89 30 m/min 3800 2400 1500 1000 600 400 200 20 m/min 2500 1600 1000 600 400 300 200 20 m/min 2500 1600 1000 600 400 300 200 15 m/min 1900 1200 800 500 300 200 100 60 m/min 7600 4800 3000 1900 1200 800 500 40 m/min 5100 3200 2000 1300 800 500 300 35 m/min 4500 2800 1800 1100 700 400 300 25 m/min 3200 2000 1300 800 500 300 200 0,05 0,08 0,12 0,18 0,25 0,32 0,4 0,05 0,08 0,12 0,18 0,25 0,32 0,4 0,05 0,08 0,12 0,18 0,25 0,32 0,4 0,06 0,1 0,16 0,22 0,3 0,4 0,5 0,06 0,1 0,16 0,22 0,3 0,4 0,5 0,08 0,12 0,2 0,28 0,38 0,5 0,63 0,08 0,12 0,2 0,28 0,38 0,5 0,63 0,05 0,08 0,12 0,18 0,25 0,32 0,4 Heller uses selected HSS steels for its metal drill bits. At the same time, we focus on high-quality workmanship, ev- ident for instance in the precision grind of the tip and helix as well as the low run-out values. Heller always focuses on the demands of professional users. After all, all Heller prod- ucts contribute to faster and more cost-effective working for traders. HELLER QUALITY FOR PERMANENTLY OUTSTANDING RESULTS METAL DRILL BITS Material Cutting speed Rotational speed per minute for Ø Cooling lubricant 3 mm 4 mm 6 mm 10 mm 16 mm 25 mm 40 mm Non-alloy construction steel < 700 N/mm² Cooling lubricant emulsion Non-alloy construction steel > 700 N/mm² Cooling lubricant emulsion Alloy steel < 1000 N/mm² Cooling lubricant emulsion Cast iron Dry (compressed air) CuZn alloys Dry (compressed air) Al alloys Cooling lubricant emulsion Thermoplastics Water, compressed air Thermoset plastics Dry (compressed air) Material Feed speed in mm per revolution for Ø 3 mm 4 mm 6 mm 10 mm 16 mm 25 mm 40 mm Non-alloy construction steel < 700 N/mm² Non-alloy construction steel > 700 N/mm² Alloy steel < 1000 N/mm² Cast iron CuZn alloys Al alloys Thermoplastics Thermoset plastics SPEEDS & FEED SPEED TIPS AND TRICKS Removing chips during drilling Regularly pulling back (venting) the drill bit prevents chips from depositing in the helical of the drill bit. If the hole is not vented and hence the chips are not removed, the drill bit will jam in the hole and may crack. Material suitability The sharpness of the drill bit – and thus the cutting capability in metal and plastic – can be maintained over a prolonged period of time if the drill bits are handled with care. For this purpose, it is important not to use the tools in ceramics, ma- sonry or any other "unsuitable" materials. Guiding the drill Drilling with a box column drill creates precise holes and a straight progression of the drilling action. Drills with a hand- held drill require very accurate guiding. Cooling Drilling into harder material may cause the tools to heat up. The blade wear progresses more severely and the probability of cracks increases. For a longer service life it is important to supply a suitable coolant over the entire drilling time.