Key Engineering Materials Vol. 499

Abstract: Cutting sound signal are acquisited in the vertical machining center using electret microphone, and would be applied to monitor tool wear. Linear Predictive Cepstrum Coefficient (LPCC) of milling sound signal within audibility threshold would be extracted as acoustic spectrum characteristic parameters, and the relativity between LPCC each order component and tools radial wear was analyzed. The experiments and analysis results conclude that there are characteristic components associated with tool wear in characteristic parameters LPCC of milling sound signal; the characteristic components associated with tool wear are mainly concentrated in the 6th, 7th and 8th order components LPCC; the method by characteristic parameters LPCC monitoring tool wear is feasible.

Abstract: In a manufacture system, the inventory control is one of important issues. This paper proposes a fuzzy economic order quantity (EOQ) inventory model for solving the inventory control problem in the manufacture system. Firstly, this paper discusses the square roots of a trapezoidal fuzzy number. Secondly, the square root of fuzzy number is applied to the EOQ inventory model in the manufacture system.

Abstract: Carbon fiber reinforced plastics (CFRP) is difficult to machine because of the extremely abrasive nature of the carbon fibers and its low thermal conductivity. CVD diamond films have many excellent properties such as wonderful wear resistance, high thermal conductivity and low friction coefficient, therefore depositing diamond films on the surface of drills is thought to be an effective way to elongate the lifetime of drills and improve the cutting performance. In this study, diamond films are deposited on the WC-Co drill using hot filament chemical vapor deposition (HFCVD) method. The results of characterization by the scanning electron microscope (SEM) and Raman spectrum indicate that the fabricated CVD diamond coated drill is covered with a layer of uniform and high-purity diamond films. The cutting performance of as-fabricated CVD diamond coated drill is evaluated in dry drilling CFRP, comparing with the uncoated WC-Co drill. The results demonstrate that the CVD diamond coated drill exhibits much stronger wear resistance. Its flank wear is about 50μm after drilling 30 holes, about one-third of that of WC-Co drill. Machining quality of the exit and internal wall of drilled holes shows better surface finish obtained by coated drill, which suggests that CVD diamond coated tool has great advantages in drilling CFRP.

Abstract: To improve the machining efficiency as well as surface roughness, a resin-bonded fixed abrasive tool is developed for lapping process of stainless steel substrate. To optimize the lapping ability of the fixed abrasive tool, the influences of bond material concentration on the mechanical properties of fixed abrasive lapping tool, including structure hardness, shear strength, the water-absorbing capacity and modulus of elasticity in compression are investigated. The micro structure of tools is also observed. Tools made of #1000 SiC abrasive and resin with different concentrations is employed in the tests. It is found, the hardness, shear strength, and modulus of elasticity in compression reach highest value, as the 35%wt bond material are used. The water-absorbing capacity increases as the bond material concentration decreases. It is judged from the SEM images that the number of pores in tool with 35%wt bond material is at the most.

Abstract: Lean Production, which was born in manufacturing industry, is considered to be the most suitable production mode for the modern manufacturing enterprises. This paper investigates the application of Lean Production Thinking in the assembly technology, and proposes the concept of Lean Assembly. The Lean Assembly could be described as follows: Eliminating all wastes in assembly process through certain management tools and technologies. There are three sub goals of Lean Assembly: zero inventories, high flexibility, zero defects. What’s more, this paper studies several key technologies, such as assembly line balancing, mixed-model scheduling, part supplying, assembly cell, virtual assembly etc.

Abstract: Laser triangulation was used to measure the topography of vitrified CBN wheels and optimum sampling interval was obtained by comparing measuring results with different sampling intervals. Four evaluation indexes including the mean protrusion height of abrasive grains Hm, the standard deviation of grain protrusion height Hv, the standard deviation of the distance between two adjacent grains Dv and the number of micro cutting edges per square millimeter Nm were put forward to assess wheel topography and grinding performance. These indexes were verified to be effective by comparing 3D topography of newly manufactured wheel and dressed wheel.

Abstract: The necessity of fixed abrasive CMP in polishing semiconductor materials processing was analyzed. Compared the shortcomings of traditional free abrasive polishing with the advantages of fixed abrasive polishing, the applications of fixed abrasive polishing technology in semiconductor processing were described. A variety of fixed abrasive polishing pad production methods were introduced. The development trend of fixed abrasive polishing was prospected.