Rules and techniques for filing. General techniques and rules for filing manually

Filing is an operation for processing metals and other materials by removing a small layer of metal with files manually or on machine tools.

With the help of a file, the parts are given the desired shape and size, the parts are fitted to each other, the edges of the parts are prepared for welding, and other work is performed.

Files process planes, curved surfaces, grooves, grooves, holes of any shape, surfaces located at different angles, etc.

Sawing allowances are left small - from 0.5 to 0.025 mm. Processing accuracy from 0.2 to 0.05 mm. In the artistic processing of metal, manual filing, as one of the methods, is of great importance.

A file is a steel bar of a certain profile and length, on the surface of which there are notches that form sharply sharpened teeth (teeth) that have a wedge shape in cross section.

Files are made from steel U10A or U13A and after notching are subjected to heat treatment. Allowed alloyed chromium steel ШХ15 or 13Х. Files are subdivided according to the size of the notch, the shape of the notch, the length and shape of the bar, according to their purpose.

The notches on the surface of the file form teeth that remove chips from the material being processed. File teeth are obtained on sawing machines using a special chisel, on milling machines- cutters, on grinding - special grinding wheels, as well as by rolling, pulling on broaching machines - broaches and gear-cutting machines.

With each method of exposure, its own tooth profile is cut. However, regardless of the method of obtaining a notch, each tooth has a relief angle, a taper angle and a cutting angle.

The fewer notches per 1 cm of file length, the larger the tooth. There are files with a single, i.e. a simple notch, with a double, or cross, dot, i.e. with rasp and arc.

Single cut files can cut wide chips equal to the length of the entire cut. They are used when filing soft metals - brass, zinc, babbitt, lead, aluminum, bronze, copper, etc.

Single cut files are used when filing materials with low cutting resistance, as well as non-metallic materials. They are used for sharpening saws, knives, for processing cork, wood.

Files with double, i.e. cross cut is used for filing steel, cast iron and other hard materials with high cutting resistance.

In files with a double notch, the lower deep notch, the main one, is first cut, and on top of it is the upper, shallow notch, the auxiliary one. It cuts the main notch into many individual teeth. The cross cut makes the work easier, as it breaks up the chips more.

The distance between adjacent notch teeth is called the pitch. The step of the main notch is greater than the step of the auxiliary. As a result, the teeth are located one after another in a straight line, making an angle of 5 degrees with the axis of the file, and when it moves, the teeth marks partially overlap each other, therefore, the roughness on the treated surface decreases, the surface is cleaner and smoother.

A rasp (point) notch is obtained by pressing the metal with special trihedral chisels, leaving roomy recesses arranged in a checkerboard pattern, contributing to best accommodation shavings. Rasps are used to process very soft metals and non-metallic materials - rubber, leather, etc.

The arc notch is obtained by milling. The notch has a large cavity between the teeth and an arcuate shape, providing high productivity and improved surface quality.

Files with an arc notch are used when processing soft metals - duralumin, copper, etc.

Files can be general purpose, special purpose, needle files, rasps, machine.

General purpose files are designed for general plumbing work. According to the number of notches (cuts) per 1 cm, the lengths are divided into six numbers - 0, 1, 2, 3, 4, 5.

Files with a notch 0 and 1 (bastard) have the largest teeth and are used for rough filing when it is necessary to remove a large layer of metal - 0.5 - 10 mm. Processing accuracy does not exceed 0.1 - 0.2 mm.

Files with a notch 2 and 3 (personal) are used for fine filing of products with an accuracy of 0.02 - 0.05 mm. The removed metal layer does not exceed 0.02 - 0.06 mm.

Files with a notch 4 and 5 (velvet) serve for the final finishing of products. They remove a layer of no more than 0.01 - 0.03 mm with a processing accuracy of 0.01 to 0.005 mm.

File types.

Files are divided into the following types:

A - flat

B - flat pointed ones are used for filing external or internal flat surfaces, as well as for sawing slots and grooves;

B - square files are used for sawing square, rectangular and polygonal holes, as well as for filing narrow flat surfaces;

D - trihedral files are used for filing sharp corners with both outside parts, as well as in grooves, holes, grooves, for sharpening saws on wood;

D - round files are used for sawing round or oval holes and concave surfaces of a small radius;

E - semicircular files are used for processing concave curved surfaces of a significant radius and big holes(convex side); planes, convex curved surfaces and angles over 30 degrees (flat side);

G - rhombic files are used for filing the teeth of gears, disks, sprockets, for deburring these parts after processing them on machines, as well as for filing angles over 15 degrees and grooves;

Z - hacksaw files are used for filing internal corners wedge-shaped grooves, narrow grooves, planes in trihedral, square and rectangular holes, as well as in the manufacture of cutting tools and dies.

Flat, square, trihedral, semicircular, rhombic and hacksaw files are made with a notched and cut tooth. Hacksaw files are made to special order.

Special-purpose files are used for processing non-ferrous metals, alloys, light alloy products, etc.

Files for processing non-ferrous alloys, in contrast to general-purpose metalwork files, have other, more rational for this particular alloy, angles of inclination of the notches and a deeper and sharper notch, which ensures high performance and durability of the files.

Files are produced only flat and pointed with a notch N 1 and are intended for processing bronze, brass and duralumin. Such files are marked with the letters TsM on the shank.

General-purpose files used for processing products made of light alloys and non-metallic materials have a fine notch; during operation, they quickly become clogged with chips and fail.

Files with a special holder are used to eliminate these shortcomings. These files have dimensions of 4x40x360 mm and are notched in the form of arc grooves for the release of chips with a significantly increased pitch compared to general-purpose bastard files. The productivity of work with such files is increased three times.

Diamond files are used for processing and finishing hard-alloy parts.

A diamond file is a rod with a working surface and a section of the desired profile, on which a thin diamond layer is applied. Diamond coating on the working part is made of various grain sizes for preliminary and final finishing.

Needle files are small files that are used for pattern, engraving, jewelry work and other artwork for metal, for cleaning in hard-to-reach places - holes, corners, etc. Needle files have the same shape as bench files.

They are made of steel U12 or U12A.

The length of the needle files can be 80, 120 and 160 mm.

