How to sharpen a drill for hardened steel - Metals and their processing

Drills for drilling hardened metal - Metalworker's Handbook

When doing repairs, many owners have to perform a wide variety of work, among which drilling is quite common. However, to perform this task well, you must have a suitable drill available. There are no problems with purchasing this device, given that there are a large number of different types on the building materials market.

Therefore, every home craftsman who has purchased a drill should also worry about choosing good drills. Otherwise, they will quickly use up their service life, and you will have to spend money on new ones.

In stores you can find a large number of different drills, differing in length, diameter, and material for which they are intended. And even before you start creating a hole on the surface of the structure, you should decide on the appropriate drill size . To avoid mistakes here, it is necessary to take into account the type of work being performed.

Marking and color of metal drills

Those owners who have had to do drilling at least once, I think, tried to understand what material is used to make these devices, what is meant by the marking on the tool? What makes it possible to create holes on a surface made of the same material from which the drill itself is made?

The efficiency of working with a drill is achieved due to the fact that high-quality and high-strength steel is used as the material for it. But cheap options that are produced on a raw material basis are not able to cope with most of the problems that many owners face.

What does the drill marking mean?

Typically, the marking of a metal drill contains a certain set of letters and numbers . The letter of the main element is usually indicated first, followed by a number that corresponds to the percentage of this element in the material used to produce the drill.

After the first two characters, other elements are often specified.

P – corresponds to tungsten;
K - indicates cobalt;
F - means vanadium;
M – means molybdenum.

Most often, the labeling does not include the designation of chromium, since this element is necessarily included in the source material, in which its share is about 4%.

Among the elements that are missing from the labeling, carbon should be highlighted.

For example, if a drill is marked P7M6K6 , then it can be understood that the manufacturer used high-speed steel as a material, which contains tungsten in the amount of 7%, molybdenum - 6%, cobalt - 6%.

If you pay attention to domestic products, there is no such information. However, this applies primarily to products whose diameter is less than 2 mm. Devices with a diameter of 2-3 mm contain information about the geometry and grade of steel. Drills that represent other standard sizes have additional data: they also provide the trademark and sometimes the accuracy class of the drilling product.

What does the drill color mean?

Each of the offered drills can be designed in one of the following colors:

bright gold;
black golden;
grey;
black.

By the golden color, you can understand that the manufacturer used titanium nitride in the manufacture of the instrument. This operation provides such a drill with increased strength characteristics. Working with such a device will ensure less friction between surfaces.

A black golden hue indicates that the raw material contains a temper, the purpose of which is to eliminate internal stress.

The gray color indicates that the drill in question has not been finished 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 workmanship, and therefore it will fail quite soon .

The black color suggests that during the manufacture of the drill, an operation was carried out that involved exposing the product to superheated steam. The benefit of it is to increase its wear resistance.

Advantages of cobalt drills for metal

Prices for cobalt metal drills are 4-5 times higher than regular ones. What makes them so popular among home craftsmen? What merits made them so highly rated?

A distinctive feature of cobalt is its high melting point . For this reason, metal drills, created on the basis of high-quality high-speed steel alloyed with cobalt, perfectly withstand high temperatures and demonstrate improved mechanical properties.

They are characterized by the ability to cope with significant thermal loads, for which they do not have to resort to additional cooling. Similar properties of these metal drills are primarily manifested in situations where it is necessary to create holes in high-strength alloy and high-viscosity steels.

Among other properties that cobalt metal drills have, we should highlight a fairly large sharpening angle of the tip, which is 135 degrees . Thanks to this design of the tip, it becomes possible to drill on smooth round surfaces.

These drilling devices can also be used to create holes in pipes and welds where high precision requirements are important. An important advantage of such metal drills is that when working with them, the master has to exert less physical pressure on them.

Drilling with a cobalt drill for metal

Even before you start drilling, you should decide the issue with the cutting mode. To clarify, let us inform you that the main parameters that affect such a mode are the following:

Cutting speed . It is usually understood as the conditional peripheral speed of a drill for metal, which is demonstrated by the drill in relation to the element being processed. In other words, this parameter means the degree of rotation speed of the drill through metal. For example, it is possible to ensure the same cutting speed of 20 m/min, provided that a drill with a diameter of 1.0 is used for the work, and its rotation speed is 6366 times per minute, or you can use a device whose diameter is 10.0, and the frequency rotation is 637 rpm.
Submission . We are talking about the degree of movement of the working device in the direction of the drilling axis over a period equal to one revolution. Accordingly, the unit of measurement is millimeter per revolution.
Torque . This parameter determines the level of load that falls on the metal drill during cutting.

Each of the above parameters influence each other, and when choosing them it is necessary to take into account:

The material in which the hole needs to be created;
The material from which the metal drill is made is cobalt;
Equipment used for work and type of cooling;
Other factors, which include the degree of surface roughness, contamination, etc.

Features of drilling stainless steels

When creating holes in a stainless steel surface, you have to face problems that boil down to the fact that this material is characterized by sufficient ductility. Therefore, during operation, the drilling product sticks to the working surface, as a result of which the device heats up too much and subsequently fails.

This can be avoided if:

The problem with heat removal will be solved, for which cooling is used;
Work will be carried out with drills that best cope with heat and have the ability to better remove chips.

Do-it-yourself metal chasing

The material used for cobalt metal drilling products is high-speed steel HSSCo (M35) or similar marked. The peculiarity of these drills is that during their manufacture, manufacturers incorporated special properties into them that allow them to effectively create holes in difficult-to-cut stainless steels.

