Many variables factor into cutting metal efficiently with a saw. From choosing the right blade and optimizing speed and feed rates to managing vibration and regularly going through the maintenance checklist, many factors are at play when trying to achieve a quality cut as well as high production rates. There’s another vital piece of the overall sawing strategy, however: the use of cutting fluids at the point of contact between the blade and material.
Rick Klipp, president of Behringer Saws Inc., says coolant (also referred to as lubricant or cutting fluid) is unquestionably an important component of cut quality, but he adds that, in actuality, coolant has a greater impact on blade life than the quality of the cut itself.
“Coolant reduces friction and cools the blade,” he says, “allowing it to pass through the material easier. Poor coolant quality, or lack of coolant, significantly reduces the overall life of the blade.”
Furthermore, Klipp says the function of coolant in chip removal, in conjunction with a quality chip brush system, has a direct impact on cut quality because “dragging chips around” the wheels or leaving them in the blade gullet will “unequivocally impact the quality of the cut and leave drag marks. High-pressure coolant combined with a chip brush that is synchronized with the blade speed is the best possible combination to achieve good chip removal.”
Daniel Fernandes, senior product marketing manager at Lenox, agrees that proper lubrication is essential for long blade life and economical cutting.
“Cutting fluids provide better surface finish, prevent corrosion of the workpiece and tool, and prevent chip welding,” he says. “Without lubrication, excessive friction can produce heat high enough to weld the chip to the tooth. This slows down the cutting action, requires more energy to shear the material and can cause tooth chipping or stripping, which can destroy the blade.”
When correctly selected and properly used, according to Patrick Schmidt, northeast regional sales manager at DoAll Sawing Products, “cutting fluids provide for faster cutting rates by providing a proper balance of cooling and lubrication, allowing for the use of heavier feed rates and increased band speeds, promoting better surface finishes and increased band life.”
Cutting fluid risks
With so many benefits to using cutting fluids, could there be a downside? Lenox’s Fernandes says he’s hard pressed to find any major side effects, aside from the labor it takes to clean up fluid around the machine, maintaining the fluid and properly administering it.
However, with shop safety always a factor, any fluid that spills outside the cutting area and onto the surrounding floor is a slip risk and definitely something to think about, DoAll’s Schmidt notes.
There is also the rust factor to consider. “If not correctly mixed,” he says, “water-based coolants promote rusting of the unpainted areas on the sawing machine. Synthetic coolants have a tendency to become very sticky when not properly mixed or cleaned up and allowed to dry on the machine, encapsulating chips that may be on the machine.”
Justin Eastwood, warehouse supervisor at Cosen Saws, concurs that cutting fluids can be slip hazards and can also cause potential damage to the paint on a saw.
“Some fluids can cause gumming up of parts on the machine,” he says, “which means they will need to be cleaned more often. Understanding that cleanup can be time-consuming at times is key.”
Jerry Kroetch, president of Scotchman Industries Inc., says frequent cleaning is definitely an issue. Cutting fluid can also become stagnant (and in some cases rancid), which means operators need to keep an eye on the coolant tank, clean it and replace the fluid as needed. However, once these practices become habit, the time involved will pail in comparison to what could be if the habit wasn’t adopted in the first place.
Getting the best performance out of a saw can sometimes include factoring in the type of cutting fluid being used for a specific application and aiming it precisely where it is needed. Joe Suydam, regional sales manager at Behringer Saws, says some sawing applications simply have different needs, and that includes where the fluid is directed.
“When cutting at high speeds for aluminum,” he offers as an example, “typically, a spray mist lubrication is used. This provides lubrication directly on the teeth of the blade. When cutting high nickel material, a proper emulsion coolant is ideal. Some applications require no residual liquids are left on the material depending on downstream operations, therefore, cutting dry may be needed.”
Scotchman’s Kroetch maintains that when cutting thin-walled material, only a light amount of fluid is required, but when cutting solid or stainless steel, a higher volume of coolant is a good idea.
As mentioned, “cutting fluid” is often interchangeable with the terms “lubricant” and “coolant.” And while lubricant can bring cooling properties and vice versa, Dan Royer, West Coast regional sales manager at DoAll Sawing Products, says most manufacturers using saws are concerned about heat, “and therefore use a product that offers coolant more so than lubricity.”
DoAll’s Schmidt offers that when lubricity is the concern, “soluble oils provide the best lubricity by far, but do not provide the best cooling or sump life.”
Type and application
The type of lubricant and the way it’s applied can both have a big effect on the final cut. So when it comes to application, what is the proper method of using cutting fluid – flood or mist/spray? As is often the case, the answer varies depending on what’s being cut, but DoAll’s Royer says when cutting thick-walled pipe, for example, it is especially important for fluid to be applied to the blade as it cuts into the second wall of the pipe.
Behringer’s Suydam goes on to explain that with hollow structural materials, such as tubes and beams, the interrupted cutting, “typically in structural steel applications, doesn’t allow a ‘flood’ of coolant to cool the blade,” therefore, the cutting fluid must be sprayed “directly onto the teeth of the blade to reduce heat and allow for faster blade speeds.”
DoAll’s Schmidt adds that best practices regarding fluid application in most cases is to ensure the fluid is applied evenly and not to “starve the middle of a cut.”
“Make sure the cutting fluid is being applied as close to the point of cut as possible,” he says. “Keep in mind that the harder or tougher the materials, the higher lubricity needed in a product.”
What also needs to be considered is that there are different types of cutting fluids in terms of synthetic, semi-synthetic and vegetable-based products. Behringer’s Suydam says semi-synthetic lubricants are among the most commonly used as they can be mixed with water, allowing the cooling effect to cut down frictional heat, which is a great benefit when cutting solid material, particularly high-alloy steels.
“Cooling, along with great chip evacuation, allows for faster cut rates and helps extend blade life,” he says.
Cosen’s Eastwood notes semi-synthetic fluids have the flexibility to be of use on ferrous and non-ferrous materials. “They aid in chip formation and heat,” he adds, “and also protect against rust. Usually, they are biodegradable.”
DoAll’s Schmidt offers that semi-synthetic fluids provide a “true solution,” meaning they will not separate like soluble oils. “They are also more tolerant to water condition than soluble oils,” he says. “However, keep in mind they do not provide the same lubricity as soluble oils.”
Lenox’s Fernandes notes vegetable-based fluids have environmental and health-related advantages over mineral oil-based fluids and maintains that the best application for vegetable-based fluids is in spray or mist applications.
“With that said,” he says, “vegetable-based lubricants are getting more advanced every day, making them an option in many more applications. Many studies show that vegetable-based lubricants can match the same or provide better efficiency as mineral-based lubricants with cleaner manufacturing and environmental standards.”
Overall, Behringer’s Klipp says for the best quality results, the cutting fluid is just one component to consider among many for quality production.
“In summary,” he says, “the blade, coolant and saw must all work together, along with incorporating the correct sawing parameters, to achieve quality cutting. The cut quality will only be as good as the weakest link in that chain. This is especially true on more difficult materials, including Inconel or other super alloys where proper blade selection and saw capabilities deliver the best possible combination of cut quality, blade life and cost per cut.”