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The purpose of this paper is to mainly focus on the relationship between the scanning strategy and surface quality. Surface quality, including surface roughness and flatness, is important for printed parts. So this paper optimizes the surface quality by changing the scanning strategy.

This paper is based on the phenomenon after the printed parts. A clear trend can be seen that the surface roughness on the side face shows a clear zigzag shape, so an optimized scanning strategy is used. Surface roughness in measured in macrostructure first by Mitutoyo and the flatness is measured by Hexagon Metrocogy. After that, microstructure on the side face is seen by RTEC to explain this phenomenon.

The surface quality on the side face shows a significant optimize by changing the scanning strategy. The surface quality on the positive face has some optimization to some degree.

This paper determines the relationship between the surface roughness on the side face and the scanning strategy. Few studies focus on the surface roughness, especially on the side face. Some studies try to optimize the surface roughness on the positive face. However, researchers always neglect the surface roughness on the side face. 2. This paper measures not only the surface roughness, but also the flatness. Surface roughness has a significant impact on the surface quality. However, it still has some limitations. Flatness is also measured to make this paper more representative. 3. This paper explains why scanning strategy can affect the surface quality. These images explain the research better and not just at the theoretical level.

The usage of additive manufacturing (AM) technology in industries has reached up to 50 per cent as prototype or end-product. However, for AM products to be directly used as final products, AM product should be produced through advanced quality control process, which has a capability to be able to prove and reach their desire repeatability, reproducibility, reliability and preciseness. Therefore, there is a need to review quality-related research in terms of AM technology and guide AM industry in the future direction of AM development.

This paper overviews research progress regarding the QC in AM technology. The focus of the study is on manufacturing quality issues and needs that are to be developed and optimized, and further suggests ideas and directions toward the quality improvement for future AM technology. This paper is organized as follows. Section 2 starts by conducting a comprehensive review of the literature studies on progress of quality control, issues and challenges regarding quality improvement in seven different AM techniques. Next, Section 3 provides classification of the research findings, and lastly, Section 4 discusses the challenges and future trends.

This paper presents a review on quality control in seven different techniques in AM technology and provides detailed discussions in each quality process stage. Most of the AM techniques have a trend using in-situ sensors and cameras to acquire process data for real-time monitoring and quality analysis. Procedures such as extrusion-based processes (EBP) have further advanced in data analytics and predictive algorithms-based research regarding mechanical properties and optimal printing parameters. Moreover, compared to others, the material jetting progresses technique has advanced in a system integrated with closed-feedback loop, machine vision and image processing to minimize quality issues during printing process.

This paper is limited to reviewing of only seven techniques of AM technology, which includes photopolymer vat processes, material jetting processes, binder jetting processes, extrusion-based processes, powder bed fusion processes, directed energy deposition processes and sheet lamination processes. This paper would impact on the improvement of quality control in AM industries such as industrial, automotive, medical, aerospace and military production.

Additive manufacturing technology, in terms of quality control has yet to be reviewed.

The purpose of this paper is to study the functionality of additively manufactured (AM) parts, mainly depending on their dimensional accuracy and surface finish. However, the products manufactured using AM usually suffer from defects like roughness or uneven surfaces. This paper discusses the various surface quality improvement techniques, including how to reduce surface defects, surface roughness and dimensional accuracy of AM parts.

There are many different types of popular AM methods. Unfortunately, these AM methods are susceptible to different kinds of surface defects in the product. As a result, pre- and postprocessing efforts and control of various AM process parameters are needed to improve the surface quality and reduce surface roughness.

In this paper, the various surface quality improvement methods are categorized based on the type of materials, working principles of AM and types of finishing processes. They have been divided into chemical, thermal, mechanical and hybrid-based categories.

The review has evaluated the possibility of various surface finishing methods for enhancing the surface quality of AM parts. It has also discussed the research perspective of these methods for surface finishing of AM parts at micro- to nanolevel surface roughness and better dimensional accuracy.

This paper represents a comprehensive review of surface quality improvement methods for both metals and polymer-based AM parts.

Glass is a brittle material produced from silica, which has fine material properties, Owing to its sophisticated material properties, glass has found wide application in various high-technological fields such as aviation, aerospace, communication, optics, biomedical and electronics. However, glass is known as difficult to machine material because of its tendency to brittle fracture during machining. This paper aims to investigate the effects of cutting parameters on surface quality and machining time during micro-milling of brittle glass components.

A comprehensive genetic algorithm-based optimization strategy is used for selection of process parameters such as cutting speed, feed rate and depth of cut. Effectiveness of the proposed strategy is validated by conducting micro-milling cutting experiments on soda-lime glass material.

