What is Cutting: Definition and 128 Discussions

Cutting is the separation or opening of a physical object, into two or more portions, through the application of an acutely directed force.
Implements commonly used for cutting are the knife and saw, or in medicine and science the scalpel and microtome. However, any sufficiently sharp object is capable of cutting if it has a hardness sufficiently larger than the object being cut, and if it is applied with sufficient force. Even liquids can be used to cut things when applied with sufficient force (see water jet cutter).
Cutting is a compressive and shearing phenomenon, and occurs only when the total stress generated by the cutting implement exceeds the ultimate strength of the material of the object being cut. The simplest applicable equation is:





{\displaystyle {\text{stress}}={{\text{force}} \over {\text{area}}}}



{\displaystyle \tau ={\frac {F}{A}}}

The stress generated by a cutting implement is directly proportional to the force with which it is applied, and inversely proportional to the area of contact. Hence, the smaller the area (i.e., the sharper the cutting implement), the less force is needed to cut something. It is generally seen that cutting edges are thinner for cutting soft materials and thicker for harder materials. This progression is seen from kitchen knife, to cleaver, to axe, and is a balance between the easy cutting action of a thin blade vs strength and edge durability of a thicker blade.

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  1. martijn_tholen

    Propane/Oxygen - from Cylinder to Oxy/Fuel cutting torch

    For one of our projects we are at present using quite large amounts of gas & oxygen. What I was trying to figure out was how to calculate the total available amount of gas in a cylinder (be that either Propane/Oxygen or Propylene (Propene)) and then to determine whether or not -given a certain...
  2. abdulbadii

    Reading a wood cutting blade specification

    How do we read and understand a wood cutting blade specification (e.g. below) ? Is the grinder spacer flange nut for 16 mm center diameter metal cutting disc can safely be used for 20 mm one of such blade?
  3. F

    Anyone experienced with laser cutting?

    Hello, Does anyone own a laser cutter and knows how to operate it with some level of experience? I have some questions... Thanks!
  4. DaveC426913

    Advice about Dremel cutting wheels

    As mentioned in another post, I'm cutting brass hobby tubing. I'm cutting a lot of brass hobby tubing. Like several hundred cuts. I'm using a Dremel, but I'm open-minded. Using the little ceramic cutting wheels is cheap, and easily replaced when they break, but they are slow and they waste a...
  5. J

    B Why are serrated knives more effective than normal knives?

    What physical processes does serration take advantage of that make cutting something with a serrated knife more effective than cutting something with an ordinary knife? What is the optimal shape of each tiny segment of a serrated knife? Would cutting effectiveness increase as you add more...
  6. Luke2642

    Force & energy in cutting and stretching magnetic field lines?

    I have an ordinary switchable magnet for holding tools to a lathe. It's like a magnetic force gearbox, but I can't quite understand the force multiplication. When placed on a steel surface the switch force is approximately ~5N on both finger and thumb at 1.5cm radius acting over a 3cm arc...
  7. H

    B Blunt force vs cutting force in penetration

    My thought is that they both stem from PRESSURE. Sharp objects have more pressure than blunt objects given the same force and therefore can penetrate softer material better. Some of my associates are suggesting that cutting by stabbing is entirely different than blunt force. But the definition...
  8. B

    Analyse the cutting force of this bolt cutter

    The question is to determine the force in the small opening, delivered from the 250 N on both sides of the plier. i tried multiple things but can't get the answer right. Anyone that could help me? This is my work so far:
  9. russ_watters

    Streaming/Cord Cutting vs Discs

    This is a spin-off of the streaming vs disc discussion in this thread: https://www.physicsforums.com/threads/terminator-dark-fate-movie-review.979853/ I'd really like to hear more opinions on discs vs streaming and/or cord cutting because the landscape is complicated. I'm a movie fan and I've...
  10. vivek_salman

    Shearing / Cutting Force - Rubber bale

    I have been assigned by my tutor to design a hydraulic guillotine (rubber bale cutter). After designing its features of the hydraulic, cutting blade etc. I tried to calculate the force needed of cutting a piece of Rubber bale (Natural as reference) having an ultimate tensile strength of 30 MPa...
  11. E

    Why have a feed force in the cutting process?

