How to drill holes in metal. Drilling precise holes with a drill. Secrets of mastery. Accessories for drills - how to make your life easier

Metal drilling is one of the many operations that is often performed during metalworking. Drilling is performed for various collapsible/non-dismountable connections when a certain hole diameter is required for rivet, bolt or stud fasteners.

Metal itself is a highly durable material, so when working with it, regardless of whether you need to drill or cut through it, you use cutting tools that are much stronger than it. Drilling of metal parts can be done both in special industrial workshops and at home when carrying out various repair work, in a garage or small workshop. For home drilling, a hand-held electric drill is usually used.

Drilling holes in metal workpieces or parts is a specific technology for removing thin numerous layers of metal with a drill rotating around its axis. In this case, the main condition for drilling is to keep the drill, fixed in the drill chuck, clearly perpendicular to the workpiece being drilled.

This is especially important when drilling thick metal. If during operation the drill deviates relative to the axis of the hole being drilled, it will simply break. To prevent this from happening, the drill must be firmly fixed. For this purpose, special devices are provided that can be bought at a tool store or made on your own.

Drilling modes

When working with a drill, it is important not only to secure it firmly, but also choose optimal mode its rotation. When processing metal, an important factor remains the number of revolutions made by the drill over a certain period of time and the force that is transmitted to it during this time to ensure penetration into the metal.

For working with metals of different hardness, drills designed for different operating modes are also recommended. The speed of rotation of the drill directly depends on the thickness and hardness of the metal, as well as the diameter of the drill itself. The stronger the material being processed and the larger the diameter of the drill, the slower the drilling mode should be. An indicator of a correctly selected mode is long, spiral-shaped chips.

Core marking, template and jig

You can drill through the metal according to the markings made with a core, use a template or a special jig.

A core is a sharpened metal pin made of heavy-duty steel. With its help, a small recess for the drill is made on the metal part prepared for drilling in the place where it is planned to drill a hole.

To do this, the core is placed with its sharp end at the intended drilling point, after which a strong blow is applied to it with a hammer. The tip of the drill is inserted into the recess left by the core and drilling begins, and at the beginning of work the drill will no longer be able to move away from the marked point.

To mark the center of a cylindrical workpiece, experienced mechanics often use a strip of tin bent at 90 degrees. In this case, one shoulder must correspond to the diameter of the workpiece; it is applied to the workpiece, after which a line is drawn with a pencil along its edge. The operation is carried out 2-3 times, and the point of intersection of the lines will indicate the center of the cylinder, where a core can be used to make a recess for the drill.

The template is made to mark blanks of the same type, on which several points for drilling are marked. It is very convenient when you need to work with several parts from sheet metal, which are stacked in a common stack and secured together with a clamp.

In cases where high accuracy and perpendicularity of the drilled channel is required or it is necessary to strictly maintain the distance between several holes, It is recommended to use a conductor. Also, a conductor will be needed when working with thin-walled pipes when it is impossible to make a hole for the drill with a core.

When deep drilling, special devices are used to firmly fix the drill in a perpendicular position to the workpiece.

Drilling accessories

Working with metal is a rather labor-intensive process even for experienced professionals. Sometimes you need long time hold the drill in exactly the same position towards the workpiece. To make work easier and drill metal efficiently, a right-angle drilling device is used.

There are three types of such devices:

1. Stand for holding the drill.

This device is in the form of a box with guide bushings installed inside, which are made of heavy-duty steel that is resistant to drills. The jig can be used for almost all drill diameters up to 20 mm. After installing this device above the center of the intended hole, the drill will no longer move away from its axis

The jig is convenient to use for working with pipes of small diameter, when it is impossible to use a core for marking.

Guide clamp for drill

This mechanism is designed to hold the drill stationary during operation. It consists of two posts, rigidly attached to the sole in the form of a large circle. Moves along the racks ​ a mechanism into which a drill is inserted and fixed to it by the neck. There, on the racks, under the drill locking mechanism, there are return springs.

As the drill deepens into the metal, under the force of the master, they compress, but as soon as the force stops, the springs straighten, and the mechanism holding the drill rises along the racks to its original position.

Drill Holder

Essentially this is a simplified vertical machine for drilling work, but with minimal functions.

It consists of a massive flat sole (platform) and a rigid rod attached to it. The rod is fixed to the platform at a strictly right angle. It also contains a movable carriage with a mount for holding the drill, and a handle for controlling it.

