Example data mode. The sample companies, offers and requests shown here are fictional (AI pictures) and are not counted in the figures below.
Lesson 6 of 8
A small bandsaw in practice: time, handling and downtime
A well-documented small mill
Borz et al. (Romania and Italy, Forests, 2021) monitored a small mill in Harghita County, Romania, with a manually driven horizontal bandsaw. It processes mainly Norway spruce and silver fir; it has a 7.5 kW motor, water-cooled blades (4585 mm long, 38 mm wide, 1.1 mm thick) and is usually run by one worker. Over seven operating days the company processed 86 logs, about 26 m3 over bark, using video-based time study. It is a single mill and effectively one operator, so treat it as a method template.
Where the time goes
Share of the delay-free work cycle (approximate):
| Work element | Share |
|---|---|
| Effective sawing | 27% |
| Workplace preparation | 22% |
| Fixing lumber | 12% |
| Saw return and blade height adjustment | 11% |
| Unloading lumber | 9% |
| Loading logs | 8% |
Effective sawing is about a quarter of the productive cycle. The listed handling and setup elements other than sawing add up to 22 + 12 + 11 + 9 + 8 = 62%.
The output figures:
- Products about 18 m3 from about 26 m3 of logs: 18 / 26 = about 69%, in line with the reported average recovery rate of around 69% (range 38.8% to 95%).
- Net productivity about 0.5 m3 per hour, reported as 2.045 h/m3 net and 2.539 h/m3 gross. Check: 1 / 2.045 = 0.489 m3/h net and 1 / 2.539 = 0.394 m3/h gross.
- Time to process 10 m3 at the net rate: 10 x 2.045 = about 20.5 hours.
The paper quotes the delay-free share of time as 89.2% in one place and about 65% in another and does not reconcile them. Check definitions in the original before reusing either.
What the authors and the portal conclude
From the paper: handling dominates the cycle; the authors recommend mechanical log-handling devices, modernised machinery, noise reduction at source, blade and equipment maintenance, and training. Cycle time was explained well by log diameter, volume and number of pieces (83 to 88%), but net productivity only moderately (about 44 to 47%).
Portal interpretation, not claims of the paper: a modest investment in a log turner, loader or unloading aid is likely to improve productivity and posture more than a faster saw, and a mill can test this by timing its own cycle with smartphone video.
Downtime
Downtime is where theoretical capacity meets reality. Two open data points:
- Wiedenbeck and Blackwell (USA, 2003) report that for a hardwood mill producing 20,000 board feet per day, five extra minutes of daily downtime cost 21 to 73 US dollars a day (an average of about 47). The numbers are old; the logic of costing minutes scales to any mill.
- Liibert (Estonia, 2019) observed a small sawmill for 11 days. As shares of total working time, saw blade problems took 4.0% in winter and 0.8% in spring, preparatory work 16.8% and 22.9%, breaks 22.6% and 12.1%, log rolling 5.3% and 7.4%, and turning logs on the saw frame 3.7% and 4.8%. It is one small mill and a bachelor's thesis, so it shows categories of loss, not a benchmark.
The practical reading (portal interpretation) is that saw maintenance matters most when it prevents unplanned stops and thickness variation, while log handling and preparation can consume more time than blade problems.
Checklist: a one-week time study
- Fix a camera or phone on the work area and record complete shifts.
- Define elements in advance: loading, fixing, sawing, return, unloading, preparation, blade change, delays.
- Label each log (diameter, length) so cycles can be matched to size.
- Time each element from the video in seconds.
- Compute shares of time and h/m3, and separate delays from the work cycle.
- Choose one change (for example a turning aid), repeat the study and compare.
Worked example
A mill finds that saw blade problems took 1 hour of a 40-hour week while preparation took 8 hours. Even removing all blade problems would free 2.5% of the week; halving preparation would free 10%. Order the improvements by the time they actually consume.
Key points
- In the Romanian case effective sawing was only about 27% of the delay-free cycle; handling and setup took most of the rest.
- Recovery averaged around 69% and net productivity about 0.5 m3/h (2.045 h/m3).
- Time by element can be modelled from log diameter or volume, but hourly output only moderately.
- Observed downtime categories show log handling and preparation can outweigh blade problems.
- Time your own cycle before deciding where to invest.