R6M5K5 steel contains 5% cobalt , due to which the drill acquires increased red resistance. We are talking about the property of remaining as hard and resistant to wear as in the normal state, under conditions of heating to a red-hot temperature. 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 grinding machine is used to create 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 of 135 degrees and is distinguished by the presence of a cross-shaped point. A similar angle is formed by the working edges of the device. It ensures a reduction in the area of the product's working area. As a result, it is subject to less stress. As for the cross-shaped point of the top, its presence reduces the dead zone between the working edges.

How to drill stainless steel with a cobalt drill

If you have equipment at your disposal that allows you to accurately select the optimal speed, feed and provide cooling, the following parameters are recommended for working with stainless steel:

Cutting speed. The optimal value would be 10 m/min. The value given will be optimal for drilling most stainless steels. In addition, its use will provide the opportunity to select speeds.

You can determine the speed using the following formula:

n=3180/D , where

for a drill with a diameter of 1.0 – 3180 rpm;

for drill 5.0 already 636 rpm;

Innings. To calculate this parameter you should also use a simple formula:

0.005-0.01d mm/n,

where d is the diameter of the drill.

In simpler terms, in one minute a metal drill with a diameter of 5 mm should create a hole 3 mm deep . When working with a metal drill with a diameter of 10 mm, the hole created should have a size of 1.6 mm.

The problem with overheating is solved with the help of oleic acid, which will act as a coolant.

Features of drilling in the field

If special coolant is not available, olive oil can be used instead. Also suitable here is vegetable, in which the proportion of oleic acid content is only 2 times less - 40%. If none of these substances is at hand, then ordinary lard or fat can come to the rescue: the level of oleic acid in them can reach 44% .

When creating holes, you must set the minimum speed to no more than 200 rpm. Some drill models do not have the ability to select speed. In this case, the problem is solved by using the “on-off” technique, in which a depression in the material is created due to inertia.

Make sure that the feed to the drill is minimal. At the same time, it is important that it is uniform.

Conclusion

Cobalt metal drills can help create holes in particularly strong materials, primarily stainless steel. However, to successfully complete this work, it is necessary to take into account a number of nuances.

Drilling holes with a cobalt drill for metal will not give you problems if you correctly determine the operating parameters: cutting speed, feed, and also solve the issue of cooling. In this case, it will be useful to know how to work with such drills correctly.

Then they will become good helpers for you when carrying out repairs.

Nikolay Ivanovich Matveev

Source: https://ssk2121.com/sverla-dlya-sverleniya-kalenogo-metalla/

How to drill hardened steel at home with a regular drill - Site about

To improve the basic characteristics of the metal, it is often hardened. This technology involves increasing the hardness of the product due to strong heating of the metal and its rapid cooling.

In some cases, after heat treatment it is necessary to perform drilling. By increasing this characteristic, drilling hardened metal becomes more difficult.

Let's take a closer look at all the features of drilling hardened steel.

Drilling a hole in hardened steel

The widespread question of how to drill through hardened steel can be associated with the fact that when using conventional technology, the tool quickly becomes dull and becomes unusable. That is why you need to pay attention to the features of drilling hardened alloy. Among the features of the technology, we note the following points:

It is necessary to properly prepare the hardened workpiece.
In some cases, a special tool is required.
Coolant is being used.

If necessary, you can make a drill for hardened steel with your own hands, which requires certain equipment and skills. However, in most cases, a purchased version is used, since it will cope better with the task when cutting hardened steel.

Hardened steel drilling process

Nuances when drilling

The technology in question has a fairly large number of features that need to be taken into account. Drilling of hardened metal is carried out taking into account the following points:

Before carrying out work, pay attention to the hardness of the surface. This parameter is used to select the most suitable drill. Hardness can be determined using a variety of technologies.
During drilling, a large amount of heat is generated. This is why rapid wear of the cutting edge occurs. In this regard, in many cases, cooling liquid is supplied to the cutting zone.
When cutting difficult-to-cut material, it is necessary to sharpen the cutting edge from time to time. For this, a conventional sharpening machine or a special tool is used. Only diamond-coated wheels are suitable as an abrasive.

Steel Drilling Tool

There are a variety of methods for cutting hardened steel. Some of them significantly simplify the processing. Only by taking into account all the nuances can the quality of the resulting hole be improved.

Useful drilling techniques

A variety of technologies can be used to work with hardened steel. The most common technologies are characterized by the following features:

Surface treatment with acid. This technology is characterized by long-term use, since it takes quite a lot of time to reduce the surface hardness. Sulfuric, perchloric or other acid can be used for etching. The procedure involves creating a lip that will contain the substance used in the cutting zone. After prolonged exposure, the metal becomes softer, and it will be possible to drill using the conventional version.
You can use a welding machine to achieve your goal. When exposed to high temperatures, the metal becomes softer, which greatly simplifies the procedure.
Most often, a special drill is used. There are versions on sale that can be used for processing hardened steel. In their manufacture, metal with increased resistance to wear and high temperatures is used. However, the complexity of manufacturing and some other points determine that the cost of a special tool is quite high.

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In addition, to achieve this goal, a punch is often purchased. It can be used to make a small hole, which will simplify further drilling.

