Cuttermasters Professional JXT - Page 14

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CUTTERMASTER Professional JXT User’s Manual
Page 14
Types of Relief
Endmillscanbesharpenedwiththreedi󰀨erenttypesofreliefonthediameter:
 1. aconcave,almostatsurfaceisproducedwiththefaceofaplainwheel;
 2. aatreliefsurfaceisproducedwithacupwheel.
3. a radial or eccentric relief is produced by presenting the face of a plain wheel at an
  angletothecuttingaxisofahelical-utedendmillorbydressinganangleontheface
of a wheel rotating on a parallel axis.
Eccentricreliefproducesarelativelynecuttingedgefreefromminutenicksandasaresultisstron-
gerthanthoseproducedbyothermethods.Anotherbenetofthismethodofre-grindingisthata
secondary clearance is not needed. If the grinding wheel face width is maintained so that it is wider
than the relieved land (measured in an axial direction), wide primary lands are possible without dan-
geroftheheelofthelandcontactingthenishedsurfaceproducedwhentheendmilliscutting.This
is due to the fact that the clearance angle formed by the curve or angle on the wheel increases as it
progresses further from the cutting edge. Most manufacturers, however, consider it good practice to
provide a secondary clearance on end mill teeth, except on the smallest size of cutters.
Onecautiontobeobservedifsingleclearanceisused,isthataverylightnishinggrindmustbe
takenbecauseofthelongerlineofcontactbetweenthewheelandtheendmill.Heavynishingcuts
inviteburning,causeaccuracytobesacricedandcancausethediametertobereducedmorethan
necessary.
Test Tools
A grinding project is like all other operations in a machine shop, in that it may be unadvisable to take
trialcutsonanishproduct.Forthisreasonitisgoodtohavesetuportestcuttingtoolskeptaside
totestanglesandnishespriortogrindingthenalproduct.