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Signature Redacted August 7, 2015 C Ifdb Y Scale-up of a High-Technology Manufacturing Startup: Improving Product Reliability Through Systematic Failure Analysis and Accelerated Life Testing MASSACHUSETTS INSTITUTE by OF TECHNOLOGY, All Shabbir OCT 0 12015 B.A.Sc. Mechanical Engineering, University of Waterloo (2014) LIBRARIES Submitted to the Department of Mechanical Engineering in partial fulfillment of the requirements for the degree of Master of Engineering in Manufacturing at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY September 2015 @ Ali Shabbir, MMXV. All rights reserved. The author hereby grants to MIT permission to reproduce and to distribute publicly paper and electronic copies of this thesis document in whole or in part in any medium now known or hereafter created. Signature redacted A uthor . ......... ........... Department of Mechanical Engineering Signature redacted August 7, 2015 C ifdb y...................------------ David E. Hardt Ralph E. and Eloise F. Cross Professor of echanical Engineering Accepted by ..... ............ Signature redacted ...... David E. Hardt Chairman, Department Committee on Graduate Theses Scale-up of a High-Technology Manufacturing Startup: Improving Product Reliability Through Systematic Failure Analysis and Accelerated Life Testing by Ali Shabbir Submitted to the Department of Mechanical Engineering on August 7, 2015, in partial fulfillment of the requirements for the degree of Master of Engineering in Manufacturing Abstract Ensuring product reliability is a key driver of success during the scale-up of a high- technology manufacturing startup. Reliability impacts the company image and its financial health, however most manufacturing startups do not have a solid under- standing of their product's reliability. The purpose of this thesis is to introduce systematic failure analysis to the engineering design process and to establish a frame- work for testing and analyzing product life so that imperative business decisions and design improvements could be made with regards to reliability. A detailed study and implementation of these process improvements to address reliability issues was con- ducted at New Valence Robotics Corporation (NVBOTS) in Boston, Massachusetts. Systematic failure analysis was achieved through the creation and implementation of Failure Modes and Effects Analysis (FMEA) procedures. A single FMEA iteration was performed on the NVPro printer to identify the top risk component-linear ball bushings-for detailed life analysis. Following an in-depth investigation of potential failure modes of the linear bushings, an Accelerated Life Test (ALT) was designed us- ing Design of Experiments (DOE) principles. An accompanying test apparatus with mechatronic control was also designed. The ALT was not actually executed but rep- resentative data was analyzed for illustrative purposes using the General Log-Linear (GLL) life-stress relationship and a 2-parameter Weibull distribution for the accel- erating stresses of mechanical load and lubrication. The work performed provides NVBOTS and similar high-technology manufacturing startups a complete starting point for systematically analyzing their product's reliability and quantitatively eval- uating its life in a resource efficient way. Thesis Supervisor: David E. Hardt Title: Ralph E. and Eloise F. Cross Professor of Mechanical Engineering 2 Acknowledgments This thesis is the culmination of months of direct, and years of indirect, contribution from multiple people. I would like to express my sincerest gratitude and thank the following people: Professor David Hardt, my thesis advisor, for your valuable guidance throughout the project and in writing this thesis, invaluable advice about life, and conta- gious passion for manufacturing. Rahul Chawla and Derek Straub, my project teammates, MEngM classmates, and great friends for always being there in any capacity. This project and my thesis would not have been possible without you. The lasting memories created during our shared MEngM experience will always stay with me. Mateo Peia Doll, VP Engineering at NVBOTS, for your continuous support of all project work and help propelling the project to successful completion. NVBOTS, for sponsoring the project and supporting the MEngM program at MIT, and specifically AJ Perez, CEO, for your enthusiasm for manufacturing and entrepreneurship that has inspired me to someday pursue the same. Jose Pacheco and others behind the scenes within the MEngM program, for man- aging this incredible program and making it an enriching experience. My parents, for your unconditional love, unwavering support, and constant encour- agement to be the best I can be. I would not be where I am today without you. My brother Omar, for your support and admiration that motivates me to achieve my goals, one of which is to one day be as great of a person as you are. My sister Sarah, for always putting a smile on my face and reminding me there is more to life than work. "3PC" and "PHC", for keeping me sane with your friendship and brotherhood. And most of all, Anaum, for always being there for me unconditionally, for en- couraging me to pursue my ambitions, for being my reason to succeed, and for a few hundred other things that would take the rest of the thesis to cover. 