ME 477 Lecture Notes - Lecture 3: Hot Working, Plane Stress, Stress (Mechanics)
Document Summary
List the advantages and disadvantages of using a lubricant in forging operations. Advantages: lowers friction, reduces barreling, improves metal ow. This will cause the material to ow more in the longitudinal direction, decreasing spreading: in addition to rolling, the thickness of plates and sheets can also be reduced by simply stretching. This would not be feasible for high-volume production because it is used in low volume production. Other defects include tailpipe or shtailing, and chevron cracking. (b) defects in drawing include poor surface poor surface nish and chevron cracking. In backward extrusion, the billet is stationary, while in direct extrusion, it is moving relative to the container walls. The main advantage becomes clear if a glass pillow is used to provide hot- working lubricant in between the die and the workpiece. The maximum die pressure is at the die entry because the state of stress at the die entry is plane stress with equal biaxial compression in the radial direction.
