A Study on Heat Transfer in High-Speed Grinding of Titanium Matrix Composites

High-speed grinding experiment of titanium matrix composites is carried out with cubic boron nitride (CBN) superabrasive wheels in this work. The heat transfer into the titanium matrix composites (TMCs) is discussed based on theoretical analysis. A calculation method of thermal ratio passing into the workpiece is represented. Results obtained show that high-speed grinding of PTMCs using vitrified CBN wheel has a greater thermal ratio passing into the workpiece than using electroplated CBN wheel. Moreover, a linear relationship is established between es and ds1/4ap-3/4vw-1/2.

Development of Novel Long-Life CBN Grinding Wheel at High Efficiency Condition

Vitrified CBN wheels have been widely employed for precision and high efficiency grinding in industry. However, the high stock removal grinding tends to generate the grinding burning which causes tensile residual stress, cracking and hardness softening on the ground surfaces, and it leads to shorten the wheel life. In order to overcome these issues and extend the wheel life, a novel vitrified CBN wheel has been developed. This paper describes features of bond material, and wheel structure applied to the developed CBN wheels. Grinding performances of the new wheel under high efficiency conditions are discussed. Finally it concludes that the newly developed wheel having uniform dispersion structure with new bond with high bending strength significantly improves the wheel life and the ground surface quality. The mechanism for achieving the high performance is discussed from the view point of grinding fundamentals.

Grinding Characteristics of Porous Composite-Bonded CBN Wheels

Based on the orderly distribution alumina bubbles in working layer the porous composite-bonded CBN wheels were fabricated and grinding experiments of nickel-based alloy were carried out in comparison of the vitrified counterpart. Results show that the grinding force decreases and increases respectively with the increasing wheel velocity and depth of cut. The specific grinding energy reduces graduately from 465 to 93 J/mm3when the maximun underformed chip thickness increases from 0.4 to 1.7 μm. Compared to the vitrified CBN wheel, the grinding forces, temperatures and specific grinding energy of the porous composite-bonded CBN wheel are always lower than that of the vitrified one. Its attributed to the graphite lubricating and alumina bubbles pore-forming effects. The larger chip storage space, sharper grit edge and less adhesion on the wheel surface surpport the advantages of the porous CBN wheel.

Grinding Experiments on PTMCs with Vitrified CBN Wheel

Grinding experiments were conducted using vitrified CBN wheel on particulate reinforced titanium-based matrix composites (PTMCs) and Ti-6Al-4V matrix. The issues discussed are grinding forces, surface roughness, and the formation of surface integrity. The main results are summarized as follows: (1) The grinding forces increase with the increasing workpiece speed and depth of cut during grinding PTMCs and Ti-6Al-4V materials. (2) Decreasing depth of cut properly contribute to obtaining finished surface with good surface during grinding of PTMCs using CBN wheel, but the workpiece speed has little influence on the surface roughness value of PTMCs. (3) The formation of surface integrity of PTMCs is due to the combined removal of the TiC and TiB reinforcements and the Ti-6Al-4V matrix.

Experimental Investigation on Surface Integrity in Grinding Titanium Alloys with Small Vitrified CBN Wheel

Titanium alloys have been widely used in aerospace and manufacturing industry because of their unique high strength-weight ratio, fracture resistance, and superior resistance to corrosion. In this paper, a series of experiments were carried out to research the surface integrity in grinding Titanium alloy TC11 on a milling centre with small vitrified bond CBN wheel. Nine runs involved in the orthogonal array are designed in accordance with three factors at three levels. The surface roughness Ra 0.72 um and Rz 4.73 um are obtained. Subsequently ANOVA is employed to analyze the relative importance of all control factors on surface roughness and the optimal combination of grinding parameters is gotten. The measurement of microhardness is also taken and the microhardness profile is then drawn. The metallographic analysis shows that a plastically deformed layer are formed beneath the ground surface at 0~80 um and no white layer is observed. Experimental results validate the feasibility of grinding Titanium alloys on a milling machine with a small vitrified CBN small wheel.

Experiment Study on Abrasives Performance on Vitrified CBN Wheel

In this paper, accord to effect of CBN abrasives in vitrified wheel, eight kinds CBN abrasives were analyzed for its room performance, microcosmic crystal photographs, high temperature performance and corrosion resistance, by right of single grain pressure-resistant intensity apparatus, SEM and DTA etc advanced apparatus. The test results indicated performance of domestic part single crystal CBN has been reached or exceed overseas same product.

Analysis of the Vitrified CBN Wheels for the Performance of Grinding Hardened Steel

This paper investigates the effect of the CBN abrasive types, sizes, concentration, bond amount, and porosity of a vitrified-bonded CBN wheel on grinding ratio, grinding forces, and surface roughness of grinding hardened steels. The experiment results showed that during grinding hardened steels the amount of bond with increase of the depth of cut increased, which makes the wheel to have a better bonding strength to get a better grinding ratio and surface roughness of the workpiece. The grinding forces produced increased with the increase of the depth of cut. In addition, too much porosity of a vitrified CBN wheel will cause the low bond strength, leading the wheel to wear rapidly. Hence, to obtain a higher grinding ratio and better surface roughness of the workpiece during the grinding hardened steels should select relatively a higher amount of bond, a lower porosity, and a higher grit strength and concentration, but the grinding forces produced were relative higher.