Coolants and Lubricants 101 – a primer.
Heat is one of the main reasons for blade failure. Lubricating the cutting edge of a band saw blade will reduce the heat that is generated by the cutting friction of the blade as it comes into contact with the material in production.
A flood of coolant will help to wash away the chips from the gullets of the blade. Chips can become work-hardened during the cutting process occurs due to the friction heat and by compaction. If the chips are dragged back into a cut more than once, they can damage the saw blade’s teeth.
Coolant is also used to cool the cutting edge of the saw blade as well as the blade guides. The heat that is generated from cutting needs to be minimized in order to help maintain the life of the saw blade.
The most important aspect of Coolants and Lubricants (two different fluids) is to understand that while they are most often used interchangeably terminology-wise, they are both unique products and each helps to serve a different purpose.
Plain cutting oils are derived from petroleum and other origins used either straight or in combination with one another. Mineral oils, which are a petroleum-based product, are the most efficient. To make them more effective and efficient, additives are incorporated into the mix to help increase the efficiency of the product being used.
However, they are generally restricted to light duty sawing.
Polar additives, on the other hand, can be any one of a number of types of fluids used in combination with a coolant or lubricant.
- Animal fats and oils make excellent lubricants but based on their origin can often develop bacteria as well producing disagreeable odors
- Vegetable oils are derived from coconut oil and castor oil
- Marine oils are derived from the fatty tissue of fish and other ocean mammals. They often have a foul odor and are not the most politically correct (whale oil) or green (environmentally friendly) additive as those of other ocean mammals
- Chemicals which contain sulfur, chlorine, and phosphorous are additives that provide an excellent lubricant through the chemical reaction of the surface of the blade
Lubricant-type cutting fluids are generally not effective at higher SFPM rates for two reasons: one being the movement of the chips into the gullets is too fast to be an effective wash, and two being that the higher cutting speeds generate higher temperatures, which means the oil tends to evaporate before it can effectively lubricate.
Soluble oils are created by suspending or adding oil droplets to water. Additives used in this process included animal and vegetable oils in addition to mineral oils and chemical additives such as the above-mentioned products. Soluble oils can provide a combination of cooling and lubricating qualities despite the differences in the products.
Soluble oils are also popular with professional operators of band saw machines for several reasons: first, they provide a combination of cooling and lubricating as noted above. Second, they are cleaner to use than oils. Third, they are economical to use based on their being water-based, and Fourth, there is less chance of bacterial contamination.
However, due to that water-based origin, there is a rust control issue that occurs, the lubricating qualities may be less effective, and due to the foam-up potential, using a soluble can be slightly more messy.
Synthetic and semi-synthetic fluids are gaining in popularity. While slightly more expensive, the advantages of using these manufactured fluids may out-weigh the cost factor for the operator.
Synthetic fluids consist of chemicals rather than oils mixed into the solution. Semi-synthetic fluids do, however, contain small quantities of mineral oil plus oil additives. These are meant to help improve the lubrication’s characteristics of the fluid together with the chemicals.
Synthetic and semi-synthetic fluids provide good visibility of the material being worked, allow for lighter film residue, mix easier in the tank, provide for better tank life, and do not foam as easily as soluble oils.
Disadvantages of using these fluids can include potential skin irritation, a lack of rust control, and inferior lubrication.
If you have questions about extreme pressure (E.P.) additives (another aspect to consider), discuss the particulars with your professional band saw supplier or sales representative. There is a lot of debate about the use of spray lubricants versus flood lubricants. Intelligent, informed discussions with your supplier regarding the complexities of flood versus spray applications should help to answer any of your questions/concerns.
Regardless of the type of coolant you choose, there are several consistent rules which must be followed in order to maximize coolant performance.
- Specific concentrations must be maintained in order to maximize the performance of the fluid
- Proper application of the coolant is required
- As with every other aspect of band saw use, proper maintenance of the chip filter and pumps should be a high priority and performed on a regular basis
This is a lot of information, yet critical to the proper functioning of any band saw machine. The information provided is necessary to obtain higher production rates.
Talk to your local rep in order to gather the latest information and to help make the best, most informed decision for your specific needs.