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The purpose of this paper is to explore the possibility of an enhanced continuous liquid interface production (CLIP) with a porous track-etched membrane as the oxygen-permeable window, which is prepared by irradiating polyethylene terephthalate membranes with accelerated heavy ions.

Experimental approaches are carried out to characterize printing parameters of resins with different photo-initiator concentrations by a photo-polymerization matrix, to experimentally observe and theoretically fit the oxygen inhibition layer thickness during printing under conditions of pure oxygen and air, respectively, and to demonstrate the enhanced CLIP processes by using pure oxygen and air, respectively.

Owing to the high permeability of track-etched membrane, CLIP process is demonstrated with printing speed up to 800 mm/h in the condition of pure oxygen, which matches well with the theoretically predicted maximum printing speed at difference light expose. Making a trade-off between printing speed and surface quality, maximum printing speed of 470 mm/h is also obtained even using air. As the oxygen inhibition layer created by air is thinner than that by pure oxygen, maximum speed cannot be simply increased by intensifying the light exposure as the case with pure oxygen.

CLIP process is capable of building objects continuously instead of the traditional layer-by-layer manner, which enables tens of times improvement in printing speed. This work presents an enhanced CLIP process by first using a porous track-etched membrane to serve as the oxygen permeable window, in which a record printing speed up to 800 mm/h using pure oxygen is demonstrated. Owing to the high permeability of track-etched membrane, continuous process at a speed of 470 mm/h is also achieved even using air instead of pure oxygen, which is of significance for a compact robust high-speed 3D printer.

This paper aims to present experimental and numerical analyses of fused filament fabrication (FFF) printed parts and show how mechanical characteristics of printed ABS-MG94 (acrylonitrile butadiene styrene) are influenced by the void volume fraction, cooling rate and residual thermal stresses.

Printed specimens were experimentally tested to evaluate the mechanical properties for different printing speeds, and micrographs were taken. A thermo-mechanical finite element model, able to simulate the FFF process, was developed to calculate the temperature fields in time, cooling rate and residual thermal stresses. Finally, the experimental mechanical properties and the microstructure distribution could be explained by the temperature fields in time, cooling rate and residual thermal stresses.

Micrographs revealed the increase of void volume fraction with the printing speed. The variations on voids were associated to the temperature fields in time: when the temperatures remained high for longer periods, less voids were generated. The Young's Modulus of the deposited filament varied according to the cooling rate: it decreased when the cooling rate increased. The influence of the residual thermal stresses and void volume fraction on the printed parts failure was also investigated: in the worst scenarios evaluated, the void volume fraction reduced the strength in 9 per cent, while the residual thermal stresses reduced it in 3.8 per cent.

This work explains how the temperature fields can affect the void volume fraction, Young's Modulus and failure of printed parts. Experimental and numerical results are shown. The presented research can be used to choose printing parameters to achieve desired mechanical properties of FFF printed parts.

The purpose of this paper is to investigate the effect of different viscosity models (Cross and Al-Ma’aiteh) and different printing speeds on the numerical results (e.g. pressure over stencil) of a numerical model regarding stencil printing.

A finite volume model was established for describing the printing process. Two types of viscosity models for non-Newtonian fluid properties were compared. The Cross model was fitted to the measurement results in the initial state of a lead-free solder paste, and the parameters of a Al-Ma’aiteh material model were fitted in the stabilised state of the same paste. Four different printing speeds were also investigated from 20 to 200 mm/s.

Noteworthy differences were found in the pressure between utilising the Cross model and the Al-Ma’aiteh viscosity model. The difference in pressure reached 33-34% for both printing speeds of 20 and 70 mm/s and reached 31% and 27% for the printing speed of 120 and 200 mm/s. The variation in the difference was explained by the increase in the rates of shear by increasing printing speeds.

Parameters of viscosity model should be determined for the stabilised state of the solder paste. Neglecting the thixotropic paste nature in the modelling of printing can cause a calculation error of even approximately 30%. By using the Al-Ma’aiteh viscosity model over the stabilised state of solder pastes can provide more accurate results in the modelling of printing, which is necessary for the effective optimisation of this process, and for eliminating soldering failures in highly integrated electronic devices.

The paper aims to present results of investigations carried out on the front electrode of the solar cell. The front-side electrode for solar cells based on crystalline material is obtained by the screen printing method. Screen printing has been the prevailing method of electrode deposition because of its low cost. One of the ways to improve the cell efficiency and reduce the production costs is a further refinement of the metal electrode screen printing process.

