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Navod obsl OR 50(F)_2006-08-01_EN.doc
Sharpening and Setting
There is no definite recommendation for an ideal saw band because each kind of timber
needs a specific ideal saw band to achieve the optimum efficiency.
This, however, can be also very different in the same kind of timber as a result of the
landscape origin.
Because of a permanent bend change when running on the running wheels and due to
the sawing pressure, enormous loads and forces are exerted on the relatively thin saw
band.
The teeth roots are critical saw band points.
A timely sharpening of the tooth root is important because very small hair cracks expand
inevitably causing saw band cracks. Avoid long idle runs because tooth root cracks may
develop during idle run rather than during cutting.
Do not let the machine run idle, if it is not necessary.
Important:
Do not use the same saw band for more than approximately 2 hours and let it
“have a rest” then allowing for recovering of the steel structure. The saw band life
substantially increases in this way. Slacken the saw band in the machine after shift end.
Adherence to the rules and instructions for saw band maintenance will bring high sawing
performances, accurate cuts and a long life of the tool.
If there are suddenly bad sawing results or if the saw bands break more frequently, it is
usually difficult to find out the reason. The most frequent reason for breaks is wrong
handling of the saw band. The breaks can also be caused by operators. You can find
below the most frequent causes of cracks. Consider all items because there are often
several of them acting simultaneously.
1. Using blunt saw bands is the most frequent cause of saw band breaking, blunt bands
are excessively tensioned and hair cracks develop. Change saw bands on time!
2. The tooth shape is not observed when the tooth is being sharpened.
3. The saw band has been set in a wrong manner.
4. Excessive sawing pressure does not result in any increase in performance. The saw
band is overloaded and warms up.
5. Do not let the machine run idle, if it is not necessary.
6. Make a correct setting of the saw band guide.
7. The grinding wheel hardness or the particle size are unsuitable – microcracks on the
tooth root.
8. The grinding wheels are not trued up on time.
9. Excessive feed (of grinding wheel) causes heating of the tooth root (grinding until blue
color develops).
Cleaning and Ascertaining of Cracks
Remove saw dust and deposits from the saw band. Check the saw band for cracks
between the teeth. Small cracks may be ground while the saw band teeth are being set. If
the cracks are too big to be eliminated by grinding, the saw band must be rejected.
The cracks in saw bands are the most frequent cause of saw band break.
