Vertical Mill Operations Unit 62

Objectives Align the vertical head and vise to within ±.001 in. (0.02 mm) Insert and remove end mills from spring collets Accurately machine a block square and parallel Drill holes to an accurate location

Vertical Milling Machine Versatile and easy setup Performs wide variety of operations End milling, face milling Keyway and dovetail cutting T-slot and circular slot cutting Gear cutting, drilling, boring, reaming Cutting tools used relatively small so cost lower

Aligning the Vertical head Head must be square to table (90º) Procedure to check spindle alignment Mount dial indicator on suitable rod, bent at 90º and held in spindle Position indicator over front Y axis of table Carefully lower spindle until indicator button touches table and dial indicator registers no more than ¼ revolution; set bezel to zero; Lock spindle in place

Carefully rotate spindle 180º by hand until button bears on opposite side of table; Compare readings If differences, loosen locking nuts on swivel mounting and adjust head until indicator registers approximately ½ difference between two readings; Tighten locking nuts Recheck accuracy of alignment Rotate vertical mill spindle 90º and set dial indicator as in step 3

Rotate machine spindle 180º, check reading at other end of table If two readings do not coincide, repeat step 5 until readings are same Tighten locking nuts on swivel mount Recheck readings and adjust if necessary  

Aligning the Vise When vise aligned on vertical milling machine, dial indicator may be attached to quill or head by clamps or magnetic base Same method of alignment followed as outlined for aligning vise on horizontal milling machine

Collets Hold end mills, cutting tools and accessories in machine spindle Spring collet Pulled into spindle by draw-bar that closes on cutter shank Driven by means of friction between collet and cutter Solid collet More rigid Pulled into spindle by draw-bar Driven by setscrews that bear against flats of cutter shank Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

To Mount a Cutter in a Spring Collet Shut off electric power to machine Place proper cutter, collet, and wrench on piece of masonite, wood, or soft plastic on table Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Clean taper in machine spindle Place draw-bar into hole in spindle top Clean taper and keyway on collet Insert collet into spindle bottom, press up, and turn until keyway aligns with key in spindle Hold collet up with one hand and with other, thread draw-bar clockwise into collet Hold cutting tool with cloth and insert it into collet for full length of shank Tighten draw-bar into collet (clockwise) by hand Hold spindle brake lever and tighten draw-bar tightly as possible with wrench

Procedure to Remove Cutter from a Collet Operation for removing cutting tools similar to mounting, but in reverse order Shut off electric power to machine Place piece of masonite, wood, or soft plastic on machine table to hold necessary tools Pull on spindle brake lever to lock spindle, loosen draw-bar with wrench (counterclockwise)

Loosen draw-bar, by hand, only about three full turns Hold cutter with cloth With soft-faced hammer, strike down sharply on head of draw-bar to break taper contact between collet and spindle Remove cutter from collet Clean cutter and replace it in its proper storage place where it will not be damaged by other tools

To Mount a Cutter in a Solid Collet Shut off electric power to machine Place cutter, collet, and necessary tools on piece of masonite, wood, or soft plastic on machine table Slide draw-bar through top hole in spindle Clean spindle taper and taper on collet

Align keyway or slots of collet with keyway of drive keys in spindle, insert collet into spindle Hold collet up in spindle and thread draw-bar clockwise with other hand Pull on brake lever and tighten draw-bar as tightly as possible with wrench Insert end mill into collet until flat(s) align with setscrew(s) of collet Tighten setscrews securely using hand pressure only

Procedure to Machine a Flat Surface Clean vise and mount work securely in vise, on parallels if necessary Check that vertical head square with table Select cutter that will just overlap edges of work Set proper spindle speed for size and type of cutter and material being machined; check cutter rotation

Tighten quill clamps Start machine, and adjust table until end of work under edge of cutter Raise table until work surface just touches cutter. Move work clear of cutter. Raise table about .030 in. and take trial cut for approximately .250 in. Move work clear of cutter, stop cutter, measure work Raise table desired amount; lock knee clamp Mill surface to size using auto feed

