Most people are well aware that drills are designed to produce even holes of a given diameter in parts or material. Holes or recesses can be of very different purposes, but since we are talking about metal drills, we will disclose this information specifically in relation to metal.
As a rule, drilling of metal parts or parts of a material is carried out to fasten them to each other using bolts, screws or rivets. You may also need a hole for mounting any equipment, etc. To make holes in metal products, usually classic drills are used.
They are a short metal bar made of stainless steel, on the working side of which there are spiral grooves.
Unlike hammer drills, the part of the drill that is clamped into the chuck has a smooth surface. Chips are removed along the grooves from the drilling site.
The tip of the drill is made in such a way that the central part cuts into the material in a small area. This is done to reduce friction and make it easier to remove the layer of material at the point of drilling.
Regardless of what metal you plan to drill, you need to buy the same drills. This we mention for those who want to try to find aluminum or copper drills.
Of course, there are also core or conical drills for metal, but we will consider them in other articles devoted directly to these consumables. In the meantime, back to the classic metal drills.
The difference between drills for metal and drills for wood
Drills for metal are quite similar to drills for wood. But they can be distinguished. The fact is that the wood drill has a small pin in the central part of the drill tip, which, when piercing the wood, serves as a guide when drilling. Drills for metal do not have this pin, and so that the drill does not move to the side, it is best to make a small dimple at the site of the future hole (punching - from the word core - a tool for creating these dimples). Also, drills differ in the angle of sharpening, since metal is a denser material than wood.
Dimensions and marking of drills for metal
The main indicator of a drill for metal is its diameter, or rather the diameter of the future hole in the metal, which is obtained as a result of using the drill. Drills for metal come in diameters of 1 mm or more. Moreover, if at first the step of the drill size goes through 0.5 mm, then for thicker drills it decreases to 0.1 mm. That is, you can find 1 mm, 1.5 mm, 2 mm drills on sale .... 4.5mm, 4.6mm, 4.7mm etc.
It should also be noted that the drilling diameter corresponds to the diameter of the drill shank. That is, if you take a drill with a diameter of 10 mm, its shank will also have a diameter of 10 mm. This must be understood so that it does not happen that you simply cannot insert the drill into the chuck of an electric drill or a screwdriver or a drilling machine. Most household drilling tools - more precisely, the cartridges of electric drills, machine tools and screwdrivers are designed for a maximum drill diameter of 13 mm. But it’s better to immediately check in the instructions for what maximum drill size it can be used before buying a drill.
If we talk about marking drills for metal, then we note that they put the diameter and hardness in accordance with the standards. The brand name may also be applied. On drills with a diameter of up to 3 mm, only the diameter is set (there is just not enough space). Hardness can be expressed as a steel grade, for example "R6M5" - high-speed tool steel - in accordance with GOST for Russian tools, or according to the European standard, for example "HSS" - means the same P6M5. The name of the manufacturer's company, we think, does not need to be explained. Also, after hardness, there may be a designation of an additional coating in the form of a designation of the metal used for this (chromium or titanium).
Metal drill color
The color of drills for metal may be different, but they can be used to judge the quality and strength of the drill.
1. Black drills.
This color is obtained in the course of special processing of the drill with the help of superheated steam, which quite well increases the life of the drill.
2. Gold tone drills.
This color is obtained from hardened drills that have been tempered. They are very strong, however, during the heat, internal stress arises in them and they turn out to be quite fragile. To eliminate or reduce this drawback, they are gradually heated and cooled during the manufacturing process - vacation to relieve stress.
3. Gold shade drills.
This color indicates that a thin layer of titanium nitride has been applied to the drill, which reduces friction and increases the strength of the drill. These drills are the most expensive.
4. Gray drills.
This type of drill does not undergo additional processing, has a relatively short service life and hardness, and is correspondingly cheaper than other drills.
We will immediately warn our readers that you should not immediately run to the store and buy golden drills. The fact is that you can easily buy a fake, which is China's main sin, although there are enough of our swindlers.
You can purchase regular quality drill bits that are simply painted and electroplated with a gold metal or alloy layer. It is better if the drills are bought by a professional, but in extreme cases, ask the seller - they usually do not recommend bad drills. And yes, the price says a lot. If you see cheap golden drills, you know that they are almost 100% fake.
Drill sharpening angle
If the drill becomes dull during operation, do not immediately throw it away. It can be further sharpened and used in work. For different metals, it is best to use your own sharpening angle. For soft metals it is 140 degrees, for steel 110 degrees. The standard sharpening angle of the purchased drill will most likely be 120 degrees, but it is never too late to change it for your material. Sharpening drills is best done by a person who knows how to do this well, if you haven’t done it, it’s better not to try - you’ll just ruin everything.
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