Page 334 - ISCAR(HOLE_MAKING_CATALOG_65)

USER GUIDE
REAMERS Cutting Speed Coolant/Lubrication

The cutting speed has the highest influence on the
wall being reamed demands the use of a fluid for
surface quality of the reamed hole and on the life of the
lubrication and cooling. Using lubrication is more
tool. Increasing the cutting speed beyond the optimum The high degree of friction between the tool and the
speed will cause increased tool wear due to the increased critical for maintaining tolerances than using a coolant.
cutting temperature. The increased speed also causes General cutting oils and emulsions may be used. It
an increase in the built-up edge (material that is welded should be noted that in some cases emulsions will yield
to the cutting edge). The built-up edge damages the a better surface finish than cutting oils. Emulsions are
surface finish and shortens the life of the tool. In order thinner fluids that are able to reach and more uniformly
to achieve high surface quality and longer tool life, the lubricate the cutting edges better than viscous cutting
cutting speed for reaming should be kept relatively low. oils (especially when performing deep applications).
In order to determine the most suitable lubricant
Feed Rate for a particular application, tests should be run on
The feed rate directly influences the wear on the cutting the material to be cut, on a case-to-case basis.
edge. As the feed rate is increased, the cutting forces
increase almost proportionally. The feed, however, Reaming Prerequisites
has less influence on the machined surface quality In order to achieve high tolerances for
and tool wear than the cutting speed (i.e. the feed reaming applications, there are certain
can be varied in a relatively wide range without having requirements that must be considered.
material influence the quality of the machined hole and 1 Condition of the tool - If the tool is reground, both an exact
the respective tool life). It is therefore recommended concentricity and high quality grinding are indispensable.
to select the highest possible feed in order to shorten 2 Workpiece material - Axis shifting and warping (i.e.
reaming times without significantly reducing the tool life. incorrect hole positioning) can only be corrected to a
certain degree when reaming. A critical factor is the
Reaming Allowance initial opening in the workpiece. This opening must be
The reaming allowance (the amount of material to be even, or if the prepared hole is countersunk, a cone
reamed) also influences the tool life. In order to achieve countersink must be used. Failure to properly prepare
high tool life, the reaming allowance should be kept the initial opening can result in irregular countersinking
at a reasonable minimum considering the process to that leads to the reamer being pushed out of its
be performed. If the reaming allowance is too small, it proper alignment. Ideally, pre-machining should be
may result in a high dimensional variation (inability to performed in a chuck to avoid alignment defects.
maintain the required tolerances) and a decrease in the 3 Through holes - For best results, the holes to be reamed
machined surface quality. When reaming materials that should extend completely through the workpiece
have surface defects or have been welded or flame material. This allows for easy exit of both the cutting
cut, the reaming allowance should be increased so fluid and the reamed material. Negative flute reamers
these factors do not appear on the reamed surface. are advantageous in through hole reaming.
4 Blind holes - Use straight flute reamers for blind holes.

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