The workpiece is secured to the platform using clamps or a vice. The master lowers the carriage with the drill down by the handle and holds it during the entire drilling process.

Types of holes and methods for drilling them

Drilled holes in metal can be:

1. Completely end-to-end.
2. Muffled.
3. Deep.
4. With a large diameter.

Through holes: pierce the workpiece completely through. The peculiarity of this process is to protect the surface of the workbench on which the workpiece is located from damage when the drill leaves the part. In this case, you may also get damaged. cutting tool. To prevent this from happening, you can use:

1. Workbenches with holes.
2. Place a thick wooden spacer under the workpiece.
3. Place the part on two metal or wooden beams.
4. At the final stage of drilling, reduce the force on the drill and reduce its rotation speed.

The latter method should usually be used when drilling on site so that nearby parts are not damaged.

Blind holes: This type of drilling is not performed using the through method, but only to a set depth. The drilling depth limitation is set in the following ways:

1. Using a bushing stop.
2. Chuck adjusting stop.
3. A ruler attached to a machine or drill.
4. Other ways of combining in the form of various gaskets between the drill and the workpiece.

Modern machines are equipped with automatic feeding of the drill to a given depth, after which the work stops.

: This is usually used for lathe. Moreover, if a cylindrical part is processed, it is not the drill that rotates, but the workpiece itself. During operation, the drill must be constantly cooled, and chips must be forcibly removed from the passage being processed.

For this purpose, special grooves are located on the surface of the deep drill. If they are missing, it must be periodically removed from the body of the part and cleaned of metal shavings. Ordinary water can be used as a coolant. During deep drilling in living conditions It is necessary to firmly fasten the drill, otherwise after the drill breaks, part of it will remain in the body of the workpiece, which can be considered damaged.

How to drill a large diameter hole in metal

This procedure is much more complicated than deep drilling. For small metal thicknesses, this procedure is performed with a special crown, or with ordinary metal drills in several passes.

Crown

It consists of a kit that includes a regular drill that evenly punches a channel in the workpiece and the crown itself of a certain diameter. The working process is carried out at low speeds of the drill, while forced cooling of the cutting edges of the drill and bit is carried out.

Multi-stage drilling

If the part is thick, it is necessary to have a certain supply of drills, the difference in diameter should be within 25% of each other. Work should begin with the thinnest drill. As soon as a through channel is drilled, the drill is replaced with a diameter larger than the previous one. Thus, gradually, the drills are changed to the diameter of the given size.

Step cone drill

This is a set of cone-shaped drills of various diameters located on one common axis. Enough handy tool for working with steel sheet metal. The operating principle is practically indistinguishable from conventional drilling.

A step-cone drill is driven into the workpiece until the desired size of the hole being drilled is reached.

Punching holes

The technology of punching holes in metal alloys is quite common. It is used when working with sheet metal. The advantages of the technology are that holes are punched exactly at a given point with a clear diameter and practically without losing a certain amount of time. For this purpose, specialized pressing machines are used.

For punching thin sheet metal a manual punch can be used. This tool for punching holes in metal is made from a steel pipe. Pipes of various diameters can be used for the punch. To punch a hole, the punch is placed at the marked point, after which several strong blows with a hammer. The result is a neatly punched hole.

When working with any power tools, you must always follow safety precautions and protect the tool from premature wear. To do this, it is recommended to take into account a few simple tips:

Everyone good mood! Today we’ll look at the issue of drilling precise holes in solid metal with a drill. The topic may seem quite simple, but still, there are certain secrets of skill, having mastered which you will drill holes with particular ease.

Drilling holes in metal using a drill and special tools.

At home, it is often necessary to drill holes in metal to install fasteners and other mechanical parts. Although in some cases it is possible to drill holes quite accurately using a conventional hand-held electric drill, however, to obtain high-quality work, you should use a vertical drilling machine. To change the rotation speed of the machine, you need to move the drive belt from one pulley to another.

Drill selection.

Regardless of the drilling device used, the size and shape drilled hole determined by the drill used. A cylindrical hole (sometimes not entirely correct geometrically) is usually drilled with a twist drill. This drill is a pointed metal cylinder with a spiral channel running along the axis of the drill. In soft metals such as aluminum and copper, these drills often produce holes with jagged edges. To drill such metals, you can use a drill for sheet material, which is made in the form of a cone and has one cutting edge on the side.

Holes in metal should always be drilled using high-speed drills. Made from the hardest steels, these drill bits range in diameter from 0.5mm to 25mm or more.

