TABLE OF CONTENTS Few published sources recommend countersinking speeds or feeds or discuss tool life. This chapter concentrates on each of those topics beginning with general practice and moving to details for specific tool designs or materials.
A confusing array of recommendations faces the user who diligently digs for information on countersinking feeds and speed. Table 4.1 is one of the few broad-based recommendations for a variety of materials and standard countersink designs. When using the suggested speeds it is best to start at the lower end of the range. Increase speeds as necessary up to the maximum. When countersink tools are run too fast, chatter may become a problem and cutting edges may overheat and dull prematurely.
| Recommended surface speed (sfpm) | ||
|---|---|---|
| Material | HSS cutter | Carbide cutter |
| Aluminum/aluminum alloys | 150-250 | 300-500 |
| Brass/bronze (ordinary) | 75-125 | 150-250 |
| Iron - cast (soft) | 75-125 | 125-225 |
| Iron - cast (medium hard) | 50-100 | 100-175 |
| Iron - hard-chilled | 10-20 | 20-35 |
| Iron - malleable | 80-90 | 90-150 |
| Magnesium/magnesium alloys | 125-250 | 250-400 |
| Monel, high nickel steel | 30-50 | 50-75 |
| Plastics, bakelite | 100-250 | 250-400 |
| Steel - mild (0.2-0.3 carbon) | 80-100 | 120-170 |
| Steel - mild (0.4-0.5 carbon) | 70-80 | 80-150 |
| Steel - tool (1.2 carbon) | 50-60 | 60-100 |
| Steel - Forgings | 40-50 | 50-80 |
| Steel - alloy (300-400 Brinnell) | 20-30 | 30-50 |
| Steel - high tensile (35-40 Rc) | 30-40 | 40-60 |
| Steel - high tensile (40-45 Rc) | 25-35 | 35-55 |
| Steel - high tensile (45-50 Rc) | 15-25 | 25-40 |
| Steel - high tensile (50-55 Rc) | 7-15 | 15-20 |
| Stainless steel... |
