Instructions for Wire EDM Machining of Somma Throwaway Quick Change Form Tool Inserts 1/8" Thick

ALL RQC STYLE SHAVE TOOL HOLDERS ARE DESIGNED FOR A 12 DEGREE FRONT CLEARANCE ANGLE AND A 5 DEGREE TOP RAKE, THEREFORE, INSERTS MUST BE OFFSET AT 17 DEGREES IN RELATION TO THE TOP AND BOTTOM FACES WHEN BEING EDM MACHINED AND STEP CORRECTIONS CALCULATED ACCORDINGLY.

ALSO INSERTS MUST BE A PARALLELOGRAM FORM, THEREFORE, BACK SURFACE MUST ALSO BE AT 17 DEGREES PARALLEL TO FORMED FACE.

INSERTS ARE OVERSIZE ON LENGTH AND WIDTH TO ALLOW FOR EDM WIRE THICKNESS AND ARE RECESSED ON BACK END FOR  MOUNTING IN THE GRINDING FIXTURE SO THAT BACK EDGES CAN BE MACHINED AT THE SAME TIME AS FORMED SURFACE WITHOUT REMOVING FROM FIXTURE.

FIXTURE IS SUPPLIED WITH WEDGE CLAMP TO HOLD 8 INSERTS.

IMPORTANT: BACKUP ANVIL SHOULD BE EDMed SEPARATELY USING SPACERS TO HOLD IT IN FIXTURE.  ALSO CUTTING CONDITIONS SHOULD BE CHANGED SO AS TO LEAVE APPROXIMATELY 005" CLEARANCE ON ALL SIDE CUTTING SURFACES TO PREVENT SIDE RUBBING ON PART.

INSERTS SHOULD BE CAREFULLY MOUNTED IN FIXTURE AND TIGHTENED SECURELY WITH CLAMP SCREW.  BE CERTAIN THAT INSERTS ARE FULLY SEATED IN BOTTOM 17 DEGREE ANGLE BASE OF FIXTURE.  THIS IS IMPORTANT BECAUSE IF FACE ANGLES ARE NOT EXACTLY 17 DEGREES, THERE MAY BE DIAMETRAL DIFFERENCE ERRORS IN THE WORK PIECE.

ALSO, INSERTS SHOULD BE IN ALIGNMENT WITH EACH OTHER AND CLEARANCE ANGLE CUTOUT IN INSERT SHOULD BE CENTERED ON FIXTURE WITH EQUAL SPACE ON BOTH SIDES OF FIXTURE BODY.

WHEN WIRE EDMing WE RECOMMEND MACHINING ALL THE WAY AROUND THE FORM STARTING ON THE LEFT SIDE IN THE SPACE BETWEEN THE FIXTURE AND THE RECESS IN THE INSERT AND ENDING IN THE GROOVE ON THE OPPOSITE SIDE (SEE SAMPLE PRINT ATTACHED).  THIS GROOVE PREVENTS OUTER SHELL FROM BREAKING OFF AND JAMMING WIRE.  SHELL SHOULD BE BROKEN OFF MANUALLY AND ANY REMAINDER GROUND AWAY SO THAT IT DOES NOT INTERFERE WITH SEATING OF INSERT IN HOLDER.

OPPOSITE IS SHOWN A SAMPLE INSERT TOOL DESIGN FOR A RIGHT HAND CUTTING INSERT.  (NOTE THAT ON BROWN & SHARPE MACHINES, INSERT MAY HAVE TO BE LEFT HAND CUTTING AT TIMES. FIXTURE IS REVERSIBLE FOR LEFT HAND CUTTING INSERTS.)  IT IS IMPORTANT THAT OVERALL LENGTH BE HELD TO FOLLOWING DIMENSIONS:

WIDTH            LENGTH

3/8                    .630

 3/4                    .630

1-1/8                  .630

1-1/4                  .956

1-3/4                  .956

 

ENCLOSED ARE MASTER INSERT DESIGN SHEETS FOR INSERTS FOR RIGHT AND LEFT HAND CUT.  ADDITIONAL SHEETS ARE AVAILABLE UPON REQUEST.

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IS-47A. Throw Away Insert 3/4" Wide-Right Hand Cut


IS-47B. Throw Away Insert 3/4" Wide-Left Hand Cut


IS-47C. Throw Away Insert 1-1/8" Wide-Right Hand Cut


IS-47D. Throw Away Insert 1-1/8" Wide-Left Hand Cut Form Tool


IS-47E. Throw Away Insert 3/8" Wide-Right Hand Cut