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Multi-axis Additive Manufacturing and 3D Scanning of

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Multi-axis Additive Manufacturing and 3D Scanning of Freeform Models
by
Mohammed Adamu Isa
A Dissertation Submitted to the Graduate School of Sciences and Engineering in Partial Fulfillment of the Requirements for
the Degree of Doctor of Philosophy
in Mechanical Engineering
December 24, 2018

To my parents, brothers, sisters, teachers and friends

ABSTRACT
Additive manufacturing has earned reputation as an advanced manufacturing method capable of making revolutionary impact on the manufacturing sector. It emerged as a rapid prototyping method capable of fabricating complex products directly from digital models. In a world that has been molded by digitized data over last few decades, additive manufacturing progressed harmoniously to become a manufacturing method that spread into various fields. While the applications and compatible materials of additive manufacturing are continuously been discovered, there has been little change in the process of successive addition of layers of materials to produce parts. Fabrication using this common additive method is predominantly carried out using planar layers based on its established process plan.
The critical impediment of additive manufacturing is the poor quality of products, which can be partially attributed to the fixed build direction found in the common planar layering. As a result, the parts produced by additive manufacturing have jagged surfaces and lower mechanical strength along the build direction. Another problem that contributes negatively to the quality of products and the production time is the requirement of additional support structures.
The extension of additive manufacturing process to integrate multi-axis manufacturing results in production along variable build direction which can open up new avenues for improvements. This work studies the scope of multi-axis additive manufacturing in fabrication of overhang structures and freeform geometries. Multi-axis processes lack the additive-specific facilities and knowledge to address some of the issues holding back the progress of additive manufacturing. Hence, a 5-axis additive manufacturing scheme is suggested where the layering method and the build path are tailored based on the shape of a freeform NURBS-based 3D model. The manufacturing processes are investigated on an additive manufacturing system designed and built in the Manufacturing and Automation Research Center (MARC).
To digitize and assess the shape of existing physical objects, a new 3D scanner is designed with wide viewing space. By acquiring uniformly dense points, the scanner measurements are evaluated, and its uncertainty is analyzed. Benchmark geometries are used for both assessment of measurement accuracy and optimization of the 3D scanner parameters. Optimization of

influencing parameters based on the derived 3D scanner model is performed using least squares method. A standard measurement analysis is also carried out by uncertainty propagation using Monte Carlo simulation.

ÖZETÇE
Eklemeli üretim, imalat sektörü üzerinde büyük ve yenilikçi bir etki yapan gelişmiş bir üretim yöntemi olarak ün kazanmıştır. Başlangıçta, dijital modeller ile doğrudan kompleks ürünleri imal edebilen hızlı-prototip oluşturma yöntemi olarak ortaya çıkmıştır. Son birkaç on yılda sayısallaştırılmış verilerle kaplı olan bir dünyada, eklemeli üretim çeşitli alanlara yayılan bir üretim yöntemi haline geldi. Eklemeli üretim uygun malzemelerin sayısı ve uygulanması artmış olsa da, katmanların başarılı bir şekilde eklenmesi konusunda çok yol alınamadı. Bu güne kadar, bu üretim yönteminin uygulanması katmanların düzenli olarak üste üste konulması ile gerçekleştirilmiştir.
Eklemeli üretimin önündeki en büyük engel, ürünlerin düşük kalitesidir. Bu düşük kalite, üretimde, katmanların baskısının tek bir yöne (takım yönü) sabitlenmiş olması ürünlerin kalitesizliği ile de ilişkilendirilebilir. Sonuç olarak, eklemeli imalat ile üretilen parçalar pürüzlü yüzeylere ve baskı yönü boyunca daha düşük bir mukavemete sahip olur. Ürünlerin kalitesini ve üretim zamanını olumsuz etkileyen başka bir sorun da ek destek yapılarının gerekliliğidir.
Eklemeli üretim sürecini çok eksenli üretime entegre etmek yeni çalışma alanlarını ve fırsatları doğuracaktır. Bu çalışmada, “overhang” (sarkıtlı) yapıları ve NURBS serbest geometrilerin üretiminde çok eksenli eklemeli imalat konusunda çalışılmıştır. Genelinde, çok eksenli eklemeli üretim üzerine çalışmalar yürüten tesisler ve ilgili yazılımlar konusundaki eksiklikler göze çarpmaktadır. Bu nedenden ötürü, çok eksenli eklemeli üretimde çok büyük bir gelişme kaydedilememektedir. Bu nedenle, bu çalışmada katman baskı yönteminin ve takım yolunun serbest forma sahip üç-boyutlu modelin şekline göre ayarlandığı bir üretim planı önerilmektedir. Üretim ve Otomasyon Laboratuarı'nda (MARC) tasarlanan ve üretilen bir eklemeli üretim yazıcısı ile bu üretim yöntemleri araştırılmıştır.
Fiziksel objelerin şeklini değerlendirmek ve dijital ortama geçirmek için geniş görüntüleme alanına sahip bir üç boyutlu tarayıcı geliştirilmiştir. Düzenli ve yoğun noktalar elde edilerek tarayıcı ölçümleri değerlendirilmiş, belirsizliği analiz edilmiştir. Ölçümlerin doğruluğun değerlendirilmesi ve üç boyutlu tarayıcının parametrelerinin optimizasyonu için referans geometriler kullanılmıştır. Taranacak olan üç boyutlu modelleri etkileyen parametreler en küçük