Marking of drills and design features.

One of the options drill markings(according to the sizes) is to indicate their diameter in millimeters. For drilling recesses large size Instead of a drill, you can install a hole saw - a cylinder with teeth that can cut holes up to 150 mm in size and up to two-thirds the height of the saw itself. You can also use a special drill, which differs from the usual one by the presence of an elongated L-shaped cutting edge. Special drills are available for drilling conical or cylindrical recesses for the heads of fasteners, such as bolts, rivets or screws.

To give the drilled hole precise geometric dimensions, provided that the diameter of this hole does not exceed 35 mm, it is necessary to process it with a reamer. This processing is done manually or on a machine. Hand reamers are straight drills with four or more cutting edges, which, as they rotate, gradually process the inner surface of the hole. Machine reamers are installed in vertical drilling machines.

Precise drilling of metal on a machine.

When drilling precise holes, you should always use a special cutting fluid that reduces friction and cools the drill during operation. In addition, it is necessary to use clamps and a vice for precise, stationary installation of the workpiece. When marking the drilling site, you should use a center punch, with which a small depression is made at the drilling site.

When drilling on a machine, to determine the position of the hole, you need to use a ruler to draw two short lines intersecting at right angles in the center of the hole. To prevent the drill from slipping, it is necessary to make a small depression in the found center using a center punch and a hammer.

Determination of tool rotation parameters.

Determine the required rotation speed and set the machine to rotate at this speed. To set the rotation speed, you need to open the casing cover and loosen the belt tension by unscrewing the handle that secures the motor in the casing. To change the speed, the engine moves forward and the belt is moved from one level of pulleys to another in accordance with the necessary change in speeds, which are determined from the nameplate or operating instructions. The lowest speed is achieved when the belt is placed in its lowest position - between the smallest motor pulley and the largest spindle pulley. On the contrary, the highest speed is achieved when the belt is installed in the uppermost pulleys. Next, you need to make sure that the belt is tensioned horizontally between the pulleys, move the engine to its original position and tighten the knob securing the engine to the casing.

Setting up tools and fixtures.

Before drilling begins, the drill is installed in the chuck and tightened. Don't forget to adjust the vertical movement of the spindle by lowering the drill along the workpiece and moving the stopper to the desired point on the graduated stopper movement scale. The spindle rises to a height sufficient to install the workpiece under the drill and is fixed in this position. The workpiece is moved so that the intended hole is exactly under the drill. The workpiece is securely clamped before drilling begins.

Subsequently, it is necessary to lower the spindle sleeve lock and turn on the drilling machine. Squeeze a drop of coolant and lubricant onto the recess, lower the drill with the lever and start drilling. Even pressure should be applied during operation. A brush is used to remove shavings and sawdust. The appearance of smoke from the drilled hole indicates the need to check the color of the metal shavings. They should be white or straw yellow. Blue color means overheating. In this case, you need to add cutting fluid or reduce the rotation speed. After finishing drilling, you must slowly release the feed handle and turn off the machine.

Drilling precise holes in metal with a hand drill.

If there is no need to maintain the precision that a vertical drilling machine provides, you can use a powerful hand-held electric drill. However, if this drill is not multi-speed, then when drilling holes in metal, it should be turned on for short periods of time by briefly pressing the switch in succession.

The key to success in most cases depends on how you hold the drill. Before drilling begins, the workpiece is clamped in a vice or pressed firmly to the table. Then, without turning on the drill, the end of the drill is installed on the point marked with the center punch. To increase the starting point, you can manually rotate the drill chuck several times while pressing down on the drill bit. After applying the cutting fluid, the voltage will turn on. The drill body is held motionless by the left hand, right hand the tool itself is pressed when the drill starts to increase speed. If possible, place a vertical square next to the drill to facilitate installation of the drill in vertical position. This will make it easier to drill precise holes.

If the drill cannot go deep into the surface of the metal workpiece, a second, larger depression is made using a center punch at the desired point.

Safety precautions when working with a hand drill.

When working with drills, one should not neglect the rules. To prevent the risk of accidents when drilling metal products The following instructions must be strictly adhered to:

• It is prohibited to drill a product that is held only by hands;
• It is forbidden to work with dissolute long hair or wearing loose clothing that is not fastened, as well as wearing gloves, since there is a danger of the glove material being caught by the drill;
• Safety glasses should not be neglected;
• Before turning on the machine, make sure that the drill in the chuck is tightened tightly and the key is removed.

