Since 1934, Harris Sawing Equipment (HSE) has manufactured a variety of saws for various applications including saw milling. Today –more than eight decades later –this family-owned business is one of the leading saw manufacturers in South Africa.

By Dineo Phoshoko | All photos by Harris Sawing Equipment

In March 2019, HSE introduced its new line of Trucut saw blades, specifically targeting the furniture industry. “The blade is a high-quality blade manufactured from imported steel from Germany,” explains Michael Harris, director at HSE. The combination of high-quality raw materials together with a high-quality manufacturing process, results in a blade that can compete with other blades internationally. The HSE blade’s affordability offers a competitive advantage when compared to international blades.

Initial testing and phasing of the blades was conducted in 2018 and they were launched to the market in March 2019.

Automatic saw blade polishing

Automatic saw blade polishing. Image credit: Harris Sawing Equipment

Although the blades have only been available for a couple of months, they have been well-received by the market. “Initial sales are going well and everyone who’s purchased our blades are really happy with their performance,” says Harris.

The raw materials (carbide tips and steel sheets) to manufacture the blades are not available locally so they are imported, and the actual manufacturing of the blades is carried out in South Africa. “We do the laser cutting of the bodies, heat treatment, straightening, tensioning, surface grinding, tipping [and] sharpening – all of that is all done here,” explains Harris.

There are various factors that make HSE’s Trucut blades appealing to the timber industry. Harris explains that the maximum run out on the blades are a tenth of a millimetre. This means that the straightness of the blade – when inserted into a machine to cut – total variation from the centre of the blade to the cutting surface of the tip is a tenth of a millimetre, which exceeds all ISO standards. He adds that ISO standards on other blades are between three tenths of a millimetre and eight tenths of a millimetre.

Because of the high-quality carbide, the carbide is always uniform, making it possible for repeatable cutting. It is highly unlikely to find a blade that cuts well but is quick to get blunt, and then the next blade does not cut well at all. As the carbide is from Europe, the quality is high and consistent. “You can purchase a blade that you know is going to cut straight and it’s going to last the appropriate amount of time.”

The Trucut blades also ensure that the correct grade of carbide for the required application is used, because cutting raw timber or chipboard board requires the use of different grades of carbide. For example, chipboard is a lot more abrasive because of the different types of glue and other materials used with it. As such it requires a corrosion resistant grade of carbide which ensures improved cutting and a longer life span, leading to better results due to the cutting quality.

Maintenance and lifespan

As with any product, the lifespan is highly dependent on the type of application and the way it is used. Harris explains that it is difficult to estimate the lifespan of the Trucut saw blades because of different factors. Some of the factors to consider include how much is being cut; the number of times the machine is being used each day; what is being cut and the lengths at which it’s being cut. “It’s much easier on a continuous line, for example on the trimming ends of chipboard when it’s manufactured.

“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.”

Automatic tip brazing.

Automatic tip brazing. Image credit: Harris Sawing Equipment

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.

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  tensioning on a PSR 1200.

Straightening and
tensioning on a PSR 1200. Image credit: Harris Sawing Equipment

Material is heated to between 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.

Harris Sawing Equipment

Harris Sawing Equipment cc