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The availability of an in-situ monitoring and feedback control system during the implementation of metal additive manufacturing technology ensures that high-quality finished parts are manufactured. This study aims to investigate the correlation between the surface texture and internal defects or density of laser-beam powder-bed fusion (LB-PBF) parts. In this study, 120 cubic specimens were fabricated via application of the LB-PBF process to the IN 718 Ni alloy powder. The density and 35 areal surface-texture parameters of manufactured specimens were determined based on the ISO 25,178–2 standard. Using a statistical method, a strong correlation was observed between the areal surface-texture parameters and density or internal defects within specimens. In particular, the areal surface-texture parameters of reduced dale height, core height, root-mean-square height, and root-mean-square gradient demonstrate a strong correlation with specimen density. Therefore, in-situ monitoring of these areal surface-texture parameters can facilitate their use as control variables in the feedback system.

Metal additive manufacturing technology requires a real-time monitoring and feedback control system to assure the quality of the final products. In particular, it is essential to reveal the phenomena of recoating and melting-solidification processes in laser powder bed fusion using a real-time monitoring system because they influence strongly the occurrence of defects. This study was conducted to elucidate the correlation among the powder characteristics, recoating conditions, and surface morphology of a powder bed in the recoating process to determine the relationship between the surface morphology of the powder bed and the final product quality. To this end, a surface morphology measurement system composed of a powder recoating test bench and a layer surface morphology measurement apparatus was first designed and fabricated. Then, it was used to quantify the surface morphology of the powder bed. Specifically, the influences of the different powder characteristics and the recoating parameters of the powder supply ratio and recoating speed on the surface morphology of the powder bed were investigated using various powders of Al-10Si-0.4Mg (AlSi10Mg) alloy and Inconel 718 (IN718) alloy. The surface morphology of the powder bed was measured as the value of 2σ at a resolution of 30 μm in height. It was found that the angle of repose and the basic flow energy of the bulk powder are promising parameters for evaluating the surface morphology. The surface morphology was significantly affected by the powder characteristics and recoating speed. The value of 2σ for the AlSi10Mg powder increased rapidly over a recoating speed of 50 mm/s for all powders. The value of 2σ for the irregularly shaped AlSi10Mg powder was approximately 19 μm, and the 2σ values for the other powders were approximately 17 μm at a recoating speed of 15 mm/s. However, at a recoating speed greater than 300 mm/s, the irregularly shaped powder exhibited better surface morphology than did the spherical powder. The recycling process deteriorated the flowability of the new powder. However, the surface morphology of the spherical recycled powder was similar to that of the spherical powder. Consequently, the correlation among the powder characteristics, recoating conditions, and surface morphology of the powder bed was revealed by employing the surface morphology measurement system. Quantification of the surface morphology of the powder bed using the monitoring system facilitates control of the recoating process to prevent the occurrence of defects.

In this study, process parameter optimization was performed for the powder bed fusion of H13 tool steel under low- (400 W) and high-power (1000 W) conditions using the SLM 280HL machine. The effects of process parameters such as the laser power, scan speed, and hatching pitch on the density and microstructure of the as-built H13 tool steel were investigated. The specimen density was found to be slightly lower under the high-power condition than that under the low-power condition. Electron backscattering diffraction analysis identified that the as-built specimens showed a prolonged columnar microstructure in the build direction under the low-power condition. In contrast, for the specimens fabricated using the hull-core method under the high-power condition, the hull and core parts showed prolonged columnar and equiaxed microstructures, respectively. Phase distribution images indicated that the microstructures of the as-built specimens under the low- and high-power conditions contained martensite (bcc) and austenite (fcc) with a grain size of approximately 1 μm. Thus, it was found that the specimen density achieved using the 400-W laser is higher than that achieved using the 1000-W laser; moreover, the microstructure of the as-built specimen using the 400-W laser is different from that using the 1000-W laser.

Additive manufacturing (AM) technology has been dramatically attracted attention because of advantages in building free-shaped parts and simplification of manufacturing process. Recently the most relevant alloys, such as TiAl6V4, Inconel 718, AlSi10Mg and so on, are able to manufacture the parts using metal AM technology. However high-strength 2024, 6061 and 7075 aluminum alloys are difficult to fabricate using selective laser melting (SLM) owing to solidification cracking during solidification. In this research, the melting and solidification behaviors of AlSi10Mg alloy during SLM process were observed under various fabrication conditions of laser power and scan speed using a high-speed camera. It was found that the melting and solidification behavior of the alloy is greatly different by the fabrication conditions. And also the mechanism of solidification cracking in 2024 and 6061 aluminum alloys is investigated by the observation of the surface morphology and microstructure of the alloys using OM, SEM and EDS, comparing with Al10SiMg alloy. As a result, crack-free 2024 and 6061 aluminum alloy parts can be obtained by fabrication at the higer enrgy density.