Depending on the number of notches per each 10 mm of length, the needle files are divided into six types: 1 - bastard, 2 - personal; 3 - 6 - velvet.

According to the cross-sectional shape, needle files can be round, semicircular, flat, pointed, oval, hacksaw, square, trihedral, trihedral one-sided, grooved and diamond-shaped.

Diamond needle files are used for processing carbide materials, various kinds ceramics, glass, etc.

When processing with needle files, surfaces of 9-10 roughness classes are obtained.

Rasps are designed for processing soft metals (lead, tin, copper, etc.) and non-metallic materials (leather, rubber, wood, plastics), when conventional files are unsuitable due to the fact that their notch is quickly clogged with chips and they stop cutting.

Depending on the profile, general-purpose rasps are divided into flat (blunt-nosed and sharp-nosed), round and semi-circular with a notch N 1 and N 2 and a length of 250 to 350 mm. The rasp teeth are large and have large grooves in front of each tooth.

Filing can be done on machines using machine (rod for filing machines with reciprocating motion) and rotating (boron files - shaped heads, disk and lamellar) files.

Attachment of file handles.

For the convenience of working with a file, a wooden handle (handle) made of linden, ash, birch, maple or pressed paper is mounted on its shank.

The surface of the handle must be smooth. The length of the handle should match the size of the file and fit comfortably in the palm of your hand.

The diameter of the hole in the handle should not exceed the width of the middle part of the file shank, and the depth of the hole should correspond to the length of the shank.

The hole for the file is drilled or burned out, and so that the handle does not split, a steel ring is placed on its end. To fit the file, its shank is inserted into the hole in the handle and, taking the file by the notched part right hand, do not hit the handle head very hard on the workbench or the handle with a hammer.

To remove the handle from the file, the handle is wrapped around the handle with the left hand, and two or three light blows are applied with a hammer to the upper edge of the ring with the right hand, after which the file easily comes out of the hole.

At the workplace, all files must be with attached handles. After long use, a wooden pin can be inserted into the developed hole.

Rules and techniques for filing

For a specific job, choose the type of file, its length and notch number.

The type of file is determined by the shape of the surface to be treated, the length is determined by its dimensions. The file is taken 150 mm longer than the size of the surface to be treated.

For filing thin plates, fitting and finishing work, short files with a fine notch are taken.

When it is required to remove a large allowance, they work with a file 300 - 400 mm long with a large notch. The notch number is chosen depending on the type of processing and the size of the allowance.

For roughing, files with a notch N0 and N1 are used. They remove the allowance up to 1 mm.

Finishing is done with an N2 file.

For processing with personal files, an allowance of up to 0.3 mm is left.

For final filing and finishing of the surface, files NN 3, 4, 5 are taken. They remove the metal layer to 0.01 - 0.02 mm.

Hardened steel blanks are best filed with a file with a notch N 2.

Non-ferrous metals are treated with special files, and in the absence of general-purpose files No. 1. Personal and velvet files are unsuitable for filing non-ferrous metals.

Before filing, it is necessary to prepare the surface by cleaning it of oil, sand, scale, foundry skin, etc. Then the part is clamped in a vise with the sawn-off plane horizontally about 10 mm above the vise jaws.

The workpiece with machined surfaces is fixed by putting on the jaws of a vice made of soft material - copper, brass, aluminum.

When filing a thin part, it is fixed on a wooden block with wooden plates, which ensure the immobility of the part.

When filing, you need to monitor the correct coordination of hand movements and the effort transmitted to the file. The movement of the file must be horizontal, so the pressure on the handle and the toe of the file must change depending on the position of the fulcrum of the file on the surface being processed.

When moving the file, the pressure with the left hand gradually decreases. By adjusting the pressure on the file, they achieve a smooth sawn surface without blockages along the edges.

If the pressure of the right hand is weakened and the left hand is strengthened, the surface may roll forward.

With increased pressure of the right hand and weakening of the left, a blockage will turn back. It is necessary to press the file against the surface being processed during the working stroke, i.e., when the file moves away from itself.

During the reverse stroke, the file goes freely without pressure, however, it does not need to be torn off the part so as not to lose support and not change the position of the file.

The smaller the notch, the lower the pressing force should be.

The position of the worker at the time of filing in relation to the workpiece is important.

It should be positioned to the side of the vise at a distance of about 200 mm from the workbench so that the body is straight and rotated at an angle of 45 degrees to the longitudinal axis of the vise.

When the file moves away from itself, the main load falls on the left leg slightly extended forward, and when the file is idling, it is on the right. With a slight pressure on the file when finishing or finishing the surface, the feet are located almost side by side. Such work, as accurate, is more often performed while sitting.

The position of the hands (grip of the file) is also important. It is necessary to take the file by the handle in the right hand so that it rests on the palm of the hand, while four fingers grab the handle from below, and the thumb is placed on top.

The palm of the left hand is placed somewhat across the file at a distance of 20 - 30 mm from its toe.

The fingers should be slightly bent, but not hanging down; they do not support, but only press the file. The elbow of the left hand should be slightly raised. The right hand from the elbow to the hand should form a straight line with the file.

When processing small parts with a file, as well as when working with a needle file, press the end of the file with the thumb of the left hand, support it from below with the rest of the fingers.

The index finger of the right hand is placed on a needle file or file. With this position of the hands, the pressure is minimal, the chips are removed very thin, and the surface is brought to the desired size without the danger of going beyond the marking line.

Surface filing is a complex labor-intensive process. The most common defect when filing a surface is non-flatness.

Working with a file in one direction, it is difficult to get a correct and clean surface.

Therefore, the movement of the file, the position of its strokes, traces on the processed surface must change, i.e. alternately from corner to corner.

First, filing is performed from left to right at an angle of 30 - 40 degrees to the axis of the vise, then, without interrupting work, with a straight stroke and finish filing with an oblique stroke at the same angle, but from right to left. Such a change in the direction of movement of the file makes it possible to obtain the necessary flatness and surface roughness.

The sawing process must be constantly monitored.

The part needs to be checked quite often, especially at the end of filing.

For control use calibration rulers, calipers, squares, calibration plates.