Use of lubricants

When drilling through hardened steel, serious friction occurs. That is why it is recommended to purchase and use various lubricants. Among the features of this processing method, we note the following points:

First, the drilling area is processed. A small amount of lubricant is applied to the surface where the hole will be located.
Oil is added to the cutting edge. To process hardened steel, a small amount of the substance is required, but it must be added from time to time, since it scatters when the tool rotates.
During work, it is recommended to take breaks to cool the cutting surface and the surface being processed.

Lubricating steel with special oil

Special oil not only simplifies drilling, but also increases the service life of the tool used.

This is because oil can reduce the temperature of the cutting edge.

Drill selection

Twist drills, which are represented by a vertical rod with two grooves, have become quite widespread. Due to the specific arrangement of the grooves, a cutting edge is formed. Among the features of the choice, we note the following points:

The pobedite drill bit has become quite widespread. It can be used to work with various hardened alloys. However, a surface with too high hardness cannot be processed with such a tool.
The choice is also made based on diameter. It is worth considering that it is quite difficult to obtain a large diameter hole. The larger diameter version is much more expensive due to the use of a large amount of material in its manufacture.
Attention is also paid to the sharpening angle, the purpose of the product and the type of material used in manufacturing. For example, cobalt versions are characterized by higher resistance to high temperatures.
It is recommended to pay attention to products exclusively from well-known manufacturers. This is due to the fact that Chinese versions are manufactured using low-quality materials. However, such an offer is much cheaper and can be used for short-term or one-time work.
When choosing a drill, you can be guided by the markings. It can be used to determine which materials were used in production. The diameter of the hole that can be obtained when using the tool is also indicated.

Drill for hardened steel

In a specialized store you can find almost everything you need to carry out the work. However, the fairly high cost of the product and some other factors determine that some decide to make a drill themselves from scrap materials. Similar work can be done if you have the required tools.

Making a homemade drill

If necessary, a drill can be made from hardened steel. Among the main recommendations for carrying out such work, we note:

Rods are selected that are made from tungsten and cobalt alloys. People call this metal victorious. Compared to a conventional drill, this version is characterized by increased wear resistance.
To process the workpiece, you need to secure it in a small vice. Otherwise, the work will be quite difficult.
To sharpen such a surface, a diamond stone is required. The usual one will not withstand long-term work.
The end surface is sharpened to create a surface that resembles a flat-head screwdriver. The cutting edges are then sharpened to produce a sharp tip.

In order to reduce the degree of surface machinability, oil is added. This ensures long-term processing due to reduced friction and lower temperature.

Homemade drill bits

In conclusion, we note that processing of hardened steel should be carried out exclusively with the use of special tools. The work requires a drilling machine, since a manual one will not allow you to get the required hole.

Source: https://nzmetallspb.ru/tehnologii/kak-prosverlit-kalenuyu-stal-v-domashnih-usloviyah-obychnym-sverlom.html

How to sharpen a drill correctly?

When drilling metal, the cutting tool loses its initial sharpness of the working edge. Don't throw it away to buy a new one.

Even the strongest grade of steel, subject to heat treatment, cannot ensure drilling operations without restoring the cutting part. Sharpening a drill for metal will help restore its previous performance properties.

It is easy to make a device with your own hands at home without the use of special equipment. Let's look at how to return a tool to its original cutting properties.

At home, work is often done to make holes of the required size in metal. When drilling, it is not always possible to quickly replace a worn-out tool with a new one of the required size. Home craftsmen try to select the required diameter, but if the sharpening angles of the drills are not maintained, then it is problematic to quickly and efficiently complete the task.

The discrepancy between the sharpness of the cutting edge and geometric parameters can be determined by a number of signs:

increased noise level emitted by an unsharpened shank;
intensive increase in the temperature of the workpiece during machining;
sudden heating of the working part and the body fixed in the cartridge;
unsatisfactory quality of formed holes;
an increase in the axial force applied to the electric drill;
the quality of the chips, which crumble and do not have a spiral shape.

Drills intended for metal work have to be sharpened much more often than those used for wood processing.

In addition, the load on the electric motor increases significantly when trying to apply a force in the axial direction sufficient to immerse the cutting edge into the metal. The dullness of the chamfer is a source of additional resistance between the cutting part and the processing surface. Knowing how to properly sharpen a drill for metal, if any of these signs are detected, you must immediately stop drilling and begin restoration.

A worn working part not only reduces machining efficiency, but also affects safety. At high temperatures and elevated temperatures, performing machining at significant speeds, breakdown is possible. Metal fragments can fly in all directions and cause serious injury.

Sharpening drills - preparatory activities

Home craftsmen are often upset by the impossibility of further implementation of plans due to the fact that the drill has become dull. How to sharpen it yourself? Indeed, in the conditions of manufacturing enterprises, special equipment is used to solve such a problem.

It allows for increased accuracy, securely fixes the cutting shank and restores the condition of the cutting edge in a limited time. When thinking about how to sharpen a metal drill at home, check what household power tools are available.

The following equipment will be suitable:

Sander;
grinder;
electric drill.

You should carefully consider what you will need to complete the work and what you will need to add to the power tool.

Sharpening a drill for metal using a special device greatly simplifies the task

Do-it-yourself drill sharpening should be done using additional accessories:

grinding wheels of varying hardness. The grain size of the wheel is selected depending on the hardness of the material being processed;
container intended for coolant. In terms of cooling efficiency, machine oil will provide a greater effect than ordinary water;
a fixing device to ensure the required sharpening angle. It is important to ensure reliable fixation when processing the cutting part.

To ensure immobility, a complex adjustable angle jig or a simple drill bit sharpener can be used on a drill.

