【Application】The application and selection of lubricants

1Standard of oily or water-soluble lubricants application

• Oily lubricant: good anti-rust, usually used in fine finishing. The downside is it produces oil gas easily, causing odor and air-pollution. Also, it increases the chance of oil stinking on the workpieces and environmental mess. On the other hand, new oil can be added directly depending on the consumption level without any dilution.
• Water-soluble lubricant: good cleaning and cooling features, mainly used for high-speed and rough machining, which requires better cooling performance. Needs to be diluted with water, which is more economical than oily lubricant. However, water-soluble cutting fluid application can be impacted by factors such as concentration, pH value, environment, etc. It can deteriorate, corrupt or cause odor without proper controls. To extend the service life of cutting oil and reduce oil replacement cost, it is recommended to adapt high quality water-based cutting oil or oil-water separator, which removes oil, dust and impurities.

2Working method (grinding, turning, milling, drilling, tapping and broaching, etc.)

• Better cooling feature: roughing, grinding, turning and drilling
• Better lubricity: finishing, tapping, threading and broaching

3Working material (e.g. cooper, aluminum, iron, steel, etc.)

Cutting oil is not mandatory when processing brittle materials such as cast iron, however, it can produce waste fines and black dust easily. Copper and aluminum alloys are sensitive materials thus inert sulfur extreme pressure agent is preferable. Extreme pressure cutting fluids should be used to improve efficiency for high-strength steels, high-temperature alloys, etc., due to extreme pressure lubrication and friction during processing.

4Water quality

The quality of water will affect the use of cutting fluid. When the water is too soft, it foams easily. On the contrary, when it is too hard, it rusts and causes oil and water separation.

5The compatibility between cutting fluid and slippery oil

If the cutting fluid combines with slippery oil easily, it can cause emulsification. If the emulsification situation got worse and the slippery waste oil had not been filtered off, the cutting fluid is prone to be metamorphic, deteriorative and stinks after a period of time.

6Deployed concentration

• Steel, iron: 4%-6% under normal processing ，8%-10% under strict processing
• Stainless steel：6%-8% under normal processing ，10%-12% under strict processing
• Aluminum, copper alloy：4%-6% under normal processing ，8%-10% under strict processing

7PH value

PH value is divided into 0-14，>7 is alkaline、PH=7 is neutral、<7 is acidic. Most cutting fluids are alkaline. Whenever the value is over-high, it causes irritation and allergy to human skin, erodes the colored metal and reduces the lubricity of the cutting fluid. If the value is lower than 8, it is easy to breed bacteria, cause odor, and reduce the rust resistance and anti-corruption abilities of cutting fluid. It also reduces the life of the cutting fluid. Generally, the acidity and alkalinity of cutting fluids should be kept between 8.5 and 9.5, and additionally, the pH level should be checked periodically to maintain the quality.

8Viscosity

Mainly oily lubricants. Low-viscosity oils are thinner with better permeability and wettability. The appropriate selection of additives allows the oil to reach the cutting zone faster. Its cooling and cleaning ability are better because of its thinness. High-viscosity oil is denser and has better lubricity and greater metal surface isolation, however, the fluidity and cooling are not as good as low-viscosity oil.

9Defoaming

The cause of foaming depends on the quality of cutting fluid, soft water, over-high pressure stamping, nozzle of the machine and numerous right angles in the sink. It is recommended to add an appropriate amount of defoamer to improve it, or apply a good defoaming oil.

10Antioxidant trait

The materials like aluminum alloys can easily oxidize. The cutting oil requires anti-oxidation effect to prevent oxidation and blackening of aluminum during processing.

11Skin irritations

The machine operator closely contacts with cutting fluid during the operation process. As mentioned in above, cutting fluid can be erosive to human body when the pH value is above 9 and when bacteria level is high. Therefore, it is crucial to take into account the cutting fluid is skin-friendly.

12Filter system

The slippery oil and dust often permeate into the fluid during operation process. If the tramp oil is not removed, it can result in breeding of bacteria and cause odor. Taiwan Fimitech has introduced Centrifugal separator and Chip removal machine to remove tramp oil or particles and extend the life of cutting fluids.

13Cleaning and quality management

Machine cleanliness and quality management of cutting fluid are crucial to maintain the service life of cutting fluids. Our sales visit the customers regularly to assist them on monitoring the use of cutting fluids. On top of that, we offer fluids replacement and machines sterilization services.