The surface quality was analyzed according to roughness and waviness standard parameters and to the depth of torn grain. The results showed that surface quality was not affected by the cutting speed.
The maximum depth of the torn grain present in each board was measured with a Micromeasure confocal microscope.
Torn grain. A maximum depth of 1/32" (.8mm) will be permitted on machine-run stock in not over 10 per cent of the length in any one piece and not more than 5 per cent of the quantity of any one item.
Torn grain. Torn grain with a maximum depth of 1/32" will be permitted on molded stock in not over 10 per cent of the length in any one piece.
In addition, no torn grain was observed for surfaces prepared with a rake angle of 10[degrees] regardless of feed speed.
The numerous knots and grain deviation generated torn grain, while differences in density between earlywood and latewood brought raised grain.
Distorted or sloping grain around knots may lead to torn grain
or fuzzy grain in later machining.
The maximum depth of torn grain
produced by planing was also measured for eight cutting conditions.
It saws well, but torn grain
can be a problem when dressing quartered faces.
, raised grain, and chipmarks are reduced in helical planing, due to a gradual cutting action (Jones 1994).
Defect type and severity were also classified according to raised, fuzzy, and torn grain
. The descriptive grade then assigned to the surface of each piece was the largest average (of three graders) of the three defect types.
The quality of planing was also evaluated on a quantitative basis by measuring the depth of the torn grain