When performing work, it is necessary to use personal protective equipment to comply with safety requirements.

For sharpening activities you will need:

protective glasses. They will protect the mucous membrane of the eyes from clogging with chips and dust, as well as sparks during machining;
mittens. They will reliably protect the skin of your hands from cuts when touching a sharply sharpened edge and flying fragments of metal shavings.

Having prepared everything you need to complete the work, you should learn how to sharpen a drill correctly at home. This will avoid mistakes and significantly speed up the completion of sharpening activities.

Working with a worn drill is not only ineffective, but also unsafe.

How to sharpen drills for metal correctly

Unfortunately, not all home craftsmen have any idea how to properly sharpen a drill. Some spend money on buying a new one and throw away the dull ones. At the same time, restoring a dull surface is a simple operation that allows you to return to its previous performance characteristics.

Depending on the shape of the cutting part, various methods for restoring the working surface are used:

single-plane;
two-plane;
conical;
cylindrical;
screw.

Before starting work you should:

decide on the method of restoration work;
inspect the condition of the working surface;
check the functionality of the sharpening device;
prepare the fixing device.

Using the example of the most common methods - single-plane and conical, we will consider the algorithm of actions.

In order for the drill to be sharpened with high quality, it is necessary to ensure that it is fed into the processing area at the required angle

When performing work using the single-plane method, it is necessary to bring the cutting tool to the emery wheel, ensuring that the cutting edge is parallel to the plane of the circle. Then you need to press it to the circle, keeping the rear angle in the range of 26–30 degrees. This is a fairly simple method, used for products with a diameter of no more than 3 mm.

Please note the serious points:

the abrasive wheel should rotate towards the surface being sharpened;
maintain a constant angle and do not allow displacement relative to the axis;
carry out the work of restoring the working edge in one approach;
Cool the heated shank when changing positions.

When visually inspecting the tip, the working edges should have the same slope and equal length, which can be easily checked using a template.

The conical restoration method is more complex and requires some preparation. It has fundamental differences from the single-plane one, and is used for tools with a diameter of over 4 mm. The tool to be sharpened should be held with both hands.

Having touched the working part of the abrasive surface, it is necessary to smoothly rotate along the back side, giving it a cone-shaped shape. In this case, it is prohibited to open the tool from the sanding surface.

It is necessary to start each cycle from the working edge and end with a full rotation, followed by checking the angles.

After completing work on restoring the cutting edge, remember that it is necessary to finish the tool.

When sharpening drills at home, you always have to look for ways to make the result of this process high-quality

Finishing task:

grinding the working part;
removal of the smallest roughness.

To do this, you can use a wheel with a fine abrasive.

There is a general rule when performing sharpening work - first you should sharpen the rear base, and then approach the processing of the cutting element.

It is important to follow the following recommendations:

hold the tool with the cutting edge parallel to the abrasive wheel;
use a special device that provides the required sharpening angle.

When sharpening, pay attention to the following points:

compliance with the front angle of the working part. It is measured in the main plane and is located between the working part of the tool and the base of the cutting edge;
correct sharpening of the rear corner of the cutting edge. It is controlled similarly to the front one, but is located in the rear plane of the instrument;
correspondence of the angular position of the two cutting edges. The angle is located at the top of the working surface and is located between both cutting edges.

Following the sharpening recommendations will allow you to fully restore performance characteristics.

An emery machine equipped with a grinding wheel is a universal device that allows you to sharpen a drill for metal with high quality even at home.

Drill sharpening angle - use a control template

When performing sharpening work yourself, you should eliminate the possibility of mistakes. To do this, you need to check the correctness of processing using a special template. You can buy it in specialized stores or make it yourself using aluminum, copper or steel sheet with a thickness of 1–1.5 mm. It is advisable to use a steel template, which has an increased service life.

The test device allows you to check the following parameters:

cutting edge length;
apex angle;
relative position of the cutting part and the jumper.

By controlling the sharpening angle and other parameters, you can achieve the correct geometry of the working part. After checking using a control template, you can perform a test drilling and, if necessary, re-finish the working surface.

Metal drills - sharpening using a device

To restore cutting tools at home, it is convenient to use a homemade device. Sharpening a drill for metal is a simple operation that you can do yourself. To ensure structural rigidity, it is necessary to assemble the device on a powerful base plate.

The following elements are attached to the base:

drive motor with an emery wheel mounted on the shaft;
rotary column with a tool locking mechanism.

Using a rotating device will allow you to sharpen in different spatial positions. In this case, the angle of location of the cutting part relative to the abrasive surface of the wheel will be guaranteed.

Using an attachment with a circle installed in the chuck of a regular household drill, you can also restore the cutting edge.

To do this you need to do the following:

Secure the cutting tool in a vice or fixture.
Set the required angular position.
Secure the abrasive disc in the chuck.
Bring the drill with the attachment at the required angle.

Similar tasks can be performed using a grinder, on which is attached a disk designed for metal processing.

Let's sum it up

Having understood all the intricacies of sharpening work, you should decide which power tool is best to use. Home craftsmen have developed many different devices that provide increased sharpening accuracy. It is important to carefully study their design and choose the best option. It is advisable to restore the instrument for the first time under the supervision of a specialist. Patience and perseverance are the main qualities in this work.

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Source: https://pobetony.expert/poleznye-stati/zatochka-sverl

Drilling hardened steel and metal

It is better to drill steel before the heating process, since this will not cause any difficulties. If you come across a hardened workpiece (of great thickness), release it, drill holes with a standard drill and re-harden if the situation requires it. However, this option is not always possible.