Results showed that the generated surface quality drastically decrease with increase in the amount of removed material. Lower depth of cut and feed rate result in less amount of cracks formed on machined surface. Also, it is observed that the increase in cutting speed results in better surface quality. Having desired surface quality in shorter machining time directly reduces energy consumed during manufacturing, which is reducing environmental impact of glass parts.

The novelty of this research work lies in simultaneously considering the effects of cutting speed, feed rate, depth of cut on surface quality and machining time for micro-milling operation of brittle glass material. The model is able to find optimum process parameters for high surface quality and minimum machining time.

The purpose of this paper is to improve the performance and quality of Ti-6Al-4V fabricated by laser powder bed fusion.

Single-track experiments were conducted during the fabrication process to obtain the single tracks with excellent wettability to narrow the process parameter window. The effects of process parameters on the build surface, cross-section, relative density, defects, surface roughness, microstructure and mechanical properties of the parts were analyzed through multilayer fabrication experiments and surface optimization experiments.

The point distance has the greatest influence on the build surface of the fabricated parts, and the unmelted defects can be eliminated when the point distance is 35 µm. The relative density of the fabricated parts decreased with the increase of the point distance, and the hatch spacing has different characteristics with respect to the relative density of the fabricated parts under different laser powers. It was observed that the most of experimental groups with higher relative densities than 99%, and the highest density could reach 99.99%. The surface roughness can be reduced to less than 10 µm through remelting optimization.

The research results can provide theoretical support for scientific researchers and data support for engineers.

The purpose of this study is, to compare laser-based additive manufacturing and subtractive methods. Laser-based manufacturing is a widely used, noncontact, advanced manufacturing technique, which can be applied to a very wide range of materials, with particular emphasis on metals. In this paper, the governing principles of both laser-based subtractive of metals (LB-SM) and laser-based powder bed fusion (LB-PBF) of metallic materials are discussed and evaluated in terms of performance and capabilities. Using the principles of both laser-based methods, some new potential hybrid additive manufacturing options are discussed.

Production characteristics, such as surface quality, dimensional accuracy, material range, mechanical properties and applications, are reviewed and discussed. The process parameters for both LB-PBF and LB-SM were identified, and different factors that caused defects in both processes are explored. Advantages, disadvantages and limitations are explained and analyzed to shed light on the process selection for both additive and subtractive processes.

The performance of subtractive and additive processes is highly related to the material properties, such as diffusivity, reflectivity, thermal conductivity as well as laser parameters. LB-PBF has more influential factors affecting the quality of produced parts and is a more complex process. Both LB-SM and LB-PBF are flexible manufacturing methods that can be applied to a wide range of materials; however, they both suffer from low energy efficiency and production rate. These may be useful when producing highly innovative parts detailed, hollow products, such as medical implants.

This paper reviews the literature for both LB-PBF and LB-SM; nevertheless, the main contributions of this paper are twofold. To the best of the authors’ knowledge, this paper is one of the first to discuss the effect of the production process (both additive and subtractive) on the quality of the produced components. Also, some options for the hybrid capability of both LB-PBF and LB-SM are suggested to produce complex components with the desired macro- and microscale features.

In this study, experimental studies were carried out using different process parameters of the soft pneumatic gripper (SPG) fabricated by the fused deposition modeling method. In the experimental studies, the surface quality of the gripper was examined by determining four different levels and factors. The experiment was designed to estimate the surface roughness of the SPG.

The methodology consists of an experimental phase in which the SPG is fabricated and the surface roughness is measured. Thermoplastic polyurethane (TPU) flex filament material was used in the fabrication of SPG. The control factors used in the Taguchi L16 vertical array experimental design and their level values were determined. Analysis of variance (ANOVA) was performed to observe the effect of printing parameters on the surface quality. Finally, regression analysis was applied to mathematically model the surface roughness values obtained from the experimental measurements.

Based on the Taguchi signal-to-noise ratio and ANOVA, layer height is the most influential parameter for surface roughness. The best surface quality value was obtained with a surface roughness value of 18.752 µm using the combination of 100 µm layer height, 2 mm wall thickness, 200 °C nozzle temperature and 120 mm/s printing speed. The developed model predicted the surface roughness of SPG with 95% confidence intervals.

It is essential to examine the surface quality of parts fabricated in additive manufacturing using different variables. In the literature, surface roughness has been examined using different factors and levels. However, the surface roughness of a soft gripper fabricated with TPU material has not been examined previously. The surface quality of parts fabricated using flexible materials is very important.

This paper aims to investigate the influences of process parameters on part quality, electrical energy consumption. Moreover, the relationship between part quality and energy consumption of UTR9000 photosensitive resin fabricated by stereolithography apparatus (SLA) was also assessed.