Selective laser melting (SLM) process has advantages in building free shape and simplification of manufacturing process. Since Ni-base superalloys have lower ductility at lower temperature, it is difficult to produce the parts by means of other process like forging. Therefore, SLM process has already applied to produce Ni-base superalloy parts. However, SLM process needs a long process time comparing to casting and machining. One of the means to solve this problem is an application of the high scanning speed condition under high power laser output. In this research, the optimum fabrication condition of Inconel 718 superalloy by SLM process under high power and high scanning speed condition was investigated. As a result, the optimum fabrication condition was obtained using the process map. However, the relative density of the as-built specimen fabricated under high power and high scanning speed condition is lower than that of the as-built specimen fabricated under the condition of 300 W and 600 mm/s. This may be mainly due to the occurrence of gas-pores by key-hole like phenomenon in melt pool and the increase of spattering at high power and high scanning speed condition.

Appropriate building parameters for selective laser melting of 99.9% pure copper powder were investigated at relatively high laser power of 800 W for hatch pitch in the range from 0.025 mm to 0.12 mm. The highest relative density of the built material was 99.6%, obtained at hatch pitch of 0.10 mm. Building conditions were also studied using transient heat analysis in finite element modeling of the liquidation and solidification of the powder layer. The estimated melt pool length and width were comparable to values obtained by observations using a thermoviewer. The trend for the melt pool width versus the hatch pitch agreed with experimental values.

The purposes of this research were to use fig protease for texture tenderizing, and to inhibit angiotensin I-converting enzyme (ACE) action and gamma-aminobutyric acid (GABA) formation of meat. Liberated peptides by the enzymatic action of fig protease in processing meat and free amino acids were determined and ACE inhibitory activity was assayed. Meat treated with fig protease became tender as indicated by shear force value (SFV) which was half of those of non-fig treated meat during storage even at 5 degrees C. Liberated peptides, free amino acids and GABA increased while extremely low levels of Glu were detected after storage. The optimal temperature of fig protease against meat was 80 degrees C. However, the activity of fig protease decreased after pre-heating more than 40 degrees C. High ACE inhibitory activity of a mixture of fig and meat was found around 80 degrees C, and the value corresponded to the amount of liberated peptide. A lot of liberated peptides were found at 60-80 degrees C and pasterization of meat product becomes convenient to produce peptides. Production of ACE inhibitory peptides and GABA can be expected as the healthy functional meat product such as antihypertensive activity and improve brain function.

The effect of surface roughness on glossiness and surface color for anodized 5052 aluminum alloy plates were investigated. The surface roughness of aluminum alloy plate was controlled by processing of shot blasting to satisfy the condition of arithmetical mean roughness, Ra, less than 1.0 μm. The specimens with several different conditions were prepared: shot blasting, anodizing after blasting, and, in addition, it dyed it to red, green and blue respectively. CIELAB (L*a*b* color system) was applied to the surface color evaluation method. The results of experiments, the glossiness value, Gs (60°), increased as decreasing Ra. The lightness, L*, decreased as decreasing Ra. The hue angle, hab, of the anodized surface changed into the green direction. The a, b chroma, C*ab, decreased as decreasing Ra of the anodizing red and blue specimens. However, the a, b chroma, C*ab, increased as decreasing Ra of the anodizing green specimen. This was caused by the fact that the hue angle, hab, changes into the green direction by anodizing.

In this study, the effect of surface roughness on glossiness and surface color for a pure titanium and a TiN coating surface was investigated based on the experimental discussions. CIELAB (L*a*b* color system) was applied to the evaluation method of surface color. Specimens were machined so that the arithmetical mean roughness, Ra, is less than 1.0 μm. From the results of experiments, the arithmetical mean roughness, Ra, decreased, as the glossiness, Gs (60°), increased. Especially, the glossiness value in the roughness range Ra?0.2 μm was distributed from 50 to 400. Moreover, the arithmetical mean roughness, Ra, decreased, as the lightness, L*, and a, b chroma, C* ab , decreased. The TiN coated surface with vividness had a pronounced tendency to decreasing lightness, L*, and a, b chroma, C* ab . This was attributable to the smaller difference of elevation of the spectral reflectance curve by reason that the short wavelength was diffused more than the long wavelength.