The researches were focused on the modification of mechanical parameters of screen printing process to ensure the best possible cross-section of the front electrode geometry. The main printing process parameters were constant, however, the print speed was variable. The obtained fine line of front contact was characterized morphologically – the dimension and geometry of the front contact cross-section – by scanning electron microscopy technique.

The thin paths of 100 μm in width were screen printed applying a new silver-paste made by Du Pont. The printing speed has significant effect on print quality in the way that the lower speed enhanced the printed results.

For newest pastes (e.g. PV17D) influence of screen printing parameters on the front metallic electrodes geometry of solar cell is not so significant. Presented screen printing process can still give good results, but the further optimization for the new paste must be performed to achieve better cross-section geometry.

This paper confirms that one-step screen printing process can still give good results. The screen printed thin paths of 100 μm in width have good cross-section aspect ratio.

This work aims to investigate the interaction effects of printing process parameters of acrylonitrile butadiene styrene (ABS) parts fabricated by fused deposition modeling (FDM) technology on both the dimensional accuracy and the compressive yield stress. Another purpose is to determine the optimum process parameters to achieve the maximum compressive yield stress and dimensional accuracy at the same time.

The standard cylindrical specimens which produced from ABS by using an FDM 3D printer were measured dimensions and tested compressive yield stresses. The effects of six process parameters on the dimensional accuracy and compressive yield stress were investigated by separating the printing orientations into horizontal and vertical orientations before controlling five factors: nozzle temperature, bed temperature, number of shells, layer height and printing speed. After that, the optimum process parameters were determined to accomplish the maximum compressive yield stress and dimensional accuracy simultaneously.

The maximum compressive properties were achieved when layer height, printing speed and number of shells were maintained at the lowest possible values. The bed temperature should be maintained 109°C and 120°C above the glass transition temperature for horizontal and vertical orientations, respectively.

The optimum process parameters should result in better FDM parts with the higher dimensional accuracy and compressive yield stress, as well as minimal post-processing and finishing techniques.

The important process parameters were prioritized as follows: printing orientation, layer height, printing speed, nozzle temperature and bed temperature. However, the number of shells was insignificant to the compressive property and dimensional accuracy. Nozzle temperature, bed temperature and number of shells were three significant process parameters effects on the dimensional accuracy, while layer height, printing speed and nozzle temperature were three important process parameters influencing compressive yield stress. The specimen fabricated in horizontal orientation supported higher compressive yield stress with wide processing ranges of nozzle and bed temperatures comparing to the vertical orientation with limited ranges.

In pursuit of affordable and nutrient-rich food alternatives, the symbiotic culture of bacteria and yeast (SCOBY) emerged as a selected food ink for 3D printing. The purpose of this paper is to harness SCOBY’s potential to create cost-effective and nourishing food options using the innovative technique of 3D printing.

This work presents a comparative analysis of the printability of SCOBY with blends of wheat flour, with a focus on the optimization of process variables such as printing composition, nozzle height, nozzle diameter, printing speed, extrusion motor speed and extrusion rate. Extensive research was carried out to explore the diverse physical, mechanical and rheological properties of food ink.

Among the ratios tested, SCOBY, with SCOBY:wheat flour ratio at 1:0.33 exhibited the highest precision and layer definition when 3D printed at 50 and 60 mm/s printing speeds, 180 rpm motor speed and 0.8 mm nozzle with a 0.005 cm³/s extrusion rate, with minimum alteration in colour.

Food layered manufacturing (FLM) is a novel concept that uses a specialized printer to fabricate edible objects by layering edible materials, such as chocolate, confectionaries and pureed fruits and vegetables. FLM is a disruptive technology that enables the creation of personalized and texture-tailored foods, incorporating desired nutritional values and food quality, using a variety of ingredients and additions. This research highlights the potential of SCOBY as a viable material for 3D food printing applications.

Environmental concerns over hazardous materials being placed in landfills have caused many countries to enact legislation to limit and/or eliminate the use of lead in electronic devices. As a result, the electronics manufacturing industry has undertaken efforts to comply with the legislation. Solder paste is typically used as the joining material between boards and components. The standard solder paste alloy has traditionally been a tin/lead eutectic. Lead‐free should, in theory, have the same functionality as the standard pastes to be utilized as a drop‐in replacement. Typically, solder paste is deposited on to a land pattern site by a stencil printer. In the manufacturing environment, speed and accuracy are desirable characteristics of the stencil printing operation. The purpose of this paper is to determine how fast a selection of lead‐free pastes can be successfully printed.

A representative sample of four lead‐free solder pastes containing different alloys was selected. A series of experiments at an increasing print speed was used to deposit these solder pastes on to printed circuit boards and the printed solder volumes were measured. The maximum print speed for each paste was observed and noted for future use.

