Bandsawing is one of the many cutting/machining operations that can benefit from the application of cutting fluid. That’s because cutting fluid helps to reduce temperatures, remove chips and, in some cases, act as a lubricant.
The effectiveness of cutting fluid largely depends on the selection of the cutting fluid and its method of application. In general, cutting fluid is selected based on the workpiece-bandsaw blade combination.
However, studies have shown that the effectiveness of the cutting fluid also depends on the flow rate of the fluid, location of the fluid application and the viscosity of the cutting fluid mixture, among other considerations. Cutting fluid application positively affects the integrity of the cut surface. It also helps to extend the blade life.
Providing a Roadmap
With a handful of factors to consider, the major goal of this article is to provide the bandsaw user with a roadmap in selecting cutting fluid and application parameters based on cutting requirements. This roadmap can be used to improve blade life and cut-surface integrity and also reduce cutting fluid waste.
As is true with all industrial fabricating equipment, bandsaw users can immensely benefit from having a good understanding of the consumables used alongside the machinery itself. For bandsaw users, it is important to understand the cutting fluid application intricacies. At the end of the day, the user should know the answers to two questions: Which cutting fluid to use? and What is the ideal lubricant-to-coolant ratio?
In general, improper cutting fluid maintenance is one of the main reasons for the lubricant-to-coolant ratio’s imbalance. Over a period of time, the water (coolant in the cutting fluid mixture) evaporates from the cutting fluid, leading to a rise in the cutting temperatures. Higher cutting temperatures can be associated with blade wear, the emergence of a built-up edge and a deteriorated surface finish.
Another common mistake can be seen through the incorrect selection of the cutting fluid. Cutting fluid should be selected based on the workpiece material-bandsaw blade combination. Most cutting fluid suppliers provide the cutting fluid dilution ratios for different materials. If the workpiece changes, the dilution ratio should be modified accordingly.
Along with the cutting fluid maintenance, the fluid delivery system should be checked periodically. Recent studies have shown that the location of the cutting fluid nozzle plays a critical role in improving the blade life and the cut surface finish.
Another tip to reduce the cutting temperature while cutting large cross sections is to apply cutting fluid at multiple locations.
Cutting fluids can be categorized into straight oil, soluble oil, semi-synthetic fluid and synthetic fluid. Straight and soluble oils are used to improve the lubricity while the semi-synthetic and synthetic fluids are used to reduce the temperatures at the cutting/deformation zone.
Like any other machining process, bandsaw operations have both frictional and thermal issues to be addressed by the cutting fluid. The frictional zones for the bandsaw application are along the “tool-chip” interface and “tool just-cut surface” interface.
The tool just-cut surface zone can be defined as the machined area around the top and side of the bandsaw blade tip. Research has shown that the chances of having any fluid in the tool-chip interface are minuscule. Thus, in bandsaw applications, lubricant is limited to improve the tool just-cut surface zone.
In many bandsaw applications, cutting fluids are predominantly used to control the temperatures along the cutting/deformation zones and the frictional zones. Reducing the temperatures along the fictional zones positively affects the tribological performance of the bandsaw.
Semi-synthetic and synthetic cutting fluids are formulated to reduce the cutting temperatures. Coincidentally, most high-production bandsaw users use semi-synthetic and synthetic fluids. Again, reducing the temperatures in these types of operations can improve the blade life and cut surface finish.
The tool rake face wear can be reduced by lowering the cutting temperatures. One easy trick to reduce the cutting temperatures is by adding more coolants (like water) to the cutting fluid mixture. Thus, if an operator sees wear along the rake face, diluting the semi-synthetic or synthetic fluid is a good option.
For low thermal conductivity materials, heat buildup can lead to localized thermal expansion along the just-cut surface to cause tool flank/relief wear and side face wear. In such situations, along with diluting the cutting fluid, checking the fluid flow rate and location of the fluid nozzle reduces the cutting temperatures.
For thermally conductive materials, the tool flank/relief wear or the side face wear can be delayed by adding the lubricant to the cutting fluid mixture. Adding more cutting fluid concentrate to the cutting fluid mixture is a good option. Finding the right combination of lubricant (concentrate) and coolant (water) is key to successfully reduce the cutting temperatures. In summary, a comprehensive understanding of the role of cutting fluid and its method of application can be beneficial for the manufacturing industry.