Perhaps we'll end here. Drilling precise holes in metal is useful not only at home but also when performing industrial tasks.

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Andrey was with you!

The work of drilling holes in metal, depending on the type of holes and the properties of the metal, can be performed with different tools and using different techniques. We want to tell you about drilling methods, tools, as well as safety precautions when performing this work.

Drilling holes in metal may be necessary for repairs. engineering systems, household appliances, car, creating structures from sheet and profile steel, designing crafts from aluminum and copper, in the manufacture of circuit boards for radio equipment and in many other cases. It is important to understand what tool is needed for each type of work so that the holes are of the required diameter and in the strictly intended location, and what safety measures will help avoid injuries.

Tools, fixtures, drills

The main tools for drilling are hand and electric drills, and, if possible, drill presses. The working body of these mechanisms - the drill - can have different shapes.

Drills are distinguished:

• spiral (most common);
• screw;
• crowns;
• conical;
• feathers, etc.

Drill production various designs standardized by numerous GOSTs. Drills up to Ø 2 mm are not marked, up to Ø 3 mm - the section and steel grade are indicated on the shank; larger diameters may contain additional information. To obtain a hole of a certain diameter, you need to take a drill a few tenths of a millimeter smaller. The better the drill is sharpened, the smaller the difference between these diameters.

Drills differ not only in diameter, but also in length - short, elongated and long are produced. Important information is also the ultimate hardness of the metal being processed. The drill shank can be cylindrical or conical, which should be kept in mind when selecting a drill chuck or adapter sleeve.

1. Drill with a cylindrical shank. 2. Drill with tapered shank. 3. Drill with a sword for carving. 4. Center drill. 5. Drill with two diameters. 6. Center drill. 7. Conical drill. 8. Conical multi-stage drill

Some jobs and materials require special sharpening. The harder the metal being processed, the sharper the edge should be sharpened. For thin sheet metal, a regular twist drill may not be suitable; you will need a tool with a special sharpening. Detailed recommendations for various types drills and processed metals (thickness, hardness, type of hole) are quite extensive, and we will not consider them in this article.

Various types of drill sharpening. 1. For hard steel. 2. For stainless steel. 3. For copper and copper alloys. 4. For aluminum and aluminum alloys. 5. For cast iron. 6. Bakelite

1. Standard sharpening. 2. Free sharpening. 3. Diluted sharpening. 4. Heavy sharpening. 5. Separate sharpening

To secure parts before drilling, vices, stops, jigs, angles, clamps with bolts and other devices are used. This is not only a safety requirement, it is actually more convenient, and the holes are of better quality.

To chamfer and process the surface of the channel, a cylindrical or conical countersink is used, and to mark the point for drilling and so that the drill does not “jump off,” a hammer and a center punch are used.

Advice! The best drills are still considered to be those produced in the USSR - exact adherence to GOST in geometry and metal composition. German Ruko with titanium coating are also good, as well as drills from Bosch - proven quality. Good reviews about Haisser products - powerful, usually with a large diameter. The Zubr drills, especially the Cobalt series, performed well.

Drilling modes

It is very important to correctly secure and guide the drill, as well as select the cutting mode.

When making holes in metal by drilling important factors are the number of revolutions of the drill and the feed force applied to the drill, directed along its axis, ensuring the depth of the drill with one revolution (mm/rev). When working with various metals and drills, various cutting modes are recommended, and the harder the metal being processed and the larger the diameter of the drill, the lower the recommended cutting speed. Indicator correct mode- beautiful, long shavings.

Use the tables to choose the right mode and avoid dulling the drill prematurely.

