Abstract: With more and more applications of glass in advanced science fields‚the demand for glass machining preci -sion increases greatly．More and more attention is paid to glass cutting because of high efficiency‚low cost and precise glass parts with various shapes．In order to improve the machining precision of the part surfaces and to facilitate the tooldesign and cutting parameter selection‚the initiation and propagation laws of glass cracks in specimens subject to nor-mal loading by symmetric wedges were investigated．The research results show that the initiation and propagation laws are the same with the interior symmetric wedge angles of30°～120°‚while the laws are different with the interior sym-metric wedge angles equal to or more than150°．The relationship between the medial crack length and the normal load-ing was also investigated when specimens are indented by symmetrical wedges with the interior angles of30°～120°．

Key words: glass cutting, symmetric wedges, indentation, glass crack