A selection of drills have the right to be offered to cut circular holes in workpieces. In this post you will discover out in which applications action drills are supplied and what attributes they have.

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Step drills have, as the name argues, different actions that cut the preferred diameter. Before we take a closer look at the attributes, we would certainly like to briefly go into the term "CBN process".

CBN process

If you check out messages about step drills on the Net, you will always stumble across the abbreviation CBN. But what does it suppose once action drills are developed making use of the CBN process?

CBN represents cubic crystalline boron nitride. Boron nitride is a chemical compound of boron and nitrogen. The enhancement "cubic" describes the crystal structure of the chemical compound. CBN is much harder than standard abrasive materials such as silsymbol carbide or corundum and is provided for grinding hardened high-speed steels (HSS).

This also uses to us.


The 5 attributes of a action drill


Point angle

The head of action drills deserve to be compared to the head of twist drills. Centering in the workitem need to be as easy as feasible via both drills. The suggest angle is responsible for this.

The point angle is situated at the head of the action drill. The angle in between the 2 cutting edges is measured at the point. As already discussed, a suggest angle is required so that the action drill have the right to center itself in the material.


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Our action drills have a tiny suggest angle of 118° and needs much less push once centering in the product. The bigger the point angle, the higher the contact push and the centering in the material calls for even more press.

In our article "8 features of a twist drill and also its functions" we discuss the point angle in even more information.

Point cuts and also point thinnings

For straightforward tapping, the step drill needs a matching pointing in addition to the small suggest angle.

The assorted points are standardized in DIN 1412 forms. The the majority of widespread develop for step drills is the separation point (form C).


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Step drills with form C center perfectly in thin sheet steel and also are suitable for drilling in solid and also high-alloy steel. The allude reduced is additionally ground utilizing the CBN grinding process.

The illustration mirrors the point reduced of a twist drill from the side and also from above. The suggest reduced of action drills and twist drills is the same.


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Additional information about the various develops deserve to be discovered in our blog post"Point cuts and point thinnings of twist drills for metal cutting".


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Step drills usually have two cutting edges and also profile of flutes. The cutting edges cut the material. We have actually step drills with even three cutting edges through straight flutes in our product array.

Profile of flute (groove profile)

The groove profile serves as a channel mechanism for collection and also for chip removal. It is crucial that the chips are rerelocated easily, as otherwise high warmth will certainly develop and also the drill will certainly burn out. Non-breaking chips in specific are transported conveniently, as with a twist drill.

Tip drills deserve to have spiral and also directly grooves. With the spiral groove, chip removal is a lot much better than through the right groove. The organization life can be considerably extfinished by good chip removal.


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Due to the CBN-deep-ground spiral grooves, the chisels, in comparison to the traditionally milled flutes, are burr-complimentary and sharp. This reduces the formation of built-up edges and also cold welds on the cutting edges, leading to a considerably higher cutting performance.

Tip angle

The action angle of step drills is 90° and specifies the change from action to step. The transitions in between the individual steps need to be as simple as possible and also hardly noticeable.


The step transitions are used to chamfer or deburr the hole as soon as the wanted diameters are got to.

Number and also diameter of steps

Tip drills are indicated in sizes. These sizes determine the diameters and also the variety of steps.


A step drill size 1 has actually nine measures through different diameters in between 6.0 and also 20.0 mm (see picture).

Application

Tip drills are best for sheet metal working and also are suitable for cutting non-ferrous metals, stainmuch less steel sheets as much as a thickness of 1.5 mm, thermoplastic and also thermosetting plastics and also all current steel sheets as much as a thickness of 4.0 mm. You can tap, drill and deburr in one action with the step drill.

They are mostly supplied in the sectors of industrieselectric (dimension 4 + size 9),sanitary engineering and also heating technics (size 6 + dimension 7),automotive, mechanical design, aviation (size 0/5, dimension 0/9, dimension 1, dimension 2, dimension 3, size 5) andswitching systems (dimension 0/9k, dimension 1k, size 2k) up to 2,0 mm sheet thickness.

Use coolants and also lubricants for cutting metals. By utilizing them you can significantly extend the organization life of the step drill.


We lug action drills with tool steels HSS and also HSSE-Co 5 and with coatings TiN and TiAlN. Depending on the tool steel and coating, harder or softer products can be reduced.


You deserve to read more about the 2 coatings in our articles:

Here you have the right to downfill a summary of applications depending on size and also a speed table as PDF. Click on one of the pictures.


In this video you have the right to watch just how step drills are made and also in which applications you usage them:


Conclusion and summary

Tip drills are ideally suited for cutting steels, plastics and timber up to 4 mm, for stainmuch less steel as much as 1.5 mm.

The production of step drills by utilizing the CBN process allows measuring and shear cutting edges due to the better hardness in the time of the grinding process. The product structure is cut via smoothly by the much harder abrasive material.

The allude angle and also the suggest thinning ensure straightforward centering and also a easier tapping into the workpiece. As quickly as the step drill has actually been drilled via, the 2 or three cutting edges are currently in place. The burr-cost-free and sharp cutting edges reduced the workpiece and overview the chip over the groove profile.

The step angle is 90° and also determines the shift from one step to the following. The transitions are provided for chamfering or deburring the hole.

Step drills are obtainable in assorted variants in the tool steels HSS and also HSSE-Co 5 and the coatings TiN and also TiAlN. You have the right to uncover our finish product array of action drills under Products > Step drills.

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If you have actually trouble finding the right step drill, please execute not hesitate to contact us.