In an industrial environment, a bandsaw is often the first machine used to prepare material for what can be dozens more steps that come before the product is complete. The saw sets the
scene for what’s to come and, therefore, it’s critical that it is maintained properly.
“When preventative maintenance is at an optimal level,” says Jay Gordon, sales manager for saws and hand tools, The L.S. Starrett Co. North America, “sawing and blade performance tend to consistently mirror a similarly high level.”
So, what are some of the more common preventative maintenance best practices? Gordon and two additional sawing experts offer their advice.
Fortunately, saws today are equipped with sensors and actuators that offer feedback on how the machine is operating and can even automate some processes. Despite these modern technologies, saws still need to be cleaned and inspected daily, according to Stefan Dolipski, vice president, Kasto.
“The inspection points include coolant levels,” Dolipski begins, “band guides for cleanness, and the always-undervalued chip brush, which can save lots of money on blades and cutting performance. Most modern machines are equipped with a band deviation setup, so if the machine gets used correctly, with operational chip brushes, the sensor should remain clean. However, it’s a good idea to check this daily. Most machines can be checked over in less than 5 min. to ensure long-lasting performance and cutting accuracy.”
Paul Beha, products manager at HE&M Saw, says cleaning chips out of the band wheel areas is an obvious daily task that can keep everything running smoothly, but offers that the chips must also be removed from the cutting area, vise ways, shuttle ways and bar feeder, if the saw has one.
“You should also keep an eye on the fluid levels,” Beha says, “like cutting fluid and hydraulic oil, but those are generally checked weekly.”
Starrett’s Gordon recommends a handful of preventative maintenance tasks, including inspecting the band guides, because if they are loose or worn, misaligned cuts and blade failure are the outcome. Feed and speed calibration is also on the task list, as it will optimize blade performance. Blade alignment makes the list, as does checking blade tension, as too low tension speeds blade wear and excessive tension can cause blade failure, which can also damage the machine. Finally, Gordon recommends checking the band wheel and bearings, as worn flanges and out-of-round wheels can cause blade stress, which in turn creates blade failure and poor cuts.
Fluid and oil changes
Most saw manufacturers offer individual recommendations on when hydraulic fluid and transmission oils should be changed. The consensus among most is that changing out fluids is an annual event, but Beha recommends making frequent visual inspections, including looking for moisture contamination, which causes the hydraulic fluid to appear “foamy or milky.”
“Many times, the problem is not recognized until there is damage to the saw,” Beha says. “That’s why it’s a good idea to initiate a preventative maintenance program, adhere to it and change the fluid annually.”
As for the oil associated with a saw’s gearbox, Beha says there is plenty of discussion on the topic and not everyone is on the same page.
“Typically, the oil is retained in the gear reducer (gearbox) unless there is a seal leak,” he says. “Some say leave it alone. Others say everything wears out at some point and that gearbox oil can degrade or break down and to replace it every two years. Gearboxes that use polyalkylene glycol oil supposedly are filled ‘for life,’ but some service technicians warn that if contamination is introduced, it will be too late when the gearbox fails. I think changing gearbox oil every two to five years is a good idea, depending on use.”
Kasto’s Dolipski adds that when gearbox oil breaks down, which can happen after 2,000 hours of use, it loses its ability to lubricate between the teeth of the gears, which means the life of the gearbox is “drastically reduced.”
“A loud sound from the gearbox can be a sign of an advanced point in the life of the oil,” he warns. “Most new machines have an hour meter in the control that can be used for this purpose. Many oil producers have additives in their oils to extend the life, but the replacement of oil is cheap – the replacement of a gearbox? Not so much.”
Band wheel wear
The band wheel is an important part of the saw, as the wheels put the blade (band) in motion. If there is a consumable in the band wheel it’s the bearings. Starrett’s Gordon says when the bearings go bad, they make a grinding noise.
“In the worst cases, they fail completely and there is a noticeable wobble,” he says. “The bearings should be checked regularly and with any sign of wear, should be replaced.”
Dolipski recommends a daily check of the bearings because the moment they go bad, users will notice poor quality cuts, broken blades or abnormal wear on the blades.
“Depending on the machine and material being cut,” he says, “we see bearings needing to be replaced every other year or even five-plus years. It also depends on the quality of the bearing used. If a high-quality OEM bearing gets replaced by a lower quality one, the lifespan may be significantly shortened.”
HE&M’s Beha says checking the quality of the bearings and their potential wear involves grabbing the band wheel and checking for looseness by rocking it forward and backward, looking for abnormal movement.
“As the bearing wears out,” he says, “and the wheel begins to wobble, the wheel can be damaged beyond repair or, at a minimum, require a sleeve or bushing. The drive wheel can be checked with the blade on or by removing the blade and running the motor, observing the track as the wheel turns and looking for a wobble.”