Feed S 0 , mm/rev	Drill diameter D, mm
	2,5	4	6	8	10	12	146	20	25	32
	Cutting speed v, m/min
When drilling steel
0,06	17	22	26	30	33	42	—	—	—	—
0,10	—	17	20	23	26	28	32	38	40	44
0,15	—	—	18	20	22	24	27	30	33	35
0,20	—	—	15	17	18	20	23	25	27	30
0,30	—	—	—	14	16	17	19	21	23	25
0,40	—	—	—	—	—	14	16	18	19	21
0,60	—	—	—	—	—	—	—	14	15	11
When drilling cast iron
0,06	18	22	25	27	29	30	32	33	34	35
0,10	—	18	20	22	23	24	26	27	28	30
0,15	—	15	17	18	19	20	22	23	25	26
0,20	—	—	15	16	17	18	19	20	21	22
0,30	—	—	13	14	15	16	17	18	19	19
0,40	—	—	—	—	14	14	15	16	16	17
0,60	—	—	—	—	—	—	13	14	15	15
0,80	—	—	—	—	—	—	—	—	—	13
When drilling aluminum alloys
0,06	75	—	—	—	—	—	—	—	—	—
0,10	53	70	81	92	100	—	—	—	—	—
0,15	39	53	62	69	75	81	90	—	—	—
0,20	—	43	50	56	62	67	74	82	-	-
0,30	—	—	42	48	52	56	62	68	75	—
0,40	—	—	—	40	45	48	53	59	64	69
0,60	—	—	—	—	37	39	44	48	52	56
0,80	—	—	—	—	—	—	38	42	46	54
1,00	—	—	—	—	—	—	—	—	—	42

Table 2. Correction factors

Table 3. Revolutions and feed at different diameters drill bits and carbon steel drilling

Types of holes in metal and methods of drilling them

Types of holes:

• deaf;
• end-to-end;
• half (incomplete);
• deep;
• large diameter;
• for internal thread.

Threaded holes require diameters to be determined with the tolerances established in GOST 16093-2004. For common hardware, the calculation is given in Table 5.

Table 5. The ratio of metric and inch threads, as well as the selection of hole size for drilling

Metric thread				Inch thread				Pipe thread
Thread diameter	Thread pitch, mm	Threaded hole diameter		Thread diameter	Thread pitch, mm	Threaded hole diameter		Thread diameter	Threaded hole diameter
		min.	Max.			min.	Max.
M1	0,25	0,75	0,8	3/16	1,058	3,6	3,7	1/8	8,8
M1.4	0,3	1,1	1,15	1/4	1,270	5,0	5,1	1/4	11,7
M1.7	0,35	1,3	1,4	5/16	1,411	6,4	6,5	3/8	15,2
M2	0,4	1,5	1,6	3/8	1,588	7,7	7,9	1/2	18,6
M2.6	0,4	2,1	2,2	7/16	1,814	9,1	9,25	3/4	24,3
M3	0,5	2,4	2,5	1/2	2,117	10,25	10,5	1	30,5
M3.5	0,6	2,8	2,9	9/16	2,117	11,75	12,0	—	—
M4	0,7	3,2	3,4	5/8	2,309	13,25	13,5	11/4	39,2
M5	0,8	4,1	4,2	3/4	2,540	16,25	16,5	13/8	41,6
M6	1,0	4,8	5,0	7/8	2,822	19,00	19,25	11/2	45,1
M8	1,25	6,5	6,7	1	3,175	21,75	22,0	—	—
M10	1,5	8,2	8,4	11/8	3,629	24,5	24,75	—	—
M12	1,75	9,9	10,0	11/4	3,629	27,5	27,75	—	—
M14	2,0	11,5	11,75	13/8	4,233	30,5	30,5	—	—
M16	2,0	13,5	13,75	—	—	—	—	—	—
M18	2,5	15,0	15,25	11/2	4,333	33,0	33,5	—	—
M20	2,5	17,0	17,25	15/8	6,080	35,0	35,5	—	—
M22	2,6	19,0	19,25	13/4	5,080	33,5	39,0	—	—
M24	3,0	20,5	20,75	17/8	5,644	41,0	41,5	—	—

Through holes

Through holes penetrate the workpiece completely, forming a passage through it. A feature of the process is to protect the surface of the workbench or tabletop from the drill going beyond the workpiece, which can damage the drill itself, as well as provide the workpiece with a “burr” - a burr. To avoid this, use the following methods:

• use a workbench with a hole;
• put a wooden gasket or a “sandwich” under the part - wood + metal + wood;
• place a metal block with a hole for free passage of the drill under the part;
• reduce the feed rate at the last stage.

The latter method is required when drilling holes “in situ” so as not to damage nearby surfaces or parts.

Holes in thin sheet metal are cut with feather drills, because a twist drill will damage the edges of the workpiece.

Blind holes

Such holes are made to a certain depth and do not penetrate through the workpiece. You can measure the depth in two ways:

• limiting the length of the drill with a sleeve stop;
• limiting the length of the drill with a chuck with adjustable stop;
• using a ruler attached to the machine;
• a combination of methods.

Some machines are equipped with an automatic feeding system to a given depth, after which the mechanism stops. During the drilling process, you may need to stop work several times to remove chips.

