Date of Graduation

12-2016

Document Type

Thesis

Degree Name

Master of Science in Industrial Engineering (MSIE)

Degree Level

Graduate

Department

Industrial Engineering

Advisor/Mentor

Pierson, Harry

Committee Member

Liao, Haitao

Second Committee Member

Rossetti, Manuel D.

Keywords

Applied sciences; Additive manufacturing; Design of experiments; Process improvement; Surface profile analysis

Abstract

Additive patching is a process in which printers with multiple axes deposit molten material onto a pre-defined surface to form a bond. Studying the effect of surface roughness and process parameters selected for printing auxiliary part on the bond helps in improving the strength of the final component. Particularly, the influence of surface roughness, as established by adhesion theory, has not been evaluated in the framework of additive manufacturing (AM). A full factorial design of experiments with five replications was conducted on two levels and three factors, viz., layer thickness, surface roughness, and raster angle to examine the underlying effects on bond strength. Analysis of variance (ANOVA) was used to test the resultant index and distributions were plotted to analyze various conditions. Experimental results indicated that bond strength increased up to 27% at higher surface roughness and lower layer thickness levels. Full factorial experiments with additional levels were conducted to realize the direction of improvement and find optimum values of layer thickness and surface roughness. It was found that at a layer thickness of 0.1 mm and 502.94 µin of surface roughness bond strength attains the highest value. This research represents a first step towards understanding bond strength in patching/re-manufacturing, allowing manufacturers to intelligently select process parameters for the production of both the substrate and the added geometry.

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