Maintain it Before it Breaks
BY Neil R. Hise, Ted Powell
Using predictive maintenance to keep crushing, production equipment up
During CONEXPO-CON/AGG 2023, Neil Hise, Ted Powell and Travis Vliem shared with an audience of aggregates producers and other interested contractors how to perform predictive maintenance at the crushing operation. Hise pointed out this is not only a wonderful industry, but it’s also a dangerous industry if you aren’t staying aware of your surroundings and your equipment. “You can’t afford to make very many mistakes,” Hise told the attendees of the Predictive Maintenance: Plan the Work and Work the Plan education session.
Hise shared that while crushing and processing rock may not have changed over the past 100 years or so, issues with the supply chain have changed recently. He spoke not only of measuring and tracking your parts and components for uptime and efficiency, but also of planning ahead on maintenance for uptime and efficiency.
Measure to Manage
“And the word of the day is ‘measure,’” Hise said. You measure what your conveyor belt has on it. “What does your screen have on it? You measure what your VSI is doing and what your wash plant has done.”
He stressed the importance of measuring and knowing your production numbers. Armed with actual measurements and numbers, the savvy groundman or quarry manager can track belt and component wear and react to a situation before it creates a hazard for a Mine Safety and Health Administration (MSHA) inspector to notice or for a surprise downtime occurrence.
“We measure everything in our production and our manufacturing process,” Hise shared. “But for our production plants…if you don’t communicate effectively and specifically,” the measuring won’t help you prevent mistakes. You want to communicate what’s going on around your production process in order to prevent problems. In other words, effective communication goes hand in hand with measuring to get predictive maintenance up and running in your operation.
Consider a crushing plant that has fines and material buildup under a conveyor transfer point. If the buildup is starting to look like a mini stockpile is growing to reach the conveyor belt, you have a problem that should have been noticed by a groundman, communicated to the maintenance personnel, and resolved before a safety hazard developed. As Hise said, sometimes these maintenance issues develop because someone in the production chain wasn’t paying attention.
“Because of lack of communication, lack of awareness and lack of [caring].” He suggested looking at maintenance as a continuing job and not something that can be a one-and-done.
Powell led the audience through a real-life scenario of how The Rogers Group put in place a program that took the company’s fixed plant production facilities from 75% availability to 92% availability “in a few short years.” He started with Hise’s word of the day: measuring.
“Number one: Identify pieces of equipment and components that have moving or maintainable parts by assigning them asset numbers,” Powell said. “Assign them modes of operation that will track the hours the component worked. The plant manager then reports the total up- and down-hours of production by hours of operation for that particular day of operation. After this information is placed into a database, the hours for each component will be tracked and service will be performed per manufacturer’s specifications.”
Tracking actual operation leads to automating maintenance. Powell shared that he used a simple Excel spreadsheet and common software used in the industry to model every single plant component, assigning existing or new asset numbers to the parts. Then he, or the companies’ IT departments, developed a program to track the usage of the assets in the flow of their processing plants.
“Every aggregate company requires a daily report of productive and downtime hours and records them on daily and weekly basis. In our plan, this information is used to populate—by the hours worked—each asset’s usage in real time, which can be automated with the proper hardware and software.” He recommended using the equipment manufacturers’ recommended hours for service sampling and maintenance for the components of each of these assets, such as gearboxes, bearings, screens and crushers.
“Develop preventive maintenance sheets for every asset from the manufacturer’s recommendation,” Powell advised. “Crushers, screens, conveyors, screws, pumps, dryers, drums. I know this seems like a lot of maintenance sheets. But a conveyor is a conveyor. One sheet covers them all.”
Powell pointed out that with all this new information you’ll be able to gather by tracking equipment usage, you’ll be able to employ a multitude of new technologies that you can use to measure how these pieces of equipment are performing.
Hise shared another way to gather this information: physical inspection. “Take your camera and walk through your plant,” Hise told the audience. “You document and you measure. And if you’re the manager of the plant, you assign a fix to someone. And if you’re not the manager of the plant, you go to the manager of the plant and say, ‘I walked through my plant, here’s what I’ve documented, and this needs to be fixed.’ And if your manager doesn’t appreciate your efforts then shame on him. But let me tell you, the safety of each one of you in the plant is paramount. Production is what makes the money…but the safety is something that we just can’t let slide.”
By walking the plant and performing visual inspection with your camera or your clipboard or what have you, you can predict fixed plant maintenance. Powell shared a real-world example of predicting when a vital component was nearing failure.
