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| REAMING BERYLLIUM COPPER |
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Reaming is a hole sizing operation and should only be included in the machining process when holes of close dimension or good finish are required. For best results, the reamer should be held in a floating holder so that it is free to follow the previously drilled or bored hole. The hole diameter should be sized so that the reamer has sufficient material
into which it can cut. An excess of .005 to .010 inch on a side is recommended.
The tendency is to use a very slow feed when performing reaming operations. This is generally done to produce a smooth surface finish. It is important to note that, being a work hardenable material, beryllium copper will tend to harden at the surface which is in contact with the cutting edges of the reamer. This, in turn, makes it more difficult to cut. A feed rate between and .010 in./rev will minimize this hardening effect. Feed rates below .002 in./rev can be |
REAMER CONFIGURATION - FIGURE
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used when the material is in the AT or HT temper since
this material is already in the hardened state and the effect of
cold working will be minimal.
To maximize the life of the reamer and the quality of the reamed holes produced, a cutting fluid should be used in copious amounts. In addition to cooling the reamer, an adequate supply of coolant will also facilitate chip removal.
Recommended speeds, feeds and reamer configuration are shown in Table 4 and Figure 5. |
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| Recommended reaming parameters - Table 4 | ||||||||
| ALLOY | TEMPER | SPEED (ft./min.)* | FEED (in./rev)* | MARGIN WIDTH (in.) | CHAMFER ANGLE | CHAMFER LENGTH MAX. (in.) | CHAMFER RELIEF ANGLE | RADIAL RAKE |
| 25, M25M 165 | A, H | 100-300 | .002-.010 | .005 | 40° | 3/32 | 6-10° | 5-10° |
| AT, HT | 50-200 | .002-.010 | .015 | 40° | 3/32 | 6-10° | 5-10° | |
| 3, 10 | A, H | 200-600 | .002-.010 | .005 | 30-50° | 3/32 | 5-10° | 5-10° |
| AT, HT | 125-500 | .002-.010 | .015 | 30-50° | 3/32 | 5-10° | 5-10° | |
| 275C, 245C, 20C, 21C, 165C | C, A | 100-300 | .002-.010 | .005 | 40° | 3/32 | 6-10° | 5-10° |
| CT, AT | 50-200 | .002-.010 | .015 | 40° | 3/32 | 6-10° | 5-10° | |
| 3C, 10C | C, A | 200-600 | .002-.010 | .005 | 40° | 3/32 | 5-10° | 5-10° |
| CT, AT | 125-500 | .002-.010 | .015 | 40° | 3/32 | 5-10° | 5-10° | |
| *Speeds and feeds should be reduced when using reamers smaller than about 3/16" diameter. | ||||||||
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