Lubrication Of Metal Cutting Machine Tools
The machining of metal parts and components on metal cutting machine tools is a complex process which involves high compressive strength, large cutting forces, heat generated and displaced swarf. If a cutting fluid is utilized, it must be sufficient to keep the cutting edge cool and properly lubricated to reduce friction, increase tool life times and to ensure the highest possible quality and finish of the component.
In order to ensure this, the correct choice of lubricants must be made which can vary from light machines oils, soluble oils, semi-synthetic and fully-synthetic fluids. The choice depends primarily on the machining operation, type of cutting tool and material being machined as well as shop temperature and environmental concerns.
For most metal cutting operations, light machines oil can provide sufficient lubrication to aid the cutting action. This can be applied directly in the form of a spray or through drip orifice systems. While cost effective and can provide good results for low compared to exchange operations, it can negatively affect indoor air quality (particularly if the machine is located indoors) and the generated swarf may become sticky and difficult to process.
Soluble cutting fluids provide a higher level of lubrication than oil and cooling and can often be seen bused in operations such as drilling, tapping, threading, and reaming. They are a blended mix of oil, emulsifiers and corrosion inhibitors and use water as the primary component. The lubricant is applied to the cutting tool through a recirculating solution, utilizing pumps and tanks to mix, filter and maintain the solution’s consistency. The disadvantage with this type of lubricant is the need for the constant maintenance of the system and the additional expense of disposing of the cutting fluid at the end of its usable lifespan.
Semi-synthetic and fully-synthetic metal cutting fluids require minimal maintenance and contain rust and corrosion inhibitors as well as lubricating properties. They are not based on oil, and in some cases, do not contain any metalworking oil. Despite the cost associated with these types of cutting fluids, they offer an efficient and clean method of cutting on all materials, including many difficult-to-machine materials such as titanium, stainless steel, and nickel alloys as well as providing longer tool life, minimizing consumable costs.
In conclusion, for successful metal cutting operations, it is important to choose the most suitable lubricant available to keep tool cutting edges cool and properly lubricated. Oil and soluble oils have been used successfully for many years, however, semi-synthetic and fully-synthetic cutting fluids offer a much higher level of effectiveness, particularly when machining difficult materials. It is essential to carefully consider the application and environmental needs before determining the ideal cutting fluid for your operation.
