Hyd-Mech H-22A, Operation And Maintenance Manual

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Pg 2.14
H1822
STEP 4, DETERMINE OPTIMUM BLADE SPEED, V (ft/min) (m/min)
The relationship between optimum
blade speed and effective material
width for various materials is
represented on the graph shown.
The graph shows that as effective
material width gets wider or as
material gets harder, lower blade
speeds are recommended. If material
is narrow or soft, higher blades
speeds should be selected.
In Example #1
- 8" (200mm) diameter #1045 Medium Carbon Steel solid bar is to be cut.
- On the graph above find the Medium Carbon Steel Curve which represents the optimum blade speeds for
1045 Carbon Steel.
- On the horizontal axis (effective material width axis) find number 8 which represents effective material
width of an 8" (200mm) diameter solid.
- Find the point where a vertical line from 8" (200mm) intersects the Medium Carbon Steel Curve.
- From this intersection point run horizontally left to the vertical axis (optimum blade speed axis) and find the
point marked “200”.
For 8" (200mm) diameter, 1045 Carbon Steel solid bar 200 ft/min (60m/min) is the optimum blade speed.
NOTE: 1) Higher than optimum blade speed will cause rapid blade dulling. Lower than optimum blade
speeds reduce cutting rates proportionately and do not result in significantly longer blade life except where there
is a vibration problem. If the blade vibrates appreciably at optimum speed as most often occurs with structurals
and bundles, a lower blade speed may reduce vibration and prevent premature blade failure.
2) Material Hardness - The graph above illustrates blade speed curves for materials of hardness
20 RC (225 Bhn) or lower. If the material is hardened then the multipliers need to be used. These multipliers are
given in the NOTE at the bottom right of the graph. As the hardness increases the optimum blade speed
decreases.
STEP 3, DETERMINE OPTIMUM BLADE PITCH - TEETH PER INCH (T.P.I.)
Selecting a blade with proper tooth pitch is important in order to achieve
optimal cutting rates and good blade life.
For cutting narrow or thin wall structural materials a fine blade with many
teeth per inch (T.P.I.) is recommended. For wide materials a blade with a
coarse pitch should be used. The sketch can be referenced for the blade
pitch changes for differing effective material widths.
It is impractical to change the blade to the proper pitch every time a
different width of material is cut and it is not necessary, but remember that
the optimum blade will cut most efficiently. Too fine a blade must be fed
slower on wide material because the small gullets between the teeth will get
packed with chips before they get across and out of the cut. Too coarse a
blade must be fed slower because it has fewer teeth cutting and there is a
limit to the depth of a cut taken by each tooth. Allowance for the use of a
non-optimum blade is made in STEP 5.
In our Example #1 : Effective material width of 8" (200 mm) & Optimum blade has 2/3 teeth per inch.
Optimum Blade Pitch ( T.P.I. )
Optimum Blade Speed Curves