Our V-Flange CAT 40 blanks are machined from mill certified AISI 4150 preheated-treated alloy steel. The body is hardened to 28-32 RC to allow for easy machinability and post flame hardening for those special pockets and features. Manufactured in accordance with AISI / ASME B5.50 standard (Per ISO-1947) the 7/24 fast taper is hardened to 56-60 RC and precision ground to AT-3 standards; providing optimal radial repetitive accuracy to your CNC machining center's tool-spindle. With a black-oxide finish these v-flange blanks are resistant to corrosion and fretting. With our large selection and on the shelf inventory we are sure to meet your machine shop's needs.