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Bi-metal hole saws and its applications

August 2, 2018

Bi-metal hole saws are available in the tool steels HSS and HSSE-Co 8, in which materials you can drill best with them you will find out in this article.

In our last article What you should know about HSS and carbide hole saws we took a closer look at the properties and applications of HSS and carbide hole saws. There we learned that the hole saws are particularly suitable for metal cutting.

The bi-metal hole saws are suitable not only for metal cutting but also for wood processing. The bi-metal hole saws are available in the two tool steels HSS and HSSE-Co 8 (8% cobalt).

Red (HSS) and white (HSSE-Co 8) bi-metal hole saws from RUKO

Red (HSS) and white (HSSE-Co 8) bi-metal hole saws from RUKO

Characteristics of bi-metal hole saws

The main body and the cutting edges of the bi-metal hole saw consist of two different tool steels (bi-metal). The main body consists of a special flexible steel and the teeth that cut the material are made of HSS or HSSE-Co 8.

HSS with varied toothing

HSS with varied toothing

HSSE-Co 8 with fine toothing

HSSE-Co 8 with fine toothing

The teeth are welded to the main body. The two bi-metal hole saws have two different toothings:

The varied and fine toothing ensure that the hole saw does not get caught in the material and runs smoothly. Bi-metal hole saws have a larger number of cutting edges than carbide hole saws, which allow a clean cut.

HSS with varied toothing

HSS with varied toothing

HSSE-Co 8 with fine toothing

HSSE-Co 8 with fine toothing

To drill a hole with the bi-metal hole saw you also need a arbor holder incl. guide drill.

Arbor holder incl. guide drill

Since the hole saw and holder are separate, you can quickly change the different hole saw diameters (available from us: 14 to 210 mm) with the arbor holder. The guide drill allows simple centering and clean guidance in the material. There are different holders for the corresponding drill chuck.

Optionally, you can also use an ejector spring that ejects the cut material from the hole saw.

Application of bi-metal hole saws

The bi-metal hole saws are best suited for cutting of metal and wood. Best results are achieved in steel up to max. 5.0 mm material thickness.

The areas of application are mainly in sanitary and electrical installations.

When cutting steel or metal, pay attention to the correct number of revolutions. In the speed table for bi-metal hole saws you will find the corresponding speeds.

Bi-metal hole saw HSS with varied toothing

With easily cutable materials such as aluminium, wood or plasterboard, the varied toothing clears the cut material better. Compared to the bi-metal hole saw HSSE-Co 8 with fine toothing, the cut is slightly coarser.

It is often used to drill holes for sockets and light switches (68 mm diameter) and cable ducts in desks or kitchen worktops.

Bi-metal hole saw HSSE-Co 8 with fine toothing

The high cobalt content ensures high hot hardness. This means that the tool steel does not lose its hardness at high temperatures.

The fine toothing ensures a smoother running, better cutting pattern and less effort.

For these two reasons (high heat hardness and clean cut) the bi-metal hole saw HSSE-Co 8 particularly suitable for metals such as unalloyed and alloyed steel (up to 5 mm) and less for soft materials.

Compared to the bi-metal hole saw HSS, the lower heat generation during cutting increases the service life, especially with metals.

Bi-metal hole saw Fields of application
HSS with varied toothing Unalloyed teel up to 5 mm cutting depth (up to 700 N/mm2), non-ferrous and light metals, plastics, plasterboard, and light building boards, fibreboard, plywood and wood
HSSE-Co 8 with fine toothing alloyed and non-alloyed steels (up to 1,000 N/mm2), high chromium alloyed steels such as stainless steel, steels resistant to rusts and acids, non-ferrous and light metals (aluminium)

When drilling alloy steels you should use coolant.


Summary

Bi-metal hole saws are suitable for various applications.

With the bi-metal hole saw HSS you work more in the drywall sector, especially in. With wood or soft plastics you can achieve a cutting depth of up to 28.0 mm.

You can use the bi-metal hole saw HSSE-Co 8 for metal processing and achieve best results with steel (up to 1,000 N/mm2) up to a maximum of 5.0 mm. With softer materials you can also achieve a cutting depth of up to 28.0 mm.

Hole saws can be used with the hand or stand drilling machine and have a high concentricity.

Compared to the carbide hole saws, the bi-metall hole saws are suitable for larger cutting depths. For this you cut much harder material with the carbide hole saws (steel up to 1,000 N/mm2).

The following table gives you an overview of the properties and application fields of the carbide and bi-metal hole saws.

Our complete range of bi-metal hole saws including accessories such as ejector spring and arbor holders can be found under Products > Hole saws.

If you have trouble finding the right bi-metal hole saw, please do not hesitate to contact us.

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