Grizzly G0705 User Manual
-28-
Model g0705 (Mfg. since 09/09)
failure to follow cutting speed guidelines
when setting spindle speed may threaten
operator and bystander safety with ejected
parts or broken tools, and will put undue
strain on moving parts, shorten tool life,
and create poor workpiece results.
calculating spindle
speed for milling
it is important to note that the cutting speeds
shown in
shown in
figure 29 do not represent the recom-
mended spindle speed in rpM. the relation-
ship between cutting speed and spindle rpM is
dependent on the diameter of the installed cutting
tool. When a tool's cutting edge rotates, as is the
case with a milling machine, the cutting speed of
that tool is directly proportional to its diameter.
tools with larger diameters produce greater cut-
ting speeds because each cutting edge travels
farther per revolution of the spindle. therefore, a
larger diameter cutting tool will require a slower
spindle speed to achieve the same cutting speed
as a smaller cutting tool.
ship between cutting speed and spindle rpM is
dependent on the diameter of the installed cutting
tool. When a tool's cutting edge rotates, as is the
case with a milling machine, the cutting speed of
that tool is directly proportional to its diameter.
tools with larger diameters produce greater cut-
ting speeds because each cutting edge travels
farther per revolution of the spindle. therefore, a
larger diameter cutting tool will require a slower
spindle speed to achieve the same cutting speed
as a smaller cutting tool.
to calculate the needed spindle speed in
rpm:
1. use the table in figure 29 to find the cutting
speed required for the workpiece material.
2. Measure the diameter of your cutting tool in
inches.
3. use the following formula to determine the
needed spindle speed in rpM for your opera-
tion:
tion:
cutting speeds for high speed steel (hss)
cutting tools
Workpiece Material
Cutting speed (sfm)
aluminum & alloys
300
Brass & Bronze
150
Copper
100
Cast iron, soft
80
Cast iron, hard
50
Mild steel
90
Cast steel
80
alloy steel, hard
40
tool steel
50
stainless steel
60
titanium
50
plastics
300-800
Wood
300-500
note:
For carbide cutting tools, double the cut-
ting speed. these values are a guideline only.
refer to the
refer to the
MACHINERY'S HANDBOOK for
more detailed information.
figure 29
. Cutting speed table for hss cutting
tools.
Before calculating the spindle speed for a milling
operation, you must first understand the concept
of "Cutting speed" and how it differs from "spindle
speed."
Cutting speed is defined as the rate at which a
cutting tool's edge passes across the surface of a
workpiece. it is generally measured in "surface feet
per minute" (sfm), which represents the theoretical
distance the cutting edge would travel across the
material in a straight line in one minute.
operation, you must first understand the concept
of "Cutting speed" and how it differs from "spindle
speed."
Cutting speed is defined as the rate at which a
cutting tool's edge passes across the surface of a
workpiece. it is generally measured in "surface feet
per minute" (sfm), which represents the theoretical
distance the cutting edge would travel across the
material in a straight line in one minute.
every workpiece material type has an ideal cut-
ting speed to maximize cutting tool life, based
on the hardness and microstructure of the mate-
rial. the cutting speeds listed in
ting speed to maximize cutting tool life, based
on the hardness and microstructure of the mate-
rial. the cutting speeds listed in
figure 29 are
intended to serve as a basic guideline only. For a
high degree of accuracy, we recommend referring
to MACHINERY'S HANDBOOK
high degree of accuracy, we recommend referring
to MACHINERY'S HANDBOOK
or spindle speed
calculators on the web for more detailed informa-
tion.
tion.
4. refer to speed changes on the next page to
set your spindle speed to the position closest
to the rpM value given by the formula.
to the rpM value given by the formula.
5. during operation, adjust the feed rate by
increasing or decreasing how fast you turn
the handwheels to fine-tune the performance
of the cutting operation. to maximize tool life,
use the highest feed rate possible without
bogging down the machine or causing the
tool to chatter.
the handwheels to fine-tune the performance
of the cutting operation. to maximize tool life,
use the highest feed rate possible without
bogging down the machine or causing the
tool to chatter.