b'\x1b\x1a\x19 \x1f\x18\x1d\x17\x16Shop OperationsFULL-DIAMETER SLOTTING OF STEELBy John SaundersF ull-diameter slotting is not the preferred method for remov-ing large amounts of material, but sometimes part geometry makes slotting the bestor onlyop-tion. ProvenCut recipe 551 shows how to achieve a high material re-moval rate while maintaining a reli-able cut using a light-duty machine with a 6.35 mm (0.25") endmill to slot 4140 alloy steel.When developing this slotting recipe, we adjusted the spindle speed, feed rate and DOC with the goal of creating a dependable,RECIPE ID: 551productive process. We discovered that maximizing the DOC did not maximize the MRR. Rather, the rec- Machine:Tormach 1100MXipe that achieved the best balanceCNC millof removal rate and reliability was atTool: Niagara Cutter6.35 mm,a 6.35 mm axial DOC (A p ). The re- four-flute endmillsult was an MRR of 15,403.84 mm 3 / Material:4140 alloy steelmin. (0.94 in. 3 /min.). Our initial hy- Cut type:slottingpothesis that a larger axial engage-ment would lead to a higher MRR was wrong. Reducing the A pfrom 200% to 100% allowed an increase in the feed rate that resulted in a 30% higher MRR. contact points that an endmill hasa 12.7 mm DOC has two contact Two notable differences betweenwith the workpiece material. A 6.35points and produces two chips at the 6.35 mm and 12.7 mm (0.5")mm axial DOC results in one con- a time.axial DOCs are enhanced chip evac- tact point with the material and pro- More points of contact can help uation and the number of radialduces one chip at a time, whereasstabilize a tool when using adap-about the authorctemag.comJohn Saunders owns Saunders MachineTo view a video of the slotting Works LLC, Zanesville, Ohio, and foundedoperation at www.ctemag.com, ProvenCut, a website with a videoscan the QR code with your library of speeds and feeds. For moresmartphone or enter this URL on information, visit www.provencut.com,your web browser: cteplus.delivr.www.saundersmachineworks.com orcom/2n4xtwww.nyccnc.com.18JUNE 2020ShopOps.indd 18 5/14/20 12:30 PM'