Hyd-Mech V18APC - Page 39

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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 ne 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 di󰀨er-
ing e󰀨ective material widths.
It is impractical to change the blade to the proper pitch every time a di󰀨erent width of material is cut and it is not neces-
sary, but remember that the optimum blade will cut most e󰀩ciently. Too ne a blade must be fed slower on wide mate-
rial 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: E󰀨ective material width of 8” (200 mm) & Optimum blade has 2/3 teeth per inch.
STEP 4 - DETERMINE OPTIMUM BLADE SPEED, V (ft/min) (m/min)
The relationship between optimum blade speed and e󰀨ective material width for various materials is represented on the
graph shown.
The graph shows that as e󰀨ective material width gets wider or as material gets harder, lower blade speeds are recom-
mended. If material is narrow or soft, higher blades speeds should be selected.