Materials Science Forum Vols. 697-698

Abstract: This study focused on the side milling surface roughness of titanium alloy under various cooling strategies and cutting parameters. The experimental results show that the cooling strategies significantly affect the surface roughness in milling Ti-6Al-4V. Surface roughness (Ra) alterations are investigated. Cutting fluid strategy made nearly all the smallest and most stable roughness values. The surface roughness values produced by all cooling strategies are obviously affected by feed, radial depth-of-cut and cutting speed. However, axial depth-of-cut has little influence.

Abstract: From the view of implementation and machine protection, this paper presents a novel scheme of programming spindle-speed variation for regenerative chatter suppression. It is based on the research of the necessary conditions of chatter, from a new perspective. Through standard test method, research are carried on the influence of the interval time and the speed variation amplitude on vibration suppression effectiveness. In this work, cutting process keeps relatively more stable without motor continuous overload, which is verified by theoretical analysis and experiments.

Abstract: The effects of cutting parameters and tool wear on the surface damage generated in hole making of cast GH625 nickel-based alloy were investigated. The machined surfaces were examined by employing a scanning electron microscopy (SEM). The SEM micrographs of the machined surfaces showed that surface damages induced by boring operation comprised surface cavities, smeared material and ridges parallel to feed marks. Surface cavities were associated with the carbide particles contained in workpiece material and the intrinsic defect of cast GH625 alloy. The cutting conditions had little impact on the extent of surface cavities, but they significantly affected the extent of smearing. Severe smearing of workpiece material could occur at higher cutting speed due to the relatively high cutting temperature generated and the relatively rapid tool wear.

Abstract: Surface roughness is one of the most important requirements in the cutting process. In this paper, advantages of Taguchi’s experimental design technique, experimental measurements, and analysis of variance (ANOVA) are integrated to statistically investigate surface roughness in hard milling H13 steel (HRc50±1) with coated round inserts under dry cutting conditions. A 12-parameter cubic regression model for surface roughness is developed, which simultaneously takes into consideration the main effects and the interactions of four cutting parameters. A good correlation is observed between the predictive values and the experimental data.

Abstract: The study focused on surface burn of titanium alloy (TC4) in the grinding process using a novel segmented cup wheel with internal cooling structure. The threshold burn temperature was found in grinding TC4. Plastically deformed coating layers and micro-cracks were observed on ground surface by SEM (Scanning Electronic Microscopy) and depth of microstructure alterations was more than 180 microns in high temperature. Finally, a novel wheel with internal cooling structure was developed for reducing grinding temperature and suppressing surface burn.

Abstract: Cutter runout will redistribute the instantaneous uncut chip thickness and the cutting forces in multi-fluted milling process. In this paper, a new procedure is proposed to identify the cutter runout parameters for flat end milling process. By combining least-square method, mathematical derivations and implementation procedures are carried out based on the relative deviation between each cutting edge and the spindle rotation center, measured by a dial gauge. Numerical verifications are conducted to validate the proposed procedures, and the results show that they are efficient and reliable. It is also suggested that to weaken the influence of noise signal, measurements should be conducted at multiple axial positions.

Abstract: Analysis of instantaneous uncut chip thickness (IUCT) in peripheral milling of curved surface with variable curvature is nontrivial due to the combined influences of both process geometry and cutter runout. This paper gives a systematic analysis of IUCT including the effects of changing workpiece geometry and the cutter runout in peripheral milling. The prominent feature of this analysis procedure lies in that the novel equation for computing the IUCT is mathematically derived in detail. Numerical simulations are performed to study the effect of workpiece curvature and cutter runout on IUCT. The proposed model is validated by comparing the measured cutting forces with those predicted based on the IUCT which is obtained using the current approach.

Abstract: It is essential to control the heat generated in the cutting zone in order to ensure the workpiece quality after grinding. This article deals with an investigation in using graphite and hexagonal boron nitride as solid lubricants to reduce friction and thereby improve the surface integrity of Ti-6Al-4V alloy. The polymer-based solid lubricant coating wheels have been prepared. Grinding experiments have been conducted to study the effect of the graphite and hexagonal boron nitride lubricants on the grinding temperature and the surface quality of the workpiece while grinding Ti-6Al-4V. Results indicate that there is a considerable improvement in the performance of grinding Ti-6Al-4V using graphite and hexagonal boron nitride as solid lubricants in dry grinding in terms of grinding temperature and surface quality of the work piece. The indigenous polymer-based solid lubricant coatings are effective in dry grinding.

Abstract: Machining parameters and spindle radial runout have great influence on the micro-ball-end cutter deflection in the micro-end-milling process. In this study, a 3D (three-dimensional) thermal-mechanical FEM (finite element method) model of micro-milling with non-rigid cutter is built to study how radial runout, cutting depth, feed and spindle speed influence the cutter deflection when feed has the same direction with the spindle radial runout. Cutter deflection under different groove lengths, cutting depths, feeds and spindle speeds is investigated, which shows that cutter deflection increases with spindle radial runout significantly. The largest deflections with runout of 2μm are 3.26μm, 3.26μm, 4.71μm and 4.52μm respectively under the adopted machining conditions, while the largest deflections without runout are 1.85μm, 1.85μm, 2.26μm and 3.79μm respectively. It is also shown that the runout effect increases with groove length, cutting depth, while it decreases with feed.

Abstract: In recent years taking into account the environmentally friendly property and low viscosity of water, water lubrication technology has been developing rapidly. However, the water itself contains easily-rust metal. Thus in order to meet the need of the spindle system of our research, we need to add antirust additives in water. Through the analysis of antirust additive, suitable composition of water-based antirust additive is obtained, and a new water-based lubricant is formed. Through orthogonal experiments of testing antirust properties, the optimal formula of lubricant is gained, and the ratio of various additives is confirmed.