The straightedge is chosen depending on the length of the surface to be checked, i.e. The length of the straightedge should cover the surface to be checked.

Checking the quality of filing the surface with a straightedge is carried out in the light. To do this, the part is taken out of the vise and raised to eye level. The straightedge is taken by the middle with the right hand and the edge of the straightedge is applied perpendicular to the surface to be checked.

In order to check the surface in all directions, first the ruler is placed along the long side in two or three places, then along the short side - also in two or three places, and finally, along one and the other diagonals. If the gap between the ruler and the surface being checked is narrow and uniform, then the plane has been processed satisfactorily.

During the control, the ruler is not moved along the surface, but each time it is taken away from the surface being checked and rearranged to the desired position.

If the surface is to be filed especially carefully, the accuracy check is carried out using a paint test plate. In this case, a thin uniform layer of paint (blue, red lead or soot diluted in oil) is applied to the working surface of the calibration plate with a swab.

Then the surface plate is applied to the surface to be verified, several circular motions then remove the plate.

On insufficiently accurately processed (protruding) places, paint remains. These places are filed additionally until a surface is obtained with a uniform layer of paint over the entire surface.

With a caliper, you can check the parallelism of two surfaces by measuring the thickness of the part in several places.

When filing planes at an angle of 90 degrees, their mutual perpendicularity is checked with a bench square.

The control of the outer corners of the part is carried out by the inner corner of the file, looking at the clearance.

The correctness of the internal corners in the product is checked by the outer corner.

Sawing concave surfaces. First, the necessary contour of the part is marked on the workpiece.

Most of the metal in this case can be removed by cutting with a hacksaw, giving the depression in the workpiece the shape of a triangle, or by drilling. Then, the edges are filed with a file and the protrusions are cut off with a semicircular or round bastard file to the applied risk.

The cross-sectional profile of a semicircular or round file is chosen so that its radius is less than the radius of the sawn surface.

Not reaching about 0.5 mm from the risks, the bastard file is replaced with a personal one. The correctness of the sawing shape is checked according to the “clearance” template, and the perpendicularity of the sawn surface to the end of the workpiece is checked with a square.

Sawing convex surfaces

Filing of convex surfaces is carried out as follows. After marking with a hacksaw, the corners of the workpiece are cut off, after which it takes on a pyramidal shape. Then, with the help of a bastard file, a layer of metal is removed, not reaching the risk by about 1 mm, after which the metal layer is carefully removed with a personal file at risk.

Sawing of cylindrical blanks.

A cylindrical rod is first filed into a square, the side of which is equal to the diameter plus the allowance for subsequent processing. Then, the corners of the square are filed and an octahedron is obtained, from which a hexagon is obtained by filing, then a round shape is achieved by filing the corners of the faces.

Uniform rounding of the surface during filing is achieved by continuously turning the workpiece.

When obtaining four and eight faces, the metal layer is removed with a bastard file, and the octahedron and hexagon are filed with a personal file.

Processing control is carried out with a caliper in several places.

Sawing small parts

Small parts are clamped in a hand vise and, resting them on a workbench, turn them with their left hand towards themselves during the working stroke, i.e. when moving the file forward, and away from you when idling.

In this case, the file or needle file is held with the right hand with the index finger and they are being pressured.

Filing thin plates with conventional methods is impossible, as they bend, crumple and blockages are obtained on them.

Do not clamp the record between two wooden planks, as this will quickly clog the notch of the file with sawdust.

It is best to use special sliding steel hardened frames. They consist of two bars, between which the workpiece is clamped, fixedly connected on cylindrical pins, and clamped in a vice.

Processing is carried out until the file touches the upper plane of the frame, which makes it possible to dispense with the control of the correct filing with a special ruler.

Sawing along a copier (jig) is the most productive for workpieces with a curved profile.

A copier (jig) is a fixture, the working surfaces of which are machined according to the contour of the workpiece with an accuracy of 0.5 to 0.1 mm, hardened and ground.

The workpiece to be filed is inserted into the copier and clamped together with it in a vice. After that, the protruding part of the workpiece is filed to the level of the working surface of the copier. When manufacturing a large number of identical parts from thin sheet material Several blanks can be fixed in the copier.

Surface finishing. The choice of finishing method and the sequence of transitions depend on the material being processed and the requirements for the quality of the surface, its condition, design, dimensions of the part and the allowance, which can reach 0.05 - 0.3 mm.

Manual cleaning with sandpaper. In cases where high precision is required, surfaces after filing are finished with velvet files, linen or paper sandpaper and abrasive stones.

When finishing surfaces, use wooden blocks with sandpaper glued on them. In some cases, a strip of skin is applied to a flat file, holding the ends with your hand while working.

To finish curved surfaces, the skin is wrapped on a mandrel in several layers. Stripping is carried out first with coarse skins, then with thinner ones. Manual cleaning is an inefficient operation, so it requires a lot of time.

Sawing is the processing of holes in order to give them the desired shape.

Processing of round holes is carried out with round and semicircular files, triangular holes - with triangular, hacksaw and rhombic files; square - square files.

Preparation for sawing begins with marking and punching the marking marks, then drill holes according to the marked marks and cut out the armholes formed by drilling.

The best marking is obtained with a polished sandpaper metal surface. When sawing, one hole is drilled when the armhole is small; and in larger armholes, two or more holes are drilled in order to leave the smallest sawing allowance.

Large tabs are difficult to remove from a drilled armhole, but do not place the holes too close together to avoid squeezing, which can lead to breakage of the drill.

When sawing a square hole in a workpiece, first mark the square, and a hole in it, then drill a hole with a drill, 0.5 mm in diameter less than the side of the square.

IN drilled hole four corners are sawn with a square file, not reaching 0.5 mm to the marking marks, after which the hole is sawn to the marking marks in the following sequence: first two opposite sides, then the rest, after which the hole is adjusted to the required size.

When sawing a trihedral hole in the workpiece, mark the contour of the triangle and drill a hole in it with a drill, without touching the marking marks of the triangle. Then, three corners are sawn in a round hole and the sides are sequentially sawn, not reaching 0.5 mm to the marking line, after which the sides of the triangle are adjusted. It is necessary to work with a triangular file in a strictly straight line to avoid undercutting the sides.

