Bandsaw blades are like any consumable – they’re not meant to last forever. Yet choosing the right blade for the job is extremely important, not just for extending the life of the blade, but also for achieving quality cuts. As any saw operator can attest to, getting on the right road to extended blade life and quality cuts requires attention to detail and the right amount of guidance.
Manufacturers constantly face challenges to decrease production costs while battling increasing costs on everything from raw materials to equipment. While the per-blade-cost might seem negligible compared to overall operations, it can build up over time – especially if the maximum life expectancy of the blade isn’t reached. More importantly, the quality of the cut can represent an unexpected expenditure, as the scrap heap filled with poorly cut pieces continues to grow.
The first layer of protection against unexpected expenditures is initially choosing the right blade. This is something Lenox can help saw operators achieve. And that help
can be accessed day or night via the company’s SawCalc online resource that offers everything from sawing definitions and troubleshooting guides to info on drilling down on the exact blade an operator should be using in a specific application.
“Users can plug in the material they’re cutting, the dimensions of the material, their saw machine info and operational goals,” says Dan Fernandes, senior product manager at Lenox. “From there, SawCalc provides a recommendation in terms of product, tooth pitch and some starting cutting parameters for efficient operation.”
Even when the perfect blade is selected for a job, things can go awry, at which point it’s not the blade’s fault. The blame can be pinned on the operator, erroneous sawing parameters or both.
Preventing Blade Wear
The way a blade wears can say a lot about what action to take next. For example, heavy back edge wear on a blade is telling by a polished appearance or abnormal grooves in the surface. Swagging of the corners of the blade might also be visible in this situation. According to Lenox’s “Guide to Band Sawing,” this often occurs because of an excessive feed rate. Simply making a feed rate adjustment could be all that’s required to fix the issue.
Another common blade failure issue involves heavy wear on the gullets, which is an indication that there is a lack of gullet capacity for the chips being produced. Again, an excessive feed rate could be to blame, but running the blade too slowly could also cause the problem. If the operator chose a blade with too fine of a tooth pitch, they may also see heavy wear in the shallowest gullets.
Metalworking fluid also comes into play with many common blade failures. Discolored tips due to excessive frictional heat, tooth strippage, chips welded to the tooth tips, gullets loading up with material – these can all be at least partially related to improper coolant or lubrication.
“Proper fluid maintenance is important to success,” Fernandes says. “Using the proper concentration and monitoring pH levels are keys to successful cutting. In addition, the fluid must be properly applied to the shear zone to reduce heat and produce good chip flow. Those are the important items to check to help achieve long blade life and efficient cutting.”
Making the Break
Breaking in the blade might seem like an elementary procedure that all saw operators should be well aware of, but some have a tendency to skip the process and jump right in to cutting at production speeds and feeds to meet daily cut quotas.
Lenox’s troubleshooting guide in SawCalc lists three common blade failure issues that are at least partially attributed to not breaking in the blade properly. Chipped or broken teeth, premature heavy even wear on the tips and corners of teeth, and tooth strippage are all potential consequences of improper break in.
Mark Cranna, senior engineering manager for bandsaw product development at Lenox, says the idea behind breaking in a blade is to make sure the blade is behaving in a smooth and predictable manner.
“It’s absolutely still a problem,” Cranna says of operators who continue to disregard proper break-in procedures. “You need to start with a sturdy, well-honed tip radius that is free of micro-imperfections that can lead to fracture.”
While breaking in the blade continues to be a critical component of the sawing process, new product features have emerged to make the blades more resistant to improper break-in procedures. These features include optimized tooth patterns, precision tooth tip micro-geometries and cold worked edges.
“From a product development standpoint,” Cranna says, “we’re well equipped in-house to test new product development concepts on a variety of sawing situations and circumstances. We spend a great deal of time out in the field. Being able to talk to the actual saw operators is incredibly important because they’re a wealth of insight for us.”
Fernandes stresses that while choosing the right blade is important, maintaining the saw itself is an equally valuable part of achieving efficiency.
“If you try to run your car with no oil, then you’re not going to get very far,” he says. “With a saw, if the common wear parts are not in good shape, you aren’t going to be successful either.”
A scenario that points to improper saw maintenance is when one side of each tooth has heavy wear markings. In most situations, the wear is caused by the saw’s worn wheel flange or improper blade tracking, which allows the side of the tooth to contact the wheel surface. The saw’s side guides could also be loose or improperly positioned. Another cause could be the blade rubbing against the return stroke of the machine head. And finally, the teeth could be rubbing against the chip brush assembly, guards or other components.
Lenox has factory-trained technical representatives that perform a 13-point tune-up on customers’ saws, which optimizes blade and machine performance. Fernandes explains that the audit of the saw includes looking at 13 distinct parts of a saw, no matter the brand, to ensure everything is in good condition.
“If you have the right blade and sawing parameters,” he says, “you should be successful in making cuts.”
In the past, it wasn’t uncommon for manufacturers to simply seek out the lowest upfront machine cost in their sawing operation, disregarding fundamental aspects of the job, such as getting the right saw and blade for optimal performance. Times have changed. Manufacturers are now much more focused on machine uptime and limiting secondary processing steps, including the need to deburr parts following the sawing operation.
“Now they want to have the complete picture – to know what the total cost will be for their sawing operation,” Cranna says, “and, with that understanding, of course, comes a desire to hold tighter and tighter tolerances.”