chip formation
DESCRIPTION
Chip Formation. Machinability. relative difficulty of a machine operation with regard to tool life, surface finish, and power consumption generally softer materials - easier to machine. Metal does NOT split off ahead of cutter as in wood. Metal is sheared off at SHEAR PLANE. - PowerPoint PPT PresentationTRANSCRIPT
![Page 1: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/1.jpg)
Chip Formation
![Page 2: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/2.jpg)
Machinability
relative difficulty of a machine operation with regard to tool life, surface finish, and power
consumption
generally softer materials - easier to machine
![Page 3: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/3.jpg)
Metal does NOT split off ahead of cutter as in wood
![Page 4: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/4.jpg)
Metal is sheared off at SHEAR PLANE
metal is forced ahead of tool
![Page 5: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/5.jpg)
![Page 6: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/6.jpg)
![Page 7: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/7.jpg)
Surface finish affected by:
speeds feeds depth of cut tool shape use of cutting fluid rigidity of the setup
![Page 8: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/8.jpg)
Optimum chip for operator safety is figure “9”
![Page 9: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/9.jpg)
Chip breaker
curls chip to break it off keep from tangling in machine safer
![Page 10: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/10.jpg)
3 basic types of chip formation
![Page 11: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/11.jpg)
1. Continuous chip
![Page 12: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/12.jpg)
Continuous chip characteristics
better surface finish soft or medium hardness materials
that are ductile low coefficient of friction - pass
across top of well polished tool chips curl or are straight and stringy chip breaker used to break the chip
![Page 13: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/13.jpg)
2. Discontinuous chip (segmented)
![Page 14: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/14.jpg)
Discontinuous chip characteristics
materials that fracture easily (cast iron)
fails or breaks after only a small amount of deformation
no chip breaker required chips are cleaned up easily
![Page 15: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/15.jpg)
3. Continuous chip (with built up edge on tool)
![Page 16: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/16.jpg)
Continuous chip (built of edge) characteristics
soft materials - high coef of friction stick to top of entering edge of tool caused by heat and pressure of cutting
action material temporarily welds to tip of
cutting tool then releases rougher surface finish tool life shortened
![Page 17: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/17.jpg)
Solutions for built up edge
• no single solution• change tool geometry• use chip breaker• cutting fluids• best combination of speeds and feeds
![Page 18: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/18.jpg)
![Page 19: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/19.jpg)
Cutting tool geometry
positive rake neutral rake negative rake
![Page 20: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/20.jpg)
Positive rake tools
![Page 21: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/21.jpg)
Positive rake tool characteristics
freer cutting at low speeds pos rake tools, cutting fluids, and
higher speeds decrease tendency for built up edge - however,
large pos rake = continuous chip
![Page 22: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/22.jpg)
Negative rake tools
![Page 23: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/23.jpg)
Negative rake tool characteristics
surface disrupted more require more power stronger and have longer working life
than positive low cutting speeds = poor surface
finish high cutting speeds = good surface
finish
![Page 24: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/24.jpg)
![Page 25: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/25.jpg)
![Page 26: Chip Formation](https://reader036.vdocuments.us/reader036/viewer/2022062423/56814400550346895db092ff/html5/thumbnails/26.jpg)
Most carbide tools have negative rake because:
indexable insert can be turned over withstands more cutting pressure higher cutting speeds used