Holes of complex shape

Holes located on the edge of the workpiece (half holes) can be made by connecting the edges and clamping two workpieces or a workpiece and a spacer with a vice and drilling a full hole. The spacer must be made of the same material as the workpiece being processed, otherwise the drill will “go” in the direction of least resistance.

A through hole in a corner (profiled metal) is made by fixing the workpiece in a vice and using a wooden spacer.

It is more difficult to drill a cylindrical workpiece tangentially. The process is divided into two operations: preparing a platform perpendicular to the hole (milling, countersinking) and the actual drilling. Drilling holes in surfaces located at an angle also begins with preparing the site, after which a wooden spacer is inserted between the planes, forming a triangle, and a hole is drilled through the corner.

Hollow parts are drilled, filling the cavity with wood plug.

Shouldered holes are produced using two techniques:

1. Reaming. The hole is drilled to the full depth with a drill of the smallest diameter, after which it is drilled to a given depth with drills of diameters from smaller to larger. The advantage of the method is a well-centered hole.
2. Reducing the diameter. A hole of maximum diameter is drilled to a given depth, then the drills are changed with a successive decrease in diameter and deepening of the hole. With this method it is easier to control the depth of each step.

1. Drilling a hole. 2. Diameter reduction

Large diameter holes, ring drilling

Making large-diameter holes in massive workpieces up to 5-6 mm thick is labor-intensive and costly. Relatively small diameters - up to 30 mm (maximum 40 mm) can be obtained using conical, or better yet, stepped conical drills. For larger diameter holes (up to 100 mm), you will need hollow bimetallic bits or bits with carbide teeth with a center drill. Moreover, craftsmen traditionally recommend Bosch in this case, especially on hard metal, such as steel.

Such annular drilling is less energy-intensive, but can be more costly financially. In addition to drills, the power of the drill and the ability to work at the lowest speeds are important. Moreover, the thicker the metal, the more you will want to make a hole on the machine, and when large quantities holes in a sheet more than 12 mm thick, it is better to immediately look for such an opportunity.

In a thin-sheet workpiece, a large-diameter hole is obtained using narrow-toothed crowns or a milling cutter mounted on a grinder, but the edges in the latter case leave much to be desired.

Deep holes, coolant

Sometimes it is necessary to make a deep hole. In theory, this is a hole whose length is five times its diameter. In practice, deep drilling is called drilling that requires forced periodic removal of chips and the use of coolant (cutting fluids).

In drilling, coolant is needed primarily to reduce the temperature of the drill and workpiece, which heat up from friction. Therefore, when making holes in copper, which has high thermal conductivity and is itself capable of removing heat, coolant may not be used. Cast iron can be drilled relatively easily and without lubrication (except high-strength).

In production, industrial oils, synthetic emulsions, emulsols and some hydrocarbons are used as coolants. In home workshops you can use:

• technical petroleum jelly, castor oil - for soft steels;
• laundry soap— for aluminum alloys type D16T;
• a mixture of kerosene and castor oil - for duralumin;
• soapy water - for aluminum;
• turpentine diluted with alcohol - for silumin.

Universal coolant can be prepared independently. To do this, you need to dissolve 200 g of soap in a bucket of water, add 5 tablespoons of machine oil, or used, and boil the solution until a homogeneous soap emulsion is obtained. Some craftsmen use lard to reduce friction.

Processed material	Cutting fluid
Steel:
carbon	Emulsion. Sulfurized oil
structural	Sulfurized oil with kerosene
instrumental	Mixed oils
alloyed	Mixed oils
Malleable cast iron	3-5% emulsion
Iron casting	No cooling. 3-5% emulsion. Kerosene
Bronze	No cooling. Mixed oils
Zinc	Emulsion
Brass	No cooling. 3-5% emulsion
Copper	Emulsion. Mixed oils
Nickel	Emulsion
Aluminum and its alloys	No cooling. Emulsion. Blended oils. Kerosene
Stainless, heat-resistant alloys	A mixture of 50% sulfur oil, 30% kerosene, 20% oleic acid (or 80% sulforesol and 20% oleic acid)
Fiberglass, vinyl plastic, plexiglass and so on	3-5% emulsion
Textolite, getinaks	Blowing with compressed air

Deep holes can be made by continuous and circular drilling, and in the latter case, the central rod formed by the rotation of the crown is not broken out entirely, but in parts, weakening it additional holes small diameter.

