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December 2005
by , Senior Editor |
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When Dave Balch started working as superintendent at a Knife River
dredging operation in the Northwest United States more than a year
ago, the maintenance schedule was completely unorganized. In fact,
there really wasn’t a schedule. There were two guys working 12-hour shifts, six days per week, performing maintenance during the production shifts. But this led to major problems because of the downtime that was incurred. “[The dredges] had to be shut down during production hours to do maintenance,” Balch tells Aggregates Manager. “There was no timing involved. They did maintenance whenever they felt like it.” However, when Balch came on board, he organized the maintenance process, which he says has turned out to be critical — and it’s made all the difference with executing an effective maintenance plan. Balch, who has worked at several aggregates operations in the Northwest United States, said lack of organization is often a problem. Scheduling regular maintenance Balch hired two more operators to serve as “extras” so a day shift and a night shift for maintenance were created. Together, the two original operators and the new hires worked the new 12-hour shifts, and Sunday was set aside completely for maintenance. The operators who work the Monday through Friday shift spend Monday and Tuesday completing any repairs that need to be done — such as rotating pipes — to prepare for the all-day Sunday maintenance routine. Additionally, the dredge is shut down at 8 a.m. and 6 p.m. daily to be degreased, which takes about 30 minutes. |
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Previously, the process would take nearly two hours because in addition to degreasing the dredge, the teeth and oil were changed, adjustments were made, as well as some other maintenance procedures. Now, this additional maintenance is done on Sunday. “Before, we had two guys six days per week with no Sunday,” Balch notes. “This was totally ineffective. Now, I have four guys that work five days per week and have two days off, and it works well. “The extra guys then spent about three days out of the week doing any other necessary maintenance to prepare for Sunday,” Balch continues. “On Sunday, major maintenance is completed such as a pump change, adding a pipeline, moving the dredge, or preparing for when the crane was to come in.” Prior to the operation’s dredge maintenance being organized, the dredge was only running about 45 to 50 percent of the time, Balch points out. Now, the dredge is operated close to 79 percent of the time, including the conveyor system (with nearly 3,500 feet of conveyor belt) and the dewatering plant. “There are a lot of things we could shut down for during the week, but it would cost in production.” Balch says. Now, all maintenance is scheduled for the Sunday shift. “Everything is scheduled and based on hourly repairs and change outs,” Balch explains. A maintenance log is kept, and “every little thing we do, we write down in the log,” he notes. Keeping parts on hand Even the best scheduled maintenance plan can go awry if the proper parts aren’t available, so Balch also recommends keeping a good supply of the major components necessary for maintenance in inventory. “Anything that takes more than two weeks to get, we like keep on hand,” he says, citing such examples as pump parts, bearings, and hydraulic pumps. That’s why Bob Wetta, vice president of marketing and sales for Reserve, Louisiana-based Dredging Supply Co., a manufacturer of dredges and dredging parts, advises all of his customers to keep these types of parts on hand. He says whenever his company sells a dredge, it gives customers a list of parts that they should be keep on hand. “Many companies keep the parts on hand, but not all of them,” Wetta says. Moreover, he says, some parts just may not be stocked because they are specialty parts of specific to a particular dredge.” Bolt categories, electrical parts, and hydraulic components are the major parts that are stocked, and most companies keep structural parts, such as welding machines and steel, in reserve. But if a component on the dredge needs to be replaced and you don’t have it, Wetta says, lost production time results — which means lost dollars. He also suggests that dredging operations ask for the part number for each component so it is easy to identify in case the tag falls off. “Ask for the original manufacturer part number so you can find local suppliers,” he says. “For example, assume that the part you need costs $5,000. If you can get it locally, you pay the $5,000 and you’re only down for five hours. Say that every hour you are down, you’re losing $1,000. That alone is a $10,000 loss. If you don’t have a local person, it might take you three days to get the part. That’s more like $30,000 now. These are extreme examples, but they can happen. And if you’re not producing, you’re not selling.” Making equipment modifications Even though it’s important to keep quick-wearing as well as specialty parts in stock to expedite maintenance and have minimum downtime, Balch says that finding ways to extend the life of some parts by modifying them is even a better plan. “A lot of parts wear out fast, so I have done some modifications to the dredge,” he explains. “We went from a normal pump shell to a T5 pump shell.” Now, Balch says, the pump shell lasts 1,750 hours — about 250 percent longer than the original one that came with the dredge. “I am into getting rid of downtime,” he says. “I’m looking for specialty parts that can reduce the downtime to change out and make things last tremendously longer.” Balch also modified the suction on his operation’s dredge by swapping out the steel piping for a rubber hose, which he says lasts about two and one-half times longer. Balch also modified the cutter teeth by finding teeth that were made of harder metal than the original ones. “Our teeth now last two weeks instead of two days,” he says. “This reduces the downtime.” Additionally, Balch redesigned the cutter from the original manufacturer specs to make them last longer. “We turned the teeth in the right direction,” he says. “We watched how the original cutter was working and saw that the teeth were in the wrong position of how we needed them. We repositioned them and went to a harder tooth for cutting cobble and gravel.” The teeth now last about two weeks longer, he says. It’s small modifications such as these that make a big difference when it comes to making the most of maintenance. “One of the main things we do to make the dredge last longer is if we see anything that may cause a problem in the future, we modify so it will last longer,” Balch says. “We want to catch it before it breaks.” But such was not the case with a hydraulic pump. Not too long ago, Balch says, a hydraulic pump failed, and it shut down production for three days. “We lost 80 hours of production because of the filter,” he says. Those performing maintenance on the pump realized that there wasn’t a filter between the