Coupled Cavities -
| What are these things anyway? Why are they made that way and why
do they have to be to .0002 precision? Well, that is not the easiest question ever asked,
and certainly not a dumb one. Here is an attempt at an explanation. Step 1 - Before anything can be machined in a CNC environment, there needs to be a drawing of what the part will look like. We use two environments for this MasterCAM Mill 8.1, and/or AutoCAD 2000 |
| Every aspect has to be accounted for in the drawing, then the machinist decides on the tool, feed rates, and other factors considering the material, conditions in the room, amd finish requirements |
| You can see the the portion of the cavity plate that is
"coupled" to the other cavity. The small cavity is known as the coupling cavity
while the larger cavity is the Accelerator cavity. The volume of each cavity is extremely
important. Each side is tested with an RF probe. When we first made these they were made from 6061 Aluminum, which is inexpensive compared to the material the final piece will be made of, Glidcop. Glidcop is a 50% gold and 50% copper alloy. It has very predictable conductivity and can be machined to a very fine surface without polishing. Polishing is not allowed on this project due to the residual left by the polishing agents. Even Scotchbrite leaves an unwashable residue that will scrap the part. It must be finished with the tooling on the mill and not polished in any way. |
| Plenty of fluid is need to cut this part, Very little stock is removed at a time, even during the aluminum stage, to ensure that the cutter paths chosen by the CNC programmer will be appropriate for the expensive glidcop stock. A perfect program will be established on the aluminum model before the Glidcop stock is mounted on the Mill. Some operations, such as jig boring the cavity axes, requires a CNC Lathe instead of a CNC Mill. |
| With the Aluminum Model finshed and Past QA inspection, It's time to mount the Glidcop Stock on HAAS Mill.The exact same program is used that was used on the Aluminum model. The operator can change feed rates and other partameter as necessary during the machining steps |
| After the part has been Brazed with a gold alloy it is re-machined back to within .0002 of the original specifications. |
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