|
|
|
 |
 |
|
Page 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20
|
| TURNING BERYLLIUM COPPER |
Metal removal by turning is probably the most common method employed by industry to produce finished shapes. Beryllium copper is easily machined in all types of turning equipment, from the small engine lathes to automated CNC machines. All turning operations are performed satisfactorily with either high speed steel tools or carbide tools. The high speed steel tools are best employed where the production runs are short or the total amount of material to be removed is small.
Carbide tools are used to the best advantage when the cutting speeds and feeds are high, and the production quantities are large. Beryllium copper is easily sheared and cutting tools should be ground with generous positive rake angles. Zero or negative rake angles on the tools should be avoided when turning beryllium copper. Recommended speeds, feeds and tool geometries, for both high speed steel and carbide tooling, are listed in Table 1 for the tooling configuration shown in Figure 1. A carbide grade adjustment guide is provided in Appendix A. It is important to note that low feed rates (<0.005 in./rev) will work harden beryllium copper, changing its temper, decreasing its machinability and causing excessive tool wear.
The high material removal rate which can be achieved when machining beryllium copper sometimes presents chip removal problems. Beryllium copper alloys, in the A or H tempers (before heat treatment) tend to form long, stringy, tough chips which may cause handling problems. With single point tools, this problem can be overcome by using chip breakers. Chip breakers curl and break the chips, making them easier to handle, and should be used whenever possible. The chips produced when machining Alloy M25 material or material in the AT or HI condition (heat treated) break up and are easily handled.
The various chip breaker configurations are shown in Figure 2.
Although turning operations can be performed without cutting fluids, tool life and surface finish can be improved by using any of the coolants recommended earlier. Heavy duty soluble emulsion and mineral-lard oil mixtures should be used for critical form tool applications. It is important to note that recommended cutting speeds should be reduced 25% when turning dry. |
| SINGLE POINT TURNING TOOLS - FIGURE 1 |
|
|
|
