This paper presents a set of process parameter selection rules to deposit a good metal part. A CO2 laser is used to melt metal powder to achieve layer by layer deposition for fabricating three-dimensional parts. Dimensionless numbers characterizing this powder deposition process are identified using Buckingham’s Π-Theorem. These dimensionless numbers are used to identify a range of values for the process parameters, such as the laser power, spot diameter, speed of the xyz stage and powder flow rate, to achieve good quality layers for different materials. The yield and ultimate strengths are examined for parts fabricated with stainless steel 304 (SS 304) powder under three different processing conditions. These stresses are correlated to the operating conditions and physical dimensions of the deposit through the dimensionless similarity parameters. Experimental data indicate that the yield strength of the part is close to the value of standard sample (250 MPa, same as wrought stainless steel SS304). It is also observed that the direction of maximum yield strength is oriented very close to the dominant direction of material solidification. The ultimate strength is found to be considerably less than the ultimate strength of wrought SS 304 (540 MPa) which may be due to the residual stresses generated in the part.

Issue Section:
Technical Papers
Keywords:
laser beam applications, tensile strength, manufacturing processes, powders, melting, stainless steel
Topics:
Lasers, Manufacturing, Tensile strength, Yield strength, Stainless steel, Dimensionless numbers, Metals, Laser beams, Solidification
1.
Atwood, C., Grifith, M., Harwell, L., Schlienger, E., Ensz, M., Smugeresky, J., Romero, T., and Reckaway, D., 1998, “Laser engineered net shaping (LENS™): A tool for direct fabrication of metal parts,” ICALEO98, Laser Institute of America, Beyer, E., Chen, X., and Miyamoto, I., eds., Orlando, FL, pp. E1–E7.
2.
Chen, Z., Mai, T., and Lim, G., 1998, “Rapid tooling by laser cladding,” ICALEO98, Laser Institute of America, Beyer, E., Chen, X., and Miyamoto, I., eds., Orlando, FL, pp. E8–E14.
3.
Backes, G., Kreutz, E., Hoffmann, E., and Poprawe, R., 1998, “Laser-shape reconditioning and manufacturing of tools and machine parts,” ICALEO98, Laser Institute of America, Beyer, E., Chen, X., and Miyamoto, I., eds., Orlando, FL, pp. E48–E56.
4.
Miller
,
D.
,
Deckard
,
C.
, and
Williams
,
J.
,
1997
, “
Variable beam size SLS workstation and enhanced SLS model
,”
Rapid Prototyp. J.
,
3
, No.
1
, pp.
4
–
11
.
5.
Breitinger, F., 1997, “Rapid Tooling—A New Approach to Integrated Product and Process Development,” SPIE Europto Series, 3102, Ahlers, R., and Reinhart, G., eds., pp. 43–54.
6.
Krastel, K., and Drechsel, J., 1997, “Integration of laser processing in machine tools and their economy,” SPIE Europto Series, 3102, Ahlers, R., and Reinhart, G., eds., pp. 64–72.
7.
Sankaranarayanan
,
S.
,
Guo
,
W.
, and
Kar
,
A.
,
1998
, “
Characteristics of Laser-Fabricated Metal Structures
,”
Mater. Manuf. Processes
,
13
, No.
4
, pp.
537
–
554
.
8.
Kahlen, F.-J., and Kar, A., 1997, “One-Step Microlithography,” SPIE Symposium on Micromachining and Microfabrication, 3225, Friedrich, C., and Umeda, A., eds., Austin, TX, pp. 119–125.
9.
Kahlen, F.-J., and Kar, A., 1997, “One-Step Prototyping: Rapid Manufacturing,” ASME International Mechanical Engineering Congress & Exhibition, Design for Manufacturability Symposium, DE-94, Billatos, S., and Kim, B., eds., Dallas, TX, pp. 17–24.
10.
Kahlen, F.-J., and Kar, A., 1997, “Plasma Spectroscopy in Laser Rapid Manufacturing of Copper, Titanium, Aluminum and Steels,” ICALEO97, Laser Institute of America, 83, No. 1, Fabbro, R., Kar, A., and Matsunawa, A., eds., San Diego, CA, pp. C-93–C-102.
11.
Kahlen, F.-J., Kar, A., Watkins, T., and Cavin, B., 1997, “Stress Analysis in Rapid Manufacturing,” ICALEO97, Laser Institute of America, 83, No. 2, Fabbro, R., Kar, A., and Matsunawa, A., eds., San Diego, CA, pp. E-76–E-83.
12.
Kahlen, F.-J., Sankaranarayanan, S., and Kar, A., 1997, “Surface Damage Repair Using Laser Cladding,” SAE Airframe/Engine Maintenance & Repair Conference & Exposition, White, N., ed., Vancouver, BC.
13.
Kahlen, F.-J., and Kar, A., 1998, “Process Quality in Rapid Manufacturing,” ASME International Mechanical Engineering Congress & Exhibition, Design for Manufacturability Symposium, DE-99, Billatos, S., and Kim, B., eds., Anaheim, CA, pp. 49–58.
14.
Kahlen, F.-J., 2000, “Plasma Diagnostics and Mechanical Properties in Laser Rapid Manufacturing,” Ph.D. thesis, University of Central Florida.
15.
Kahlen, F.-J., von Klitzing, A., and Kar, A., 1999, “Hardness, chemical and microstructural studies for laser-fabricated metal parts of graded materials,” ICALEO99, Laser Institute of America, Denney, P., Miyamoto, I., and Watkins, K., eds., San Diego, CA.
16.
Kahlen, F.-J., 1994, “The Development of a Laser Reflectometer Diagnostic Technique for Laser Keyhole Welding Studies of Stainless Steel SS 304,” M.S. thesis, University of Tennessee.
17.
Herziger, G., Kreutz, E., and Wissenbach, K., 1986, “Fundamentals of Laser Processing of Materials,” SPIE, Laser Processing: Fundamentals, Applications, and System Engineering, 668, Duley, W., and Weeks, R., eds., pp. 2–10.
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