closer to a “just-in-time” inventory than today’s “just-in-case” situation.
You’ll have far more trades than planners and schedulers and warehouse staff. Those planners are highly leveraged. Each of them keeps many trades busy. Achieving 60% “wrench time”, nearly doubling it from today, justifies the cost of a few planners quite easily. So now your crews are busy and most of their time is on the wrenches where you want them. Fantastic. The good news is that we can go even further.
Efficiency isn’t everything we can do! We can also become far more effective at choosing the work we do. Yes – choosing the work. We don’t need to wait for the equipment to fail before we work on it.
Repairs following breakdown are more expensive than repairs done before the breakdowns. There’s less disruption to operations, less equipment damage to reverse, less likelihood of damaging other equipment and the work itself is often easier to do because parts are easier to get apart. They don’t become one with each other as they crash to a halt.
Equipment breaks down in ways that are related to age or usage and randomly. Very few failures outside of electronics are sudden and completely unpredictable. Most failures give us some warning that they are occurring before they get so far as to cause us to lose the asset’s capability. If we understand the specific failure mechanisms at play and their causes, we can often do something proactively to either avoid the failure (preventive) or forecast when it will occur (predictive) so we can act before the random failure progresses too far.
We have methods to identify this proactive work. The simplest is to follow manufacturers’ recommendations, but they are often flawed. Arguably the manufacturer benefits from having you follow prescriptive preventive maintenance routines and overhauls, but that’s not why their recommendations are so flawed. Few manufacturers actually operate and maintain their own products. They don’t really know what goes wrong. They only know what you buy from them – parts. They may assume they broke and develop some maintenance recommendations around that, but more likely they rely on the good old, “we’ve always recommended that”. Someone, likely a long time ago, made recommendations that have stood the test of time in technical manuals and instructions. The manufacturer has little reason to question and change them. But you do.
The biggest exception to this are the mobile equipment manufacturers. They know their equipment, they maintain a lot of it, they do so in your operating environments, they have large numbers of units in the field and they get a lot of customer feedback. They are more likely to employ engineers to focus on reliability. As a rule, their recommendations are good, although they may be a bit on the conservative side. After all, even with all their knowledge, whatever they recommend to your sea level mine is likely the same for the folks at higher altitudes or in hot and cold climates. You will always know more than they do about your environment.
You know how the equipment works, how it fails, the operating conditions you expose it to, the overloading, how long it’s idle, how often it starts and stops, the inclines you climb, the altitude you run your engines at, the cleanliness of the fuel you use, the quality of lubricants, the care your operators give the equipment, the temperatures, dust, humidity, etc. In short, you know your operating context, and it matters. Each of those factors influences failures. No manufacturer tailors their instructions to your unique environment – only you can do that.
The best method for doing that comes from the airline industry, reliability centered maintenance (RCM). Arguably it is overkill for low criticality assets, but it will pay for itself many times over if used for your critical assets. It produces recommended actions to manage failure consequences. Those actions include: maintenance (preventive, predictive), operator tasks (like oil checks, circle checks, listening for abnormalities), testing for already failed protective devices, changes that address human error (training, procedures, check lists) and allowing some items (always with very low consequences) to run to failure.
The most cost effective maintenance programs will comprise a blend of those strategies. You need to follow the recommendations. That gets us back to how well you comply with work schedules.
Planning and scheduling alone won’t improve equipment reliability. RCM (and its more streamlined cousins) will, if you follow the schedules they produce. We have a bit of a chicken and egg dilemma. You need to be capable of following schedules in order for RCM’s outputs to be executed properly. You also need to execute the outputs properly and on schedule before you will improve reliability enough that schedule compliance becomes easy to achieve.
You need to work on both of these in parallel. As schedule compliance improves your ability to execute proactive work on time improves. As you do that, your failures will drop taking reactive work down. That frees up repair crews to do more proactive work.
Equipment is always designed with an inherent level of achievable reliability even if the designer can’t tell you what that is. They rarely attempt to do define it, because achieving it is dependent on how well you can maintain it far more than on how well they designed it. However, if you maintain it well based on an RCM type of analysis and operate it within its limits, you should then achieve what the asset is capable of achieving. If that’s not up to what you need, then you need to cycle back to engineering and equipment selection – closing the reliability loop.
Costs come down from being more efficient at execution of our work and more effective at doing the right work. The technical prize is high reliability. That means fewer breakdowns. The efficient work execution means less downtime for those fewer repairs. Operations gains uptime and stability. The mine gets productivity at a lower cost. There are also gains in safety (less breakdown means lower risks) and environmental compliance (less failure means fewer leaks and emissions). Both of those can ultimately lead to lower insurance premiums. The increased production stability increases confidence in your forecasts and potentially better market performance.
Maintenance and reliability are far more than cost centers – they are major contributors to your whole mine performance.
James Reyes-Picknell is a mechanical engineer (University of Toronto 1977) with 39 years in maintenance and asset management, and the author of “Uptime – Strategies for Excellence in Maintenance Management,” now in its 3rd edition.