Drill for metal: types and marking

Drill for metal: types and marking
Drill for metal: types and marking

There are several ways to make holes in metal. In industry, they make their way on hydraulic presses and dies, they can be squeezed out (for this, the steel must be heated above the recrystallization temperature in order to eliminate the hardening effect and correct the fibrous structure). Holes are cut on a laser cutting machine, on an electroerosive machine, and by many other technological methods. However, the most common method for cutting holes in steel and metal alloys is drilling. At home, you can hardly find any alternative to a metal drill.

Features of Hole Drill Tool

A drill for metal has characteristic external features, due to which it cannot be confused with a tool designed for processing other materials (concrete, wood).

This drill is double-threaded, has two spirals. The sharpening of the drill for metal takes place on an abrasive (preferably diamond) wheel aswear and fatigue scratching of the working part. The special heat treatment (hardening plus low annealing) of the drill makes it quite resilient, it does not burst when struck and distorted, which are inevitable when working with a hand drill.

Light in the cartridge

The purpose of spiral grooves is to remove chips from the cutting zone. Through them, in the conditions of industrial production, during cutting on machine tools, a lubricating coolant is supplied to a hot cutting edge. The grooves also improve the cleanliness of the inner cylindrical surface of the hole.

However, there are drills with one spiral groove. They are designed to perform very specific tasks: for example, for cutting the barrels of firearms.

Recommendations for choosing a tool

When working with drills of a specific diameter or if you have a whole set of drills for metal, use tools from well-known manufacturers. Yes, it will come out a little more expensive, but it will last a long time, unlike numerous fakes that quickly break and become dull, since the production of a cheap tool is carried out in violation of the technological process.

Another pretty good reason why you should buy a branded instrument is a manufacturer's warranty. If the drill was used strictly for its intended purpose and in accordance with established standards, but there were problems with it, then the manufacturer assumes the obligation to reimburse the money spent on the purchase of the drill (as well as any other tool).

Metal drill at work

Drills of domestic production are marked in accordance with the state standard No. 19265-72 "High-speed tool steel for the manufacture of drills for metal." The marking is applied to the cylindrical shank of the drill.

If there is an opportunity to purchase an old instrument from the times of the USSR, be sure to use it. The Soviet instrument is very reliable, it was valued all over the world in its time. The tool industry of the state supplied many countries around the world with high-quality products.

What can the color of the drill say?

By the appearance of the drill, a professional can tell a lot about the stages of its manufacturing technology. Drills are often additionally hardened by applying wear-resistant coatings, diffusion saturation with atoms of other chemical elements (nitriding or boriding is mainly used).

Gray matte color are drills for metal, which have not been subjected to additional hardening treatment, except for hardening and tempering. Such a tool also serves well and is ideal for the home, since at home the drill is not used very often, so there is no point in overpaying for a hardening layer.

Drill for metal with a nozzle

Golden color has a coating based on titanium nitride. The coating is wear-resistant, anti-friction, that is, the tool heats up so much, and therefore does not allow red brittleness to appear (decrease in the operational properties and strength of the metal when it isheating) and does not cause a decrease in the modulus of elasticity.

Design and geometry of a simple drill

The word "simple" in this situation, perhaps, is not entirely appropriate, since the technological process of tool production is quite complex and requires high qualifications from performers. So in professional slang they call the most common type of metal drill - a one-piece tool made of high-speed steel, or a conventional cylindrical twist drill. Sometimes such drills are additionally hardened by chemical-thermal treatment methods. At the same time, they strive to obtain a small diffusion layer of the saturating element (nitriding).

These drills can be reground a large number of times. And this, of course, is their significant plus. The cutting edges form a cone with a vertex angle of 118 o. Allowed deviation in the angular size is not more than 30 о. Even a drill that has broken can be re-sharpened. This will change its overhang and, accordingly, the drilling depth.

