Advantages of Reaming
. use of remers
. the advantage of reaming
. distinguish hand and machine reaming
. name the elements of a reamer and their functions.
What is Reamer?
A reamer is a multipoint cutting tool uses for enlarging by finishing previously drilled holes to accurate sizes.
Reaming produces
High quality surface finish
Dimensional accuracy to close limit.
Also small holes which cannot be finished by other processes can be finished.
Classification of reamers
Reamers are classified as hand reamers and machine reamers.
Reaming by using hand reamers is done manually for which great skill is needed.
Machine reamers are provided with Morse taper shanks for holding on machine spindles.
Hand reamers have straight shanks will 'squre' at the end, for holding with tap wrenches.
Parts of hand reamer
Axis
The longitudinal centre line of the reamer.
Body
The portion of the reamer extending from the entering end of the reamer to the commencement.
Recess
The portion of the body which is reduced in diameter below the cutting edges, pilot or guide diameters.
Shank
The portion of the reamer which is held and driven. It can be parallel or taper.
Circular land
The cylindricaly ground surface adjacent to the cutting edge on the leading edge of the land
Bevel lead
The bevel lead cutting portion at the entering end of the reamer cutting its way into the hold. It is not provided with a circular land.
Taper lead
The tapered cutting portion at the entering end to facilitate cutting and finishing of the hole. It is not provided with a circular land.
Bevel lead Angle
The angle formed by the cutting edges of the bevel lead and the reamer axis.
Taper lead angle
The Angle formed by the cutting edges of the taper and the reamer axis.
Terms relating to cutting geometry flutes
The grooves in the body of the reamer to provide cutting edges, to permit the removal of chips, and to allow the cutting fluid to reach the cutting edges.
Heel
The edge formed by the intersection of the surface left by the provision of a secondary clearance and the flute.
Cutting edge
The edge formed by the intersection of the face and the circular land or the surface left by the provision of primary clearance.
Face
The portion of the flute surface adjacent to the cutting edge on which the Chip impinges as it is cut from the work.
Rake angles
The Angles in a diametral plane formed by the face and a radial line from the cutting edge.
Clearance angle
The angles formed by the primary or secondary clearances and the tangent to the periphery of the reamer at the cutting edge. They are called primary clearance angle and secondary clearance Angle respectively.
Helix angle
The angle between the edges and the reamer axis.
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