| Technical
Center
In this section
we will feature answers to commonly asked
questions. Check back often, as this page is
regularly updated.
International
Mold Steel specializes in pre-hardened mold and
tool steels that are considered to be the finest
available in the market place today. Because of
their unique and homogenous make-up, deviation
in hardness or hard spots is a thing of the
past. When machining these materials it will
become immediately apparent that much faster
metal removal rates can be achieved.
Machining
Pre-hardened Mold and Tool Steels for PX5
and NAK55
In a recent independent tool study, it was
determined that International Mold Steel
products can be machined up to twice as fast as
conventional 30 R.C. P-20 material and still
show equal or less cutting tool wear.
The machine used
was a heavy-duty vertical milling machine
equipped with #50 taper tool holders.
The cutting tool
was a 4-inch in diameter and 8-octagon shaped
T.I.N. coated carbide inserts at a positive
rake. Cutting depth was .150 inches. At 400
surface feet per minute we were able to cut up
to .025 inches per insert or .200 inches per
revolution of cutter. Even at this rate we were
getting 22 to 25 minutes of 'tool life' before
the insert had to be indexed.
Material
Removal Rates
Consider this: material removal rate during this
time span in approximately 300 pounds of steel.
It showed that we could remove a lot of steel
with moderate surface feet but a heavy chip
load. Once again, the clean make-up of the
material made this possible.
To
Calculate Surface Feed
Surface speed is usually given in feet per
minute. It is the distance (in feet) that the
outermost cutting edge of a rotating tool
(circumference) covers in the span of 1-minute.
To understand how
this translates into spindle speed, or
revolutions per minute (rpm) that the cutting
tool is revolving, review this example:
Example:
Surface feet 400
feet per minute Diameter of cutting tool is 4
inches. Revolutions per minute (rpm) if cutting
tool is ____
Equation:
C = Surface feet
per minute (feet) D = Diameter of cutting tool
(inches) R = Revolutions per minute of cutting
tool (rpm)
R = (C x 12)
= (400 x 12) = 4800 = 382 rpm
(D x Pi) (4
in. x 3.14) 12.56
If you need to
know surface feet per minute and the cutter
diameter and spindle speed is known, you will
have this equation:
C = Pi x D x R
= 3.14 x 4 x 382 = 400 sf.
12
12
To
Calculate Chip Load
Chip load is the
amount of materials (in .001 inches) that each
cutting flute or cutting insert of a rotating
tool removes.
Chip load is
calculated by dividing the distance of the table
travel or feed per minute in inches by the
spindle speed of the machine. This will give you
the distance the cutter traveled in one
revolution. This number is then divided by the
number of cutting flutes or inserts.
Example:
Spindle speed
is 450 rpm. Table travel or feed rate is 60
inches per minute. Number of flutes or cutting
inserts is 6.
Equation:
R = Spindle
speed (rpm)
I = Number of cutting flutes or inserts
S = Distance of feed rate or table travel in
inches.
C = Chip load
|
( |
S
R |
) |
( |
60
450
|
) |
|
. |
| C
= |
=
.13333 |
=
.0222 |
|
I |
|
6 |
|
To
Calculate Feed Rate
S = C x I x R =
S = .0222 x 6 x
450
To find rpm of
spindle or R with chip load and feed rate known:
R =
S =
60
= 450 rpm
I x C
6 x .0222
|
International Mold Steel, Inc.