lecture_5_-_cutting_tools_and_economics_of_machining_-_chs_23___24.20110201.4d483777435a13.62592384

Lecture_5_-_cutting_tools_and_economics_of_machining_-_chs_23___24.20110201.4d483777435a13.62592384

Info iconThis preview shows pages 1–13. Sign up to view the full content.

View Full Document Right Arrow Icon
Ch 23 - CUTTING TOOL TECHNOLOGY Ch 24 - ECONOMIC AND PRODUCT DESIGN CONSIDERATIONS IN MACHINING
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Three Modes of Tool Failure 1. Cutting force is excessive and/or dynamic, leading to brittle fracture: 1. Cutting temperature is too high for the tool material: 1. Preferred wearing of the cutting tool:
Background image of page 2
Preferred Mode: Longest possible tool life, wear locations: Crater wear location: Flank wear location:
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Tool wear as a function of cutting time. Flank wear (FW) is used here as the measure of tool wear. Crater wear follows a similar growth curve. Tool Wear vs. Time
Background image of page 4
Effect of cutting speed on tool flank wear (FW) for three cutting speeds, using a tool life criterion of 0.50 mm flank wear. Effect of Cutting Speed
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Log‑log plot of cutting speed vs tool life. Tool Life vs. Cutting Speed
Background image of page 6
Taylor Tool Life Equation C vT n = where v = cutting speed; T = tool life; and n and C are parameters that depend on feed, depth of cut, work material, and tooling material, but mostly on material (work and tool). n is the C is the on the speed axis at one minute tool life
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Tool Near End of Life Changes in sound emitted from operation Chips become ribbon-like, stringy, and difficult to dispose of Degradation of surface finish Increased power required to cut Visual inspection of the cutting edge with magnifying optics can determine if tool should be replaced
Background image of page 8
Desired Tool Properties Toughness ‑ to avoid fracture failure Hot hardness ‑ ability to retain hardness at high temperatures Wear resistance ‑ hardness is the most important property to resist abrasive wear
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Plain carbon steel shows a rapid loss of hardness as temperature increases. High speed steel is substantially better, while cemented carbides and ceramics are significantly harder at elevated temperatures. Hot Hardness
Background image of page 10
Coated Carbide Tool Photomicrograph of cross section of multiple coatings on cemented carbide tool (photo courtesy of Kennametal Inc.)
Background image of page 11

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Typical Values of n and C Tool material n C (m/min) C (ft/min) High speed steel:
Background image of page 12
Image of page 13
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 36

Lecture_5_-_cutting_tools_and_economics_of_machining_-_chs_23___24.20110201.4d483777435a13.62592384

This preview shows document pages 1 - 13. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online