Page 400 - 04. Subyek Engineering Materials - Manufacturing, Engineering and Technology SI 6th Edition - Serope Kalpakjian, Stephen Schmid (2009)

380 Chapter 15 Metal Extrusion and Drawing Processes and Equipment

QUANTITATIVE PROBLEMS

|]l5.33. Estimate the force required in extruding 70-30 the other with a capacity of 10 MN, are available for the op-
brass at 700°C if the billet diameter is 150 mm and the extru- eration. Is the smaller press sufficient for this operation? If
sion ratio is 30. not, what recommendations would you make to allow the
|}l5.34. Assuming an ideal drawing process, what is the use of the smaller press?
smallest final diameter to which an 80-mm diameter rod can ll l5.38. A round wire made of a perfectly plastic material
be drawn? with a yield stress of 275 MPa is being drawn from a diame-
ter of 2.5 to 1.5 mm in a draw die of 15°. Let the coefficient
l5.35. If you include friction in Problem 15.34, would the
of friction be 0.15. Using both Eq. (15.3) and Eq. (15.4), esti-
final diameter be different? Explain.
mate the drawing force required. Comment on the differences
ul5.36. Calculate the extrusion force for a round billet in your answer.
300 mm in diameter, made of stainless steel, and extruded at
l5.39. Assume that you are an instructor covering the top-
1000°C to a diameter of 70 mm.
ics described in this chapter and you are giving a quiz on the
I] |5.37. A planned extrusion operation involves steel at numerical aspects to test the understanding of the students.
1000°C with an initial diameter of 100 mm and a final diam- Prepare two quantitative problems and supply the answers.
eter of 20 mm. Two presses, one with capacity of 20 MN and

SYNTHESIS, DESIGN, AND PROIECTS

|5.40. Assume that the summary to this chapter is miss- l5.43. Survey the technical literature, and explain how ex-
ing. Write a one-page summary of the highlights of the wire- ternal vibrations can be applied to a wire-drawing operation
drawing process. to reduce friction. Comment also on the possible directions of
vibration, such as longitudinal or torsional.
l5.4l. Review the technical literature, and make a detailed
list of the manufacturing steps involved in the manufacture of |5.44. Assume that you are the technical director of trade
common metallic hypodermic needles. associations of (a) extruders and (b) rod- and wire-drawing
operations. Prepare a technical leaflet for potential customers,
l5.42. Figure 15.2 shows examples of discrete parts that can
be made by cutting extrusions into individual pieces. Name stating all of the advantages of these processes.
several other products that can be made in a similar fashion.