Distinguishing Features of Tapered Drills

This type of tool is intended for cutting on machine tools of machine-building plants. The shank is made in the form of a Morse cone. Its parameters are strictly unified. A cone drill for metal is installed in a mandrel. To remove the drill (for example, in order to give it to the grinding department), you need to insert a wedge from sheet metal into the opening in the mandrel and hit it with a hammer.

Step drills for metal

It should be said beforedrills were made, the chuck of which was designed for the conical shank of the drill. The spindle speed of such devices is relatively low, and besides, they are low-power.

HSS metal core drill

This type of drill is an exception to the rule and is completely different from its counterparts. Outwardly, it looks more like a concrete drill, but it is not. HSS drills are designed for drilling holes of large diameters. It should be remembered that such a tool can only make a through hole in relatively thin sheet metal.

Carbide drill

Hard alloy is a special type of material obtained by special high-tech methods of sintering nanoparticles of various elements under high pressure. It has much greater wear resistance and endurance than traditional tool steel. However, a tool made of such a material is much more expensive, so this type of drill should be used for processing only especially strong structural alloyed materials with high cutting speeds. It is mainly used in processing on machining centers with numerical control (CNC).

Drilling metal on the machine

Normally, the drill bit is not entirely made of carbide material. The most common are drills with indexable inserts. And this solution is very successful: after the wear of the cutting part of the plate, it is enough just to unscrew and turn the other side. This saves the worker fromnumerous adjustments and setting relative coordinates in the CNC system and running around in the grinding department of the workshop.

Description and features of step drill

Such drills appeared on the market relatively recently and immediately gained popularity in home workshops and households. With such a drill, there is no need to keep an uncomfortable case with a set of tools of various diameters in the house. Only one step drill for metal allows you to make holes in sheet material from 6 to 30 mm. But still, such a drill can only penetrate thin sheet material. Unfortunately, it is impossible to get deep and blind holes with it.

Assignment of the left-hand drill

The industry produces left-handed drills. They are quite rare to find, but they do exist. They are mainly used by machine operators for drilling a broken tool (drills, taps, alignments, etc.). Such a drill is simply indispensable if a broken tool is stuck in an expensive workpiece, and there is no EDM machine at your disposal.

Combination self-tapping screws

In the slang of turners, self-tapping screws, at the end of which there is a drill, are called bedbugs. The thread is retracted into the head of such a screw. The thread pitch is very small, which allows you to securely fasten thin metal products to each other. For the manufacture of self-tapping screws for metal with a drill, ordinary structural steel is not suitable. High-strength alloyed material grades are used.

Self-tapping screw with a drill for metal

Self-tapping drill for metal can easily piercesheet material up to 2 mm thick, no more, otherwise the drill will burn.

Sharpening a drill at home

The drill is sharpened when it sits down and begins to enter the metal tightly when cutting, while it heats up, an unpleasant smell is felt in the air. You may need to regrind a tool that has been in the hands of an inexperienced craftsman. And finally, the drill can break during operation. In this case, it is not thrown away, but sharpened and reused if the length meets the requirements.

To ensure symmetry and correct geometry, it is better, of course, to sharpen drills on special machines. But not every household has such equipment. Even on ordinary emery, you can sharpen a drill for metal. How to do it qualitatively? You need to fill your hand first. After a few unsuccessful attempts, you will start to get it right.

Sharpening of the axial tool

The main thing in the process of work is to correctly designate and adhere to the axis of the tool so that the cutting edges are the same length. Without this, the drill will "drive" during operation, intensively crumble and eventually break.

The surfaces of the cutting edges are alternately ground on emery, while a characteristic bridge is formed between the cutting edges, which first touches the metal when cutting. In the course of work, both hands are involved. While the left hand fixes and holds the tool, the right hand gives it a rotary motion.

Working on emery involves a he alth hazard: the workpiecemay break out, a small piece may be chipped off, which, if bounced off, may damage the eyeball, the instrument may fly off the emery wheel and injure hands. Therefore, in these types of work, you need to be vigilant and follow the safety standards and regulations when working on industrial equipment.

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