Dormer Tools produce a range of Reamers to 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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| 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). |
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- 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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