There are often situations when you need to make a hole in a steel workpiece, but it is already heavily hardened. In production and by folk craftsmen, many options and technologies for drilling hardened steel have been created. You need to proceed from the situation, the materials that are at hand.

An obligatory factor is the goals for which this work is required.

At home

Sometimes, to get a hole, it is enough to make a slot with a grinder. Pass a screw through it, then secure the workpiece. To make the hole smaller, it needs to be made from 2 sides. In this case, the disk of the smallest diameter is used. A practically erased disk would be better.

Before work, the steel must be examined for hardness. Based on this, choose a method. If the workpiece bends well, a drill with pobedit tips will do, i.e. on concrete. A prerequisite is that it must be spicy. You can sharpen it with a diamond wheel. Otherwise, the use of special tools is required.

During work, the workpiece is pressed tightly with a drill, and high speeds are set. The drilling site is pre-lubricated. It would be better to initially use a drill of a smaller diameter, and then replace it with a larger one. This reduces the resistance area and increases efficiency.

If a special drill made of carbon steel is used, you need to work taking into account the following subtleties:

Do not press the drill too hard against the workpiece;
Do not turn on high speeds.

The following method will take from 2 hours. First, the metal is etched with sulfuric or nitric acid. A side is made from paraffin, and acid is placed there. The diameter of the “eye” turns out to be slightly wider than the side itself, so when making it, this nuance is taken into account. To speed up the process, the workpiece is heated to 50 degrees.

The hole is also made with a conventional welding machine. The place itself is burned or “released”, and then simply drilled. Melted edges must be sanded.

In production

To drill thicker hardened workpieces, special machines are used. In them, the drill is mounted in a special drill chuck, which is secured with a conical tail in the tailstock quill.

Drilling work is carried out thanks to the linear feed of the drill and the quill feed wheel. At the same time, both the workpiece and the drill rotate. The maximum usable drill diameter is 1.5 centimeters.

Large drills are secured with a tail with adapter sleeves. They come in standard sizes. They are called Morse cones.

Drills are:

Spiral with cylindrical and conical shanks. They can drill not only hardened steel, but also cast iron, as well as other “strong” materials;
With inserts made of carbide materials. Also suitable for thick, hardened steel;
Deep drill bits. They are used in cases where a hole is made with a depth of 5 times the diameter of the drill.

Before work, the surface of the workpiece is processed. A recess is also made with a centering drill. Otherwise, the drill begins to “walk” in front of the steel sheet, and the hole moves away from the central axis of rotation.

The depth of the hole is controlled by notches with markings on the quill. If there is a dial on it, then the drilling depth will be accurate to 0.01 millimeters. Drilling must be done in several stages. Having made a hole 2 mm deep, the drill is removed from the steel and chips are removed (from the hole and drill outlet channels). After which the process continues. If you do not follow this technology, the drill may jam and break. Don't forget to use lubricant.

Before you start drilling, you must remember that the diameter of the hole is larger than the diameter of the drill. This value is called breakdown. For a drill with a diameter of 1 centimeter, the breakdown will be 0.15 millimeters. Splitting occurs due to insufficient precision during drill sharpening.

To obtain a high-quality hole, the first step is to use a drill whose size is 70% of the diameter of the required hole. At the second stage, it is changed and the required size is used. More precise processing is obtained using countersinking and reaming.

Countersinking

Suitable for cast machined workpieces with pre-drilled holes. Countersinks help improve surface finish and increase accuracy for further reaming. Compared to standard drills, they have three or more helical flutes and a short cutting part. When countersinking, use lubricating fluid. The spindle speed should be lower than when drilling.

Scan

A tool that pre-machines and finishes a hole with the required precision. The diameter of the hole that is prepared for the reamer should be less than half a centimeter of the reamer itself. The spindle speed should not be high, 50-200 per minute. During reaming, lubricating fluid is also used.

Boring

During boring, the following cutters are used:

Boring curved. Processes a through hole before roughing;
Boring scoring machine. Processes blind holes. Trims the internal corners of the ends;
Grooved. Not used often. Mostly for threaded grooves. Cutters are made of hard steel;

Size control

After obtaining the holes, size control is carried out. A caliper is used for measurements. If the hole made has ledges, or the length of the measuring jaws of the caliper is not enough to measure the size of the hole, gauges (measuring plugs) are used.

These are two measuring cylinders. One of them is equal to the diameter of the hole, the second is 0.3 mm larger. During measurement, a cylinder “to size” is immersed in the “eye”, but the second one should not enter there. In case of piece production, such calibers can be made yourself.

In production, instruments with high measurement accuracy are used.

Source: https://m-ser.ru/articles/sverlenie_zakalennoy_stali_i_metalla/

Drill sharpening. Drill sharpening angle for steel

The sharpening angle of the drill is set in contrast to the properties of the material. In other words, the property of the material affects the sharpening angle of the drill.

In everyday use, twist drills are popular and, due to their characteristics, are used to make steel and even wood harder.

Let's get acquainted with the angles at the tip of the drill. So, if steel is being processed, then the sharpening angle of the drill for steel will be 116-118 degrees.

The drill sharpening process begins by shaping the cutting edges by targeting the areas of the spiral flutes through which the chips pass. You need to hold the drill so that the sharpening area is always opposite the axis of rotation of the circle.

Do the same action with the other edge. For steel the angle is 140 degrees.

120 degrees is the optimal angle for most drills.

