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Cutting Tools
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Reamers |
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Reamers are available upto finish holes to
H7 tolerance. Reaming has always been considered
a finishing process and drilling a roughing
process. Today, however, many tolerances that
used to need a reaming process, can now be
met by high-tech drills, such as in the CDX
and ADX ranges.
Most common Reamers have
a left hand helix because the main application
is in through holes requiring chips to be
pushed forward. For blind holes, Reamers with
straight flutes or right hand reamers are
recommended.
Reamers only cut on the
bevel and taper leads; the lands on the body
do not cut. They are normally designed with
an uneven pitch and an even number of teeth
to prevent chatter and ensure good hole surface
finish and roundness. They include Hand, Chucking
and Machine Reamers with straight or Morse
taper shanks. They are available in different
materials, including carbide which offers
the greatest resistance to wear. Carbide reamers
are successfully used to cut steels on rigid
machine set ups, but often, High Speed Steel
designs will be more cost effective. |
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General
hints on Reaming |
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To
obtain the best results when using reamers
it is essential to make them 'work'.
It is a common fault to prepare holes
for reaming with too little stock left
in. If insufficient stock is left in
the hole before reaming then the reamer
will rub quickly, show wear and will
result in loss of diameter. It is equally
important for performance not to leave
too much stock in the hole. (See Stock
Removal).
Select
the optimum type of reamer and the
optimum speeds and feeds for the application.
Ensure that pre-drilled holes are
the correct diameter.
The
workpiece must be held rigid and the
machine spindle should have no play.
The
chuck in which a straight shank reamer
is held must be good quality. If the
reamer slips in the chuck and the
feed is automatic, breakage of the
reamer may occur.
When
driving a Morse Taper Shank reamer
into a socket, sleeve or machine spindle,
always use a soft faced hammer. Make
sure there is a good fit between the
reamer shank and the sleeve or socket
otherwise misalignment will occur
and the reamer may cut oversize.
Keep
tool overhang from machine spindle
to a minimum.
Use
recommended lubricants to enhance
the life of the reamer and ensure
the fluid reaches the cutting edges.
As reaming is not a heavy cutting
operation, soluble oil 40:1 dilution
is normally satisfactory. Air blasting
may be used with grey cast iron, if
dry machining.
Do
not allow the flutes of a reamer to
become blocked with swarf.
Before
the reamer is reground, check concentricity
between centres. In most instances
only the bevel lead will need regrinding.
Keep
reamers sharp. Frequent regrinding
is good economy, but it is important
to understand that reamers cut only
on the bevel and taper leads and not
on the lands. Consequently only these
leads need regrinding. Accuracy of
regrinding is important to hole quality
and tool life.
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HSCo
Application Reamers |
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Available
in three flute styles. The B500 straight
flute reamer is primarily for blind
holes and for short chipping materials
(AMG 3, 6.2,6.3,6.4). The B156 spiral
flute reamer is ideal for through holes
in most materials (AMG 1 - 6) where
an interrupted cut is encountered. The
B157 quick spiral reamer is designed
for through holes in long chipping materials
(AMG 1, 2, 4, 5, 6, 7). All are supplied
with straight shanks to DIN 212.
Manufactured from
HSCo steel for longer edge life and
higher cutting speeds. The selection
of the correct reamer, speed and feed
can be obtained from the AMG reamer
selection chart.
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Stock
Removal |
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The
recommended stock removal in reaming
is dependent on the application material
and the surface finish of the pre-drilled
hole. General guidelines for stock removal
are shown in the following table:
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Stock
Removal
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Size
of reamed hole (mm)
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When
pre-drilled
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When
pre core-drilled
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Below
4
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0.1
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0.2
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4
to 11
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0.2
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0.2
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Over
11 to 39
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0.3
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0.2
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Over
39 to 50
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0.4
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0.2
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Stock
Removal
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Size
of reamed hole (inches)
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When
pre-drilled
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When
pre core-drilled
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Below
3/16
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0.004
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0.008
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3/16
to 7/16
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0.008
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0.008
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7/16
to 1.1/2
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0.010
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0.008
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1.1/2
to 2
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0.016
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0.008
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Selection
of Reamer Types |
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Reaming
is a recognised method of producing
dimensionally accurate holes of fine
surface finish. We produce a range of
reamers to produce holes to H7 tolerance.
Reamers are classified
into various types:
Solid
- available in two shank types,
Straight (cylindrical) and Morse Taper.
Shell
- for use on arbors.
Expanding
- with adjustable HSS blades and
used for light work.
The most common
types of reamers have a left-hand
spiral because the main applications
involve through holes requiring chips
to be pushed forward. For blind holes,
reamers with straight flutes or right
hand spirals are recommended.
The most efficient
reaming conditions depend on the application,
material, quality of hole required,
stock removal, lubrication and other
factors. A general guide to surface
speeds and feeds for machine reamer
is shown in the reamer AMG chart and
stock removal tables.
Example: When
reaming plain carbon steel (AMG 1.3),
a B101 Morse Taper Shank machine reamer
is recommended. The surface speed
is 10-12 metres/minute, while C indicates
the feed range (see reamer feed chart).
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