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| DRILLING BERYLLIUM COPPER |
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Drilling operations are performed easily on all of the beryllium copper alloys. This applies regardless of material hardness, assuming good machining practices (such as tool rigidity, tool sharpness, ample cutting fluid and the proper speed and feed rates). Standard off-the-shelf high speed tool steel drills will perform satisfactorily for most drilling operations and material conditions. Coated tools provide the advantage of extended life.
When drilling operations are performed on castings which are in the solution heat treated and aged (AT) condition, the drills should be shortened as much as possible to increase rigidity. A special point called a brass point (Figure 3) should be ground on the drill. This effectively reduces the helix angle to about 5°, and produces a much stronger cutting edge. Brass points are also recommended when drilling beryllium copper in the hardest tempers if chipping or breaking of the drill is a problem. Drills perform best when a constant speed and feed are applied. |
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DRILL
CONFIGURATIONS - FIGURE 3 |
| Beryllium copper will tend to work harden and become more difficult to drill if the drill point is allowed to rub or if the feed rate is too low.
Cutting fluid should be used for all drilling operations. The cutting fluid acts as a coolant, a lubricant, and an aid in chip removal. An active oil or a chemical emulsion is recommended.
Recommended speeds, feeds and drill configuration are shown in Table 2 and Figure 3. |
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Recommended drilling parameters and tool configurations - Table 2 |
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| ALLOY | TEMPER | CUTTING SPEED (ft./min.) |
FEED RATE (in./rev) |
HELIX ANGLE | POINT ANGLE | LIP RELIEF | POINT TYPE | TOOL MATERIAL |
| 25, M25, 165 | A | 200-350 | .002-.009 | 29° | 118° | 12° | Plain | HSS |
| H | 150-300 | .002-.009 | 29° | 118° | 12° | Plain | HSS | |
| AT, HT* | 100-300 | .002-.009 | 29° | 118° | 12° | Plain | HSS | |
| 3, 10 | A, H | 200-600 | .002-.005 | 29° | 118° | 12° | Plain | HSS |
| AT, HT* | 125-500 | .002-.005 | 29° | 118° | 12° | Plain | HSS | |
| 275C, 245C, 20C, 21C, 165C | C, A | 100-250 | .002-.005 | 29° | 118° | 12° | Plain | HSS |
| CT, AT* | 75-100 | .002-.005 | 29° | 118° | 12° | Brass | HSS | |
| 3C, 10C | C, A | 100-500 | .002-.005 | 29° | 118° | 12° | Plain | HSS |
| CT, AT | 75-200 | .002-.005 | 29° | 118° | 12° | Plain | HSS | |
| * Standard off the shelf HSS drills will perform satisfactorily and no alterations are necessary with the exception of the "brass point" which should be used when drilling these materials. | ||||||||
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