Wood drill sharpening angle

Let's get acquainted with drilling wood. For manual drilling of wood materials, a drill and a brace are used, using chucks (clamping) of certain shapes.

Note that a hand-held screw drill is often used when drilling holes with a diameter of up to 5 mm.

When drilling, it is necessary to take into account the hardness of the wood, the placement of cracks, the depth of drilling, the presence of nails and other foreign materials.

If the diameter of the hole is large, then it is better to pre-drill the centers with thin drills so that the drill does not change direction, and if the wood is fragile, it is advisable to do countersinking.

If there are through holes, you need to make a certain barrier when the drill exits, for example, from a piece of wood.

Remember! That when drilling, you cannot point the tool towards your side. Carefully examine the condition of the drill and the alignment of the drill in the chuck. Use these rules for your personal safety and efficient handling of materials.

If, during work, particles of sharpened material get into your eyes, consult a doctor immediately.

If you are drilling in wood, then you don’t have to worry about the sharpness of the drill, because the drill lasts a long time without systematic sharpening.

However, when working with metal, the sharpness of the drill plays an important role, since it is possible to drill through metal only with a sharp drill.

Thus, the sharpening angle of the wood drill will be 140 degrees.

Metal drill sharpening angle

For example, for hard metals, an acceptable drill sharpening angle is approximately 120 degrees, for softer metals - 90.

If you have to work with soft bronze, then the angle at the apex will be 120-130 degrees; red copper – 125; aluminum -140; plastics – 90-100; brittle materials –140.

The sharpening angle cannot be the same for all materials!

Thus, the sharpening angle of the drill is set depending on the characteristics of the material (its ductility and condition are taken into account).

So, the softer the material, the greater the angle of inclination. However, this principle applies in production.

At home, when the same drill is used for many materials, the angle of inclination depends on the diameter of the drill and varies from 19 - 28° for drills that have a diameter of 0.25 - 10 mm.

You can also watch the video: manual sharpening of twist drills, part 1

Selected for you:

Source: http://stroysvoy-dom.ru/zatochka-sverla-ugol-zatochki-sverla-dlya-stali/

How to drill through hardened metal

How to drill metal with a drill

Hi all! You can write a very long article about how to drill metal with a drill if you wish. But I see two main problems here:

inability to drill accurately in the place where the hole is required
rapid dulling of drills

Typically, inexperienced users encounter such problems. Experienced men know what to do in such cases. Well, considering myself an experienced person, I will take the liberty of telling you how to cope with these problems. Well, I’ll also give you some tips that will also come in handy.

How to drill in the right place?

If you think about this question a little, the answer should come to your mind even without a hint. Well, at least it seems so to me. But if you don’t want to think, then read.

For this case you will need a core. This is a tool made of durable steel, having a cylindrical shape and a point at the end.

We place the tip at the desired drilling location and hit the roll on the other side with a hammer several times.

Now that you have finished drilling, place a drill on the surface of the roughness and start drilling - the tip will not run away anywhere.

How to avoid dulling drills?

Metal drills become dull if they get too hot during operation, causing them to lose their strength. Heating occurs due to friction. Moreover, the faster it spins, the more it heats up.

Hence the obvious rule - you need to drill at low drill speeds. They should be no more than 1000 per minute. But who will measure this during work? So just don't press the start button all the way. The correct speed can be assessed as follows: the eye should see the rotation of the drill. That is, the grooves on it should not merge into one for vision.

When working with thick workpieces, additional cooling is necessary. It is provided by special lubricants or pastes that are added to the drilling site, or the drill is dipped into them. In addition, they not only cool, but also lubricate the tip, resulting in less friction.

In domestic conditions there is no need to have special lubricants and pastes. You can get by with regular machine oil.

So, use a core, drill low and add some lube or oil and this job will be a cakewalk.

Well, a few more tips on this topic.

Drill types

For drilling, use only metal drills (not wood, for example). They have their own sharpening and are made from certain types of steel. The most common ones are marked P6M5 - this is high-speed steel, which foreign manufacturers label as HSS.

To provide additional strength, the above drill bits are coated with titanium nitride. That's why they are yellow.

There are also stronger P18, which are used respectively for hard steels.

Also, to increase strength, cobalt can be added, and then the marking P6M5K5 is obtained.

Well, the most durable ones are drills with carbide tips. They are used for drilling alloy steels.

It will also take ordinary steel, but buying it just for this will be somewhat savvy, since the price for them is quite high, and although it is hard, it still dulls.

But it will be difficult to sharpen it later, since this requires a diamond blade, which is also not very cheap, and you can’t buy it everywhere.

Drilling thick workpieces

If the workpiece has a thickness of more than 5 mm, and you need a hole larger than 8 mm, then it is better to first make a hole with a thin drill, and only then work with a thick one.

Working with some types of metal

When drilling into thick aluminum pieces, chips often clog the drill channels, making it more difficult to rotate. Therefore, when working with such material, remove the drill from the recess more often and remove the chips. Well, don’t forget to pour plenty of oil on it.
If you need to drill black cast iron, then you do not need to add any lubricating and cooling substances, since it drills very well even dry
Unlike black cast iron, white cast iron has increased strength, which means strong drills and lubricants are required to process it.

These are the basic rules for drilling metal with a drill.

I hope I was able to bridge this gap in your knowledge. Good luck with your homework and see you soon!

