Safe Maintenance of Induction Furnaces… It’s All in the Details
From the moment an induction furnace goes down, whether it’s an unplanned coil change or some kind of ground-out, the stopwatch starts ticking for the in-house maintenance team to diagnose the cause and hustle to get the machine back online before production quotas are affected. Meanwhile, one question echoes through the plant: “How long is this going to take?”
“I can’t think of a single more important piece of foundry equipment than the furnace that’s melting the metal, because everything else sits unless we’ve got molten metal,” said Mark Kohler, senior product manager at AFS Corporate Member Ajax Tocco/Lectotherm. “These larger, medium-frequency furnaces are very complex animals and there’s a lot involved in them. What you don’t want is people abbreviating protocols in order to return a furnace to service quicker.”
The sense of urgency is a natural enough reaction from plant management but one that can lead to maintenance shortcuts or mistakes.
While appreciating the harried production pace foundries keep to meet their customers’ requirements, OEMs agree that if the pace of servicing an induction furnace causes a compromise in the safety of people, first, or jeopardizes the uptime and efficiency of the equipment, then it’s time to reevaluate priorities and procedures. And that can only stream from the top down within the chain of command.
The fact is, some induction furnace maintenance tasks simply take the time that they take, and to rush or cut corners could either endanger a person or necessitate a do-over––and possibly a major OEM intervention such as a rebuild. The antidote for crisis management: Consistent and correct PMs should be top of mind in the foundry leadership and a way of life out on the floor.
Manufacturers are privy to both the best and worst scenarios in foundries, and when there’s been injury and/or equipment failure or damage, the reasons can typically be traced back to a handful of root causes involving either a wrong action or some type of neglect. The No. 1 deliberate error a maintenance tech or operator can do is to disarm a ground fault detection system, which exposes anyone touching the equipment to the possibility of electrocution. Disconnected systems, also known as earth leak detection systems, are something Otto Junker service technicians sometimes find in foundries where they’re called to perform maintenance and repair tasks.
“That is one of the most egregious violations you could do, operating without that earth leakage detection system” said Tim Warner, general manager of AFS Corporate Member Otto Junker North America. “Yes, the furnace will work, but there’s a reason why it’s in place. And when you just bypass the safety system, that’s critical. We’ll still work on a furnace but that’s the first thing we check before we do.”
Failure to perform important maintenance duties is the more common source of serious maintenance-related incidents. Some responsibilities fall clearly on the shoulders of operators and others will lie squarely in the domain of well-trained maintenance team members. The most dangerous omission committed by foundry personnel is neglecting the frequent inspection––as in every shift by the operator and every week by a maintenance technician––and regular replacement of refractory linings, which may last a few days or up to six months depending on the metal and temperatures involved. Failure to understand and maintain refractory linings poses the risk of a run out where molten metal penetrates the furnace.
Next, omitting the essential lock out/tag out standard operating procedure (SOP) exposes maintenance techs to electric shock, and foregoing proper PPE also puts crews at risk of electrocution from arc flash.
A lax approach to melt deck cleanliness could be a slip, trip, and burn hazard waiting to happen, and skipping a tie-down SOP can lead to falls from the top of the unit. Good housekeeping in and around the furnace also encompasses a weekly vacuuming to collect metal dust particles, which can become lodged inside coils, resulting in inefficient furnace performance or failure. If the foundry shuts down on Sundays, that’s a good time for maintenance to perform this important task.
Allowing metal to freeze inside the machine could cause catastrophic damage to the furnace lining or even in the furnace coil, leading to major downtime and repair expenses. Ideally, molten metal should be emptied from the furnace before service work begins.
Technicians must also not neglect the important precaution of mechanically supporting a furnace before working on it. Harold Harned, training manager at AFS Corporate Member Inductotherm Corp., added this should not be done with a crane, hoist, or fork truck.
Inductotherm’s free safety kit, available to all foundries, specifies: “If work is to be performed on tilted equipment, the tilted equipment must be secured in the tilted position with a mechanical support [e.g. structural brace]. Reliance on hydraulics alone could lead to the furnace dropping without warning, causing injury or death to anyone trapped underneath.”
To prevent all types of maintenance errors, technicians should ideally use a “buddy system,” according to ABP safety training materials. “Never work on equipment alone,” the manufacturer advises. “Always have another worker by your side to observe and assist with the work, to keep an eye on you and also to get help if you are injured.”
The Human Equation
At the crux of these mission-critical maintenance activities is an aware management ensuring someone in the foundry has truly taken ownership of the induction furnace, has invested the time to thoroughly understand the specific brand features of the equipment, and embraces the utmost importance of (A) running it within proper OEM parameters and (B) performing the full regimen of PMs at the proper daily, weekly, monthly and yearly intervals.
Kohler at Ajax adamantly advocates for operators and maintenance personnel work in tandem for the good of the equipment and each other, but that’s not always what he sees in his foundry visits. If an operator runs a furnace too hard it then becomes a maintenance problem.
