11hw8-16mar-soln (1)

# 11hw8-16mar-soln (1) - EML4321HW#8Due16March,2011 1 A...

This preview shows pages 1–3. Sign up to view the full content.

EML 4321 – HW #8 – Due 16 March, 2011 1. A dental drill has a top speed of 350,000 rpm. A size 56 (0.9 mm diameter) burr with six cutting edges is mounted in the drill. a. What is the maximum cutting speed ( SFM )? 0.9 1 1 2 350000 2 25.4 12 min mm in ft rev rad vr F mm in rev π ω === ⋅ ⋅ = ft 3247 min b. What is the maximum tool passing frequency ( Hz )? 1min 350000 6 60sec rev teeth f rev =⋅ = 35000Hz 2. Consider the figure below taken from the knife in a biomass harvester (used near a biomass-to- biogas-to-IC engine-to-electricity) facility near Dresden: The white is a cross-section of the knife. The right (rough) side of the knife is the rake face. The left side (smooth edge slanting from top center) is the relief or clearance side. 400u indicates a length of 400 micrometers. (Figure from: Wild, K., Walther, V., and J. K. Schueller. 2010. Verschleißverhalten von Feldhäckslermessern beim Einsatz in der Praxis. VDI-Berichte Nr. 2111, Tagung Landtechnik 2010, S. 307 – 312.) rake angle radius a. If the clearance angle is 0 degrees, what is the rake angle? See above figure ( 45°) b. The tip is circled. What is the approximate radius of the tip? See above figure ( 50μm)

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

View Full Document
c. The knife is mainly steel with a HVOF coating of WC on the rake face. Why is the coating on the rake face rather than the relief side? Æ Because the cut material will slide along the rake face and wear that surface. The coating protects the rake face d. What is HVOF? Æ High Velocity Oxygen Fuel – A class of thermal spray processes in which fuel it combusted in oxygen and used to apply powder coatings.
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 09/06/2011 for the course EML 4321 taught by Professor Staff during the Spring '08 term at University of Florida.

### Page1 / 6

11hw8-16mar-soln (1) - EML4321HW#8Due16March,2011 1 A...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online