1576 CONTACT INFORMATION For more information please call +44 1530 261 145 or send an email to sales@atagarryson.com SPADE DRILLS PROBLEM CAUSE AND SOLUTION Accelerated corner wear Spiral or large diameter at hole start Insert Chipping Blue Chips Built up Edge (BUE) Chatter Chip Packing Chipping of point Damaged or broken tools Use of Standard & Extended Holders 1, 2, 3, 4, 27 1, 2, 3, 4, 27 1, 2, 3, 4, 27 Starting on an inclined surface 1, 3, 4, 5 1, 3, 4, 5 1, 3, 4, 5 Worn or misaligned spindle 2, 6, 7 2, 6, 7, 27 2, 6, 7 2, 6, 7 2, 6, 7 Use of low rigidity spindle 2, 4, 8, 27 2, 4, 8, 9 2, 4, 8 2, 4, 8, 9 2, 4, 8, 9 Poor workpiece support 10, 26, 27 8, 9, 10, 26 8, 10, 26 8, 9, 10 External coolant – low pressure / volume 11, 12, 13, 19 11, 12, 13 11, 12, 13 11, 12, 13, 14 9, 11, 12, 13, 14 Interrupted cuts 2, 4, 9, 15, 16, 17 2, 4, 15, 16, 17 2, 9, 15, 16, 17 2, 4, 15, 16, 17 Drilling hardened materials 12, 18, 19, 20 12, 18, 19, 20 12, 13, 18, 19, 20 12, 18, 19, 20 Poor material micro structure 9, 20, 21, 22, 23 9, 20, 21, 23 9, 20, 21, 23 Poor chip control 12, 14, 19, 24, 25 12, 19, 24, 25 Spot drilled holes 2, 23 2, 23 2, 23 High wear resistant tool grades 9, 26 9, 26 SOLUTION: 1. Use a short holder to drill a pilot hole 1×D deep. 2. Spot hole with stub tool of same or greater included angle as the insert. 3. Decrease feed minimum 50% until full diameter established. 4. Use special holder with wear pads or chrome bearing area to work with drill bushing. 5. Spot face to provide flat entry surface. 6. Align spindle or turret or tailstock. 7. Repair spindle. 8. Reduce penetration rate to fall within physical limits of machine set up, but do not fall below feed threshold required to form a chip or speed threshold to cut material. 9. Use tougher grade tool steel with higher wear resistant coating (i.e. if using powder steel 15 use Powder steel 25. If using powder steel 25 use carbide.) Special coatings available on request. 10. Provide additional support for the workpiece. 11. Run coolant through holder when drilling greater than 1×D. 12. Increase coolant volume and pressure through the holder. 13. Reduce penetration rate to fall within coolant limitations, but do not fall below feed threshold required to form a chip or speed threshold to cut material 14. Add peck cycle to clear chips, do not remove insert from hole during peck. 11 Index 10 9 OIL 8 7 6 5 4 3 2 1
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