Table 1. Compartment information.
Harvesting contractor Mecharv
Grower company CMPC – Forestal Mininco
Farm Totoras
Compartment number 3
Species Eucalyptus globulus Labill.
Established (year/month) 1998/05
Treatment Clear-cut
Fell age (years/months) 9/11
Average tree volume (m3) 0.204

Fig. 1. The chain flail delimber debarker at work: A) feeding whole trees and B) discharging debarked stems.

Table 2. Volume, bark-wood bond strength (BWBS) and work quality classes.
Volume class Volume range (m3 ub)
1. Very small < 0.050
2. Small 0.051–0.099
3. Medium 0.100–0.199
4. Large 0.200–0.299
5. Very large 0.300–0.499
BWBS class Description
1. Very good The bark comes off in a very long strip that can reach into the canopy before it severs (>10 m)
2. Good The bark comes off in long strips of half of the height of the tree (approximately from 4 to 10 m)
3. Medium The bark comes off in medium lengths of between one and four metres
4. Poor The bark comes off in short lengths of up to one metre
5. Very poor The bark will not come off by hand; it needs to be chiselled off by means of the hatchet
Quality class Description
1. Good All bark is removed from the stem: residual bark content estimated to less than 0.5 % achieved
2. Medium Strips of residual bark remain: residual bark content estimated to less than 1 % achieved
3. Poor Sections of the tree have not had bark removed: residual bark content estimated to more than 1 %
Table 3. Main results of the productivity study.
mean SD min max
Cycle time s 42 11 14 116
Trees in load n° 4.4 1.6 1 11
Load volume m3 ub 0.857 0.338 0.025 2.050
Tree volume m3 ub 0.204 0.078 0.025 0.475
Productivity m3 ub PMH–1 74.7 28.6 3.2 201.5
m3 ub SMH–1 59.1 22.6 2.5 159.4
Utilization % 80.5 - - -
DF 0.24 - - -
SD = standard deviation;
ub = under bark;
PMH = productive machine hours, excluding delays;
SMH = scheduled machine hours, including delays;
Utilization = productive time/scheduled time;
DF = delay factor, or delay time/productive time, where productive time is expressed in PMH

Fig. 2. Breakdown of work site time by productive tasks and delays. Other work = handling loads and residues, re-arranging stacks.

Table 4. Results of the regression analysis.
Productive time per cycle (s) = a + b × Load volume (m3 ub)
n = 788 R2 adjusted = 0.220
Anova Table
DF SS F-value P-Value
Regression 1 372.00 222.41 <0.0001
Residual 786 1314.72 - -
Total 787 1686.72 - -
Regression Coefficients
Coeff SE F-value P-Value
a 28.50 0.96 29.30 <0.0001
b 15.78 1.08 14.19 <0.0001
Load volume (m3 ub) = a + b ln Tree volume (m3 ub)
n = 788 R2 adjusted = 0.327
Anova Table
DF SS F-value P-Value
Regression 1 29.43 383.56 <0.0001
Residual 786 60.30 - -
Total 787 89.73 - -
Regression Coefficients
Coeff SE F-value P-Value
a 1.63 0.04 39.97 <0.0001
b 0.47 0.02 19.58 <0.0001
DF = degrees of freedom;
SS = sum of squares;
Coeff = coefficient;
SE = standard error

Fig. 3. Relationship between productivity and load volume. SMH = scheduled machine hours, including delays; the arrows indicate the position on the graph corresponding to the mean tree volume (m3 ub) indicated in the ellipses, based on the second equation shown in Table 4.

Table 5. Product quality vs. BWBS class.
BWBS 3 BWBS 4 BWBS 5 Total %
Quality 1 n 369 150 122 641 57.9
% 57.6 23.4 19.0 100.0
Quality 2 n 56 49 214 319 28.8
% 17.6 15.4 67.1 100.0
Quality 3 n 10 6 132 148 13.4
% 6.8 4.1 89.2 100.0
Total n 435 205 468 1108
% 39.3 18.5 42.2 100.0
χ2 = 365.12, P-Value < 0.0001
BWBS = bark-wood bond strength
Table 6. Results of the ordinal logistic regression analysis.
n = 1108
R2 = 0.232
Quality class 2
Coeff SE e Coeff χ2 P-Value
Constant –3.998 0.310 0.018 166.257 <0.0001
BWBS 4 0.821 0.224 2.272 13.378 0.0003
BWBS 5 2.158 0.190 8.656 128.792 <0.0001
n° trees 0.485 0.060 1.624 65.835 <0.0001
Quality class 3
Coeff SE e Coeff χ2 P-Value
Constant –6.062 0.465 0.002 169.744 <0.0001
BWBS 4 0.455 0.529 1.576 0.740 0.3896
BWBS 5 3.326 0.350 27.833 90.128 <0.0001
n° trees 0.556 0.071 1.744 61.518 <0.0001
BWBS = bark-wood bond strength;
Coeff = coefficient;
SE = standard error;
n° trees = number of trees in a load
Table 7. Results of previous chain flail studies. View in new window/tab.