Solid drilling is performed in a well-fixed workpiece with a twist drill, into the channels of which coolant is supplied. Periodically, without stopping the rotation of the drill, you need to remove it and clear the cavity of chips. Working with a twist drill is carried out in stages: first, take a short hole and drill a hole, which is then deepened with a drill of the appropriate size. For significant hole depths, it is advisable to use guide bushings.

With regular drilling deep holes We can recommend purchasing a special machine with automatic coolant supply to the drill and precise alignment.

Drilling according to markings, templates and jigs

You can drill holes according to the markings made or without it - using a template or jig.

The marking is done with a center punch. With a hammer blow, a place is marked for the tip of the drill. You can also mark the place with a felt-tip pen, but the hole is also needed so that the point does not move from the intended point. The work is carried out in two stages: preliminary drilling, hole control, final drilling. If the drill has “moved away” from the intended center, notches (grooves) are made with a narrow chisel, directing the tip to the specified location.

To determine the center of a cylindrical workpiece, use a square piece of sheet metal, bent at 90° so that the height of one arm is approximately one radius. Applying a corner from different sides of the workpiece, draw a pencil along the edge. As a result, you have an area around the center. You can find the center using the theorem - by the intersection of perpendiculars from two chords.

A template is needed when making a series of similar parts with several holes. It is convenient to use for a pack of thin-sheet workpieces connected with a clamp. This way you can get several drilled workpieces at the same time. Instead of a template, a drawing or diagram is sometimes used, for example, in the manufacture of parts for radio equipment.

The jig is used when precision in maintaining the distances between holes and strict perpendicularity of the channel is very important. When drilling deep holes or when working with thin-walled tubes, in addition to the jig, guides can be used to fix the position of the drill relative to the metal surface.

When working with power tools, it is important to remember human safety and prevent premature wear of the tool and possible defects. In this regard, we have collected some useful tips:

1. Before work, you need to check the fastenings of all elements.
2. When working on a machine or with an electric drill, clothing should not contain elements that could be affected by rotating parts. Protect your eyes from chips with glasses.
3. When approaching the metal surface, the drill must already be rotating, otherwise it will quickly become dull.
4. You need to remove the drill from the hole without turning off the drill, reducing the speed if possible.
5. If the drill does not penetrate deep into the metal, it means that its hardness is lower than that of the workpiece. Increased hardness of steel can be detected by running a file over the sample - the absence of traces indicates increased hardness. In this case, the drill must be selected from a carbide alloy with additives and operated at low speeds with low feed.
6. If a small-diameter drill does not fit well in the chuck, wrap a few turns of brass wire around its shank, increasing the grip diameter.
7. If the surface of the workpiece is polished, put a felt washer on the drill to ensure that it does not cause scratches even when it comes into contact with the drill chuck. When fastening workpieces made of polished or chrome-plated steel, use fabric or leather spacers.
8. When making deep holes, a rectangular piece of foam placed on a drill can serve as a meter and at the same time, while rotating, blow away small chips.

Drilling metal is one of the most common plumbing operations. Separable and non-separable connections - rivets, screws, bolts, studs - require holes. To drill metal, it is enough to have a drill, a drill of the appropriate diameter and a center punch with a hammer to mark the hole.

Selection of drills

If holes in metal are drilled for threads, then according to GOST 24705-81, for the most commonly used thread sizes (for standard large steps): M4, M5, M6, M8, M10 and M12 - the diameter of the drills will be equal to 3.3, respectively; 4.2; 5; 6.7; 8.4; 10.2 mm. It is quite acceptable if drilling for threads is carried out with a drill whose diameter differs slightly (by 0.1 mm) from the GOST dimensions in one direction or another.

When purchasing drills, you need to keep in mind that conventional drills made of high-speed tool steel (for example, P6M5) are intended for drilling metals that do not have high hardness. To drill through metal of increased hardness, you will need carbide drills. Such drills can be made entirely of carbide or have only a carbide tip.

Sometimes before starting drilling it is not known what hardness of the metal is to be drilled. Therefore, if you see at the first moment of drilling that the drill does not penetrate the metal, you must immediately stop drilling, otherwise the drill will be irrevocably damaged, overheating and losing hardness. Evidence of this will be the appearance of a dark blue color on it. Before drilling into metal whose hardness is unknown, you can run a file through it. If the latter does not leave marks on the metal, then the material has increased hardness.