Machining a Block Square and Parallel Important that each side be machined in definite order Machining Side 1 Clean vise thoroughly and remove all burrs from workpiece, vise and parallels Set work on parallels in center of vise with largest surface (side 1) facing up

Place short paper feelers under each corner between parallels and work Tighten vise securely With soft-faced hammer, tap workpiece down until all paper feelers are tight Mount fly cutter in milling machine spindle Set machine for proper speed for size of cutter and material to be machined Start machine and raise table until cutter just touches near right-hand end of side 1

Move work clear of cutter Raise table about .030 in. and machine side 1 using steady feed rate Take work out of vise and remove all burrs from edges with file Machining Side 2 Clean vise, work, and parallels thoroughly Place work on parallels, if necessary, with side 1 against solid jaw and side 2 up

Place short paper feelers under each corner between parallels and work Place round bar between side 4 and movable jaw Tighten vise securely and tap work down until paper feelers are tight Follow steps 8 to 11 and machine side 2 Machining Side 3 Clean vise, work, and parallels thoroughly

Place side 1 against solid vise jaw, with side 2 resting on parallels if necessary Push parallel to left so that right edge of work extends about .250 in beyond parallel Place short paper feelers under each end of corner between parallels and work Place round bar between side 4 and movable jaw, making sure round bar in center of amount of work held inside vise Tighten vise securely and tap work down until paper feelers are tight

Start machine and raise table until cutter just touches near right-hand end of side 3 Move work clear of cutter and raise table about .010 in. Take trial cut about .250 in. long, stop machine, and measure width of work Raise table required amount and machine side 3 to correct width Remove work and file off all burrs

Clean vise, work, and parallels thoroughly Machining Side 4 Clean vise, work, and parallels thoroughly Place side 1 down on parallels with side 4 up and tighten vise securely Round bar not required on side 4 Place short paper feelers under each corner between parallels and work Tighten vise securely Tap work down until paper feelers tight Follow steps 24 to 27 and machine side 4 to correct thickness

Machining the Ends Square Two common methods Short pieces held vertically in vise and machined with end mill or fly cutter Long pieces held flat in vise, one end extending past end of vise; end surface cut square with body of end mill Procedure for Short Work Set work in center of vise with one end up and tighten vise lightly

Hold square down firmly on top of vise jaws and bring blade into light contact with side of work Tap work until edge aligned with blade of square Tighten vise securely and recheck squareness of side Take about .030 in. deep cut and machine end square Remove burrs from end of machined surface

Clean vise and set machined end on paper feelers in bottom of vise Tighten vise securely and tap work down until paper feelers are tight Take trial cut from end until surface cleans up Measure length of workpiece with depth micrometer Raise table required amount and machine work to length

Procedure to Machine an Angular Surface Lay out angular surface Clean vise Align vise with direction of feed Utmost importance Mount work on parallels in the vise Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Swivel vertical head to required angle Tighten quill clamp Start machine and raise table until cutter touches work Raise table until cut desired depth Take trial cut for about .50 in. Check angle with protractor If angle correct, continue cut Machine to required depth, taking several cuts if necessary

Alternate Method Milling an Angular Surface Check if vertical head is square with table Clean vise Lock quill clamp Set workpiece in vise with layout line parallel to top of vise jaws and about .250 in. above them Adjust work so cut will start at narrow side of taper and progress into thicker metal

Check to see that cut and layout line parallel Take successive cuts of about .125 to .150 in. or until cut is about .030 in. above layout line Check to see that cut and layout line parallel Raise table until cutter just touches layout line Clamp knee at this setting Take finishing cut  

Milling Hardened Steel with PCBN Tools PCBN blank tools and inserts widely used in general machining and tool and die work Consistent part accuracy, cool-cutting features, and high productivity Can be used on abrasive and difficult-to-cut metals (alloy, tool steel hardened above 45 Rc)

Factors to Consider Before Using PCBN or Other Cutting Tool Select milling machine that is in good working order Know machine's capabilities Select proper toolholder and tool grade, and follow tool preparation procedures Calculate proper speed, feed, depth of cut Follow recommended setup and machining sequence