kareler methodu kullanılarak optimize edilmiştir. Ayrıca, standart bir ölçüm analizi Monte Carlo simulasyonu kullanılarak belirsizlik yayılımı ile yapılmıştır.

ACKNOWLEDGEMENTS
I will first start by expressing my gratitude to my advisor Prof. Ismail Lazoglu for his endless support and motivation in this research, for his tutelage and insightful knowledge in manufacturing. Indeed, his vision is behind the advanced research and development going on in the invigorating environment of the research center. Gratitude to the other members of my thesis committee (Prof. Iskender Yılgör and Prof. Murat Sözer) for their comments and suggestions that helped in propelling this work.
I will also like to thank my present and graduated colleagues in the Manufacturing and Automation Research Center for the stimulating, inspiring and debatable discussions that helped in widening my views on many issues. Special thank goes to Muzaffer Abi for his practical expertise and assistance.
I will like to also thank my family, who have been altruistically supportive and encouraging throughout my studies.

TABLE OF CONTENTS
Multi-axis Additive Manufacturing and 3D Scanning of Freeform Models .................................. 1 ABSTRACT.................................................................................................................................... 4 ÖZETÇE ......................................................................................................................................... 6 ACKNOWLEDGEMENTS ............................................................................................................ 8
LIST OF FIGURES .................................................................................................................. 12 Chapter 1 ....................................................................................................................................... 21 INTRODUCTION ........................................................................................................................ 21
1.1 Emerging Manufacturing Methods ..................................................................................... 21 1.2 Potentials of Additive Manufacturing................................................................................. 24 1.3 Standardization of AM........................................................................................................ 27 1.4 Reverse Engineering Introduction ...................................................................................... 30 1.5 Motivation and Organization .............................................................................................. 31 Chapter 2 ....................................................................................................................................... 33 ADDITIVE MANUFACTURING SYSTEMS ............................................................................ 33 2.1 History and relevant literature on Additive Manufacturing................................................ 33 2.2 Types of Additive Manufacturing Systems ........................................................................ 37 2.3 Additive Manufacturing Development in MARC .............................................................. 43
2.3.1 The first-generation AM machine................................................................................ 43 2.3.2 The second-generation AM machine ........................................................................... 45 2.4 Fused Deposition on a Cartesian Machine.......................................................................... 47 2.4.1 Fused deposition extrusion head .................................................................................. 48 2.4.2 Composite production by AM ..................................................................................... 49 Chapter 3 ....................................................................................................................................... 54

MULTI-AXIS ADDITIVE MANUFACTURING USING EXISTING PROCESSES ............... 54 3.1 Mechanical Design of Multi-axis AM System ................................................................... 55 3.2 G-code interpreter ............................................................................................................... 61 3.3 Multi-axis Additive Manufacturing .................................................................................... 64 3.4 Simple Path Generation Methods for Multi-Axis AM ....................................................... 68 3.4.1 Planar Slicing of By Part Decomposition .................................................................... 70 3.4.2 Application in Roofing Without Support..................................................................... 72 3.4.3 Use of Miscellaneous Paths ......................................................................................... 74 3.4.4 Discussion on the Need for a General Path Planner .................................................... 76 3.5 Multi-Axis AM for Manufacturing of Overhang Structure ................................................ 77 3.5.1 Multi-axis AM using 2D build platform ...................................................................... 78 3.5.2 Additive manufacturing of parts with overhangs......................................................... 80 3.5.3 Manufacturing and analysis of overhang structures .................................................... 81 3.5.4 Discussion on results.................................................................................................... 87
Chapter 4 ....................................................................................................................................... 88 FIVE-AXIS ADDITIVE MANUFACTURING OF FREEFORM MODELS USING A NEW SCHEME ...................................................................................................................................... 88
4.1 The 5-axis 3D printer .......................................................................................................... 90 4.2 Path planning ...................................................................................................................... 92 4.3 Freeform solid representation ............................................................................................. 94 4.4 Side surface tangent tool orientation along 3D path ........................................................... 97 4.5 Toolpath for infill.............................................................................................................. 103 4.6 Evaluation of build angles and kinematic error ................................................................ 112 4.7 Conclusion and discussion ................................................................................................ 116 Chapter 5 ..................................................................................................................................... 117
Additive ManufacturingManufacturingDirectionProductsScanning