Features of work with a cobalt drill on metal: advantages, features of drilling in different conditions
Doing repairs, many owners have to perform a variety of jobs, among which drilling is quite common. However, for the quality of this task it is necessary to have a suitable drill. There are no problems with purchasing this device, considering, that the market of building materials is represented by a large number of their different types.
Therefore, every homemaker, who bought a drill, should take care of the choice of good drills. Otherwise, they will quickly lose their operational life, and will have to spend money on new ones.
In stores you can find a large number of different drills, differing in length, diameter, material, for which they are intended. And even before you start creating holes on the surface of the structure, the appropriate drill size should be determined. To avoid mistakes here it is necessary to take into account the type of work performed.
Marking and color of drills on metal
Those owners, which at least once had to do drilling, it seems, tried to understand, what material is used to make these tools, what is meant by labeling, shown on the tool? Thanks to what it is possible to create openings on a surface, made of the same material, from which the drill is made?
The efficiency of the drill is achieved due to the fact, that high-strength and high-strength steel is used as a material for it. And here are the cheap options, which are produced on the basis of raw materials, unable to cope with most tasks, faced by many owners.
What does drill marking mean??
Usually the marking of the drill on the metal contains a certain set of letters and numbers. The letter of the main element is usually indicated first, and it is already followed by a figure, which corresponds to the percentage of this element in the material, used for the production of drills.
The first two characters are often followed by other elements.
- P - corresponds to tungsten;
- K - indicates cobalt;
- F - vanadium;
- M - provides molybdenum.
Chromium is often missing from the label, as this element must be included in the source material, in which it accounts for about 4%. Among the elements, which are not in the labeling, carbon should be isolated. Let's say, if the drill is marked P7M6K6, then it can be understood, that as a material the manufacturer used high-speed steel, which includes tungsten in quantity 7% , molybdenum - 6%, cobalt - 6%.
If you pay attention to domestic products, then there is no such information. However, this applies primarily to products, whose diameter is smaller 2 mm The device is the same diameter 2-3 mm contain information about the geometry and grades of steel. Additional data have drills, which represent other sizes: they also have a trademark, and sometimes the accuracy class of the drilling product.
Which means the color of the drill?
Each of the proposed drills can be decorated in one of the following colors:
- bright gold;
- black golden;
- gray;
- black.
The golden color can be understood, that the manufacturer used titanium nitride in the manufacture of the tool. Such an operation provides such a drill with increased strength characteristics. Working with such a device, less friction between surfaces will be provided.
A black golden hue indicates that, that the raw material contains leave, whose purpose is to eliminate internal stress.
You can understand the gray color, that the drill in question was not subject to finishing, in order to increase the level of protection and strength of the material. From this we can conclude, that this device has a low level of performance, and therefore it will fail soon enough.
Black allows you to talk about it, that in the manufacture of the drill operation was performed, which is the effect of superheated steam on the product. The benefit of it is to increase its durability.
Advantages of cobalt drills on metal
Prices for cobalt drills for metal are higher in 4-5 times, than on ordinary. What makes them so popular among home builders so? Thanks to what qualities they were awarded such a high grade?
A distinctive feature of cobalt is the high melting point. For this reason, drills for metal, created on the basis of high-quality high-speed steel, cobalt alloyed, perfectly tolerate high temperature effects and demonstrate improved mechanical properties. They are characterized by the ability to cope with significant heat loads, for which it is not necessary to resort to additional cooling. Similar properties of these drills on metal first of all situations are found out, when you have to make holes in high-strength alloy and high-viscosity steels.
Among other properties, which has cobalt drills for metal, it is necessary to allocate rather big angle of sharpening of a tip, which is 135 degrees. Thanks to this type of tip, it is possible to drill on smooth round surfaces.
These drilling devices can also be used to create holes in pipes and welds, where it is important to comply with the requirements for high accuracy. An important advantage of such drills for metal is that, that when working with them the master has to put less physical pressure on them.