Preparation for PCBN Milling Interactive Superabrasive Machining Advisor Software supplied by GE Superabrasives used for selection of PCBN tool and machining conditions To use effectively must know following: Material hardness, machine horsepower, maximum spindle speed, maximum table feed, depth of cut and surface finish Software recommends: Tool grade, tool edge preparation, tool geometry, surface speed and r/min, feed per tooth and in./min and coolant

Machining the Part For procedure listed in the following slides assume the following: Piece of alloy steel hardened to 53-55 Rc Standard vertical milling machine with 2 HP spindle 2.0 in diameter facemill with R-8 shank, containing single PCBN insert with geometry of CNMA 433 Insert had edge chamfer of 15º x .008 in. with .001 in. hone Insert grade was BZN® 6000 used without coolant Depth of cut of .020 in. at 500 sf/min, feed rate .006 in.

Machine Setup Set machine spindle to recommended r/min Set table feed to recommended feed in in./min Fasten single PCBN insert into proper toolholder Fasten cutter into machine spindle and lock quill in up position to ensure rigidity Tighten all table locks except table machining axis

Use .010 in. plastic shim to set tool to top of part surface Move table so cutter clears part and raise knee the thickness of shim plus desired depth of cut Feed table and machine the part surface Do NOT traverse back across part until knee lowered or table moved off part to prevent tool chipping Reposition and take additional passes until part machined to size

Producing and Finishing Holes Location of holes, slots, etc. can be located accurately by using micrometer collars on table feed screws Holes can be drilled 90º to work surface, or any angle that head can be swiveled Procedure to Drill Holes at 90º Mount work in vise, or clamp to table; work must be supported by parallels

Mount drill chuck in spindle Mount center finder in drill chuck Adjust table until center-punch mark of hole to be drilled is in line with tip of rotating center finder or Locate center of machine spindle on two adjacent edges of workpiece and move table to hole location using table feed screw micrometer collars Tighten table and saddle clamps

Stop machine and remove center finder Mount center drill in drill chuck Extend only .50 in. to prevent breakage Set spindle speed to ~1000 r/min, and feed center drill with quill handfeed lever until about half of angular portion enters work Mount drill size required in drill chuck Set depth stop so that drill just clears bottom of workpiece to prevent drilling into machine table

Set machine to proper speed and feed if automatic feed to be used for drilling hole Apply cutting fluid and use quill handfeed lever, or automatic feed, to drill hole

To Drill Angular Holes Angular holes drilled by swiveling head to required angle and feeding drill into work by using quill handfeed lever Procedure Mount work in vise, or clamp it to machine table Loosen lock nuts and swivel milling head to required angle of hole to be drilled

Tighten lock nuts, recheck accuracy of setting Check angle of head by graduations on housing, or with bevel, or vernier protractor Tighten lock nuts, recheck accuracy of setting Mount drill chuck in spindle Mount center finder in drill chuck Locate center of spindle as close as possible to where hole is to be drilled Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Lower table so there is enough room between spindle in up position and top of work to mount longest drill required for drilling operation Lock knee of machine in position and do not move it Adjust table until center-punch mark of hole to be drilled is in line with tip of rotating center finder OR Locate center of machine spindle on two adjacent edges of workpiece and move table to hole location using table feed screw micrometer collars

Tighten table and saddle clamps Stop machine, raise spindle to top position with quill handfeed lever, and remove center finder Insert large center drill or spotting tool into drill chuck Set spindle speed for size of spotting tool to be used Spot each hole location so top of hole slightly larger than size of hole to be drilled

When more than one angular hole must be drilled, wise to record crossfeed and table micrometer collar locations of each hole Stop machine and remove spotting tool Insert correct-size drill into drill chuck Set speed and feed for each hole to be drilled Drill each hole to required depth Remove all burrs from hole edges with file and scraper

To Ream on a Vertical Mill Purpose of reaming is to bring drilled or bored hole to size and shape and produce good surface finish in hole Accuracy affected by speed, feed, and reaming allowance Speed generally about ½ of drilling speed Allowance: .250 in for holes up to .500 in in diameter, .030 in. for holes over .500 in. Two types of reamers: rose (fluted) and precision end-cutting