    You knew there is a cutting force in the orthogonal process, it is exerted by cutting speed, buy why have a feed force?
  12. ramadhankd

    Shredder Cutting Area Calculation

    Hello everyone, I'm trying to design a plastic shredder machine, but I'm stuck on how to determine the cutting area of my shredder. I've already made some research, and I think that the cutting area depends on the blade thickness and the plastic thickness. As for why the blade thickness is...
  13. Z

    MHB Calculating amount left at the end of a repetetive cutting down cycle.

    Let's say I have a group of X's characters that I want to cut down. I use a tool similar to 'find-and-replace-all', which takes an amount of X's each time, deletes them, and replaces them with another, smaller amount. For example, I can state that I want an amount of 8 X's to be replaced with 5...
  14. B

    Steel chisels cutting wood and bone

    Below 17 degrees bevel , a steel chisel cuts pine wood without tearing shreds but 25 degrees is the upper limit for hardwood. Bone is said to resemble wet pine-wood. 2mm thickness is the limit for steel cutting bone. .". difficulties arise for the surgeon when using conventional chisels, due...
  15. S

    I Adhesive force between cutting oil and metal chips?

    I am working on a project to remove cutting oil from waste metal chips. I need to know the retationship between viscous force of oil and centrifugal force required to remove oil from chips, so that I can calculate the RPM P.S Design is attached
  16. barryj

    Formation of a hyperbola using a plane cutting a doubole con

    Homework Statement My question. When studying conics, the parabola circle, and ellipse can be easily see by passing a plane through a double cone. The hyperbola is generated when the plane is passed through the double cone where it passes through the top and the bottom cone. My question is...
  17. jra12222

    B Force at which a cutting disk comes off from an angle grinder

    Hi all, This is not exactly a homework question, more like for my own safety So I have a project going on and I need to use an angle grinder without the safety guard which will be enclosed in a box (made from plastic most probably). So I decided to check if the plastic box would be able to...
  18. Julio

    B Problem about a cone and plane cutting it

    It has a straight cone and a plane that cuts it as shown in the image. What angle should the plane form with the base of the cone ?, so that the plane cuts the cone in 2 parts of equal volume.
  19. Eclair_de_XII

    Studying My current study habits aren't cutting it for me at the moment

    I had a test today on my linear algebra class, and it's safe to say that I didn't get more than a seventy percent on it. I got the first two problems of the test down, but the last problem asked me to prove something involving linearly independent sequences, how if a vector isn't in the span of...
  20. M

    Flux with an infinitely long surface cutting through a sphere

    Homework Statement Bildschirmfoto 2018-06-19 um 18.50.50.png In the y-z plane there is an infinite long surface with charge density ##\sigma## that slices through a sphere with radius R. Determine the Flux.The Attempt at a Solution I have solved the problem but am stuck at the last part. I used...
  21. E

    Force required for cutting sheet metal

    hi every one can in you help me in finding the required force to cut sheet metal electrically as shown blew
  22. wolram

    How can we reduce food waste at home and beyond?

    It is amazing that we throw away 38 million tonns of food each day, This thread is for tips on reducing food waste, how to use left overs etc. https://www.epa.gov/recycle/reducing-wasted-food-home#ways. If you feel guilty about throwing away food, and you should, contribute to this thread...
  23. A

    Designing a Log Cutting Mechanism - Get Suggestions Here

    Good afternoon guys, I want to discuss with you guys a few things... So i already design a log cutting mechanism as you can see in the picture below. But there is so much defect on my mechanism.. The biggest thing that stressed me out, its still uneasy to use because after cut the log, the user...
  24. A

    How to calculate the force to cut a log?