The processing accuracy is checked with an insert.

When adjusting, make sure that the insert enters the hole to be cut freely, without distortion and tightly.

File care

Longer file life is ensured by proper care.

The files are stored in an anti-corrosion lubricant, which must be removed before work by washing the tool with a brush in clean gasoline or by rubbing the notch with chalk, which absorbs grease, and then the chalk is removed with a stiff brush in the direction of the rows of notches.

When working with a file, you must follow some rules: do not hit the files - due to their fragility, they can crack and break.

Files should not be placed on metal or stone, concrete surfaces or objects, as this may lead to chipping of the teeth.

Store files for wooden coasters in a position that prevents them from touching each other.

To protect against corrosion, it is necessary to prevent moisture, acids, and fumes on the files. Dark color indicates that the file is oxidized or poorly hardened. The new file is light grey.

Files must be protected from oil and sanding dust; oily files do not cut, but slide, so you should not wipe the file with your hand, as there is always a fatty film on the hand; emery dust clogs the cavities of the teeth, damages them, the file cuts poorly after exposure to abrasives.

To prevent clogging of soft and ductile metals with chips, the files should be rubbed with chalk before work.

To avoid premature wear of files, before filing workpieces whose surfaces are covered with rust, it is necessary to remove rust from them with a metal brush.

Do not file materials with a hardness equal to or greater than its hardness. This can lead to blunting or chipping of the teeth, therefore, when processing surfaces, the remains of fused borax, casting peel, scale, work hardening are removed with emery or a knurled edge of an old file, and only after that filing begins.

Files should only be used for their intended purpose; with a new file, it is better to process soft metals first, and after some blunting, hard metals.

All this allows you to increase the shelf life of the file.

From time to time, the file is cleaned of chips and sawdust by tapping the toe of the file on the workbench.

Clean the file with a cord brush with steel bristles. Move the brush along the notch, for files with a double notch - along the main notch. A metal rod with a flattened end is inserted into the handle of the brush, which serves to remove those particles that are stuck after brushing with a wire brush.

In the absence of brushes, the teeth of the file are cleaned with scrapers made of aluminum, brass or other soft metal.

solid steel or copper wire not suitable for this purpose, since the steel spoils the notch, and the copper copper-plated teeth.

Oily files are cleaned first charcoal by rubbing along the rows of notches and then brushing or washing in a solution of caustic soda and brushing.

Oiled files are washed in kerosene or gasoline.

To clean files from wood, bone, ebonite and plastic chips, they are lowered for 15 minutes in hot water, then cleaned with a steel brush and dried.

Old files can be renewed by immersing them in a 10% sulfuric acid solution for 10 minutes, rinsing them in running water, clean with a steel brush, rinse again in a solution of caustic soda, rinse in hot water, wipe and dry.

In a glass dish, dissolve 90 g of borax in 750 g of distilled water, add 400 g of finely ground copper sulfite and 350 g of 30 percent sulfuric acid to this solution, stirring gently. Dip a well-washed file into the liquid prepared in this way and hold for 20 minutes. Then rinse with warm water and dry.

You can clean the file in the following way: first clean it with a metal brush, wash it with soap and water, then with a weak solution of caustic soda (10 g of soda per 200 ml of water) and soak for 10 minutes in a solution consisting of 10 parts of 20% nitric acid, 30 parts of 20 percent sulfuric acid and 70 parts of water. Wash the file after chemical treatment hot water and immerse in slaked lime.

filing metal

Objective: Familiarize yourself with the basic methods of filing meth. The main tools used for filing. Acquire practical skills in filing metal.

Equipment, tools, fixtures. Locksmith vices, files of various types, instrumentation for checking the quality of filing, basting-frames and copiers.

Theoretical part

Filing is a cutting method in which a layer of material is removed from the surface of the workpiece using a file.

A file is a multi-bladed cutting tool that provides relatively high accuracy and low roughness of the workpiece (part) surface to be machined.

By filing, the parts are given the required shape and dimensions, the parts are fitted to each other during assembly, and other work is performed. With the help of files, planes, curved surfaces, grooves, grooves, holes of various shapes, surfaces located at different angles, etc. are processed.

Sawing allowances are left small - from 0.5 to 0.025 mm. The achievable processing accuracy can be from 0.2 to 0.05 mm, and in some cases up to 0.005 mm.

File(Fig. 1, but) is a steel bar of a certain profile and length, on the surface of which there is a notch (cutting).

Rice. 76. Files:

but- main parts (1 - handle; 2 - shank; 3 - ring; 4 - heel; 5 - edge;

6 - notch; 7 - rib; 8 - nose); b- single notch; in - double notch;

G - rasp notch; d - arc notch; e - handle attachment; w - removing the file handle.

The notch forms small and sharpened teeth, having a wedge shape in cross section. For knurled files, the sharpening angle β is usually 70°, the rake angle γ up to 16°, the relief angle α from 32 to 40°.

The notch can be single (simple), double (cross), rasp (dot) or arc (Fig. 1, b - d).

Single cut files remove a wide chip equal to the length of the entire notch. They are used for cutting soft metals.

Double cut files used when filing steel, cast iron and other hard materials, as the cross notch crushes the chips, which facilitates the work.

Files with a rasp notch, having capacious recesses between the teeth, which contributes to better chip placement, they process very soft metals and non-metallic materials.

Arc cut files have large cavities between the teeth, which ensures high performance and good quality processed surfaces.

Files are made from steel U13 or U13 A. After notching the teeth, the files are subjected to heat treatment,

File handles usually made of wood (birch, maple, ash and other species). Techniques for fitting handles are shown in Figure 1, e And well.

By appointment, files are divided into the following groups: general purpose, special purpose, needle files, rasps, machine files.

For general plumbing work general purpose files. By the number of notches per 1 cm of length, they are divided into 6 numbers.

Notched files No. 0 and 1 (bastard) have the largest teeth and are used for rough (rough) filing with an accuracy of 0.5-0.2 mm.

Notched files No. 2 and 3 (personal) are used for fine filing of parts with an accuracy of 0.15-0.02 mm.

Files with a notch No. 4 and 5 (velvet) are used for the final fine finishing of products. Achievable processing accuracy - 0.01-0.005 mm.