“There’s sometimes a lack of teamwork and a lack of knowledge of how one department can affect the other,” he added. “They should be both working together for a common goal. That’s why it’s important for operators and the maintenance guys to both understand the equipment and each other’s roles––so they can check and balance each other.”
The people you’ve got are one thing, but the people you haven’t got also stirs the pot when it comes to safe and attentive maintenance of induction furnaces. The scarcity of skilled labor and experienced bench-depth can weaken the barrier between smooth melting operations and equipment failure. And in the midst of hiring challenges, production volumes for many are not only remaining the same but increasing.
“A big contributor to the overall reduction of downtime and keeping a good reliable operation is staying in front of it and doing more preventative maintenance instead of crisis maintenance,” said Kohler. “But today, there are a tremendous amount of rookie furnace operators and maintenance people who lack the necessary practical experience and know-how.”
As more foundry “lifers” retire, the white-hot need for continuous training among maintenance crews has never been more poignantly felt. New employees need highly specific and detailed education, but even those with experience require refreshers and updating. People become desensitized over time to the dangers of their environment, Kohler noted––keep them on their toes and alert every day with continuous safety talks, compelling signage, and reviews of all safe maintenance SOPs. But don’t stop there.
The manufacturers of induction furnaces demonstrate their passion for safe maintenance with many training opportunities for foundry personnel; for example: online classrooms such as the ABP Virtual Academy, in-person training from Ajax that Kohler provides, hands-on training held twice a year by Otto Junker in Germany, and courses with custom training materials for participants offered by Inductotherm either at the foundry or at its facility. OEMs also chorused that installation and commissioning of furnaces, as well as every onsite service call is an important training opportunity they seize, making sure foundry maintenance techs see, hear, and learn what the factory service techs are doing.
Small Foundry Strategy
While the metalcasting industry as a whole struggles with the human dynamics of achieving safe and timely PMs and repairs, the issues are magnified inside small foundries where employees can be wearing multiple hats, and time for training, like other resources, is scarce.
“Small foundries do, in fact, have a bigger problem finding and maintaining qualified people to work on these complex systems,” said Dan Green, Ph.D., technical director at AFS Corporate Member ABP Induction. “Every type of science you can imagine goes into building an induction furnace, so it’s hard to find people who have such a broad and deep base of knowledge to be able to do everything that needs to be done to keep a furnace operating efficiently. Quite often, we are even more closely involved with these customers than with the larger ones.”
The following three strategies offer a lifeboat in the sea of complex maintenance schedules induction furnaces require.
(1) Take advantage of manufacturer PM programs––lift the burden off your strained staff and remove them from the dangers associated with furnace maintenance. You’ll also gain peace of mind that the regular attention from factory-trained technicians will keep furnaces running at peak efficiency. Cost is usually the reason less-capitalized foundries take advantage of these programs, Green said, but considering that a major coil repair could set you back $200,000 and an injury or death lawsuit could put you out of business, owners may want to rethink budgeting for a factory PM program. “Just because you can do [the maintenance] doesn’t mean you should,” Warner said.
(2) Cultivate a strong relationship with a local aftermarket service provider. Have a plan before you encounter a breakdown. “In the event that you do have an issue, you want to have people you can call that understand your equipment, know who you are, and are going to be able to rapidly help you diagnose and troubleshoot your problem,” said Kohler.
“You don’t want to wait until your furnace is not working to try to figure out who you’re going to call. A lot of places do have established vendors already in place, but other companies have such a low incidence rate that they don’t have any one vendor they use––then they’re kind of caught by surprise when something goes sideways. Know who the people are that are going to help you when you’re in a jam.”
(3) Consider a path to adopting the latest in induction furnace technology and harnessing the predictive power of machine data. Significant automated safety features, as well as monitoring systems, user-friendly control panels, and more melting power are a few of the improvements OEMS have built into modern furnaces. The cost to acquire today’s state-of-the-art induction technology is in the $1.5 million range, so it’ll take careful planning for a small foundry to budget for such an investment. Meanwhile, installing sensors and analyzing the data they accumulate can take the foundry to a new level of predictive maintenance based on anticipating wear and replacement versus waiting for failure to occur. This approach is effective for power switches, pumps, motors, and more.
“You can plan for a pump to automatically turn on and switch to a backup,” said Warner, “instead of having a failure occur and you go to turn the old pump on and find, ‘Oh, it hasn’t run for six years and the seals in the pump are completely dry rotted and blown out, and it doesn’t work.’ You can set these things up through a control system.”
OEM sources emphasized that one of the greatest resources available to the foundry, whether large, medium, or small, is the knowledgeable, obliging, and accessible community within the AFS membership base. Participation in AFS regional and national meetings, live and online training, as well as AFS committees, puts technical advice and problem-solving from experienced foundries, OEMs and component suppliers within easy reach.
“The people in this industry are willing and able to assist anybody with any issues they may have,” said Warner. “I’ll say this, there’s a wealth of knowledge in the AFS committees––there are hundreds of years of experience sitting there that a foundry could tap into.”
Click here to view the article in the August 2022 digital edition of Modern Casting.