fraisa.com 328 1.5 x d 1.5 x d of f on 1.5 x d of f Technical notes regarding use of deep hole drills Pilot hole = 1.5 x d. e.g. Supradrill® U 3xd. B62011. The pilot hole must be free of chips prior to insertion of the deep-hole drill! Insert the tool into the hole at max. 300 1/min and vf = 1000mm/min. Without cooling up to 1 mm from the bottom of the pilot hole. Coolant supply on. Drill using recommended cutting data and without chip breaking. When drilling through-holes, reduce the feed rate by at least 25% before retracting from the hole. Retract the deep-hole drill with double the feed rate (=2 x vf) – until 1.5 x d after entering the hole. Position as stated in Step 2. Next reduce the spindle speed to max. 300 1/min. Coolant feed is switched off. Withdraw the drill from the drilled hole. (max. 1000 mm/min). SAFETY NOTE Outside of the drill hole, long deep-hole drills may only turn at a low speed (max. 300 1/min). Higher spindle speeds can cause such tools to vibrate, leading to spontaneous failure. FRAISA SA recommends the following drilling strategy to increase both service life and reliability: Step 1 Step 2 Step 3 Step 4 Step 5
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