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Milling machines have made denture fabrication possible with high accuracy in a short time. However, the relationship between the milling conditions, accuracy, and milling duration has not been clarified. This study aimed to clarify the effects of milling conditions on surface roughness and milling duration. The specimen was designed using CAD software and milled using PMMA disks. In milling, the parameters of finishing the specimen surface were adjusted. Three different spindle speeds and four different feed rates were set. Twelve combinations of each parameter were used for milling, and the surface roughness and milling duration were measured. Results showed that the surface roughness significantly increased with the feed rate on the slopes of the specimen. The surface roughness differed with the spindle speed on the left and right slopes. The spindle speed and feed rate did not affect the surface roughness on the flat surface. The milling duration was not affected by the spindle speed but decreased as the feed rate increased. In conclusion, by increasing both the spindle speed and feed rate, the milling duration could be shortened while maintaining a constant surface quality. The optimum milling conditions were a spindle speed of 40,000 rpm and feed rate of 3500 mm/min. [ABSTRACT FROM AUTHOR]

Milling machines have made denture fabrication possible with high accuracy in a short time. However, the relationship between the milling conditions, accuracy, and milling duration has not been clarified. This study aimed to clarify the effects of milling conditions on surface roughness and milling duration. The specimen was designed using CAD software and milled using PMMA disks. In milling, the parameters of finishing the specimen surface were adjusted. Three different spindle speeds and four different feed rates were set. Twelve combinations of each parameter were used for milling, and the surface roughness and milling duration were measured. Results showed that the surface roughness significantly increased with the feed rate on the slopes of the specimen. The surface roughness differed with the spindle speed on the left and right slopes. The spindle speed and feed rate did not affect the surface roughness on the flat surface. The milling duration was not affected by the spindle speed but decreased as the feed rate increased. In conclusion, by increasing both the spindle speed and feed rate, the milling duration could be shortened while maintaining a constant surface quality. The optimum milling conditions were a spindle speed of 40,000 rpm and feed rate of 3500 mm/min.

• In-situ temperature measurement done for MACM and CCM. • Temperature characteristics correlated to mechanical performance. • MACM offers uniform temperature characteristics. This work is focused on the comparative study of in-situ processing temperature measurement during microwave-assisted compression molding (MACM) and conventionally compression molding (CCM) of fiber-reinforced thermoplastic matrix composite (FRTMC). In the present study, Kenaf reinforced high density polyethylene (HDPE) composite (volume fraction 20%) was chosen as the FRTMC. The processing temperature of the FRTMC was selected as per melting peak obtained from differential scanning calorimeter (DSC). The degradation temperature of FRTMC was obtained using thermogravimetric analysis (TGA). The fabrication time using MACM was found to be 84% less compared to CCM. In the MACM, temperature variation towards width and depth of specimen was found to be negligible. The thermal contours were used to observe temperature profiles during composite fabrication using CCM and MACM. Furthermore, the mechanical response of the MACM fabricated composite was better compared to CCM composite. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) has been increasingly developed and applied in many fields nowadays. However, it takes a long time for completing a part due to the layer-by-layer manner of AM process which is time-consuming. A variety of studies have been carried out to plan the process of AM to save fabrication time, such as increasing layer thickness to reduce total layer numbers and path planning to find the shortest total travel path to save printhead travel time. In this paper, a novel fabrication strategy for AM is proposed to save fabrication time. The novelty of this strategy is on the consideration that the part does not need to be fabricated in a layer-by-layer manner, but in a multilayer-by-multilayer manner when the part has some independent features. This strategy includes five steps. Firstly, the part needs to be positioned in an optimal print direction. Secondly, the independent features in this part needs to be detected. Thirdly, the closest distances between independent features in each sliced layer are calculated and recorded. Then the nozzle moving strategy between each independent feature can be generated based on the distance recorded in the previous step. Lastly, the part can be sent to the AM machine for final manufacture using the proposed novel fabrication strategy. A case study was carried out for validation. The results show that the proposed multilayer-by-multilayer strategy can save 1039s of time for fabricating the part in the case study, compared with conventional layer-by-layer method. [ABSTRACT FROM AUTHOR]

A single-visit zirconia restoration can be easily achieved if direct milling of a fully sintered zirconia block can be performed without much effort. However, no studies have yet been reported regarding the evaluation of the trueness of crown fabricated from chairside-milling of a fully sintered zirconia block in the chairside computer-aided design and computer-aided manufacturing (CAD–CAM) system for single-visit dentistry. This in vitro study aimed to evaluate the trueness of crowns fabricated by milling a fully sintered zirconia block in the chairside CAD–CAM system and investigate the clinical implications for single-visit chairside restoration. Crowns were fabricated either by chairside-milling a fully sintered block of niobium oxide containing yttria-stabilized tetragonal zirconia polycrystals ((Y, Nb)-TZP) without the sintering process (n = 12) in a chairside single-visit dentistry system (Chairside group) or by laboratory-milling a partially sintered 3 mol% block of yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) followed by the sintering process (n = 12) in a conventional laboratory system (Labside group). Crown fabrication time, milling tool diameter and the trueness of each crown were evaluated. All trueness values of both groups were within the clinically acceptable range, although a significant difference between the Chairside (43.0 ± 3.67 μm) and Labside groups (37.4 ± 2.41 μm) was observed (P < 0.05). Mean fabrication time was 0.52 h and 1.42 h for Chairside and Labside groups, respectively. A decrease in the tool diameter was observed for the Chairside group. [ABSTRACT FROM AUTHOR]