THERMOGRAPHY gives mine operators the ability to diagnose a multitude of problems; from a crack in a conveyor roller to the heat escaping from a poorly insulated pipe. In recent years the price of the technology has plummeted causing the industry to explode, but it hasn’t come without growing pains along the way.
Over the last 30 years, thermography, or thermal imaging, has become a regular part of the maintenance, predictive diagnosis and condition monitoring on most mine sites around the world.
Thermal imaging technology could detect problems invisible to the naked eye, and therefore would be able to save time, money, and create a safer environment for workers by ensuring mine equipment is not jeopardised by faulty components.
A lot has changed since the 1990s, when a thermal imaging camera would cost in excess of $250,000.
Today, a powerful camera could cost as little as $10,000 and perform all the functions and operations required of thermography on a mine site.
With a research grant from the Australian Government, Dr Alan Smith started his research in 1990 when thermography was in its infancy in Australia.
For the lens alone, “I could have bought a BMW 5 series. The whole system easily could have bought a house,” Dr Smith said.
The prohibitive price of the equipment kept it on the fringes for many years, but it also led Dr Smith and a team of four others to explore the functions and capabilities of the technology that would later be adopted by Ansett, who Dr Smith helped train.
“As with anything in aviation, they needed certification but there was nothing around, so we developed the course for them,” Dr Smith said.
“Twenty-two years ago, we set up thermography training, and it was straight out of industry need.”
Since then, the price and size of the cameras had decreased significantly, with a very capable piece of equipment now costing about $10,000, and having an attached monitor that can give real time readings.
The technology has improved to allow the lower end cameras to provide fantastic resolution and benefits to those operating them on a mine site.
Today, thermography is used on mine sites all over the world to diagnose heat spots on truck tyres, faulty or rusted bearings on large conveyors, defective or broken hydraulic rams, faulty pins in railway tracks and a multitude of other applications that have potentially avoided safety hazards, cut labour costs, saved down time on machine inspection and pre-empted costly repairs.
But the simultaneously shrinking cost of the cameras, and advancements in technology that made it readily available and made the industry expand has experienced a few hiccups along the way.
Dr Smith said that when complicated variables were involved in the imaging, unqualified operators could make costly and untimely mistakes.
“What we see with the camera is not only the temperature of the thing we’re looking at, but all of the other factors involved,” Dr Smith said.
“It is a matter of being able to interpret correctly and this [proper interpretation] is, in some ways, the biggest challenge in thermography.”
Thermal imaging cameras worked off two inputs, the emissivity and the reflective temperature.
Emissivity indicated how well a surface gives off its own energy or thermal radiation.
Reflective temperature indicated how much heat was coming off the surface, which could be much harder to correct.
When making complex assessments, each pixel would be assigned a temperature and if the numbers were entered incorrectly for the two inputs, the camera would give a false reading.
“A lot of what you see when you’re looking at a camera is not what you’re actually looking at, it is a reflection,” Dr Smith said.
“These reflections can give very misleading images and, unless you’re an expert at interpretation, you can come to some very wrong conclusions.”
Reflecting on the state of the industry, Dr Smith said that the lack of training could be detrimental to the reputation of the technology and to the thermography industry as a whole.
In the past, there were fewer people with access to the technology and, due to the prohibitive price tag of the equipment, those with access would almost always gain certified qualifications and become experts in image interpretation before operating the cameras.
“There were always cowboys in the industry, and that’s what we’re seeing more of – that’s the downside,” Dr Smith said.
“The upside is that it has opened up the market to companies who previously would not have considered the technology.
“Whoever’s looking at the images needs to be properly trained and whoever’s setting it up needs to be properly trained.
“It gives the whole industry a bad name if people misuse it.”
The technology itself – the size of the camera and the resolution of the lenses – would appear to have plateaued over the last 10 years.
As with smart phones and other devices, the quality of the display has actually seen slightly larger units being released, and while the resolution of thermal imaging cameras remain years behind the resolution in a smart phone camera, it does not affect the functionality of the technology in condition monitoring or predictive maintenance.
Dr Smith said that one area where thermography needed innovation and improvement was in the standardisation of the software available to customers.
One of the challenges facing trained thermographers, and the people who train them, is that each camera manufacturer used its own specific software, and each software used a different image format.
Sometimes images could only be viewed on an iOS or Windows operating system, some that could only be viewed on a tablet.
Essentially, this rendered the images ineffective to thermographers who could not share images and manipulate them to give a useful reading.
“Pretty much every manufacturer has their own software, it’s part of the problem. Part of the reason for that occurring is that they often have their own formats for the images themselves.
“You can’t take one manufacturer’s image and view it with another software, and it is incredibly frustrating,” Dr Smith said.
Automation ready
As mines move toward 100 per cent automation, there are some exciting prospects for the applications of thermography.
The lower cost and small size of the cameras could offer round-the-clock solutions to condition monitoring.
The applications of non-destructive predictive maintenance and condition monitoring are readily available and, with the right software, fully autonomous thermographic operations could see mines fix cameras to expensive equipment and monitor it continually in a non-destructive and non-disruptive way.
One of the biggest concerns with autonomous haul trucks was that the tyres can develop heat spots and blow out, causing major disruptions to the operation.
Thermography was already used to detect these hot spots, but by a hand held camera from a safe distance away.
“What you could do is have a camera permanently fixed to a position where trucks drive past as part of their routine, and pass those images back to the command station and say ‘yes we need to fix it,’ or ‘no it’s fine to keep driving.’
That way the truck doesn’t have to stop – it could be fully loaded and keep driving while being monitored,” Dr Smith said.
The maintenance and monitoring of long conveyors had used a hand held thermal imaging camera as a worker drives up and down a belt to detect faults in the line.
But this too, with some effort, could be replaced and completely autonomous with the existing technology.
“Conveyors have a pair of rollers every 300mm, the rollers have bearings and if those bearings seize the rollers stop turning and the belt keeps on driving, which generates heat and wears out the rollers,” Dr Smith said.
“Because they’re hollow, the worn out rollers create a knife sharp edge that will tear the belt.
“We could put an infrared camera on some sort of rail and have it travelling up and down doing the same thing that the cars do, these things can be autonomously done.”
The hydraulic rams used in many machines could potentially have a fixed camera that monitors 24/7 and flags a problem to a technician.
“Compared to what these machines are worth the price of a thermal imaging camera is nothing, and there’s really no reason why you couldn’t build one into each piece of mobile equipment,” Dr Smith said.
One thing rarely considered when discussing the 100 per cent automation of mine sites is what happens when there was no one on site to keep out unwanted guests.
One of the traditional uses for thermography has been night time security, and Dr Smith said that this is another area the cameras could be used in.
