start. machine tool practices, ninth edition by richard r. kibbe, roland o. meyer, john e. neely,...

Machine Tool Practices, Ninth EditionBy Richard R. Kibbe, Roland O. Meyer, John E. Neely, Warren T. White

© 2010 Pearson Higher Education, Inc.Pearson Prentice Hall - Upper Saddle River, NJ 07458

ReamersReamers

REAMING IN THE DRILL PRESS tab

• Reamers are tools used mostly to Reamers are tools used mostly to precision precision finish,finish, enlargeenlarge or or align existing holes.align existing holes.

There are two types of reamers:There are two types of reamers:

1.1. Machine ReamersMachine Reamers

2.2. Hand ReamersHand Reamers



Machine ReamersMachine Reamers

REAMING IN THE DRILL PRESSREAMING IN THE DRILL PRESS tab

Fig. H-106 The parts of a machine reamer (Besly Cutting Tools, Inc.).

• Machine reamers have straight or taper shanks.Machine reamers have straight or taper shanks.

– The taper usually is a standard Morse taper.The taper usually is a standard Morse taper.



Common Machine Reamers


Fig. H-107 Cutting end of a machine reamer (Besly Cutting Tools, Inc.).

• The cutting end of a machine reamer is shown.



Common Types of Machine Reamers

• Chucking reamersChucking reamers are efficient in machine reaming a wide range of materials and are commonly used in drill presses, turret lathes, and screw machines.

– Cut on the chamfer at the end of the flutes, usually at a 45-degree angle.


Fig. H-110 Taper shank helical flute chucking reamer.

Fig. H-109 Straight shank helical flute chucking reamer.

Fig. H-108 Straight shank straight flute chucking reamer.• Helical flute reamers have extremely smooth cutting action to finish holes accurately & precisely.




• Jobber’s reamers are used where a longer flute length than that of chucking reamers is needed.

– Additional flute length gives added guide to the reamer, especially when reaming deep holes.


Fig. H-111 Taper shank straight flute jobber’s reamer.



Fig. H-112 Rose reamer.

The teeth are slightly backedoff, making the diameter smaller toward the shank end by about .001 in./in. of flute length.

Lands are ground cylindrically without radial relief, & all cuttingis done on the end of the reamer.


• The rose reamer is a roughing reamer used to enlarge holes to within .003 to .005 in. of finish size.

– Typically followed by a fluted reamer.





• Shell reamers are finishing reamers.

– More economically produced than solid reamers because a smaller amount of tool material is used in making them.


Fig. H-113 Shell reamer helical flute.

Fig. H-114Taper shank shell reamer arbor.

• Two slots in the shank end of the reamer fit over matching driving lugs on the shell reamer or box

– The hole in the shell reamer has a slight taper of 1/8” per foot in it to ensure exact alignment with the shell reamer.




• Morse taper reamers, with straight or helical flutes, are used to finish ream-tapered holes in drill sockets, sleeves, and machine tool spindles.


Fig. H-115 Morse taper reamer.




• Helical taper pin reamers are especially suitable for machine reaming of taper pin holes.

– Free-cutting action produces a good finish at high cutting speeds, and chips do not get packed in the flutes, which reduces the possibility of breakage.


Fig. H-116 Helical taper pin reamer.

Taper pin reamers have a taper of 1/4” per foot of lengthand are manufactured in 18 different sizes ranging from number 8/0 to number 10.




• Taper bridge reamers are used in structural ironor steel work, bridge work, and ship construction where extreme accuracy is not required.

– Long tapered pilot points make for easy entry in theout-of-line holes often encountered in structural work.


Taper bridge reamers are made with straight & helical flutes to ream holes with diameters from 1 /4” to 1-5/16”

Fig. H-117 Helical flute taper bridge reamer.



Fig. H-118 Carbide-tipped straight flute chucking reamer.


• Carbide-tipped chucking reamers are often used in production setups, particularly where abrasive materials or sand & scale are encountered.


Fig. H-119 Carbide-tipped helical flute chucking reamer, right-hand helix.

• A right-hand helix chucking reamer is recommended for ductile or highly abrasive materials, or when machining blind holes.