The length of the files can be made from 100 to 400 mm.

According to the shape of the cross section, they are divided into flat, square, trihedral, round, semicircular, rhombic and hacksaw (Fig. 2).

For processing small parts, small-sized files-needles are used. They are produced in five numbers with the number of notches per 1 cm of length up to 112.

Processing of hardened steel and hard alloys is carried out with special needle files, in which grains of artificial diamond are fixed on a steel rod.

Rice. 2. Section shapes of files:

but And b- flat; in - square; G- trihedral; d - round; e- semicircular;

w - rhombic; h - hacksaw.

Improving conditions and increasing labor productivity when filing metal is achieved through the use of mechanized (electric and pneumatic) files.

In the conditions of training workshops, it is possible to use mechanized manual filing machines, which are widely used in production.

Universal grinder(see fig. 4, G) working from asynchronous motor 1, has a spindle to which a flexible shaft is attached 2 with holder 3 for fixing the working tool, and interchangeable straight and angular heads, which allow filing in hard-to-reach places and at different angles with the help of round shaped files.

filing metal

When filing, the workpiece is fixed in a vice, while the sawn surface should protrude above the level of the vise jaws by 8-10 mm. To protect the workpiece from dents during clamping, soft-material muffs are put on the vise jaws. working the posture when filing metal is similar to the working posture when cutting metal with a hacksaw.

With the right hand, they take the handle of the file so that it rests on the palm of the hand, four fingers cover the handle from below, and the thumb is placed on top (Fig. 3, but).

The palm of the left hand is applied somewhat across the file at a distance of 20-30 mm from its toe (Fig. 3, b).

Move the file evenly and smoothly over its entire length. The forward movement of the file is a working stroke. The reverse stroke is idle, it is performed without pressure. When reversing, it is not recommended to tear the file away from the product, as you can lose support and violate the correct position of the tool.

Rice. 3. File grip and balancing during filing:

but- grip with the right hand; b- grip with the left hand; in - pressure force at the beginning of the movement;

G- pressure force at the end of the movement.

In the process of filing, it is necessary to observe the coordination of the efforts of pressing on the file (balancing). It consists in a gradual increase during the working stroke of a small initial pressure with the right hand on the handle with a simultaneous decrease in the initial pressure of the left hand on the toe of the file (Fig. 3, c, d).

The length of the file should exceed the size of the processed surface of the workpiece by 150-200 mm.

The most rational rate of filing is considered to be 40-60 double strokes per minute.

filing they start, as a rule, with checking the machining allowance, which could ensure the manufacture of the part according to the dimensions indicated on the drawing. After checking the dimensions of the workpiece, determine the base, i.e. the surface from which the dimensions of the part should be maintained and mutual arrangement its surfaces.

If the degree of surface roughness is not indicated in the drawing, then filing is done only with a bastard file. If necessary, to obtain a more even surface, filing is finished with a personal file.

In the practice of manual processing of metals, the following types of filing are encountered: filing of planes of conjugated, parallel and perpendicular surfaces of parts; filing curved (convex or concave) surfaces; sawing and fitting surfaces.

Sawing wide flat surfaces is one of the most complex types filing. To obtain a correctly filed straight surface, the main attention should be focused on ensuring the straightness of the movement of the file. Sawing is carried out with a cross stroke (from corner to corner) at an angle of 35-40 ° to the sides of the vise. When filing diagonally, you should not go with a file to the corners of the workpiece, as this reduces the area of ​​\u200b\u200bsupport for the file and removes a large layer of metal. The so-called "blockage" of the edge of the treated surface is formed.

The correctness of the plane is checked with a ruler “in the light”, for which it is applied along, across and diagonally to the treated surface. The length of the straight edge should cover the surface to be checked.

In the case of filing parallel flat surfaces, the parallelism is checked by measuring the distance between these surfaces in several places, which should be the same everywhere.

When processing narrow planes on thin parts, longitudinal and transverse filing is used. When filing across the workpiece, the file is in contact with a smaller surface, more teeth pass through it, which allows you to remove a large layer of metal. However, when filing transversely, the position of the file is unstable and it is easy to “fill up” the edges of the surface. In addition, the formation of "blockages" can be facilitated by the bending of a thin plate during the working stroke of the file. Longitudinal filing creates a better support for the file and eliminates plane vibration, but reduces processing performance.

For creating better conditions and increase labor productivity when filing narrow flat surfaces, special devices are used: filing prisms, universal bastings, frame bastings, special conductors and others.

The simplest of them is the basting-frame (Fig. 4, a). Its use eliminates the formation of "blockages" of the treated surface. The front side of the basting-frame is carefully processed and hardened to high hardness.

The marked workpiece is inserted into the frame, slightly pressing it with screws against the inner wall of the frame. The installation is clarified, achieving the coincidence of the risks on the workpiece with the inner edge of the frame, after which the screws are finally fixed.

Rice. 4. Filing surfaces:

but - filing with the help of a basting-frame; b - reception of filing convex surfaces; in - reception of filing concave surfaces; G- filing with a universal grinder (1 - electric motor; 2 - flexible shaft; 3 - tool holder).

Then the frame is clamped in a vice and the narrow surface of the workpiece is sawn off. Processing is carried out until the file touches the upper plane of the frame. Since this plane of the frame is processed with high precision, the filed plane will also be accurate and will not require additional verification with a ruler.

When processing planes located at an angle of 90 °, first they file the plane taken as the base one, achieving its flatness, then the plane perpendicular to the base one. External corners are processed with a flat file. The control is carried out by the inner corner of the square. The square is applied to the base plane and, pressing against it, is moved until it comes into contact with the surface to be checked. The absence of a gap indicates that the perpendicularity of the surfaces is ensured. If the light gap narrows or widens, then the angle between the surfaces is greater or less than 90°.

Internal corners are processed as follows. The workpiece is marked using the outer surfaces as bases. They will also be bases during control. Then the excess metal is cut out with a hacksaw, leaving a sawing allowance of about 0.5 mm. If the sides of the inner corner must converge without rounding, a hole with a diameter of 2-3 mm is drilled in it or a shallow cut is made at an angle of 45 ° (it is almost impossible to process the inner corner without rounding inside). Sawing the sides of the corner, first of all they achieve their flatness, and then perpendicularity. The filing of surfaces along the inner corner is carried out so that the edge of the file, on which there is no notch, is facing the second surface. The control of the correctness of the inner corner is also carried out with a square.

