Page 694 - Iscar

USER GUIDE
REAMERS Cutting Speed Coolant/Lubrication

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

ISCAR
690 ISCAR
690