| Every sinker EDM needs to have electrodes in order | | | | all in the quest for finer finishes and less wear. |
| to do any machining, and usually these are made with | | | | Different substrates perform differently from one |
| carbide cutters. Very often, they are manufactured in | | | | another. Some are better for high speed machining, |
| a high speed milling machine that uses an enormous | | | | while others are designed for roughing operations. One |
| variety of carbide end mills and inserts. | | | | company even boasts that their cutter has 70 |
| Some electrodes are made by turning or grinding, but | | | | coatings applied to each individual carbide insert. |
| the vast majority are cut on a milling machine, or | | | | When cutting electrodes out of Telco copper the |
| machining center. The new high speed machines are | | | | carbide leaves an excellent surface finish. Because this |
| specially designed for electrode manufacture and have | | | | material is not nearly as abrasive as graphite, the |
| eliminated the need for an industrial dust collector as | | | | cutters last much longer. The big drawback to copper, |
| well. | | | | however, is that it tends to leave a burr on the |
| The graphite dust, such as comes from Poco graphite, | | | | electrodes. This requires hand working to remove the |
| is confined to the milling machine and vacuumed away | | | | burrs, which is an added operation and expense. |
| by the negative pressure chamber surrounding the | | | | A few of the top carbide tooling companies are: |
| spindle. | | | | Ingersoll, Sandvik, Iscar, Valenite, and Walter. These |
| In the not so distant past, high speed steel cutters | | | | world class suppliers have research and development |
| were the typical end mill used, but as EDM became | | | | departments that are dedicated to pushing the |
| more commonplace, carbide cutter began dominating | | | | technology ever forward. |
| the scene. Now, many companies have developed | | | | Because of the brittle nature of carbide, care must be |
| proprietary methods of coating different substrates of | | | | taken to use the correct speeds and feeds, and to |
| carbide to achieve speeds and feeds unheard of not | | | | have a vibration free spindle and vise. Any chatter will |
| so many years ago. | | | | tend to break or chip the cutting edge, thus leaving |
| There are many coatings available from many | | | | cutter marks on the electrodes. |
| different companies. Some of the more popular include: | | | | Coated carbide inserts perform extremely well, but |
| TiN, Ai204, TiC, ZrCN, TiAIN and TiCN. There are also | | | | they are expensive. For this reason, it is extremely |
| diamond coated carbide end mills, CBN coated ball end | | | | important to follow the manufacturers |
| mills. Newer coatings are being developed all the time, | | | | recommendations when cutting graphite or copper. |