Drilling with cobalt drill on metal
Even before you start drilling, the issue with the cutting mode should be resolved. To clarify, we will inform, that the main parameters, which affect such a regime, there are the following:
Cutting speed. Under it it is accepted to understand conditional circumferential speed of a drill on metal , which demonstrates the drill in relation to the workpiece. In other words, this parameter means the degree of rotation speed of the drill on the metal. Let's say, ensure the same cutting speed up to 20 m / min is possible provided, that a drill with a diameter will be used for work 1,0, and the speed of its rotation will be 6366 times per minute or you can use the device, whose diameter is equal to 10,0, and the speed is 637 rpm.
- Innings. It is a question of degree of movement of the working device in the direction of an axis of drilling for an interval, equal to one revolution. In accordance, the unit of measurement is the millimeter per revolution.
- Torque. This parameter determines the load level, which falls on the drill on the metal during cutting.
Each of the above parameters affect each other, at the same time at their choice it is necessary to consider:
- Material, in which it is necessary to create a hole;
- Material, from which the drill on metal cobalt is made;
- Equipment, used for work, and type of cooling;
- Other factors, which include the degree of surface roughness, pollution, etc.
Features of drilling of stainless steels
Engaged in the creation of holes for the surface of stainless steel, have to face problems, which boil down to that, that this material has sufficient ductility. Therefore, during operation, the drilling product sticks to the work surface, as a result, the device becomes very hot and further fails.
It is possible to avoid it, if:
- The problem with heat dissipation will be solved, for which cooling is used;
- The work will be carried out with drills, which best cope with heat and have the ability to better remove chips.
HSSCo high-speed steel is used as a material for cobalt metal drilling products (M35) or has similar markings. The peculiarity of these drills is that, that in their manufacture, manufacturers have laid in them special properties, which allow them to effectively create holes in hard-to-work stainless steels.
Steel P6M5K5 contains 5% cobalt, due to which the drill acquires increased redness. We are talking about the ability to remain just as solid and resistant to wear, as in the normal state, under conditions of heating to the temperature of red incandescence. A similar effect is achieved through heat treatment.
The production process involves the use of more expensive grinding technology. In other words, this device resembles a spiral, where a grinder is used to create the grooves. This eliminates the appearance of internal tension on the device, while the surfaces remain smooth. This creates more favorable conditions for chip removal.
The upper part of the working device is located at an angle 135 degrees and is characterized by the presence of cruciate sharpening. Such an angle is formed by the working faces of the device. It reduces the working area of the product. As a result, it is less stressed. As for the cross-shaped sharpening of the top, then its presence reduces the dead zone between the working faces.
How to drill stainless steel with cobalt drill
If you have the equipment, which allows you to choose the optimal speed with high accuracy, supply and provide cooling, the following parameters will be recommended for work with stainless steel:
Cutting speed. The optimal value will be 10 m / min. The given value will be optimal for drilling of the majority of stainless steels. In addition, its use will provide an opportunity to choose the speed.
You can determine the speed, using the following formula:
n=3180/D, where
for drill diameter 1,0 – 3180 rpm;
for drills 5,0 already 636 rpm;
Innings. A simple formula should also be used to calculate this parameter:
0,005-0,01 d mm / n,
where d is the diameter of the drill.
In simpler words, for one minute a drill on metal, whose diameter is 5 mm should create a hole depth 3 mm When working with a drill on metal with a diameter 10 mm created hole should be the size 1,6 mm.
The problem of overheating is solved with oleic acid, which will act as a coolant.
Features of drilling in the field
In the absence of a special coolant, you can use olive oil instead. Sunflower is also suitable here, in which the proportion of oleic acid is only in 2 times less - 40%. In that case, if none of these substances is at hand, then ordinary lard or fat can help: they can reach the level of oleic acid 44%.
When creating holes, it is necessary to set the minimum speed no more 200 rpm. Some drill models do not have the ability to choose the speed. In this case, the problem is solved by using the technique of "on-off", in which the recess in the material is created by inertia.
Watch it, so that the feed on the drill was minimal. At the same time, it is important, to make it uniform.
Conclusion
Cobalt metal drill bits can help create holes in particularly durable materials, in the first place, stainless steels. However, for the successful implementation of this work it is necessary to take into account a number of nuances. Drilling holes with a cobalt drill on metal will not give you problems, if you define the operating parameters correctly: cutting speed, filing, and resolve cooling issues. It will be useful to know, how to work with such drills. Then they will be good helpers for you during the repair.
