Cirp Annals-Manufacturing Technology最新文献

Process integration and automation are becoming increasingly important for improving productivity. When two workpieces are parallelly machined on a single machine, vibration transmission by multiple machining points makes it difficult to select optimal cutting conditions, achieving both accuracy and efficiency. This study presents a method to introduce the optimal condition in simultaneous machining with different processes. The developed simulation includes machine dynamics and simultaneous machining process model. Vibration transmissibility between the processes is calculated and the cutting condition with less roundness is proposed. An experimental result shows the proposed method can determine cutting condition the higher accuracy in short time.

The edge shape of a silicon wafer is crucial for optimal device manufacturing. In polishing processes, it is necessary to form wafers into either a flat or roll-up shape, depending on the specific requirements of the process. However, the conventional process typically results in a roll-off shape. This study identifies the factors that influence a change in the edge shape during polishing. Polishing experiments were conducted to examine the effects of the initial edge shape and contact state between the wafer and polishing pad on the removal distribution. An approach for adjusting the resulting edge shapes was proposed.

In geometric tolerancing, functional specification is becoming challenging as the complex mutual situations of geometrical features increase and the requisites for complex assembly accuracy escalate. A computational representation of sets of situation features is proposed in this paper to manage functional specification of complex assemblies. A minimum triplet set of a point, a straight line and a plane called ToLiP, is introduced to represent situation features. Functional specification operations can thus be mathematically established using projective geometric algebra (PGA). The effectiveness of the proposed approach is highlighted through a case study using quadrupole magnets of a particle accelerator.

4H-SiC is crucial for high-temperature, high-power semiconductors, yet its processing encounters challenges due to its high hardness and chemical inertness. The three-step slurry-less Electrochemical Mechanical Polishing (ECMP) with NaCl electrolyte ensured efficient and damage-free polishing for 4H-SiC. However, the final step of slurry-less ECMP required sacrificing removal efficiency to prevent oxide layer breakdown and achieve an atomically smooth SiC surface. Additionally, the use of NaCl in practical industrial applications often resulted in equipment rusting easily. This study explored the substituting of a weak alkaline KOH electrolyte for NaCl in slurry-less ECMP, detailing oxidation mechanism of 4H-SiC. This alternative achieved an ultra-smooth surface without compromising the oxidation rate, laying a theoretical foundation for efficient slurry-less ECMP process.

Since compensation for rotation centers is insufficient for accurate 5-axis manufacturing, compensation for kinematic errors of the rotary axis is demanded. Although touch trigger probes are widely used, interference with other components often limits their measurement range and accuracy. This article proposes a method to identify kinematic parameters for the entire stroke of the swiveling axis at once from a measured dataset taken at different measurement locations depending on the indexing angle of the swiveling axis. The proposed method is experimentally evaluated on a horizontal 5-axis machining center.

Mechanical and thermal processing of wire-arc additively deposited stainless steel is investigated with the purpose of improving its microstructure, surface morphology, formability, and stress response. Microscopy helps identifying the processing conditions that permit full recrystallization of the as-built columnar microstructure. Combination with strain loading paths, topography and fractography in tensile tests show that mechanical processing consisting of 20 % thickness reduction followed by annealing at 1100 °C under 4 h eliminates anisotropy and increases the fracture forming limits by 30 %. The work is a step forward to consolidate the hybridization of wire-arc additive manufacturing with metal forming as an alternative to conventional manufacturing.

The accuracy of the identification of machine tool squareness by the vision-based circular test was evaluated. The uncertainty in the squareness identification was evaluated to clarify the accuracy criteria for camera calibration and setup. The simulation and experimental results revealed that the uncertainty owing to the skew factor of the camera was dominant. The conventional calibration performed using a checkerboard plate was insufficient. In contrast, the experimental setup did not require a high accuracy because the alignment error was not significant. The obtained results demonstrated the potential of the vision-based test for an approximate and rapid identification of squareness.

This paper presents a novel control strategy to minimize residual vibrations and overshoot using inertial dampers in repetitive tasks. In this work, vibration data collected during repeating task is utilized to generate a fully pre-scheduled feedforward compensation signal that assists the inertial damper's original feedback controller to further enhance its vibration mitigation capability. Optimal feedforward signal is determined iteratively over successive operations considering the actuator stroke and force limits. Numerical and experimental results validate the approach demonstrating significant (up to 87%) reduction in peak vibration while using equal or less actuator force as compared to the conventional control.

As new AI technologies such as Large Language Models (LLM) quickly evolve, the need for enhancing general-purpose LLMs with physical knowledge to better serve the manufacturing community has been increasingly recognized. This paper presents a method that tailors GPT-3.5 with domain-specific knowledge for intelligent aircraft maintenance. Specifically, aircraft ontology is investigated to curate maintenance logs with encoded component hierarchical structure to fine-tune GPT-3.5. Experimental results demonstrate the effectiveness of the developed method in accurately identifying defective components and providing consistent maintenance action recommendations, outperforming general-purpose GPT-3.5 and GPT-4.0. The method can be adapted to other domains in manufacturing and beyond.

Additive manufacturing (AM) can be used to produce near-net-shape Inconel 718 parts to minimise the material consumption and the machining required for fabricating parts. Compared to wrought Inconel 718, there are certain characteristics inherent to AM process. These are elongated microstructural grains in the build direction, skin effect and the possibility of semi-finish machining prior to heat treatment. Micro-scratch and end milling tests were used to investigate the impact of these AM specific characteristics on machining performance and compare it with wrought alloy. The analysis demonstrated that directionality, skin effect and heat treatment affect cutting forces and tool wear within the material. Using lubrication can minimise these variations.