Title of Document: DESIGN AND ANALYSIS OF AN AUTOMATED

                               ASSEMBLY PROCESS FOR MANUFACTURING    

                               PAINT BRUSH KNOTS

                               Aleksandr Borisovich Gorbashev, M.S. 2011

                               Mechanical Engineering

Directed By: Chandrasekhar Thamire

		           Department of Mechanical Engineering

Manufacturing process for paint brushes requires handling and assembling of flexible and delicate filaments and can be cumbersome in manual assembly processes. Common issues resulting from such manual assembly process include variations in filament density, deviations in filament straightness, and issues due to right and left handed bias in assembly operations, resulting in poor quality of the end products. Coupled with operator fatigue and health problems, these issues provide an excellent motivation for refining the process.

              The primary objectives of this study were to develop an assembly system that will 1) increase product quality, and 2) improve the production rate. The secondary objective was to develop a set of design guidelines for handling flexible elements such as synthetic filaments within provided housings.

          In order to develop the automated assembly process, needs analysis and product design specification exercises were performed first, followed by functional decomposition of the process at the first level. Designs for individual subsystems were developed next using functional decomposition at lower levels, concept generation, concept evaluation, feasibility testing, testing for design parameters, design through solid modeling, strength analysis, concept testing using physical prototypes and subsystem refinement.

             In order to assess the response of filament assemblies when subjected to external loading and moving relative to the housings, experiments were designed and conducted.  For a range of factors, tests were conducted to establish limits of pulling force required to displace filament bundles within the housings. Correlations relating filament motion to applied loading were developed for a variety of housing geometries and material types. Design guideline related to motion of filaments within housings was developed. In light of the testing performed, design guidelines for development of gripper-plates used for gripping of bulk filament bundles were also established. It is expected that these guidelines will be useful in the manufacturing automation industry, involving manufacture of toothbrushes, hair brushes and fiber-optic elements. 

             Upon successful completion of the feasibility tests, full-scale prototypes using the final concepts of subsystems were fabricated. Tests were conducted to determine the reliability of the process and quality of the brush knots. Results indicate that the quality of the brushes was much higher than the traditional hand-made brushes and that the productivity would nearly double. Upon delivery of the system to the company sponsoring this research, it is expected that the system developed would be able to produce up to 3 million brushes per year.