The present disclosure provides three-dimensional (3D) objects, 3D printing processes, as well as methods, apparatuses and systems for the production of a 3D object. Methods, apparatuses and systems of the present disclosure may reduce or eliminate the need for auxiliary supports. The present disclosure provides three dimensional (3D) objects printed utilizing the printing processes, methods, apparatuses and systems described herein.

Apparatuses, systems and methods for three-dimensional printing

Today, hybrid manufacturing technology has drawn significant interests from both academia and industry due to the capability to make products in a more efficient and productive way. Although there is no specific consensus on the definition of the term ‘hybrid processes’, researchers have explored a number of approaches to combine different manufacturing processes with the similar objectives of improving surface integrity, increasing material removal rate, reducing tool wear, reducing production time and extending application areas. Thus, hybrid processes open up new opportunities and applications for manufacturing various components which are not able to be produced economically by processes on their own. This review paper starts with the classification of current manufacturing processes based on processes being defined as additive, subtractive, transformative, joining and dividing. Definitions of hybrid processes from other researchers in the literature are then introduced. The major part of this paper reviews existing hybrid processes reported over the past two decades. Finally, this paper attempts to propose possible definitions of hybrid processes along with the authors’ classification, followed by discussion of their developments, limitations and future research needs.

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A review of hybrid manufacturing processes – state of the art and future perspectives

A three-dimensional model was developed for studying thermal behavior during selective laser melting (SLM) of commercially pure titanium (CP Ti) powder. The effects of scan speed and laser power on SLM thermal behavior were investigated. The results showed that the average temperature of the powder bed gradually increased during the SLM process, caused by a heat accumulation effect. The maximum molten pool temperature (2248 °C) and liquid lifetime (1.47 ms) were obtained for a successful SLM process for a laser power of 150 W and a laser scan speed of 100 mm/s. The temperature gradient in the molten pool increased slightly (from 1.03 × 10 4 to 1.07 × 10 4  °C/mm in the direction perpendicular to the scanning path; from 1.21 × 10 4 to 1.28 × 10 4  °C/mm in the thickness direction) when the scan speed was increased from 50 to 200 mm/s, but increased significantly (from 1.29 × 10 4 to 8.24 × 10 4  °C/mm in the direction perpendicular to the scanning path; from 1.53 × 10 4 to 9.84 × 10 4  °C/mm in the thickness direction) when the laser power was increased from 100 to 200 W. The width and depth of the molten pool decreased (width from 137.1 to 93.8 μm, depth from 64.2 to 38.5 μm) when the scan speed was increased from 50 to 200 mm/s, but increased (width from 71.2 to 141.4 μm, depth from 32.7 to 67.3 μm) when the laser power was increased from 100 to 200 W. Experimental SLM of CP Ti powder was carried out under different laser processing conditions and the microstructure of SLM-produced parts was investigated to demonstrate the reliability of the physical model and simulation results.

Thermal behavior during selective laser melting of commercially pure titanium powder: Numerical simulation and experimental study

The present disclosure provides three-dimensional (3D) printing methods, apparatuses, and systems using, inter alia, a controller that regulates formation of at least one 3D object (e.g., in real time during the 3D printing); and a non-transitory computer-readable medium facilitating the same. For example, a controller that regulates a deformation of at least a portion of the 3D object. The control may be in situ control. The control may be real-time control during the 3D printing process. For example, the control may be during a physical-attribute pulse. The present disclosure provides various methods, apparatuses, systems and software for estimating the fundamental length scale of a melt pool, and for various tools that increase the accuracy of the 3D printing.

Accurate three-dimensional printing

Modelling of laser forming – An review

Laser forming is a complex thermal–mechanical process. To reveal the mechanisms dominating the forming process is essential to control accurately the deformation of metal plate. Numerous efforts had been made to understand the mechanisms of laser forming. Proposed mechanisms mainly included temperature gradient mechanism, buckling mechanism and upsetting mechanism. However, in the investigation of laser forming, it is found that the above three mechanisms cannot depict fully the process of deformation. Based on the study of thermal transfer and elastic–plastic deformation, the above three mechanisms are further explained. In addition, a new mechanism, coupling mechanism, is proposed. To verify the validity of the mechanisms proposed, numerical simulations are carried out, and simulation results are consistent with analyses of mechanisms. Further analyses of forming mechanisms provide a theoretical basis for the scanning path and heating conditions as well as high-precision forming.

Research on the mechanisms of laser forming for the metal plate

An analytical model for estimating deformation in laser forming

To obtain further insight into the deformation of a plate in the laser forming process, the temperature gradient mechanism (TGM) is studied. Through the investigation, it can be found that, under the processing conditions of TGM, the plate not only bends about the x -axis but also about the y -axis. An analytical model estimate of the bending angle about the y -axis is constructed based on the theories of heat transfer and the mechanics of elastoplasticity. Numerical simulations are carried out to investigate the deformation of the plate about the y -axis by choosing the different process parameters. The analytically based estimate is used to suggest suitable starting values for the simulation process of calculated results. The study of the bending about the y-axis may describe more fully the deformation of a plate, which is helpful in high-precision forming.

Temperature gradient mechanism in laser forming of thin plates

Numerical simulation of the laser forming of plates using two simultaneous scans

A mathematical model was established for the temperature field developed during high frequency induction heating (HFIH) by Maxwell's equations. It required solving the coupled equations of the electromagnetic and temperature fields. The numerical simulation was performed using FEMLAB. The comparison of the calculations using the proposed model with experimental results showed a very good correlation. The effects of the heating parameters in high frequency induction such as the distance between the plate and the coil, the applied current, the frequency, and the turns of the coil on the temperature profiles developed in the plate were also discussed using the established model.

Yongjun Shi

Papers

Research on the mechanisms of laser forming for the metal plate

An analytical model for estimating deformation in laser forming

Temperature gradient mechanism in laser forming of thin plates

Numerical simulation of the laser forming of plates using two simultaneous scans

Study on temperature field induced in high frequency induction heating