hydraulic pump and the motor. “It was this way when we bought the dredge,” he says. “But now we are finding things out — trying to find out why things happen and then modify them so it doesn’t happen again.” The filter ended up costing about $7,000 in parts, with an additional $3,000 in labor to have an outside hydraulic specialist come in — plus the 80 hours in downtime costs, Balch says. “Now we are going through everything to see what we can replace and modify to make more efficient.” The most recent modification is 2,600 feet of high-carbon steel that the operation has ordered. Balch says it is purported to be two and one-half to three times harder than regular steel, “so we are going to test it for the slurry (discharge) pipe. The harder the metal hardness, the longer it wears, so we are hoping to get at least twice the life out of it. We know it will last longer, and if it lasts twice as long, our high hope is to get a return off of it and save money.” Using maintenance logs Like Balch’s facility, Rick Parton, director of mining operations for the Eagleswood, New Jersey, operation of Pennsylvania-based Sahara Sand, also sets aside a specific day for maintenance. “Saturdays are reserved for maintenance,” he tells Aggregates Manager. “We put in 8 hours of maintenance every Saturday.” But, he says, for his facility, which has a 14- by 16-inch electric, underwater dredge that runs on two 8-hour shifts, the maintenance schedule is all relative to the amount of production that is required. Last year, the Eagleswood operation produced four days per week and did maintenance one day per week. Now, it produces five days per week and sets aside Saturday for maintenance because of higher production demands. But nonetheless, planning maintenance is critical, he notes. “We have set up our system with daily, weekly, and monthly or quarterly reports that are completed by the dredge operators,” Parton explains. “We require each operator to fill a log that is turned in daily.” The log was created using Microsoft Excel software. Now, any maintenance that has been performed may be tracked — and analyzed. “The operators track the hours on the dredge through the computer system on the dredge,” he says. “We have checklists they follow, such as brand of oil, quantity of oil, etc.” This is significant, Parton says, because it ensures that when the operator goes to do routine maintenance, he or she brings everything necessary instead of wasting time by having to go back to get the proper tools or amounts. “The success we’ve come with is knowing when we will be doing something and planning for it,” he says. During the daily inspections, Parton has operators inspect various components such as the oil system, wear on the cutter teeth, and the cables on the dredge. But in addition to these inspections, operators are instructed to provide feedback on the checklist forms so the plant manager may monitor everything on a daily basis. “We tell them to write down if they hear a noise so we are able to look into it immediately,” Parton says. “We track every time we do something on the dredge so we have a record of it. For example, if I change the swing cable, I record it. Then I can go through the Excel file and I’ll know every time I’ve changed it. This way, you not only know when maintenance is coming due, but the history as well.” And knowing the history of component maintenance is paramount because you’re able to determine if a part isn’t lasting as long as it should — and then figure out why. “You’ll know if you’re using an excessive amount of swing cables and then can ask, ‘What is causing this?’” Parton says. “You can figure out whether it is an operator, the location, the part itself…” Parton gives the example of a dredge that his operation purchased three years ago. “When we first bought it, we were going through swing cables every four to five weeks,” he says. The cause? Operators not being completely familiar with the equipment. “We are only going through them every four [months] now that the operators know how to properly operate the equipment.” It’s also important to select the right operator for the job, says Chris Nelson, vice president of Rohr Corp., based in Cleves, Ohio. “Selecting the proper operator for the equipment is an integral part of running the operation,” Nelson says. “There is quite a bit going on with a dredge, and you want a person who understands the machine and is properly fit for the job. You can’t just throw someone out there who has never seen a dredge before.” Practical and technical field experience is critical, Nelson says. “You need someone who will take the machine under its wing and take care of it — someone who understands that you have to do maintenance on a regular basis,” he adds. But, if you do hire someone without experience, “let them train with an experienced operator to get them up to speed.” By being “up to speed,” Nelson notes, that means checking maintenance concerns such as the following: Making sure there are fresh fluids (i.e. oil), whether there is damage to pins and bushings, ensuring there is no undue belt wear and that the take-ups are good, making sure that skirt boards are sealing well in the feed boxes as well as that temperature tolerances are proper. “The trick is making sure that all the components are functioning properly,” Nelson says. “A visual inspection needs to be done each day. You don’t want someone to be overzealous, but [he or she] needs to be proactive. It all comes down to common sense and what works for your operation.” Finding trained, local professionals When it comes to dredges, operators not only need to know how to properly operate the equipment, but how to properly perform some maintenance. If it’s not possible to have the maintenance staff trained to properly do repairs, then it is essential that the operation find a local vendor that is trained to fix the problem, says Wetta. “A lot of companies don’t have people that are 100 percent trained to do the type of maintenance required for a dredge,” he says. “You will have a dredge that will break down and won’t have a backup plan for a local vendor.” So if you don’t have people that are trained, make sure you know a local vendor that is trained in electrical and hydraulics.” The electrical makeup on dredges is comparable to that of a front-end loader because of similar components, so it shouldn’t be difficult to find a vendor, Wetta notes. “Our company, for example, is located near New Orleans,” he adds. “But if we sell a dredge to someone in Alaska and the company doesn’t have a local vendor, we’d have to fly out there to fix it — and that can take a while because of that kind of distance.” What it all ultimately boils down to is organization and planning. “The secret is to plan to do maintenance when you are not producing,” adds Sahara Sand’s Parton. “Make sure you schedule your maintenance. Unfortunately, part of the problem is that very few people really plan for it.” |
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Reprinted from Aggregates Manager Magazine |
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