How to drill metal

Low and medium speeds are optimal for drilling most metals - 500-1000 rpm. High speeds quickly heat up the drill, which can result in annealing and softening. When drilling, do not put too much pressure on the drill; the feed should be slow and smooth.

When drilling metal, the sharpness of the drill is very important, and the drill becomes dull very quickly. The rate of dulling of the drill depends, in particular, on the speed, feed force, cooling and other factors, but no matter how hard you try, if it doesn’t drill aluminum alloy, the time it takes a drill to operate unsatisfactorily is measured in minutes.

Before drilling, you need to mark the hole by tapping it. To do this, you need to place the tip of the center punch (or dowel) in the expected center of the hole and hit it with a hammer. Punching is necessary to prevent the drill from slipping at the first moment of drilling. If the core mark is not large enough to hold a large-diameter drill, then first widen the hole with a small-diameter drill.

To create better conditions When drilling, it is advisable to dip the tip of the drill in machine oil or drop it into the core site. Oil in the drilling area helps to better cool the drill and makes cutting metal easier. A drill used for drilling using oil becomes less dull, requires less sharpening and lasts longer. A special emulsion, soapy water, and kerosene are also used as a coolant. According to some craftsmen, lard is a good lubricant and cooling agent. Before drilling, a rotating drill is immersed in a piece of lard, which melts during drilling and has a lubricating and cooling effect. But still the simplest and most convenient remedy is soapy water. It doesn't get dirty, and every home has soap. It is enough to drop it once at the beginning of drilling and during the process. You can periodically dip the drill in a soapy solution.

When through drilling with a large feed, a burr (burr) is formed at the exit of the hole, to which the drill clings with its side cutters. As a result, a sharp blocking of the drill and its fracture or chipping of the incisor can occur, and even at this moment the drill dulls especially intensely. Such stops also have a negative impact on the condition of the drill. To avoid burr formation, you need to finish drilling holes in the metal with low feed. It is also advisable to place a wooden block, which prevents the formation of a burr. The block and the workpiece must be pressed tightly against each other. For greater effect, you can place not a wooden block, but a plate of the same or less hard metal, which should be tightly pressed to the point where the drill exits.

Most often it is necessary to drill steel, but often it is necessary to drill other metals that have their own drilling characteristics. Aluminum, for example, envelops the drill, making it difficult for it to penetrate deeper and widening the resulting hole. If you need to drill a precise hole in aluminum (for example, for a thread), you must use coolant and often remove the drill from the hole to clean it. Regular gray cast iron drills relatively easily and does not require coolant or lubricant. But drilling in cast iron can bring surprises. There are high-strength gray cast irons that must be drilled with a carbide drill. White cast iron, the main structural component of which is cementite, is very hard, it requires a high-strength drill.

Large diameter holes should be drilled in stages. First you need to drill the part with a thin drill, then drill the hole to a larger diameter. For example, it is better to drill a hole with a diameter of 12 mm in two or three steps - sequentially with drills of 5, 10 and 12 mm.

Dull drills need to be sharpened promptly. It is better to do this with a sharpening device, but you can do without it. In this case, you need to pay attention to the symmetry of the drill tip. If the sharpened edges do not meet exactly in the center, the hole drilled with such a drill will have a larger diameter, since one cutting edge will be longer than the other. The standard point angle (angle between cutting edges) is 118°. For drilling aluminum, the optimal angle is 130-140°, soft bronze and red copper 125-130°. However, all these metals can be drilled with a standard angle drill. Read more about drill sharpening.

When drilling, you need to maintain the verticality of the drill relative to the metal surface (if you do not need to drill an inclined hole). When making holes in thin sheets, this requirement is not as relevant as for thick-walled or hollow parts. Drilling pipes, for example, often leads to the fact that the inlet and outlet holes are displaced relative to each other - the larger the diameter of the pipe, the more so. It is quite difficult to maintain the perpendicularity of the drill by eye, so you can use homemade or purchased drilling jigs or guides that ensure the perpendicularity of the drill.

Conductors are also needed for drilling two or more holes in mating parts. The best way ensuring the holes match is by drilling them together. When drilling holes for rivets, drilling the assembly is a must. Once you've drilled the first hole, you can use it to bolt the pieces together so you can drill the remaining holes without worrying about the pieces moving relative to each other. If drilling the mating parts in the assembly is impossible or inconvenient, then a jig or guide must be used. You should know that no matter how accurately the mating holes are marked and cored, they will still not coincide absolutely exactly, since when drilling even a cored hole, the drill will move a little to the side.

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