||Optimization in Process Parameters on Double Track of Selective Laser Melting
||Department of Mechanical Engineering
Selective Laser Melting
Artificial Neural Network
Additive manufacture (AM) such as selective laser melting (SLM) has many advantages over traditional manufacture techniques. Selective laser melting is able to produce unique parts in a short time and has nearly no restriction on geometry. The parameters in selective laser melting such as laser power, scanning speed, powder layer thickness, hatch spacing and scan length have complex interactions with each other and affect the quality of the product. Determining the optimal parameters for producing the high-quality product has been an important issue for manufacturers. Based on the previous research of optimal laser power and scanning speed, this research investigates the influence of hatch spacing and scan length. A sphere packing design method was proposed to design the parameters for simulation and a three-dimensional finite element model was constructed to simulate the features of scan tracks. Artificial neural networks (ANNs) were used to predict simulation results. Finally, optimal parameters were determined based on peak temperature, difference in depth of melt pools, and overlap rate of two scan tracks. As a result, the hatch space is recommended as 73% of laser spot size in this study if the diameter of laser spot is 120μm, laser power is 180W, scanning speed is 680mm/s, and powder layer thickness is 40μm.
Table of Contents V
List of Tables VII
List of Figure VIII
Chapter 1 Introduction 1
1.1 Preface 1
1.2 Research motivation and purposes 2
Chapter 2 Theory and Method 5
2.1 Heat source simulation 5
2.2 Sampling Method 6
2.3 Simulation on Heat source and Heat transfer 10
2.4 Material Properties of Stainless Steel 316L Powder 13
Chapter 3 Double Track Simulation of SLM process 17
3.1 Basics of finite element model 17
3.2 Simulation Results 23
Chapter 4 Optimization of SLM Parameters 26
4.1 Surrogate Modelling 26
4.2 Criterion in Peak Temperature 28
4.3 Criterion in Difference of melt pool depths between adjacent tracks 30
4.4 Criterion in Overlap Rate 33
Chapter 5 Experiment and Simulation validation 40
5.1 Selective Laser Melting machine 40
5.2 Experimental Setup for Verifying the Two-track Modelling 42
5.3 Experimental Setup for Verifying the Optimization Zone 48
5.3.1 3mm × 3mm surface scanning experiment 48
5.3.2 5mm × 5mm surface scanning experiment 54
5.3.3 Experimental results and discussion 59
Chapter 6 Conclusions and Future Works 61
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