“Approximately four years ago, I met with a well-known manufacturer of gear boxes, pillow block bearings and electric motors…They wanted to know, for me, what would help the customer better predict when a bearing, gearbox or motor would fail.
“With the current technology of transducers, I suggested that if we could build a device that would attach directly into a bearing gearbox or lower, it could send a signal that measured vibration and temperature and send it to you through the cloud or database.”
Powell wanted the plant manager or maintenance manager to receive a signal in real time—preferably via a cell phone app—if the vibration or temperature should go out of spec. After six months of implementation and discussions, Powell explained, the company developed some of the devices, as well as the app. They installed the first sensor in a gearbox along with a Gateway Bluetooth router and ethernet.
“We selected one of our toughest applications that employed a 1,200-foot by 48-inch conveyor from the pit to the secondary plant,” Powell explained. “This conveyor was driven by two $50,000 gearboxes, which failed twice in the previous two years. This plant produces 1,500 tons per hour. Downtime is not an option. After mostly success, we ended up installing 30 transducer sensors along with routers to assist in carrying the signal to the database.”
Then one week, “We received a vibration alert, and the conveyor was immediately shut down and catastrophic failure was aborted. On inspection, we discovered that a tooth had broken off in one of the gears. The gear was replaced, but most importantly, it forced us to take a look at the design of these boxes.” They figured out the boxes were “grossly undersized.”
“The 5S is sort, straighten, shine, standardize and then sustain.”—Ted Powell
Implement Programs That Increase Success
While saving a $50,000 component is a benefit, averting accidents and downtime through organization and efficiency is a big selling point of predictive maintenance as well. Powell reminded the audience of this in his discussion of implementing successful programs at The Rogers Group. One of those is the 5S program, and he described it as “one that every production plant needs to implement.”
“The 5S is sort, straighten, shine, standardize and then sustain,” Powell said. “As managers, when you visit your operation, do you visit the maintenance shop? Is there a place for everything and everything in its place? Do you inspect your service trucks? Are there greasy rags on the floorboard, empty soda cans on the seat or floor? Are the seats torn or ripped? Are the tools clean, sorted and in their proper places? If you sit there and honestly say all the things that I just mentioned sound like your maintenance, you can pretty much count on the rest of the operation being in the same condition.”
Powell gave the example of the plant operator contacting the maintenance department to say three belts on driving conveyor #3 just broke. This spurs a series of questions. “Is there a correct amount of V belts the correct size with the labeling stating that these belts fit conveyor #3? Does the maintenance personnel have all their PPE media in its proper place so we’ll walk right to it and put it on? Is the switch gear and control house marked indicating which disconnect powers conveyor #3? Does the service truck or job box have the necessary tools to quickly and efficiently remove the old belts and install the new? When you put a 5S program in place at your facilities, the answer to all these questions can be yes. And your downtime is drastically minimized. Sort, straighten, shine, standardize, then sustain.”
The second program Powell outlined was the equipment maintenance review (EMR), which he tethered to safety. “It’s extremely important that as you walk about your operation, that you are looking for safety issues not only to protect your employees, but also to prevent the dreaded safety violation and fines.”
He recommended taking one of your knowledgeable maintenance staff and tasking this person with walking the plant a few days a week. Have this person take pictures of anything he sees that is unsafe while documenting maintenance issues and take those pictures to the appropriate safety director or plant manager.
“It has been measured and I have confirmed that conveyors create the largest amount of downtime in all operations. Take extra care when inspecting pressure.”
From crushers, screens, conveyors, gearboxes, and so on, Powell recommended taking pictures as real evidence as you walk through the entire processing operation from beginning to end. Then, he said, go back to those iPhone pictures and transfer them to a Word document that you can share with the area or plant manager. Discuss these issues with these managers and with those who’ll schedule their resolution.
“At this point, you’re not done with this operation. Schedule a time within one month to return to this operation and follow up on the repairs that have been made or are being made.” The key is leveraging the person that understands the mechanics of how these components work and what it takes to keep them in operation. Use that person’s knowledge and expertise.
Hise summarized that with all the technologies available to the aggregate producer today, there’s no reason why an operation can’t predict failures before they occur. Aggregates managers can employ the measuring techniques, new technologies, safety protocols and more discussed at CONEXPO-CON/AGG to stay ahead of downtime occurrences.
Neil R. Hise is the chairman of the board for CEMCO, Inc., Belen, New Mexico. Ted Powell is a retired operational improvement manager of the Rogers Group Corporation of Companies. Travis Vliem is with Flexco. They presented this information at CONEXPO-CON/AGG 2023 in Las Vegas.