Cutting force is a fundamental physics concept that describes the amount of force used in a specific amount of area. This "force per area" relationship is used to derive the amount of stress applied to an object that is being cut. When the stress overcomes the strength of the material it is being applied to, the material will shear and separate at the point where the force is being applied. Calculating the force used in any particular cut only requires a ratio.
Though it may seem counterintuitive, the cutting force applied by any machine or instrument is never greater than the material being cut. This is because once a material gives way and begins to shear, the cutting force is changed to translational motion of the cutting instrument. For example, when cutting a piece of paper with a pair of scissors, the cutting force builds until the paper begins to come apart; after that the scissors begin to close (i.e. move or translate). In short, the cutting force is changed into movement force.
Measure the blade thickness of the cutting instrument.
Multiply the stress capability of the material being cut by the blade thickness of the cutting instrument. Ensure that the unit used to measure the thickness of the cutting instrument's blade is changed to match that of the stress capability of the material being cut. For example, if the blade thickness is 1/1000 of a centimeter and the material being cut has a stress capability measured as millions per meter, you would multiply the 1/1000 value by 100 to put it in terms of meters.
Combine and cancel any extraneous units to achieve the final cutting force. This final value should fall into the dimensions of Newtons per square meter.
- "Physics"; Douglas C. Giancoli; 2005
- University of Plymouth: Manufacturing Processes--Cutting Forces