Procedure To Ream on a Vertical Mill Mount reamer in spindle or drill chuck Set speed and feed for reaming Apply cutting fluid as reamer fed steadily into hole with downfeed lever Stop machine spindle Remove reamer from hole

To Bore on a Vertical Mill Boring is operation of enlarging and truing drilled or cored hole with single-point cutting tool Offset boring chuck allows accurate settings Procedure Align vertical head square (90º) to table Set up and align work parallel to table travel

Align center of milling machine spindle with reference point or edges of work Set graduated micrometer dials on crossfeed and table screws to zero Calculate coordinate location for hole Move table so center of spindle aligns with hole location required Lock all table clamps to keep position Spot hole location with center drill or spotting tool

Drill holes under. 500 in. diameter to within. 015 in Drill holes under .500 in. diameter to within .015 in. of finish size; holes over .500 in. diameter to within .030 in. of size Mount boring chuck using largest boring bar or tool possible Rough bore hole to within .005 to .007 in. of finish size Finish boring hole to required size

To Tap a Hole on Vertical Mill Can be performed either by hand or with use of tapping attachment Procedure Mount work in vise, or clamp it to machine table Mount center drill in drill chuck, adjust machine table until center-punch mark on work aligns with point of center drill

Drill hole to correct tap drill size for size of tap to be used With center drill spot each hole to be tapped to slightly larger than tap diameter Drill hole to correct tap drill size for size of tap to be used Mount stub center in drill chuck Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Fasten tap wrench on correct-size tap and place it into hole Lower spindle using quill handfeed lever until stub center point fits into center hole in end of tap shank Turn tap wrench clockwise to start tap into hole; at same time, keep stub center in light contact with tap by applying pressure on handfeed lever Continue to tap hole while keeping tap aligned by applying light pressure on handfeed lever

Slots and Keyseats May be cut in shafts more easily on vertical milling machine, using a two- or three-fluted end mill Procedure for Cutting Layout position of keyseat on shaft, and scribe reference lines on end of shaft Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Secure workpiece in vise on parallel Using layout lines on end of shaft, set up shaft so that keyseat layout is in proper position on top of shaft Mount a two- or three-fluted end mill of diameter equal to width of keyseat, in milling machine spindle If two blind ends, two- or three-lip end mill must be used Center workpiece by carefully touching cutter to one side of shaft May place piece of thin paper between shaft and cutter

Lower table until cutter clears workpiece Move table over amount equal to half diameter of shaft plus half diameter of cutter plus thickness of paper Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

If keyseat being cut has two blind ends, adjust work until end of keyseat aligned with edge of cutter Feed cutter down (or table up) until cutter just cuts to its full diameter Adjust dept of cut one-half thickness of key, and machine keyseat to proper length

Calculating Depth of Keyseats If keyseat at end of shaft, proper depth of keyseat checked by measuring diametrically from bottom of keyseat to opposite side of shaft h = height of the segment above the width of the keyseat W = width of keyseat D = diameter of shaft H = distance from bottom of keyseat to opposite side of shaft Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Woodruff Keys Used when keying shafts and mating parts Woodruff keyseats can be cut more quickly than square keyseats Semicircular in shape and can be purchased in standard sizes designated by E numbers Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Woodruff Keyseat Cutters Have shank diameters of ½ in. for cutters up to 1 ½ in. in diameter Cutters over 2 in. in diameter mounted on arbor Size stamped on shank Last two digits indicate nominal diameter in eighths of inch Preceding numbers nominal width of cutter in thirty-seconds of an inch Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Procedure to Cut a Woodruff Keyseat Align spindle of vertical milling machine 90º to table Lay out position of keyseat Set shaft in vise of milling machine or on V-blocks Mount cutter of proper size in spindle

Start cutter, touch bottom of cutter to top of workpiece Set vertical graduated feed collar to zero Check cutter rotation Move work clear of cutter Raise table half diameter of work plus half thickness of cutter Lock knee at setting Position center of slot with center of cutter Lock table in position

Touch revolving cutter to work Cut keyseat to proper depth Set crossfeed screw collar to zero Cut keyseat to proper depth Note: Keyseat proportions may be found in any handbook.