Gordon says band wheels with worn flanges or that are out-of-round cause blade stress, which in turn creates blade failure and/or poor cuts. Another issue that Dolipski points to is that a wheel that has chips or other debris on the running surface that could also cause blade stress.
“In some instances,” Dolipski says, “broken carbide teeth can end up on the running surface of a wheel and cause further issues to the blade life.”
Beha says an out-of-round band wheel causes cuts to become “rougher,” but in his experience, he’s found that cracked wheels are more common. Cracked wheels ultimately fail as the crack worsens from use.
“We do a specific test on each raw cast to check for the continuity of the resonance before we machine the surfaces and heat treat the hubs,” Beha says. “It was something I developed almost 20 years ago after having played the drums for 40 years by then. A cracked cymbal has a different sound, a duller ‘thud-like’ sound, even if the crack is not discernable. That issue for us occurred after we discovered we were having some problems with fine cracks in the raw casts from the foundry and we worked with them to determine the root cause of the issue and we haven’t had any problems since then.”
Despite the fact that most bandsaws are constructed with high-quality materials, nothing is impervious to years of use. Even the vises that hold the material in place can wear out. Vises are typically made out of hardened steel, so they last a long time, but when material is clamped on the same place time and again, it eventually wears.
“We have seen vises wear in as little as six months,” Kasto’s Dolipski says, “but in general terms, they usually last several years under normal conditions. Once a vise plate or jaw is worn down, the material shuttling can be inaccurate, as the materials can slide in the vises and cause length issues. Also, if a vise is worn out in an area, it can lead to the vise leaving imprints in the material due to possible ridges and peaks in the material.”
Starrett’s Gordon says many machines have replaceable vise plates, but in some cases, the vise itself needs to be replaced.
“Holding material tightly is a must,” he says, “because any movement in bundled material or a single bar causes blade tooth breakage. Tighten vises or use nesting clamps for the best results.”
HE&M’s Beha adds that worn vise face plates can be a big issue if they are not easily replaceable.
“Some manufacturers use cast vises without replaceable face plates,” he says. “This means that the entire vise has to be replaced if it becomes overly worn.”
Blade guide and arm alignment
Gordon says that while checking the alignment of a blade could be practiced daily, it’s not a maintenance issue most operators bother with until there is a noticeable out-of-square cut. Dolipski says another sign that the blade guide alignment is not correct is when the blade’s backing shows irregular wear.
Beha says bad alignment on a saw, which might also be referred to as out-of-plane or out-of-parallel, can happen due to improper handling of material around the saw.
“Sometimes it is caused when the guide arms have been damaged due to materials being crashed into one or the other,” he says.
Beha has written an extensive “how to” on the topic of saw alignment in a document called “Hydraulic Dual Column Arm Alignments.” He includes several informative sections, from leveling the base of the saw to getting the blade parallel to the vise-way alignment. Tools for the job include a dial indicator, 6-in. precision angle block, machinist square, 24-in. straight edge and machinist level. In the section on arm fall alignment, he says:
“Use a dial indicator to measure the arm tracking from top to bottom on the precision angle block. Attach the mag base to the guide arm in a position so that the dial indicator probe can travel down the face of the angle plate when the saw arm moves downward. This test should be performed on each guide arm. This will indicate how the arm is tracking.”
In addition, “testing the blade tracking and arm/guides on a vertical (saw) is done similarly, but the blade is tracked with the dial indicator as the arm moves forward as opposed to the arm moving downward on a horizontal style machine.”
Dolipski adds that when a machine is not maintained as it should be, the cost of repairs can be significant and the downtime associated with the repairs can cause operational challenges.
“A clean saw is a happy saw – it will last longer and be able to cut better and more accurately. Often, issues on machines start as small problems that can be easily found during a daily or weekly check,” he says. “When caught at that point, the issues usually are rectifiable with a small investment of time and parts.”
Opener.jpg: no text necessary
Bandguides.jpg: While it’s not a daily maintenance requirement, proper band guide alignment is crucial for straight cuts.
Dial.jpg: Utilizing a dial indicator, several parts of the bandsaw can be checked for proper alignment.
Alignment.jpg: HE&M Saw has developed a specific method for measuring how the saw blade “falls” into the material being cut.
Vise.jpg: While most bandsaw vises are made with hardened steel, they will wear over time and need to be replaced.
“When preventative maintenance is at an optimal level, sawing and blade performance tend to consistently mirror a similarly high level.” Jay Gordon, sales manager for saws and hand tools, The L.S. Starrett Co. North America
“A clean saw is a happy saw – it will last longer and be able to cut more accurately. Often issues on machines start as small problems that can be easily found during a daily or weekly check.” Stefan Dolipski, vice president, Kasto
Bandsaw maintenance, preventative maintenance, bandsaw challenges, Kasto, HE&M, L.S. Starrett Co.
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A meeting of the minds reveals sawing maintenance best practices