Surfaces located at an angle greater than or less than 90° are treated in the same way. External corners are processed with flat files, internal - with rhombic, trihedral and others. Processing control is carried out by goniometers or special templates.

When processing curved surfaces, in addition to the usual filing methods, special ones are also used.

Convex curved surfaces can be machined using the rocking file technique (Fig. 4, b). When moving the file, first its toe touches the workpiece, the handle is lowered. As the file advances, the toe drops and the handle rises. During the reverse stroke, the movements of the file are opposite.

Concave curved surfaces, depending on the radius of their curvature, are processed with round or semicircular files. The file makes a complex movement - forward and to the side with a turn around its axis (Fig. 4, in). In the process of processing curved surfaces, the workpiece is usually periodically re-clamped so that the treated area is located under the file.

When manufacturing a batch of parts, it is advisable to make a special copier, similar to a basting-frame, the front part of which has the shape of a curved surface. In this case, the copier with the workpiece fixed in it is clamped in a vice and filing is carried out until the file touches the hardened surface of the copier.

Sawing called the processing of holes (armholes) of various shapes and sizes using files. According to the tool used and the methods of work, sawing is similar to sawing and is a variation of it.

Files are used for sawing various types and sizes. The choice of files is determined by the shape and size of the armhole. Armholes with flat surfaces and grooves are processed with flat files, and for small sizes - with square ones. The corners in the armholes are sawn with trihedral, rhombic, hacksaw and other files. Curvilinear armholes are processed with round and semicircular files.

Sawing is usually done in a vise. In large parts, armholes are sawn at the installation site of these parts.

Preparation for sawing begins with the marking of the armhole. Then excess metal is removed from its internal cavity.

With large armholes and the greatest thickness of the workpiece, the metal is cut with a hacksaw. To do this, holes are drilled at the corners of the armhole, a hacksaw blade is inserted into one of the holes, the hacksaw is assembled and, stepping back from the marking line by the sawing allowance, the internal cavity is cut out.

An armhole of medium size is drilled along the contour with a drill with a diameter

3-5 mm near the marking lines, then cut through the remaining jumpers with a crosscut or chisel.

To prepare for sawing small armholes, it is often enough to drill one hole with a diameter of -0.3-0.5 mm less than the diameter of the circle inscribed in the armhole.

Sawing directly is carried out, as already noted, by techniques similar to sawing.

The control is carried out with a caliper and special templates.

Fitting called the mutual fitting of two parts mating without a gap. Fit both closed and semi-closed contours. Fitting is characterized by high processing accuracy. Of the two fitting parts, the hole is usually called, as in sawing, an armhole, and the part included in the armhole is called an insert.

Fitting is used as a final operation in the processing of parts of hinged joints and most often in the manufacture of various templates. Fitting is carried out with files with a fine or very fine notch.

First, workpieces for the liner and armholes are processed. They mark them, saw the armhole and file the liner, leaving an allowance (0.1-0.4 mm) for fitting.

The first one is usually prepared for fit and one of the mating parts is fit, which is easier to process and control, in order to then use it for control in the manufacture of the mating part.

Fitting accuracy is considered sufficient if the liner enters the armhole without distortion, pitching and gaps.

Possible types of marriage when filing metal and their causes:

Inaccuracy in the dimensions of the sawn workpiece (removal of a very large or small layer of metal) due to inaccurate marking, incorrect measurement or inaccuracy of the measuring tool;

Non-flatness of the surface and "blockages" of the edges of the workpiece as a result of the inability to correctly perform filing techniques;

Dents and other damage to the surface of the workpiece as a result of its incorrect clamping in a vise.

When filing metal with hand and mechanized tools, safety regulations should be observed. Use only correct tools. File handles must be firmly attached. It is forbidden to work with files without handles or with cracked, split handles. The chips formed during the filing process should be swept away with a special brush. Do not blow it off or brush it off with bare hands to avoid hurting your hands or clogging your eyes. When working with power tools, follow the rules of electrical safety. Check the condition of the conductive parts of the tool.

General rules for handling and caring for files:

Use files only for their intended purpose;

It is impossible to file with a file materials whose hardness is equal to or exceeds its hardness;

Protect files from even minor impacts that can damage the teeth;

Protect from moisture on the files, which causes their corrosion;

Periodically clean the files from chips with a cord brush;

Store files on wooden stands in a position that prevents them from touching each other.

The task

On the instructions of the teacher, file blanks with narrow and wide surfaces with self-selection necessary files and measuring tools. Sawing curved surfaces on the proposed workpieces, pre-select files of the required profile and tools to control the work.

Questions:

1. What kind of metal processing is called filing?

2. In what cases is metal filing used?

3. What are the types of notches for the formation of file teeth?

4. What material are the files made of?

5. What groups are files divided into according to their purpose?

6. What are needle files and what do they serve?

7. What are the general rules for handling and caring for files?

8. What is the technique for performing filing techniques?

9. What mechanized tools are used for filing metal?

10. What types of marriage are possible during filing and what are their causes?

11. What safety rules must be observed when filing metals?

The direction of movement of the file, and consequently, the position of the strokes (file trace) on the machined surface can be longitudinal, transverse, cross and circular.

Working with a file only in the longitudinal or only in the transverse direction, it is difficult to obtain a correct and clean surface of the workpiece.

When filing transversely, the file removes a layer of metal faster than when filing longitudinally, since it comes into contact with a smaller surface area and cuts into the metal more easily. Therefore, to remove large allowances, it is better to use transverse filing (Fig. 81, i). The filing process in this case can be completed by placing a longitudinal stroke on the surface to be treated (Fig. 81, b). The combination of transverse and longitudinal filing of the edge allows you to achieve the desired degree of its straightness in the longitudinal direction.