This paper is investigated experimentally about the effect of topography to the glossiness and surface color in order to characterize a surface texture of aluminum alloy 5052. The surfaces of specimens are machined by using a vertical milling machine, a horizontal milling machine and a shaping machine. Four kinds of specimens are machined by each machine so that the arithmetical mean roughness value, Ra, is less than 1 μm at four cutting conditions. From the results of experiments, the glossiness values of the vertical milling surface and the horizontal milling surface were about the same value, meanwhile the glossiness value of the shaping surface was less than half the value of the others. The surface color of specimens was gray. Especially, The lightness value of surface color, L*, of the horizontal milling surface was the highest value. The surface color was whitish gray of all machined surface. Based on those experimental results, it was summarized that the surface texture of specimen machined various machine could be characterized by the glossiness and surface color. These results could be an effective indicator in choosing the most proper machining method to add value to surface texture.

Liquid extraction method for determination of myoglobin in muscle is not suitable because of changes in the derivatives and time required. Optical reflectance method is useful as a non-destructive and real-time measurement. However, the base line of reflectance method, the muscular reflectance background (MRB) imagined as colorless structural elements, has been unknown because of non-existence. The spectrum of the base line was analyzed as the analogy of bleached meat. A formula was derived for reflectance that had a linear relationship to the reciprocal of wavelength to the power 4. The reflectance characteristic of the MRB was not constant and the curve tended to rise with increasing wavelength. The reflectance at 700 nm was estimated to be 50%. By the characteristic analysis on Commission Internationale l’Eclairage color values and reciprocal reflectance, it was concluded that the reflectance spectrum of the muscular background obtained in this research was fitted as a base line for the reflectance spectrometry.

This paper describes the establishment of an evaluation method for metal surface texture. The evaluation parameters used for surface texture were roughness, glossiness and color. Seven sample materials were studied: aluminum alloys (A2017, A5052), stainless steel (SUS304) and copper alloys (tough pitch copper C 1100, brass C2801, phosphor bronze C5191 and nickel silver C7541). The surfaces of all specimens were polished using waterproof abrasive papers. The correlation of the surface texture parameters for all specimens was investigated experimentally. The surface roughness of specimens was evaluated using the arithmetical mean roughness "Ra". The method for evaluating surface color was assessed by using CIELAB color space. The CIELAB color space is one of a uniform color space defined by CIE (Commission Internationale de l'Eclairage) in 1976. The results indicated that as surface roughness value "Ra" decreased, as the glossiness value "Gs(60°)" increased exponentially. The lightness value "L*" of the CIELAB color space decreased, as surface roughness value "Ra" decreased. Thus, the relationship between the lightness value "L*" and surface roughness value "Ra" showed an inverse correlation with the glossiness value "Gs(60°)" and surface roughness value "Ra". Moreover, the surface color showed that the blue hue increased, as the surface roughness value "Ra" decreased for all seven types of materials.

In this paper, we carried out an experimental research for establishing the evaluation of metal's surface texture by analysis of surface color. The materials of samples used in the experiment were aluminum alloys (A2017, A5052), stainless steel (SUS304) and copper alloy (nickel silver C7541). The surfaces of samples were burnished by use of waterproof abrasive papers. The surface roughness of samples evaluated by arithmetical mean Ra, root mean square slope RΔq and mean width of the profile elements RSm. The experimental results showed strong correlation for three different roughness parameters. Consequently, “Ra” was used as roughness parameter. As Ra decreased, the glossiness exponentially increased. The evaluation method of surface color was applied to CIELAB. The lightness L* in CIELAB decreased as Ra decreased. Thus, it showed that relationship between L* and Ra inverse correlation between glossiness and Ra. Moreover, surface color of four different materials showed that the chromaticness of blue increased as Ra decreased.

This paper describes a quantitative evaluation method for metal surface texture. We used surface roughness and glossiness as parameters to describe surface texture. Specimen surface roughness was evaluated based on geometrical product specification data taken from japanese industrial standards. The effects of surface roughness on glossiness were investigated by aluminum alloys. The relationship between the glossiness and the roughness height, the period of the roughness profile and the slope for the surface roughness processed by a vertical milling machine were studied for determining if the topography of the surface roughness affects the glossiness. The surface of the specimens were polished using abrasive paper and blasted, so that the arithmetical mean deviation, Ra, was less than 1.00 μm. The effects of roughness on glossiness were investigated on polished surfaces and blasted surfaces. The results show that the surface roughness shape and the glossiness prove to be effective indices for evaluating the surface textures of aluminum alloys.