Source: https://steelfactoryrus.com/kak-prosverlit-zakalennyy-metall/

How to drill a steel plate - How to drill hardened steel at home with a regular drill

To improve the basic characteristics of the metal, it is often hardened. This technology involves increasing the hardness of the product due to strong heating of the metal and its rapid cooling. In some cases, after heat treatment it is necessary to perform drilling. By increasing this characteristic, drilling hardened metal becomes more difficult. Let's take a closer look at all the features of drilling hardened steel.

How to drill through hardened steel

Metal drill sharpening angles: table for correct tool geometry

Metal drills, like any other cutting tool, wear out during use, which makes them unsuitable for use. Meanwhile, in most cases, the cutting and other angles of a metal drill can be restored by selecting their values using a special table and sharpening.

Manual sharpening of drill bits for metal

Purpose and design features of the tool

Metal drills, for the manufacture of which high-speed steel alloys are used, are used to create both through and blind holes in metal parts. The most common are twist drills, the design of which includes the following elements:

cutting part;
working fluid;
shank;
paw

Structural elements of a twist drill

If the shank, which can be either cylindrical or conical, is designed to securely fix the tool in the chuck of the equipment used, then the working part simultaneously performs several important functions at once. It is the geometry of the drill that determines its performance and cutting properties.

The most important elements of the working part of a metal drill are screw grooves. Their task is to remove chips from the processing zone.

The geometry of a spiral drill for metal provides that the front side of the spiral groove is made at a certain angle, the value of which changes in the direction from the axis of the tool to its peripheral part.

During the manufacturing process of a metal drill, narrow ribbons are formed on the side area of its spiral elements, slightly protruding above the main surface. The purpose of such ribbons is to reduce the amount of friction between the tool and the walls of the hole being formed.

Features of different types of drill sharpening

Sharpening drills, as mentioned above, is necessary in order to restore their geometric parameters. The choice of a specific type of drill sharpening depends on a number of factors (tool diameter, characteristics of the metal being processed, etc.).

The most universal is normal sharpening (N), during which one transverse and two cutting edges are formed on the working part of the drill. The sharpening angle of the drill in this case is 118–120°. When choosing this type of drill sharpening, you should keep in mind that it can be used for tools whose diameter does not exceed 12 mm.

Types of metal drill sharpening

All other types of sharpening, which are designated by the letter combinations NP, NPL, DP, DPL, can be used for tools with a diameter of up to 80 mm. Each of these types of sharpening involves bringing the geometry of the metal drill to the required parameters.

Such sharpening involves sharpening the transverse edge, which is done to reduce its length and, accordingly, to reduce the loads taken by the tool during the drilling process.

NPL

In this case, in addition to the transverse edge, the ribbon is also sharpened, which makes it possible to reduce its width in the area of the cutting part. Sharpening the tape, in addition to reducing the friction force created during drilling, allows you to form an additional back angle of the drill, which facilitates the processing process.

This is a double sharpening combined with a sharpening of the transverse edge. Performing sharpening of this type allows you to form one transverse and four cutting edges on the working part of the metal drill, which look like broken lines.

DPL

This is a similar type of sharpening to the previous one, in which the ribbon is additionally sharpened. Creating four cutting edges when performing double sharpening is necessary in order to reduce the angle between the peripheral sections of the cutting edges. This approach makes it possible to improve heat removal from the cutting part of the tool and, accordingly, significantly increase its durability.

How to choose the right sharpening angles

Drill sharpening angles, as mentioned above, are selected according to special tables, where their values are presented depending on the material in which the hole needs to be formed.

Table 1. Metal drill sharpening angles for various materials

If you choose the wrong angles at which the drill will be sharpened, this will lead to the fact that it will become very hot during operation. This may ultimately lead to its failure. In addition, it is the incorrectly selected angles used to sharpen a metal drill that often become the main reason for poorly executed drilling.

Performing an operation

Traditionally, sharpening spiral-type metal drills is performed on an emery machine equipped with a sharpening wheel of appropriate hardness. You should start sharpening them by processing the back surface. By pressing the tool with this surface to the rotating grinding wheel at a certain angle, you must ensure that the correct slope is formed on it.

When sharpening the front cutting surface, it is necessary to control not only the angle at which the operation is performed, but also the size of the jumper. It is very important that when sharpening the working part of the metal drill, cutting edges of equal length and located at the same angle are formed. If you drill a hole with a drill, when sharpening these important requirements are not met, then the diameter of such a hole will be larger than the transverse size of the tool itself.

Checking sharpening angles using a template

You can check the compliance of the basic geometric parameters (including the sharpening angle) of the drill with the required characteristics using one template, which is easy to purchase in serial form or make yourself.

And in conclusion, a short video about how to sharpen a metal drill yourself.

Source: http://met-all.org/oborudovanie/prochee/ugol-zatochki-sverla-po-metallu-tablitsa-geometriya.html

Methods for sharpening twist drills

The cutting part of the drill consists of two cutting edges located at a certain angle, which is called the “sharpening angle” or “drill tip angle”. It is usually denoted as Y. This angle largely determines the working properties of the drill. It is selected depending on the material for which the drill is intended to process. See table.

Processed material	Drill sharpening angle in °
Structural steelStainless steelCast ironHardened steel Aluminum Magnesium-based alloysSilumin Electrolytic copperBronze and brass Plastics Organic glassCelluloid, ebonite	116-118120118125130-140110-12090-100125130-14050-607080-90

For hand tools, drills with a sharpening angle of 118° are usually offered, which are the most versatile. When drilling in materials with low strength, such as light alloys, plastics, etc.