    Good morning guys, So i want to make mechanism to cut log with diameter 5 cm and 120 cm length. So how i can calculate the force to cut this log perpendicular and paralel. What is tbe formula i can use? And how i can determine the saw thickness and rpm needed to cut this log? Thanks guys for...
  25. Sveral

    Cutting a FeBa Magnet for a Bloch Wall

    Hello, could someone explain to me, how I should cut a FeBa magnet, if it has one pole facing upward and the other downward so that the bloch wall would be across the entire length of the magnet. The dimensions of the magnet at hand are 152 x 102 x 52 mm. The bloch wall runs across the entire...
  26. Sveral

    Cutting magnets without losing magnetization (Curie temperature issue)

    Hello, I wanted to know, if someone knows of a realistic option of, how to cut barrium ferrite magnets without using a rock saw and without demagnetizing the magnet obviously? Thanks in advance everyone.
  27. D

    MHB How Can I Efficiently Cut Wood Boards of Different Lengths?

    Hi, New to this forum so sorry if i am not posting in the right place. I have a problem, I need to cut a number of pieces of wood to certain lengths (the width and depth are standard and not relevant here). I know the number and lengths of all the lengths I need, but i can only buy the wood...
  28. J

    Misc. Custom building a CNC mill for aluminum

    So as a quick background I've made a 3-d printer (I know a monkey could assemble one of those DIY prusas) and want to step up my game a little bit. I came to the realization that some people have made/sold DIY milling kits, but most of them are for plastics or wood. I would like to make a...
  29. Dirk

    Calculate cutting force (guillotine) GFRP

    Hey all, I want to calculate the force which is needed to cut the blades of a wind turbine in half(for transport reasons). I presume guillotine is the best option due to various reasons. But I don’t know how to calculate the cutting force which is needed for this unique structure and material...
  30. George Zucas

    Cutting a Groove -- Power Requirement

    Hello, I am designing a machine that will make grooves on round objects. Not a perfect groove actually, think of a sheave, so round profile. I have the attached formula for cutting power taken from below website: http://www.iscar.com/Products.aspx/countryID/1/ProductID/32 In my case...
  31. RedDelicious

    What is cutting lines of force? Elementary Generator

    I was reading this article on Wikipedia about single phase generators and the operation of a basic generator, and I'm having a very difficult time understanding what is meant by cutting lines of force and how the rotating armature being perpendicular to the field cuts zero lines. While when it...
  32. A

    I Matter cutting by destabilising of atoms bonding

    is there a theoretical way to cut solid mater by disrupting the electron field holding atoms together
  33. Ali Durrani

    Force required for cutting process

    hello brothers and sisters, i have got a project on making an agriculture shredder, i am having difficulty in finding the general equation for the force required to perform cutting operation can anyone help me out
  34. E

    Resources on Gear Cutting Machines

    I'm interested in learning about how original gear cutters were made, such as Polhem's manually operated gear-cutting machine or Whitworth's design. So far, I have only been able to find very brief or vague description on how they worked. Any helpful resources that explain the mathematics and...
  35. nicholas0211510

    Cutting force (large astronomical body)

    I know this is a weird topic but the thought has pestered me lately. How much energy would it take to cut a large astronomical body in half (assuming its a uniform sphere). Let's say a object the size of the moon with the same overall density of the moon. Say the blade used to cut it is as hard...
  36. T

    Cutkosky Cutting Rules: Understanding Rules & Where To Add i

    OKay, so whenever I run into explanations on the cutting rules, most of the time I see the statement to replace##\frac{1}{p^2 - m^2 + i\epsilon} \rightarrow -2i\pi \delta(p^2 - m^2)## for each propagator that has been cut taking note that there is no factor of i in the numerator for...
  37. I

    Calculating bend moment of a rotating cutting tool....?

