COVER STORY
Automatic tip brazing.
“Using the high-quality carbide, it also means that when the
blade is sharpened, you get a good quality cutting result. The
other big factor is how often they are actually removing the
blade to sharpen because a lot of people tend to overuse a
blade before sharpening.”
Harris says that during sharpening, more than a tenth of a
millimetre of the blade’s tip should not be removed. To give
customers more value add, HSE conducts reconditioning of
blades in addition to manufacturing them. Some clients bring
in their blades for reconditioning only to find that at least
two tenths to about half a millimetre of the tip needs to be
removed during sharpening.
“It means they have probably run it five or six times longer
than they should. By sharpening the blade more often, you
get a better life and a better cut out of the blade,” he says.
Some clients are reluctant to remove the blade for
sharpening, pushing the blade to the extreme, which results
in the development of cracks in the blade and poor cutting
quality because of a blunt blade. “Often you end up cutting
scrap timber because the blade is not sharp. It’s not cutting
but rather forcing its way through, and you get poor cut
quality,” he adds.
There are things to look out for that indicate whether a
blade needs sharpening or not. “The easiest way on carbide
saws to see is if you actually look at the tip on the saw, and if
you can see a dull line about the thickness of a piece of paper
on the sharp edge of the tip, that means that it is blunt and it
should be sharpened,” Harris explains.
To get the best results from the blade over a longer
duration, he advises clients to avoid distorting the blade
though excessive heating. Another useful tip is to have the
blades checked for straightness and tension. Overall Harris
believes it is better not to work the blade too hard.
CIRCULAR SAW
MANUFACTURING PROCESSES
One of the reasons HSE can produce such high-quality blades
is the manufacturing processes at its facility in Johannesburg,
South Africa. The facility is equipped with the latest
technology to carry out certain functions including laser
cutting, heat treatment, straightening and tensioning,
grinding and polishing and tipping, among others.
The laser cutting process is the initial process in the
manufacture of circular saw blades is to cut the shape of the
saw using a high fibre laser. The shape of the saw and
features are designed and drawn in a computer-aided design
(CAD) program, which is used by the laser to generate the
cutting path.
www.timberiq.co.za
All circular saw blades must
undergo a heat treatment
process where the physical
properties of the steel are
altered to make the material
harder and enable the material
to withstand the forces
generated during cutting.
Straightening and
Material is heated to between
tensioning on a PSR 1200.
860°C and 1 100°C, which
depends on the type of material, and then rapidly cooled
(quenched), which is known as hardening. After hardening,
the saws need to be tempered in packs to reduce hardness
and increase the blade’s toughness. Here blades are
clamped in packs and heated slowly to between 350°C and
560°C, depending on the material, and then cooled slowly to
ambient temperature.
Straightening and tensioning of a saw blade ensures that
the blade runs true during cutting and HSE has the most
advanced circular saw straightening and tensioning system
that is currently used in Africa. The blades are automatically
straightened and tensioned on a PSR 1 200 to attain the
desired tension and run out figures.
Saw blades are ground to the required thickness and to
ensure uniform dimensions of the saw blade. HSE has the
largest surface grinder for circular saw blades in Africa,
which is up to 2 200mm diameter. Polishing of blades up to
800mm is also done on a fully automatic polishing machine.
Brazing of tungsten carbide tips to the saw body is done
automatically on a fully computer-controlled induction
brazing machine to ensure quality of the bond and
uniformity of placement of the tip.
Harris explains that their facility is the only saw
manufacturer in the country that has its own heat
treatment facility.
As to the benefits of having their own heat treatment
facility, Harris says, “We can be much stricter on controls on
the tolerances of heat treatment on the blade.”
Another impressive factor about HSE is that it is the only
manufacturer in the southern hemisphere that has a
straightening tensioning machine which is fully automated.
This machine makes it possible to consistently produce
blades within the ISO specs. In addition, the facility also has
the largest surface grinder and tipping machine in the country,
which enables HSE to manufacture a larger range of blades
more efficiently.
The introduction of the Trucut saw blades has put HSE in a
position to benefit from different areas of the timber
industry. “The timber industry seems to be holding its own
and doing reasonably well,” Harris says. This means that the
saw manufacturer can expect good business in future.
// JUNE / JULY 2019 17