Good results in terms of productivity and surface quality when processing planes are achieved when filing with a cross (oblique) stroke; the movement of the file is transferred in this case alternately from corner to corner (Fig. 81, c). Usually, the plane of the workpiece is first filed from right to left at an angle of 35-40 ° to the side of the vise, and then also from left to right. When filing with a cross stroke on the surface of the workpiece, the mesh formed by the teeth of the file must be preserved all the time. This grid controls the quality of work; the absence of a grid on any part of the surface indicates the wrong position of the file in this place.

Filing with circular strokes is carried out in those cases when it is necessary to remove protruding parts of the metal from the surface to be treated (Fig. 81, d).

Fine sawing and surface finishing. When filing, not only the specified accuracy of processing is ensured, but also the necessary cleanliness of the surface finish. A rough finish is achieved by processing with a bastard file with a fine notch, a more thorough one - with personal files. The most perfect finish is achieved by processing with velvet files, paper or linen abrasive paper, abrasive stones, etc.

When finishing the plane with velvet files, filing is done with longitudinal and transverse strokes with light pressure on the file (Fig. 82, a). After finishing with a file over-

Nost, as needed, is treated with abrasive bars and skins, dry or with oil. In the first case, a shiny metal surface is obtained, in the second - semi-matt. When finishing copper and aluminum, the skin is rubbed with stearin.

For surface finishing, wooden blocks with abrasive sandpaper glued to them are also used (Fig. 82, b, c). In some cases, the skin is wrapped around a flat file.

Files are cleaned from chips with steel brushes, as well as special scrapers made of steel or brass wire with a flattened end (Fig. 82, d). When cleaning files from rubber, fiber and wood chips, they are first dipped in hot water for 15-20 minutes, and then cleaned with a steel brush. Oily files are cleaned with a piece of birch charcoal, with which the surfaces are rubbed along the rows of notches, and then cleaned with a steel brush. If such cleaning proves ineffective, the oily file should be washed in a hot caustic soda solution, cleaned with a steel brush, rinsed in water and dried.

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Dimensional processing refers to the processing of a workpiece (part) to give it a given shape, size and roughness of the machined surfaces. The result of processing is ready product, which can be used independently (for example, a chisel, a square), or a part suitable for installation in an assembled product (for example, handles and levers various designs). The operations of dimensional locksmith processing include filing, processing holes (drilling, countersinking, countersinking, countersinking, reaming) and cutting external and internal threads.

filing is an operation to remove a layer of material from the surface of the workpiece using cutting tool- a file, the purpose of which is to give the workpiece a given shape and size, as well as to provide a given surface roughness. In most cases, filing is carried out after cutting and cutting metal with a hacksaw, as well as during assembly work to fit the part in place. In locksmith practice, filing is used to process the following surfaces:

Flat and curvilinear;

Flat, located at an external or internal angle;

Flat parallel under a certain size between them;

Shaped complex profile.

In addition, filing is used to process recesses, grooves and protrusions.

Distinguish between rough and fine filing. File processing allows you to get the accuracy of processing parts up to 0.05 mm, and in some cases even higher accuracy. The filing allowance, i.e. the difference between the nominal size of the part and the size of the workpiece to obtain it, is usually small and ranges from 1.0 to 0.5 mm.

Tools used for filing

The main working tools used in filing, are files, rasps and needle files.

The files are hardened steel bars, on the working surfaces of which it is applied a large number of notches or cuts that form the cutting teeth of a file. These teeth provide cutting from the surface of the workpiece of a small layer of metal in the form of chips. Files are made from tool carbon steels grades U10, U12, U13 and tool alloyed steel grades SHKH6, SHKH9, SHKH12.

Notches on the surface of the file form teeth, and the fewer notches per unit length of the file, the larger the teeth. By the type of notches, files with single (Fig. 3.1, a), double (cross) (Fig. 3.1, b) and rasp (Fig. 3.1, c) notches are distinguished.

Single cut files cut metal with wide chips equal to the entire length of the tooth, which requires a lot of effort. Such files are used for processing non-ferrous metals, their alloys and non-metallic materials.

Files with a double cut have a main cut (deeper) and an auxiliary cut (smaller) applied on top of it, which provides chip crushing along the length, which reduces the effort applied to the file during operation. P1ag applying the main and auxiliary notches is not the same, so the teeth of the file are located one after another in a straight line, making an angle of 5 with the axis of the file. This arrangement of the teeth on the file provides a partial overlap of the marks from the teeth on the treated surface, which reduces its roughness.

Files with a rasp notch (rasps) have teeth that are formed by extruding metal from the surface of the file blank using a special chisel. Each tooth of the rasp notch is displaced relative to the tooth located in front by half a step. Such an arrangement of teeth on the surface of the file reduces the depth of the grooves formed by the teeth, due to the partial overlap of the tooth marks on the surface of the workpiece, which facilitates cutting. Rasps are used for filing soft materials(babbitt, lead, wood, rubber, rubber, some types of plastics).

Notches on the surface of the file get various methods: notching (Fig. 3.2, a) on special machines, milling (Fig. 3.2, b) and broaching (Fig. 3.2, c). Regardless of the method of obtaining a notch, the teeth formed on the surface of the file have the shape of a cutting wedge, geometric shape which is determined by the taper angle p>, the rear angle a, the front angle y and the cutting angle 5 (see Fig. 3.2, a).

The rake angle is the angle between the front surface of the tooth and the plane passing through its top perpendicular to the axis of the file. The taper angle is the angle between the anterior and posterior surfaces of the tooth. The posterior angle is the angle between the posterior surface of the tooth and the tangent to the machined surface. The cutting angle is the angle between the front surface of the tooth and the plane of the machined surface.

Files are classified depending on the number of cuts per 10 mm length of the file into 6 classes. The cuts are numbered from 0 to 5, while the smaller the cut number, the greater the distance between the cuts and, accordingly, the larger the tooth. The choice of file number depends on the nature of the work to be performed by it. The higher the requirements for the accuracy of processing and the roughness of the machined surface, the finer the tooth of the file must be.

For rough draft filing (roughness Rz 160 ... 80, accuracy 0.2 ... 0.3 mm), files of the 0th and 1st classes (bastard) are used, having from 5 to 14 teeth per 10 mm of the notched part, depending on the length file.

