=+20. The deposition of thick protective coatings on substrates can be facilitated by laser cladding, in which an alloy powder is melted on the substrate surface. Experiments were conducted to determine how three processing parameters, laser power (A), scanning velocity (B), and powder flow rate (C) affect the coating hardness. (“Laser Cladding: An Experimental Study of Geometric Form and Hardness of Coating Using Statistical Analysis,” J. of Engr.

Manuf., 2006: 1549–1554). Each factor had three levels, and there was one observation at each factorlevel combination. The following corresponds to the ANOVA table from the article; only main effects and two-factor interactions were considered there:

SOURCE DF SS MS

? ? ? 63.24

? 2034.74 ? ?

? ? 480.26 ?

? ? ? 6.48

? 729.04 ? ?

? ? 115.26 ?

Error ? ? 104.26 Total ? ?