Papers by Keyword: Machined Surface Quality

Abstract: AFRP(Aramid Fiber Reinforced Plastics) is widely used in the aerospace and automotive while there are many problems in machining AFRP such as furry, delamination, burns and so on. Milling experiments of AFRP have been conducted to study the influence of different helix angle (0°, 30°, 60°) and cutting tools (traditional end mill, multiple flute end mill and compression end mill) on cutting force and machined surface quality. The results indicated that the cutting force has been reduced and the surface quality has been improved with the increase of helix angle. The cutting tool structure can make greater influence on machined surface quality than the cutting parameters. A cutting tool with the structure of multiple flute or herringbone cutting edge could reduce the axial cutting force. However the cutting force is too small to cut off fibers when using a multiple flute end mill. A good processing surface can be achieved while cutting with a compression end mill or a tool with big helix angle.

Abstract: Surface roughness on machined part is a key performance index of surface quality for metal machining industry. Machining condition is a way to reduce surface roughness of the machined part. This study aimed to determine the significant factors affecting surface roughness and to obtain the optimal machining operation in turning process. The Shainin design of experiment method was used to investigate the effect of five machining factors on surface roughness in turning process of carbon steel. Furthermore, analysis of variance and multiple comparisons were used to determine the optimal machining condition of the significant factors. The results showed that set of the cutting tool angle was the only significant factor affecting the average surface roughness with the optimal operating condition of 120 degree used for reducing surface roughness of the machined part.

Abstract: This paper gives the details of turning experiments on AISI 1045 steel by using various cutting fluid and liquid nitrogen condition. Residual stress on machined surface is generated in rough machining and fine machining with different rounded cutting edge radius. The effects of cutting fluid and liquid nitrogen on residual stress state are obtained by compared with dry cutting. Experimental results show that cutting fluid and liquid nitrogen have influence on machined residual stressl and liquid nitrogen generates residual compressive stress in all specimens.

Abstract: Five-axis milling is used in the machining of complex shaped surfaces in a wide range of industries. In five-axis milling, one can adjust inclination angle to adapt such machining condition, e.g. to give high material removal and/or to avoid gouging. Choosing an appropriate inclination angle is difficult especially for complex parts with varying surface curvature. On the one hand, a small inclination angle is recommended to have good surface roughness and small scallop height. On the other hand, some regions may need much larger minimum inclination angle compared to the others to avoid gouging. The trade off for this is to have, in practice, a varying minimum (which is considered to be optimal) inclination angle along the tool path, so that while machining, the tool is dynamically adapted to be as close as possible to the surface without gouging. However, applying inclination angle change over some distances influences the quality of machined surface. This paper presented a method to control such inclination angle change to improve part accuracy. Some experimental were conducted to see the results and compared with the one when inclination angle change is not controled. The propose method effectively reduces the surface deviation thus improve part accuracy. More details about this study are presented in the paper.

Abstract: An experimental device of KOH solutions jet-assisted laser etching is designed, Laser-chemical combined etching technology is combined with the Medium-jet erosion processing ,and the influence on the etching capacity and cross section quality of material sample of laser processing parameters,jet processing parameters are studied. The results show that the laser processing parameters and jet processing have a decisive impact on the quality of the workpiece, the composite processing technology can remove most of melting slag which are produced by the laser processing, the surface roughness are effectively reduced. The blind holes of the machined materials have the regular shape.

Abstract: In this paper, the mechanism of Electrolysis In-process Dressing (ELID) lapping process using new BCB (bamboo charcoal bonded) abrasive wheel is researched. Some experiments of machining for silicon wafers were carried out for exploring the effect of some machining process parameters on material removal rate and surface roughness. Experiments show that: Material removal rate and machined workpiece surface roughness are increased with increase of the lapping wheel’s rotation speed and processing loading; The machined workpiece surface quality is affected with the lapping wheel surface condition, due to the abrasives are trued by electrolysis dressing in the lapping process, therefore the BCB lapping wheel always keeps better machining condition to obtain excellent machined workpiece surface quality efficiently.

Abstract: One-directional ultrasonic vibration assisted milling system is designed and its performance is investigated in terms of machined surface quality under 135,000 rpm. The ultrasonic vibration generator excites the workpiece with a frequency around 40 kHz and amplitude of a few micro meters. The milling tool’s cutting speed is controlled by an air-bearing spindle system. Both feed-directional and cross-feed directional ultrasonic vibration assistance are considered in order to understand the mechanism of ultrasonic vibration assistance for surface roughness generation. A comparison is done on a milled surface which is generated with and without ultrasonic vibration assistance. The experimental results show that ultrasonic vibration assistance can improve the machined surface quality which depended on the cutting edge radius and the feed per tooth.

Abstract: This paper presents the use of vibration analysis based on autoregressive (AR) trispectrum in milling process to indicate the relationship between machined surface quality of workpiece and spectrum character under a variety of different cutting parameter settings, such as the depth of cut, the feed rate and the spindle speed. The metal cutting experiments were performed on steel A3 material without using any cutting fluid. The experimental results for slices analysis of trispectra indicated that the spectral peaks were abundant as the milling process went smoothly. The roughness value measured reflects the machined surface quality of workpice. According to the changes for spectral peak and roughness value, a conclusion was made that the proposed trispectrum slices method for choosing cutting parameters and monitoring the machined surface quality in milling process was practicable.