3 Contents 1 Introduction 10 1.1 High-Technology Manufacturing Startups ....... 12 1.1.1 Risks Associated with Manufacturing Scale-up . 12 1.2 Research Motivation ..... ......... .... 13 1.2.1 Overall Problem Statement .. ........ 14 1.2.2 Overview of Sub-Projects ... ........ 14 1.3 Thesis Overview . ................... 16 1.3.1 Thesis Objective and Scope .......... 16 1.3.2 Thesis Structure ............... 16 2 Overview of the Additive Manufacturing Industry 18 2.1 Additive Manufacturing Overview ........... 18 2.2 General AM Process Work Flow ........... 19 2.3 Additive Manufacturing Technologies ......... 20 2.4 Applications ........... ............ 23 2.5 Industry and Market ................. 24 3 Company Background 26 3.1 The Product ....................... 26 3.2 The M arket ....................... 28 3.3 Company Analysis ................... 29 4 Failure Modes and Effects Analysis 31 4.1 Methodology Overview ..... ............ .. .. .31 4.1.1 Potential Failure Modes ........... .. .. .. .. 34 4.1.2 Potential Causes ................ .. .. .. .. 34 4.1.3 R isk ....................... .. .. .. .. 35 4.2 FMEA Results ..................... .. .. .. 35 4.2.1 Top Priority Risk: Linear Bushings ...... ... ... 38 4.3 Failure Modes of Linear Bushings ........... ...... 40 4.3.1 Adhesive Wear ................ .. ...... 40 4.3.2 Abrasive Wear ................. ...... 42 4.3.3 Corrosion .................... ........ 44 4.3.4 Fretting Corrosion ... ........ .... ........ 44 4.3.5 False Brinelling ..... ..... ...... ........ 44 4 4.3.6 Spalling . ... ..... .... .. 48 4.4 Sum m ary .. .. .. .. .. .. .. .. .. 50 5 Accelerated Life Testing Literature Review 51 5.1 O verview .. .. .. .. .. .. .. .. .. .. .. .. .. 51 5.1.1 Accelerating Stresses . .. .. .. .. .. .. .. 51 5.1.2 Various Stress Loadings . .. .. .. .. .. .. 52 5.1.3 Types of Data . .. .. .. .. .. .. .. .. .. 52 5.1.4 Test Design .. .. .. .. .. .. .. .. .. .. 54 5.2 Statistical Models of Accelerated Life Tests . .. .. .. 55 5.2.1 Basic Concepts . .. .. .. .. .. .. .. .. .. 55 5.2.2 Probability Distributions . .. .. .. .. .. .. 57 5.2.3 Life-Stress Relationships .. .. .. .. .. .. 65 5.2.4 Power-Weibull Model .. .. .. .. .. .. 68 5.2.5 GLL-Weibull Model. .. .. .. .. .. .. .. 70 5.2.6 Parameter Estimation for ALT Data by Maximum Likelihood Estim ation . .. .. .. .. .. .. .. .. .. .. 71 5.3 Summary .. .. .. .. .. .. .. .. .. .. .. .. 74 6 Design of Experiment for Accelerated Life Test 76 6.1 DOE Literature Review . .. .. .. .. .. .. .. 76 6.1.1 DOE Overview .. .. .. .. .. .. .. 77 6.1.2 R-DOE Considerations . .. .. .. .. .. 77 6.2 Factors Affecting Bearing Life .. .. .. .. .. 78 6.2.1 Selected Accelerating Stresses . .. .. .. .. 79 6.2.2 Noise Factors and Mitigation Strategies . .. .. 81 6.3 Response Variable Definition .. .. .. .. .. 82 6.3.1 Degradation Analysis: Wear Measurement . .. 83 6.4 Test Apparatus Design . .. .. .. .. .. .. .. 83 6.4.1 Overview . .. .. .. .. .. .. .. .. .. 83 6.4.2 Additional Loading .. .. .. .. .. .. 85 6.4.3 Mechatronic Control . .. .. .. .. .. .. 89 6.5 Accelerated Life Test . .. .. .. .. .. .. 90 6.5.1 Experimental Design .. .. .. .. .. 90 6.5.2 Standard Operating Procedure .. .. .. 93 6.5.3 Bearing Load Calculations and Test Justification . 94 6.6 Sum m ary .. .. .. .. .. .. .. .. .. .. .. 98 7 Accelerated Life Test Sample Results 100 7.1 Life Analysis . .. .. .. 100 7.1.1 Results .. .. .. 101 7.1.2 Statistical Model . .. 101 7.1.3 Bx Life . 106 7.1.4 Reliability at End of Lease . .. 106 7.2 Summary . .. .. 107 5 8 Conclusions, Recommendations, and Future Work 108 8.1 Conclusions ....... ................................ 108 8.2 Recommendations ............................ 110 8.3 Future Work ............................ 111 6 List of Figures 2-1 AM process work flow steps .... ...... ...... ....... 21 2-2 Additive manufacturing methods . ...... ....... ...... 22 3-1 NVBOTS logo ... ........ ......... ........ ... 26 3-2 NVPro printer . ......... ........ ........ ..... 27 3-3 Print preview feature ...... ........ ........ ..... 27 3-4 Printing dashboard .. ............. ............ 28 4-1 NVPro XY gantry linear bushing schematic ..... ...... ... 39 4-2 NVPro XY gantry ..... ....... ...... ...... .... 39 4-3 Bearing adhesive wear .. ...... ....... ...... ..... 43 4-4 Complete
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