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Spindle Speed
RPM = speed at which the tooling is turning. The mill can be commanded in either
clockwise (CW) or counterclockwise (CCW) direction. The type of application or style of tool
will usually dictate the spindle direction.
Depth of Cut
The distance the cutter penetrates the workpiece, also referred to as chip load. This is
determined by the following factors:
• Rigidity of the cutter and machine
• Machine capabilities
• Spindle horsepower
Machine Productivity
Use the load meter as an indicator of how the machine is cutting. Speeds and feeds
should be adjusted after the initial cut. The initial cut will give an instant read-out of the
performance of the machine. If adjustment are necessary, they should be made in 10%
increments. Pay close attention to:
• Chip formation and color
• Chip load
• Monitor part and fi xture during the cut
• Listen for any unusual noises
Surface Finish
A good fi nish depends on a number of variables. The following are a number of items to
check to achieve a good fi nish:
• Good fi nish results in slower feeds and higher speeds
• Face milling produces the best fi nish
• Increasing the number of cutters (inserts) allow for a better fi nish
• Cuts should always be in the same direction
• Lighter depth of cuts will produce a better fi nish
• Coolants use can also affect part fi nish
Accuracy
Machine accuracy can be affected by a number of variables, such as:
Is the machine properly warmed up?
Holes should be center drilled fi rst
Check the condition of the tooling
Cutting Tool Descriptions
Drill Used to create a cylindrical hole in a work piece. Drilled holes can be "through holes"
or "blind holes". A "blind hole" is not cut entirely through a work piece.
Center drill A small drill with a pilot point. It is used to create a small hole with tapered
walls. When a hole's location must be held to a close tolerance, use a center drill fi rst and
then use a regular drill to fi nish the hole. The tapered walls of the center-drilled hole will
keep the regular drill straight when it begins to drill into the work piece.
Reamer Designed to remove a small amount of material from a drilled hole. The reamer
can hold very close tolerance on the diameter of a hole, and give a superior surface fi nish.
The hole must be drilled fi rst, leaving .005 to .015 of an inch stock on the walls of the hole
for the reamer to remove.
96-0041 Rev T
January 2009
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