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Machine Reaming

Machine Reaming. Session 10. Reamers. Rotary cutting tool with several straight or helical cutting edges along body Used to accurately size and finish hole previously formed by drilling Two classifications Hand Machine. Reamer Parts. Shank Straight or tapered and used to drive reamer

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Machine Reaming

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  1. Machine Reaming Session 10

  2. Reamers • Rotary cutting tool with several straight or helical cutting edges along body • Used to accurately size and finish hole previously formed by drilling • Two classifications • Hand • Machine

  3. Reamer Parts • Shank • Straight or tapered and used to drive reamer • Hand reamers have square on end to accommodate tap wrench • Angle of Chamfer • Part of reamer that actually does cutting • Ground on end of each tooth • Clearance behind each chamfered cutting edge

  4. Reamer Body • Several straight or helical grooves or flutes and lands (portion between flutes) • Body clearance angle: clearance behind margin that reduces friction while reamer cutting • Rake angle: angle formed by face of tooth when line drawn from point on front marginal edge through center of reamer

  5. Machine Reamer Parts

  6. Hand Reamers • Finishing tools • Holes drilled to .003-.005 inch undersize • Square on shank for wrench • Teeth on end tapered so can enter hole easily

  7. Hand Reamers • Taper hand reamers • Roughing • Finishing

  8. Machine Reamers • Used in any machine tool for both roughing and finishing hole • Called chucking reamers for holding method • Wide variety of types and styles • Rose reamers • Fluted reamers • Carbide-tipped reamers

  9. Rose Reamer • Straight or tapered shanks with straight or helical flutes • Teeth on end have 45º chamfer backed off to produce cutting edge • Cut on end angle only • Usually made .003 to .005 in under normal size

  10. Fluted Reamers • Have more teeth than rose reamers for comparable diameter • Lands relieved for entire length • Fluted reamers cut along side as well as at chamfer on end • Considered finishing tools and used to bring hole to size

  11. Carbide-tipped Reamers • Similar to rose or fluted reamers, except carbide tips been brazed to cutting edges • Outlast high-speed steel reamers • Can run at higher speeds and still maintain their size

  12. Shell Reamers • Reamer heads mounted on driving arbor • Shank of driving arbor may be straight or tapered • Two slots in end of reamer fit into lugson driving arbor • Sometimes lockingscrew in arbor

  13. Advantages of Shell Reamers • Economical for larger holes • Various head sizes can be easily interchanged on one arbor • When reamer becomes worn, it may be replaced and driving arbor used with other reamers

  14. Adjustable reamers • Have inserted blades that can be adjusted approximately at .015 in over or under nominal reamer size • Adjusting nuts on either end

  15. Expansion reamers • Amount to be expanded is limited • Body slotted and tapered, threaded plug fitted into end • Turning this plug will allow 1 in. reamer to expand up to .005 in.

  16. Reamer Care • Never turn reamer backwards • Always store reamers separately prevents cutting edges from being nicked • When not in use, reamer should be oiled

  17. Reaming Allowances • Amount of material left in hole for reaming operation depends on number of factors • Type of machining operation prior to reaming • Hole punched, rough-drilled, bored • Size of Hole

  18. Reaming Allowances • General rules for amount of material to leave in hole for machine reaming • Holes up to .500 in. diameter, allow .015 in. (1/64th) • Holes over .500 in. diameter, allow .030 in. (1/32th)

  19. Reaming Speeds • Factors for determining most efficient speed • Type of material being reamed • Rigidity of setup • Tolerance and finish required for hole

  20. Reaming Speeds • Generally reaming speed 1/2 to 2/3 speed used for drilling same material • High speed – used when setup rigid • Lower speed – used when setup less rigid • Coolants improve surface finish and allows higher speed

  21. Reaming Feeds • Feed used for reaming usually two to three times greater than drilling • Rate varies with material reamed • Generally .001 to .004 in. per flute per revolution • Feed too low: glazing, excessive reamer wear, chatter • Feed too fast: reduce hole accuracy, poor surface finish • Exception: tapered holes need light feed

  22. Reaming Hints • Examine reamer and remove all burrs from cutting edges with hone • Cutting fluid should be used in reaming operation to improve hole finish and prolong life of reamer • Helical-fluted reamers should always be used when long holes and those with keyways or oil grooves are reamed

  23. Reaming Hints • Straight-fluted reamers generally used when extreme accuracy required • Never turn reamer backwards • Never attempt to start reamer on uneven surface

  24. Machine Reaming a Straight Hole • Mount work on parallels in vise and fasten securely to table • Select proper-size drill for reaming allowance required and drill hole • Mount proper reamer in drill press • Adjust spindle speed to suit reamer and work material

  25. Machine Reaming a Straight Hole • Start drill press and carefully lower spindle until chamfer on reamer cuts • Apply cutting fluid and feed reamer by applying enough pressure to keep reamer cutting • Remove reamer from hole by raising downfeed handle • Shut off machine and remove burr from edge of hole

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