• A carbide-tipped left-hand helix chucking reamer will produce good finishes on heat-treated steelsup to RC 40.

– These reamers should be used only on through holes,as chips push out through the hole ahead of the reamer.


Fig. H-120 Carbide-tipped helical flute chucking reamer, left-hand helix.



Fig. H-121 Carbide-tipped expansion reamer.


• After becoming worn, expansion reamers can be expanded and resized by grinding.

– This offsets normal wear from abrasive materials & prolongs long tool life.

– They should not be adjusted for size by loosening or tightening the expansion plug, but only by grinding.




Hand Reamers

• Various types of hand reamers areVarious types of hand reamers are

A.A.Straight flutedStraight fluted

B.B.ExpansionExpansion

C.C.AdjustableAdjustable




Speeds

• Cutting speeds, which generally depend onCutting speeds, which generally depend on::

– Type of material being reamed.Type of material being reamed.

– Amount of stock to be removed.Amount of stock to be removed.

– Tool material being used.Tool material being used.

– Finish required.Finish required.

– Rigidity of the setup. Rigidity of the setup.


• The reaming speeds for most materials are The reaming speeds for most materials are about two-thirdsabout two-thirds of the speed used for drilling.of the speed used for drilling.



Speeds


• Class Activity:Class Activity:Calculate the speed for rose chucking Calculate the speed for rose chucking

reamer if 12 mm diameter of HSS drill reamer if 12 mm diameter of HSS drill used to make the hole on Aluminum plate used to make the hole on Aluminum plate and cutting speed is 92m/min? and cutting speed is 92m/min?



Feeds

• Feeds in reaming are usually two to three times Feeds in reaming are usually two to three times greater than those used for drilling. greater than those used for drilling.

– Feed varies with different materials, but a good Feed varies with different materials, but a good starting point would be between .0015 &.004” per starting point would be between .0015 &.004” per revolution. revolution.

– Too low a feed may “glaze” the hole, work hardeningToo low a feed may “glaze” the hole, work hardeningthe material, causing chatter & excessive reamer. the material, causing chatter & excessive reamer.

– Too high a feed tends to reduce the accuracy of theToo high a feed tends to reduce the accuracy of thehole & quality of the surface finish. hole & quality of the surface finish.




Reaming Problems

• When reamers gradually start cutting larger holes, work material may be galling or forming a built-up edge on reamer cutting surfaces.


Mild steel & some aluminum alloys are particularly troublesome inthis area.

Fig. H-123 Reamer teeth having built-up edges.



Taps

• Used to produce internal threads.Used to produce internal threads.• The drill press may be used for either hand or The drill press may be used for either hand or

machine tapping.machine tapping.

• Hand tapping is generally used when only a few Hand tapping is generally used when only a few holes are to be tappedholes are to be tapped..

• Machine tapping is preferred when many holes Machine tapping is preferred when many holes must be tapped.must be tapped.

TAPS IN THE DRILL PRESS



(1) Hand Taps1) Hand Taps : : are available in sets containing three taps: are available in sets containing three taps:

•Taper, Taper,

•Plug, and Plug, and

•BottomingBottoming

Types of Taps




(2) Machine Taps : used with power

1.Gun taps

2.Stub-flute tap

3.Helical-fluted taps

or

Spiral-fluted taps

4. Flute less tap

Types of Taps


Cutting Action



INCH :

Q. Calculate the tap drill size required for a 1-in. -8 NC thread.

Tap Drill Size (TDS):




Metric Taps

Metric taps are identified with the letter M followed by the nominal

diameter of the thread in millimeters times the pitch in millimeters.

Tap Drill Sizes for Metric Threads

The tap drill sizes for metric threads may be calculated by subtracting the pitch from the nominal diameter.

T.D.S. = D - P

For example: Calculate the tap drill size for an M12 X 1.75 thread.

T.D.S. = 12 - 1.75 = 10.25 mm

Tap Drill Size (TDS):




Speeds


• Class Activity:Class Activity:

Calculate the tap drill size for an M10 x 1.25 Calculate the tap drill size for an M10 x 1.25 threads? threads?



Thank Thank YouYou

start. machine tool practices, ninth edition by richard r. kibbe, roland o. meyer, john e. neely,...

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