Effect of Elastic Deformation of the Honing Stone on the Exposure of Si-Crystals in a Hyper-Eutectic-Si Aluminum Cylinder Block

A monolithic cylinder block using a hyper-eutectic Al-Si alloy provides superior cooling performance and light weight. Through the mechanical recessing process a soft honing stone polishes the aluminum matrix away and exposes the primary-Si crystal. This is a good way to obtain superior tribological properties at the bore surface. To reveal the basic mechanism of the mechanical recessing process, this research used experimental recess testing and a boundary element method calculation simulating the actual honing process. A pin-on-disk type recess test using an elastic polyurethane pin and an A390-alloy disk was carried out. An increased number of rubbings exposed the primary Si crystals from the aluminum matrix. The exposure height of the Si particle initially increased but stayed constant to a critical exposure height above the increased rubbing number of 500. The mathematical simulation revealed that the provided pressure on the Si particle determined the critical exposure height. The effect of Young's modulus of the pin on the critical exposure height of Si revealed that the lower the modulus the higher the height.