Of the four alloys selected for experimentation, one emerged to have the most superior performance in terms of high‐speed printability. The speeds for each paste were observed and noted for future use.

Experimentation was performed in an electronics service provider's environment using equipment and materials that were normally used in production.

The parameters obtained can be used on the manufacturing floor assembling lead‐free products.

The results offer a suggestion (in the form of the parameters that can be utilized) as to what parameters to use in the stencil printing of lead‐free solder paste at high speeds.

This paper aims to establish the predictive equations of height, area and volume of printed solder paste during solder paste stencil printing (SPSP) process in surface mount technology (SMT) to better understand the effect of process parameters on the printing quality.

An experiment plan is proposed based on the response surface method (RSM). Experiments with 30 different combinations of process parameters are performed using a solder paste printer. After printing, the volume, area and height of the printed SAC105 solder paste are measured by a solder paste inspection machine. Using RSM, the predictive equations associated with the printing parameters and the printing quality of the solder paste are formed.

The optimal printing parameters are 175.08 N printing pressure, 250 mm/s printing speed, 0.1 mm snap-off height and 15.7 mm/s stencil snap-off speed if the target height of solder paste is 100 µm. As the target printing area of solder paste is 1.1 mm × 1.3 mm, the optimized values of the printing parameters are 140.29 N, 100.52 mm/s, 0.63 mm and 20.25 mm/s. When both the target printing height and area are optimized together, the optimal values for the four parameters are 86.67 N, 225.76 mm/s, 0.15 mm and 1.82 mm/s.

A simple RSM-based experimental method is proposed to formulate the predictive polynomial equations for height, area and volume of printed solder paste in terms of important SPSP parameters. The predictive equation model can be applied to the actual SPSP process, allowing engineers to quickly predict the best printing parameters during parameter setting to improve production efficiency and quality.

The purpose of this study is to explore a methodology for connecting microelectromechanical system sensors – i.e. inertial measurement unit (IMU) – to an Arduino-based microcontroller, using graphene-based conductive filament and flexible thermoplastic polyurethane (FTPU) filament and low-cost dual material extrusion technology.

A series of electrical tests were carried out to determine the maximum resistance the conductive paths may take to connect printed circuit boards (PCB). To select the most suitable printing material, three types of conductive filaments were examined. Then an experiment was carried out to find the best printing parameters in terms of printing speed, printing temperature and layer height to minimise resistivity. The size of the conductive path was also analysed. A final prototype was designed and printed according to optimised printing settings and maximum allowable resistances for each line and considering different geometries and printing strategies to reduce cross-contamination among paths.

For the Black Magic 3D conductive filament, the printing speed and layer height played a significant role regarding resistivity, while the printing temperature was not very important. The infill pattern of the conductive paths had to be aligned with the expected current path, while using air gaps between two adjacent paths resulted in the best approach to reducing cross-contamination. Moreover, the cross-section size of the conductive path did not affect the volume resistivity. When combined with FTPU filament constraints, the prototype yielded suitable electrical performance and printing quality when printed at a temperature of 220°C, speed of 20 mm/s and layer height of 0.2 mm.

This paper explores a systematic methodology for the additive manufacturing of commercial conductive material using low-cost extrusion technology to connect complex electronics when data transmission is a key feature.

This paper aims to improve the infilling efficiency and the quality of parts forming. It proposes two improved scanning path planning algorithm based on velocity orthogonal decomposition.

The algorithms this paper proposes replace empty paths and corners with circular segments, driving each axis synchronously according to the SIN or COS velocity curve to make the extruder always moves at a constant speed at maximum during the infilling process. Also, to support the improved algorithms, a three-dimensional (3D) printing control system based on circular motion controller is also designed.

The simulation and experiment results show that the improved algorithms are effective, and the printing time is shortened more significantly, especially in the case of small or complex models. What’s more, the optimized algorithm is not only compact in shape but also not obvious in edge warping.

The algorithms in this paper are not applicable to traditional motion controllers.

The algorithms in this paper improve the infilling efficiency and the quality of parts forming.

There are no social implications in this paper.

The specific optimization method of parallel-line scanning algorithm based on velocity orthogonal decomposition is replacing the empty paths with arc corners. And the specific optimization method of contour offsetting algorithm based on velocity orthogonal decomposition is to add connection paths between adjacent contours and turn all straight corners into arcs. What’s more, the 3D printing control system based on the circular motion controller can achieve multi-axis parallel motion to support these two improved path scanning algorithms.