Under certain conditions (e.g. type of stainless steel, point angle, spiral angle etc.) you can also use a TiAlN-coated HSS drill. There are some stainless steels that are easy to cut and can also be drilled with coated HSS drills.

The break sensitivity in comparison to HSS is higher in HSSE-Co or carbide tool steels. Basically you can negate this with the correct application (correct speed, feed and cooling). In general, the more cobalt, the harder and therefore more brittle the drill.

In stainless steel, it must be enriched with alloying elements such as titanium, niobium or chromium in addition to iron. Chromium (Cr) is the corrosion resistance of stainless steel and should have a minimum content of 12% and an extremely low carbon content. The chromium content creates a layer on the material surface which permanently protects against water and moisture.

What features does the twist drill have to have in order to cut stainless steel? The following criteria must be met in order to obtain a good drilling result.

If you have found the right twist drill and follow these instructions, you will get a good drilling result in stainless steel.

Transition Fit: A fit type where clearance or interference can exist between assembled parts depending on tolerance conditions.

ISO 286 establishes a system for tolerances to be used for linear sizes of features of cylinder and two parallel opposite surfaces. It provides a standardized selection of tolerance classes for general purposes from amongst the numerous possibilities. The main intention of this system is the fulfilment of the function fit.

A tool steel that is too soft would immediately overheat. So since stainless steel is a hard material, you need a twist drill type H. In the course of time, the features of twist drills have been combined differently in order to optimize them for special applications. Thus, mixtures have formed whose naming system is not standardized in the DIN manual. So you will find at RUKO for use in stainless steel types VA, FO, UTL3000, UNI, TL3000, N and UTL.

M6tolerancefor Shaft

In the application table you will find all our twist drills with which you can drill in stainless steel. If you click on the images of the twist drills in the PDF, you will be taken directly to the product page where you can find detailed information about the twist drill.

M6tolerancechart

Fits and tolerance calculator for shaft and hole tolerance calculation according to ISO 286-1 and ANSI B4.2 metric standards . The schematic representation of the fit is also drawn by tolerance calculator.

Lower deviation: The difference between the minimum limiting size and the corresponding nominal size of a feature.

With cooling you ensure that the surface quality is optimal, the temperature is lowered and the chips are swept away. This extends the life of the drill

Stainless steel is a very hard material and therefore difficult to cut. Therefore, the tool steel of the twist drill should be made of HSSE-Co 5 (5% cobalt content), HSSE-Co 8 (8% cobalt content) or solid carbide.

J6ToleranceChart

The tolerances defined in ISO 286-1 are applicable to size range from 0 mm to 3150 mm but there are exceptional cases defined in the standard which depends on tolerance selection. If the calculation results given by the tolerance calculator are "---", then this means the input parameters are not applicable according to ISO standard.

See the table below for information on the speed and feed settings and the type of cooling. You can download the speed table as a PDF file. Click on the image.

You have chosen a suitable twist drill and now you finally want to drill your hole in stainless steel. When drilling, it is important that you

Stainless steel is a metallic material which is characterized by its special purity . There are alloyed and unalloyed steel, but only the alloyed variant is also stainless.

The spiral angle determines the process of chip formation. Small spiral angles are used for hard short-chipping materials.

H8ToleranceChart

H7ToleranceChart

The need for limits and fits for machined workpieces was brought about mainly by the requirement for interchangeability between mass produced parts. In order that fit function could be satisfied, it was found sufficient to manufacture a given workpiece so that its size lay within two permissible limits, i.e. a tolerance, this being the variation in size acceptable in manufacture while ensuring the functional fit requirements of the product. Similarly, where a specific fit condition is required between mating features of two different workpieces, it is necessary to ascribe an allowance, either positive or negative, to the nominal size to achieve the required clearance or interference.

With cooling you ensure that the surface quality is optimal, the temperature is lowered and the chips are swept away. This extends the life of the drill

The point angle is located at the head of the twist drill. For hard materials such as stainless steel, the point angle should be large and e.g. 130° or 135°. For soft materials, point angles of e.g. 118° are used.

ISOToleranceChart for holes and shafts PDF

Interference: The difference before mating between the size of the hole and the size of the shaft when the diameter of the shaft is larger than the diameter of the hole.

If you do not have a pillar drill available, use the pointed side of the punch and a hammer to make a small recess in your stainless steel workpiece. This gives you better guidance and prevents slippage when drilling. The center punching compresses the material a bit, but mainly the material is displaced to the side and over the top of the material. This does not pose any extreme challenges for the twist drill.

Hole and shafttoleranceChart

Fit: Relationship between an external feature of size and an internal feature of size (the hole and shaft of the same type) which are to be assembled.

In our detailed article "8 features of a twist drill and its functions" you will learn all the important features of twist drills and which functions they have when drilling.

With a large point angle, more of the cutting edge engages in the workpiece when drilling. This also means that more force is applied to the workpiece and higher contact pressure (high feed) is required.

In each of our product groups you will find a Product finder. Under Products > Twist drills you can filter "stainless steel" in the field Applications. You will then be shown all twist drills that can be used for cutting stainless steel.

Clearance: The difference between the size of the hole and the size of the shaft when the diameter of the shaft is smaller than the diameter of the hole.

You should not have used the twist drill on other steels before. The metal particles on the twist drill can attack the stainless steel and make it susceptible to corrosion.

If you want to use a coating, e.g. to increase the tool life, it should be at least the TiAlN coating, because it has a high heat resistance. With TiAlN-coated drills, cooling is not necessarily required. In addition, they prevent cold welding on the drill.

Upper deviation: The difference between the maximum limiting size and the corresponding nominal size of a feature.

If possible, use a pillar drilling machine as it allows you to better control the centering, speed and feed . High feed rate is required and your speed is rather low when drilling.

You want to drill a hole in stainless steel but don't know which twist drill to use? In this article we explain how to drill in stainless steel and which twist drills to use.

Since stainless steel is a very hard material, you have to choose the right twist drill. The twist drill should belong to the application group Type H of the DIN 1386 division. Over time, however, mixed forms have been developed whose naming systems are not standardized in the DIN manual. So you will find at RUKO for the use in stainless steel the types VA, FO, UTL3000, UNI, TL3000, N and UTL.

Designation of the tolerance class: The tolerance class shall be designated by the combination of an upper-case letter(s) for holes and lowercase letters for shafts identifying the fundamental deviation and by the number representing the standard tolerance grade. For example H7 tolerance class for holes and h7 tolerance class for shafts.

ISOToleranceChart

GD&T A means of dimensioning and tolerancing a part with respect to relationship and function of that part. GD&T is used to define how a part feature relates the other part features in the same part or in a mating part; it’s a way to dimension and tolerance with respect to part’s function, the way it works.

You should not wear gloves, because they can get caught in the twist drill. In contrast to the gloves, you should unconditionally put on protective goggles.

The twist drills made of HSSE-Co 5, HSSE-Co 8 or solid carbide do not neccesarily need coating . Coated drills are still ideally suited for industrial use. I.e. fast speeds (high cutting speeds), high feed rates and increased heat applications.