What Is Meant By Cutting Fluid Penetration? The Mechanism, Factors Affecting Cutting Fluid Penetration

🔗Functions of cutting fluid in metal machining

 

What is cutting fluid penetration?

The penetration of cutting fluid into the capillaries in the contact zone of cutting is known as cutting fluid penetration. The effective cutting fluid penetration is important in the quality of machining process. For better cooling and lubrication it is important the fluid penetration into cutting zone as much as possible.

The important parameter that determines the efficiency and depth of fluid penetration are as the following

• Means of fluid supply – free running, forced lubrication etc
• Viscosity and surface tension
• Wetting and spreading
• Size of molecules

The vibration during the machining also favors the cutting fluid penetration.

How is cutting fluid penetration happening?

The cutting fluid molecule must show more adhesion than cohesion so that it can get attracted to surfaces than to each other. Adhesion property is important to the spreading of fluid over the surface and wets it.

The pressure differences of one atmosphere is created as a result of the creation of vacuous cavity as tool penetrates into workpiece. This pressure difference and the surface tension causes the fluid to flow in the capillary against the motion of chip and reach to the tooltip. It is shown that at a point very close to the tip of the tool the cutting fluid undergoes thermal dissociation and changes its state from liquid to vapour by absorbing the heat generated during the cutting process. The vaporized cutting fluid then physically absorbed into the freshly cut metal as it goes. The fluid of small particle size enters to voids in cutting zone more readily than fluid of larger particles.

At high cutting speed, because of the high relative velocity of chip over cutting face of the tool, the penetration of cutting fluid into chip-tool interface become harder and efficiency of liquid and gaseous cutting fluid decreases. So in order to get proper fluid penetration at higher cutting speed, the high-velocity stream of cutting fluid is used. The high velocity of the fluid is obtained by using nozzles of small diameter (3.3mm to 0.375mm).

👉The study of cutting fluid penetration is still ongoing, there is no well-adopted mechanism of fluid penetration.