Instructions for Wire EDM Machining of Somma Resharpenable Quick Change Form Tool Inserts 3/8" Thick -0 Top Rake

RQC0 DEG TOP RAKE STYLE FORM TOOL HOLDERS ARE DESIGNED FOR A 12 DEGREE FRONT CLEARANCE ANGLE AND A 0 DEGREE TOP RAKE, THEREFORE, INSERTS MUST BE OFFSET AT 12 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 12 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 TWO WEDGE CLAMPS:

CLAMP MARKED "4" IS USED WHEN HOLDING 3 INSERTS AND 1 SPACER.

CLAMP MARKED "3" IS USED WHEN HOLDING 3 INSERTS ONLY.

 

INSERTS SHOULD BE CAREFULLY MOUNTED IN FIXTURE WITH APPROPRIATE CLAMP AND TIGHTENED SECURELY WITH CLAMP SCREW.  BE CERTAIN THAT INSERTS ARE FULLY SEATED IN BOTTOM 12 DEGREE ANGLE BASE OF FIXTURE.  THIS IS IMPORTANT BECAUSE IF FACE ANGLES ARE NOT EXACTLY 12 DEGREES, THERE MAY BE DIAMETRAL DIFFERENCE ERRORS IN THE WORKPIECE.

 

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 PLACING THE SPACER IN THE MIDDLE POSITION AND 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 AT TIMES.  FIXTURE IS REVERSIBLE FOR LEFT HAND CUTTING INSERTS.)  IT IS IMPORTANT THAT OVERALL LENGTH BE HELD TO .956" AT ALL TIMES SO THAT CENTER HEIGHT OF HOLDER WILL NOT HAVE TO BE RESET WHEN CHANGING FROM JOB TO JOB.

 

ENCLOSED ARE MASTER INSERT DESIGN SHEETS FOR 1-1/4" WIDE INSERTS FOR RIGHT AND LEFT HAND CUT AND FOR 1-3/4" WIDE INSERTS FOR RIGHT HAND CUT ONLY.  ADDITIONAL SHEETS ARE AVAILABLE UPON REQUEST.