Page 2 - Spring 2024
P. 2

EDM Today Magazine                           EDM Today Magazine                            EDM Today Magazine


                                                                                    SPRING 2024











   EDM Today Magazine                           EDM Today Magazine                            EDM Today Magazine







          ELECTRODE BLANK



          SPECIFICATION AND INSPECTION


   EDM Today Magazine                           EDM Today Magazine                            EDM Today Magazine


             Shops that utilize Sinker EDM commonly order elec-
             trode blanks that are subsequently transformed into
             fi nish electrodes. It has been my experience that, often
             when ordering electrode blanks, insuffi cient attention
             is paid to how these blanks are specifi ed on the order
             or the RFQ. In like manner, it has also been my experi-
             ence that insuffi cient attention is paid to the inspection
             of  those blanks when they are received, prior to fur-
             ther processing. This article will attempt to shed light
   EDM Today Magazine                           EDM Today Magazine                            EDM Today Magazine
             on both areas as many an EDM shop has been beset
             by the expensive and embarrassing consequences of
             precious electrode machining time wasted or scrapped
             EDM’d parts due to electrode blank issues.



          Electrode Blank Specifi cation

          Recently, I was asked by a client to inspect some electrode blanks they had ordered. As is my practice, prior to
          beginning an inspection, I require both the written purchase order along with the vendor’s packing slip for the item in
          question. In this case the purchase order specifi ed:
   EDM Today Magazine                           EDM Today Magazine                            EDM Today Magazine
                                          (24) Graphite electrode blanks: 1” x 2” x 3”
          The packing list specifi ed:
                           24 – KK10 electrode blanks: 1.000 +/-.005” x 2.000 +/-.005” x 3.000 +/-.005”

          What the subsequent inspection revealed was:
                       Ground graphite blanks made from an unknown grade that were .996” x 1.997” x 2.998”

          Upon further inquiry, I discovered that the client expected the blanks to be fl at, parallel, perpendicular and sized to
          within .0002” and made from Mersen DS4 graphite.
          Obviously, this created a real problem with multiple culprits, but the primary responsibility for this disaster lies with
   EDM Today Magazine                           EDM Today Magazine                         EDM Today, Spring 2024 Issue
                                                                                              EDM Today Magazine
          the insuffi cient specifi cations indicated on the client’s purchase order, as virtually any pieces of graphite would have
          met the purchase order specifi cations provided to the vendor.
          26
   1   2   3   4   5   6   7