, the sharpening angle does not affect the performance and durability of the drill as much as when drilling hard materials. The use of hand tools during repair and installation work is characterized by occasional drilling in a variety of materials.

In this case, it makes no sense to resharpen drills for working with less durable materials.

Less commonly offered are drills with a sharpening angle of 130 - 135°. As a rule, these are drills made of special high-speed steels, originally intended for working on materials with high hardness.

In addition to the sharpening angle, the performance of the drill is greatly influenced by other parameters of the geometry of the cutting edge.

Normal sharpening

Used in most general purpose drills. One of the advantages is relatively simple regrinding. It is believed that it can be done manually, but it is strongly recommended to use special machines (see below.).

The disadvantage is the relatively long length of the “jumper” in the central part (about 1/5 of the drill diameter). In the “jumper” zone, it is not cutting that occurs, but the crushing of the workpiece material. As a result, wear of the drill increases and it moves to the side during the drilling stage.

To avoid this, it is advisable to punch the workpiece sufficiently strongly or perform initial drilling with a drill of a smaller diameter.

Pointed sharpening

It is distinguished by the implementation of small undercuts in order to reduce the length of the “jumper”. It is considered normal if the length of the “jumper” is reduced to 1/10 of the drill diameter. Such a drill behaves much better at the moment of drilling, it moves less to the side and the dimensions of the recess after punching can be smaller.

The feed force and the required drive torque are also reduced. The disadvantages of this sharpening are the high labor intensity of its implementation (especially with a small drill diameter) and the reduced strength of the sharpened cutting edge.

This sharpening is especially recommended for drills with relatively large jumpers (primarily for large-diameter drills).

Pointed sharpening with a bevel along the leading cutting edge

Requires somewhat more effort when performing it than conventional pointed sharpening. In comparison, sharpening with a bevel along the leading edge is more resistant to impacts and lateral forces. Used when working on hard steels and for drilling.

Bevel sharpening along the rear cutting edge

Also called self-centering sharpening. The jumper practically disappears. As a result, there is no sideways movement when drilling, the feed force is reduced, and chip formation is improved. After normal sharpening, this sharpening is the most common.

Double angle sharpening

Significantly improves the temperature conditions of the drill by increasing the length of the cutting edge and increasing heat output. This also increases the durability of the drill. In addition, cutting angles along the cutting edge are optimized. Recommended for drilling tough materials, such as high-speed steel.

Straight sharpening with central ridge

It is typically found in wood drills, but is also used in drills designed for drilling into thin sheet metal (commonly called resistance weld spot drills).

Compared to drills with other sharpening types shown above, this drill reduces the number of burrs during through drilling and makes it possible to drill cylindrical holes with a relatively flat bottom.

Metal drills (made of high-speed steel) with this sharpening are available in a limited range of sizes.

Among other things, it is important to maintain the proper clearance angle when sharpening cutting edges. Naturally, this is done during the initial sharpening of the drill at the factory, and the consumer only has to remember about the back angle of the drill when resharpening it.

You can see that if the leading (cutting) edge is straight, then the trailing edge has a more complex shape. Because of this, the clearance angle changes along the trailing edge and, if sharpened incorrectly, it can happen that the trailing edge catches on the walls of the hole.

The result is an increase in drill temperature, a drop in productivity and drill life. In order to accurately maintain both the front and rear sharpening angles, several sharpening schemes are used, each of which requires special devices.

Let us present one of the simplest such devices, which forms the basis of the device described below for re-sharpening twist drills.

The device itself is shown in the figure below. This device allows you to change the angle of inclination of the drill relative to the plane of the abrasive wheel by rotating the machine around axis A. This figure shows a diagram of sharpening a drill with an apex angle of 116 - 118°. By changing angle B (in the figure it is 45°), you can set different sharpening angles.

The machine with the drill fixed in it smoothly rotates around axis A while gradually feeding the drill with the feed screw) until the entire surface is sharpened, starting with one of the cutting edges (the bottom one, shown in the figure). Gradual feed is necessary to avoid overheating the drill.

Then the drill is turned over and the second cutting edge is sharpened.

It should also be especially noted that sharpening should be symmetrical. The axis of rotation of the drill always passes through the point of intersection of the cutting edges that protrudes forward, and with asymmetrical sharpening, the diameter of the hole increases, vibrations increase, and the drill may break. For this reason, when sharpening a drill with a diameter of 6 - 10 mm and below, it is advisable to control the symmetry of sharpening using a magnifying glass.

The dimensional parameters of a twist drill are diameter and length. The diameters of general-purpose twist drills with a cylindrical shank are standardized and range from 0.3 mm to 20.0 mm in increments of 0.05 to 0.1 mm.

Drills of each standard size have a certain length of the working (calibration) part. One of the requirements for drills is the ability to resharpen them.

Because of this, a reserve for regrinding the drill is added to the minimum working length of the drill, determined by the possibility of effective chip removal. In general, drills can be sharpened at a length of 3/4 of the original length of the working part.

There is a simpler rule: if the length of the groove for chip removal is less than 10 mm, the drill cannot be regrinded.

In conclusion, we can mention drills with left-hand rotation. They require the use of reversible drills and are needed only in fairly rare situations, for example for drilling out a broken fastener before removing it.

Metal-cutting tools are widely represented in the catalog of the AIST online store.

Source: https://www.aist-tools.ru/useful-information/review-articles/sposoby-zatochki-spiralnih-sverl/

How to drill a hole in hardened metal

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