    Hello - I've been trying to solve this for a little while, and feel I may not understand some core concepts required to solve the problem. If you have any ideas, please let me know! I would very much like to discuss how to solve this. I am trying to calculate the bend moment from a rotating...
  38. physicsquestion

    Finding the work done on a cutting tool

    Homework Statement A cutting tool under microprocessor control has several forces acting on it. One force is F⃗ =−αxy2j^, a force in the negative y-direction whose magnitude depends on the position of the tool. The constant is α = 2.70N/m3 . Consider the displacement of the tool from the...
  39. R

    Shearing Force - Cutting Force

    I have been assigned by my tutor to design a plastic granulator. After designing its features of the shaft, rotor etc I tried to calculate the force needed of cutting a piece of plastic (POM/Polycarbonate) having an ultimate tensile strength of 70 Mpa (shear strength assumed to be equal to...
  40. DaveC426913

    Precision Cutting Jig Options for Brass Tubing: Buy or Build?

    I need to make a lot of precision cuts in brass tubing for a project I'm working on. I'm using a Dremel with a cutoff wheel and a vise. The Dremel is strapped to my workstation via a set of wooden tracks so it can slide to and fro, enabling me to cut the tubing in the vise. It's not accurate...
  41. D

    Cutting a spring in half and then in 1/4 and 3/4

    Homework Statement A helical spring of stiffness k is cut into two halves and a mass m is connected to the two halves. The natural time period of this system is found to be 0.5 sec. If an identical spring is cut so that one part is one-fourth and the other part is three-fourths of the original...
  42. C

    Regarding volume of an ellipsoid bounded by 2 planar cutting planes

    Homework Statement Hi I require to compute the volume of a ellipsoid that is bounded by two planes. The first horizontal (xy) plane is cutting directly along the mid-section of the ellipsoid. The second horizontal plane is at a z = h below the first horizontal plane. The volume of the...
  43. G

    Cutting, at the atomic/molecular level

    I know there is supposedly no such thing as a stupid question but this might make some of you reconsider if that is true. We assume that we can never actually touch something due to electron repulsion. How then is it possible for something to cut you? I know this sounds a lot like...
  44. MarkFL

    MHB Cut 16" Pizza into 3 Equal Pieces Using Calculus

    Here is the question: I have posted a link there to this thread so the OP can view my work.
  45. D

    How to Achieve a Clean, Perpendicular Cut on a Plastic Rod?

    Hi everyone, I have a plastic rod that is cut/snapped between two metal clamps. I want the break in the material to be at an angle perpendicular to the rod's surface. Can anyone tell me what factors effect this operation? How can I select the best material for the plastic rod? Thanks in...
  46. L

    MHB Maximizing the volume of a cone formed by cutting a sector from a circle

    From A circular sheet of RADIUS "R" a sector tie is cuts so that the coil Gets a funnel. Calculate the angle of the circular sector to cut back so of funnel has the maximum capacity. Answer tha angle is 2sqrt(6)pi/3
  47. Entanglement

    Wire cutting magnetic field lines

    I have read in my schoolbook that when a wire of length l moves at velocity v in a magnetic field cutting the flux lines an emf is induced which it is calculated from emf = blv, I understand that emf is induced at time variation of magnetic flux across the wire, but I Can't see any change in the...
  48. M

    Homeomorphism through cutting and pasting of manifolds

    I am independently working through the topology book called, "Introduction to Topology: Pure and Applied." I am currently in a chapter regarding manifolds. They attempt to show that a connected sum of a Torus and the Projective plane (T#P) is homeomorphic to the connected sum of a Klein Bottle...
  49. qspeechc

    How difficult is cutting hair?

    Hi Everyone. The place I have been going to for the past 8 or 10 years to cut my hair closed down, so I went to the barber's around the corner. Now for as long as I can remember I've always had the same haircut: a number 4 clipper (or whatever the attachment is called) on the electric shaver...
  50. E

    Cutting speed, Spindle Speed Calculation for shafts

    Hello, I was searching on this forum for a long time, now I have a problem with my homework and I should complete this till tomorrow, I could use some hand :) Please somebody led me some light, and I believe this will be useful for others. Homework Statement For a transmisson shaft (material...