The last two decades changed the economy of cutting fluids. It started out as around 3% of the total cost in machining production in Toronto and around the world. Nowadays, cutting fluids take up 16% of the cost of an average machining Toronto job. While cutting tools are only around 4% of the total cost, manufacturers prefer to use tools with shorter life in the hopes of saving up in the cutting fluids without realizing that this approach is less expensive.
There is also the possibility that tool life may not even lessen because most of the materials that make up the tool is brittle such as cements, ceramics and coated carbide. These materials are easily chipped and broken once subjected to thermal stress, adding a coolant may worsen the condition.
The cutting tools used in milling experiences hot and cold as the cutter enters and exits the work area. The hot and cold temperate causes expansion and contraction which may cause stress on the material. After repeated operation, thermal cracks may form on the tool and gradually make it crumble.
Without realizing, cutting fluid can worsen the situation since fluids are known to only cool areas that are warm. When this happens, the temperature intensifies and the thermal stress inflicted on the tool is increased.
Cutting fluid is mostly used in applications such as drilling, reaming and tapping. When drilling, it is important that the drill is properly lubricated so the chips are easily ejected from the holes.
Aside from saving cost and improving the tool life, there are other factors that encourage users to try machining such as the material. There are instances when a cutting fluid can stain the surface or contaminate the material. There are also materials that can be easily cut even without applying cutting fluid such as carbon and alloyed steel or alloys of cast iron. They are easily operated on the machine and a conductor of heat. On the other hand, materials such as low-carbon steel needs cutting fluid to serve as a lubricant.
Most aluminium alloys does not required lubricants because of the low temperature when cutting. In cases where the cutting is done at a high speed, high pressure coolant may be used to break chips.
Dry machining a stainless steel material can be a bit more of a challenge. Heat is the main culprit when it comes to this material. High temperature may cause overheating and may shorten the tool’s life as a result. Also, stainless steels are considered gummy which may lead to build-up in the edges and the finish cut may have a poor finish.
For every rule there is an exception, even in machining. There are certain materials that can’t be done using dry machining. This includes high temperature alloys and alloys which are nickel and chromium based. These types of materials need enough cutting fluid if the heat is to be dissipated properly. The cutting fluid also helps lessen the heat generated while cutting.