Damped Vibration Response at Different Speeds of Wire in Slurry Wiresaw Manufacturing Operations

Abstract

Wiresaw has become a standard slicing tool especially for large ingots in the wafer preparation industry since late 1990s. To meet the requirements of the surface finish and topology, it is critical to control the process parameters to render good surface finish and to minimize kerf loss. The vibration of moving wire in the wiresaw manufacturing operation affects the wafer surface finish and kerf loss; therefore, the study and analysis of vibration of moving wire become very important and relevant to this manufacturing process. Built on the previous research, the free vibration response of axially moving wire with damping is a combination of infinite sets of response solutions, with trigonometric functions due to end constraints. The apparent damping due to the increase of speed on the first several components of responses will be presented and discussed in this paper. The results also show that the increase in speed will excite components of response except the dominating one. Since the free vibration response is a combination of infinite sets of solutions, it is not possible for the system to be completely critically-damped or over-damped because of the existence of under-damped modes at higher order. Therefore, a damped index is introduced to help in understanding the behavior of such system. When the physical damping is increased (for example, by using a more viscous carrier fluid in slurry), all components are more damped accordingly. However, in addition to the physical damping, the apparent damping caused by the increase of wire speed will also damp out the response. These two parameters, physical damping and apparent damping, control the behavior of an axially moving wire. This is a new finding in vibration analysis of moving wire that, to our best knowledge, has not been reported in the previous literature.