1

Fig. 1. Chipping Scots pine pulpwood with Kesla C 1060 A and Kesla C 4560 LF chippers at the asphalted wood terminal in Joensuu. The chipping experiment started with the Kesla C 1060 A chipper.

Table 1. Statistical characteristics of regression models.
Productivity model Dependent
variable 		r2 F-test/F-value
p 		N Term Constant/Coefficient t-test
Estimate Std. error t-value p
Chipping productivity of the Kesla C 1060 A powered by a Volvo FH 750 PChipping1060 0.67 12.332
0.013 		8 Constant ln(x1060) –127429.105 30132.281 45182.677 8580.522 –2.820
3.512 		0.030
0.013
Chipping productivity of the Kesla C 4560 LF powered by a Valtra S 280 PChipping4560 0.62 9.600
0.021 		8 Constant ln(x4560) –438.103 4100.515 6440.559 1323.463 –0.068
3.098 		0.948
0.021
2

Fig. 2. Chipping productivity of Kesla C 1060 A and Kesla C 4560 LF chippers (kg E0h–1) according to the weight of the grapple load (kg).

3

Fig. 3. Time consumption of work elements per chipped 1000 kg (dry mass) with the Kesla C 1060 A and the Kesla C 4560 LF chippers.

4

Fig. 4. Chipping productivity (kg E0h–1) of the Kesla C 1060 A and the Kesla C 4560 LF chippers according to basic density (kg m–3) of chipped wood material.

Table 2. Moisture content (%), calorific value (MJ kg–1), basic density (kg m–3) and ash content (%) of different storage time groups of pulpwood.
Age of storage, months Moisture content, % Calorific value MJ kg–1 Basic density kg m–3 Ash content, %
Kesla C 1060 A Kesla C 4560 LF Kesla C 1060 A Kesla C 4560 LF Kesla C 1060 A Kesla C 4560 LF Kesla C 1060 A Kesla C 4560 LF
2 55.8 54.4 20.66 20.70 434 443 0.43 0.43
4 47.0 46.8 20.35 20.61 417 416 0.62 0.38
7 41.6 40.9 20.32 20.32 411 406 0.63 0.58
9 45.7 45.3 20.56 20.54 412 396 0.54 0.42
12 56.0 50.3 20.36 20.54 418 420 0.47 0.35
15 47.2 47.4 20.43 20.29 420 410 0.46 0.41
17 40.7 45.6 20.28 20.32 426 433 0.49 0.47
21 37.0 38.6 20.37 20.42 425 358 0.49 0.39
Average 46.38 46.16 20.42 20.47 420 410 0.52 0.43
Standard deviation 6.82 4.95 0.13 0.15 7.69 25.83 0.08 0.07
Table 3. Yield of extractives (% of dry mass) and volatiles (% of extractives) of pulpwood in different storage time groups with the Kesla C 1060 A and the Kesla C 4560 LF chippers.
  Extractives Volatiles
Age of storage, months Chipper Lipophilic yield, % Hydrophilic yield, % In total, % %
2 Kesla C 1060 A 5.90 1.14 7.04 84.9
4 4.68 1.24 5.92 83.8
7 3.28 1.27 4.55 84.4
9 4.31 1.26 5.57 83.6
12 4.53 1.10 5.63 83.3
15 3.56 1.06 4.62 84.8
17 4.09 1.36 5.45 83.4
21 3.64 1.27 4.91 84.1
  Average 5.46 84.04
Standard deviation 0.81 0.62
2 Kesla C 4560 LF 5.95 1.13 7.08 83.9
4 4.86 1.09 5.95 84.4
7 4.24 1.08 5.31 83.4
9 4.31 1.22 5.53 84.5
12 4.60 0.97 5.57 84.3
15 3.96 0.92 4.88 84.3
17 3.18 1.32 4.50 84.4
21 4.57 1.00 5.58 84.5
  Average 5.55 84.21
Standard deviation 0.77 0.38
5

Fig. 5. Chip size distribution for the Kesla C 1060 A chipper (above) and the Kesla C 4560 LF chipper (below) with different storage times (2–21 months from logging).

Table 4. Effect of storage time on chip size distribution.
Effect of storage time
Fraction, mm df Distribution, percentage, Mean Std. deviation P-value
63–100 7 0.19 0.48 0.56
45–63 7 1.45 1.09 0.35
31.5–45 7 4.98 2.05 0.52
16–31.5 7 61.38 8.60 0.17
16–8.0 7 10.88 5.82 0.19
3.15–8 7 15.54 3.62 0.10
< 3.15 7 5.62 1.25 0.42
Table 5. Effect of chipper type and sieve mesh size on chip size distribution.
Effect of chipper type
Fraction, mm df P-value
63–100 1 0.644
45–63 1 0.752
31.5–45 1 0.007
16–31.5 1 0.115
16–8.0 1 0.115
3.15–8 1 0.115
< 3.15 1 0.292