Main effect plots and contour maps were used to analyze the interactions and effects of various parameters on energy consumption and part quality, respectively. Then, a growth rate was used defined as the percentage of the value of energy consumption (or the part quality) of the sample compared to the minimum value of the energy consumption (or the same part quality), to jointly analyze relationships between part quality and energy consumption on a specific process parameter.

The part qualities can be improved with increased energy consumption via adjusting layer thickness, without further increasing energy consumption through adjusting laser power, over-cure and scanning distance. Energy consumption can be highly saved while slightly decreasing the tensile strength by increasing layer thickness from 0.09 mm to 0.12 mm. Energy consumption and surface roughness can be decreased when setting laser power near 290 mW. Setting an appropriate over-cure of about 0.23 mm will improve tensile strength and dimensional accuracy with a little bit more energy consumption. The tensile strength increases nearby 5% at a scanning distance of 0.07 mm compared to that at a scanning distance of 0.1 mm while the energy consumption only increases by 1%.

In this research, energy consumption and multiple part quality for SLA are jointly analyzed first to accelerate the development of sustainable additive manufacturing. This can be used to assist designers to achieve energy-effective fabrication in the process design stage.

The surface characteristics of wood such as surface roughness, surface free energy (SFE) and wettability are important properties influencing further manufacturing processes such as gluing and coating. The purpose of this study is to determine the influence of surface roughness of ten tropical woods on their SFE, wettability and bonding quality for water-based acrylic and solvent-based alkyd varnishes.

The woods tested in this study were fast-growing teak, afrika, sungkai, mindi, merbau, durian, lamtoro, pulai, acacia and kempas. Wood surfaces were prepared in unsanded and sanded using an abrasive paper of 120 grits. SFE values were calculated based on the Rabel method. Wettability values were measured based on the contact angle between varnish liquids and wood surfaces using the sessile drop method, and the S/G model was used to evaluate the wettability of the varnishes on the woods surface. The bonding quality of the varnishes was measured using a cross-cut test based on the ASTM 3359-02 standard.

The results show that unsanded kempas wood had the roughest surface with a Ra value of 16.24 µm, whereas sanded lamtoro wood has the smoothest surface with a Ra value of 6.86 µm. The unsanded afrika wood had the highest SFE value of 53.61 mJ/m², whereas sanded fast-growing teak had the lowest SFE value of 36.17 mJ/m². Sanded merbau woods had the lowest K value of 0.022 for the water-based acrylic varnish, whereas unsanded afrika wood had the highest K value of 9.253 for the alkyd varnish. Afrika wood with the highest K values (highest wettability) for both acrylic and alkyd varnishes produced the highest bonding quality (grade 4-5). Compared to the water-based acrylic varnish, the solvent-based alkyd varnish was more wettable and generated better bonding quality.

Improving the quality of fast-growing wood from plantation by painting could be considered to increase their use for higher value wood products.

Compared to water-based acrylic varnish, solvent-based alkyd varnish was more wettable and generated better bonding quality.

The originality of this research is to evaluate the values of surface free energy. SFE could be used to quantitatively determined the wettability of paints liquid in the surface of wood

For the laser powder bed fusion (L-PBF) technology, the side surface quality is essentially important for industrial applicated parts, such as the inner flow parts. Contour is generally adopted at the parts’ outline to enhance the side surface quality. However, the side surface roughness (Ra) is still larger than 10 microns even with contour in previous studies. The purpose of this paper is to study the influence of contour process parameters, laser power and scanning velocity on the side surface quality of the AlSi10Mg sample.

Using L-PBF technology to manufacture AlSi10Mg samples under different contour process parameters, use a laser confocal microscope to capture the surface information of the samples, and obtain the surface roughness Ra and the maximum surface height Rz of each sample after analysis and processing.

The results show that the side surface roughness decreases with the increase of the laser power at the fixed scanning velocity of 1,000 mm/s, the side surface roughness Ra stays within the error range as the contour velocity increases. It is found that the Ra increases with the scanning velocity increasing and the greater the laser power with the greater Ra increases when the laser power of contour process parameters is 300 W, 350 W and 400 W. The Rz maintain growth with the contour scanning velocity increasing at constant laser power. The continuous uniform contour covers the pores in the molten pool of the sample edge and thus increase the density of the sample. Two mechanisms named “Active adhesion” and “Passive adhesion” cause sticky powder.

Formation of a uniform and even contour track is key to obtain the good side surface quality. The side surface quality is determined by the uniformity and stability of the contour track when the layer thickness is fixed. These research results can provide helpful guidance to improve the surface quality of L-PBF manufactured parts.