To perform finishing (roughness Rz 40 ... 20, accuracy 0.05 ... 0.1 mm), files with a finer tooth of the 2nd and 3rd classes (personal) are used, having from 8 to 20 notches per 10 mm of notched length file parts.

For fitting, finishing and finishing work (surface roughness Ra 2.5 ... 1.25, accuracy 0.02 ... 0.05 mm), files with chalk are used) and they are very fine teeth 4th and 5th classes (velvet), having from 12 to 56 notches per 10 mm of the length of the notched part.

Files with a double notch, made using the on notching method, are designed to perform plumbing work. Such files are made with different cross-sectional shapes, which are selected depending on the shape of the surface being processed.

flat files (Fig. 3.3, a, b) - for filing flat and convex wide outer surfaces and sawing rectangular holes;

square files (Fig. 3.3, c) - for sawing square and rectangular openings, rectangular grooves and narrow flat outer surfaces;

trihedral files (Fig. 3.3, d) - for sawing holes and grooves with angles of more than 60 °;

round files (Fig. 3.3, e) - for sawing round and oval holes, as well as concave surfaces of a small radius of curvature that cannot be processed with a semicircular file;

semicircular files (Fig. 3.3, e) - for filing concave surfaces with a large radius of curvature and fillets;

rhombic files (Fig. 3.3, g) - for filing the teeth of gears, sprockets, for sawing profile grooves and surfaces located at sharp angles;

hacksaw files (Fig. 3.3, h) - for filing internal angles less than 10 °, as well as wedge-shaped grooves, narrow grooves, gear teeth, flat surfaces and finishing corners in trihedral, rectangular and square holes.

Rasps in cross-sectional shape can be flat blunt (Fig. 3.4, a), flat pointed (Fig. 3.4, b), round (Fig. 3.4, c) and semicircular (Fig. 3.4, d). Rasps are made with fine and coarse notches.

For processing small parts, special files are used - needle files having a short length (80.120 or 160 mm) and a different cross-sectional shape (Fig. 3.5). Needle files also have a double notch: the main one - at an angle of 25 ° and the auxiliary one - at an angle of 45

To ensure high quality filing, it is necessary to choose the right cross-sectional profile, length and notch of the file.

The cross-sectional profile of the file is selected depending on the shape of the sawn surface:

Flat, flat side of the semicircular - for filing flat and convex curved surfaces;

Square, flat - for processing grooves, holes and openings of rectangular section;

Flat, square, flat side of the semicircular - when filing surfaces located at an angle of 90 °;

Trihedral - when filing surfaces located at an angle of more than 60 °;

Hacksaw, rhombic - for filing surfaces located at an angle of more than 10 °;

Trihedral, round, semicircular, rhombic, square, hacksaw - for sawing holes (depending on their shape).

The length of the file depends on the type of processing and the size of the surface to be treated and should be:

100 ... 160 mm - for filing thin plates;

160 ... 250 mm - for filing surfaces with a processing length of up to 50 mm; 250 ... 315 mm - with a processing length of up to 100 mm; 315 ... 400 mm - with a processing length of more than 100 mm;

100 ... 200 mm - for: sawing holes in parts up to 10 mm thick;

315 ... 400 mm - for rough filing;

100 ... 160 mm - when finishing (needle files).

The notch number is selected depending on the requirements for the roughness of the machined surface.

For comfortable holding and safety, the files are supplied with a handle, which is made of wood or plastic. Pens are disposable or reusable. Wooden disposable handles (Fig. 3.6) of files are made of birch or linden. The surface of the handle must be clean and even. To prevent splitting when installed on the file shank, the handle is equipped with a special metal ring mounted on its neck. A hole is drilled in the handle for the file shank. When fixing, the file shank is inserted into the hole, then, by hitting the head of the handle on the workbench or vise, they achieve its tight entry into the handle hole. Do not place the handle by hitting the tip of the file with a hammer, as this may cause injury.

K category: Plumbing work

Metal filing techniques

The sawn product is firmly clamped in a vice to give it a stable position.

A layer of rust and scale on the workpiece and the crust of the casting are filed with an old bastard file so as not to spoil the good one, which wears out quickly. Then they start roughing the part with a suitable bastard file and then finish it with a personal file.

Rice. 1. The position of the worker at the vice: a - the position of the body, b - the layout of the legs, c - the position of the body during rough filing

In order not to spoil the vise jaws during the final filing, they are put on overlays made of copper, brass, lead or aluminum.

The frequency and accuracy of filing depends on the installation of the vice, the position of the body of the worker at the vice, working methods and the position of the file.

The top of the vise jaws should be at the level of the worker's elbow. The correct position of the vise worker is shown in fig. one.

The person working when filing should stand on the side of the vise - half-turned, at a distance of about 200 mm from the edge of the workbench. The body must be straight and rotated 45° to the longitudinal axis of the vise. Legs are spaced to the width of the foot, left leg slightly forward in the direction of the file movement. The feet are placed approximately 60° apart. When working, the body is slightly tilted forward. This position of the body and legs provides the most comfortable and stable position for the worker, the movement of the hands becomes free.

During filing, the file is held with the right hand, resting the head of the handle in the palm of your hand. Thumb hands are placed on top of the handle, and the rest of the fingers support the handle from below. Left hand put on the end of the file near his nose and press the file.

When rough filing, the palm of the left hand is placed at a distance of about 30 mm from the end of the file, fingers half-bent so as not to injure them on the edges of the product during operation.

When finishing filing, the end of the file is held with the left hand between the thumb located on the top of the file and the rest of the fingers at the bottom of the file. The file is moved back and forth smoothly along its entire length.

The product is clamped in a vise so that the sawn surface protrudes 5-10 mm above the vise jaws. In order to avoid recesses and blockages along the edges, when moving the file forward, it is evenly pressed against the entire surface being processed. The file is pressed only when moving it forward. With the reverse movement of the file, the pressure is weakened. The speed of the file is 40-60 double strokes per minute.

To obtain a properly processed plane, the product is filed with cross strokes alternately from corner to corner. First, the surface is filed from right to left, and then from left to right. Thus, the surface is sawn off until the necessary layer of metal is removed.

After the final filing of the first wide plane of the tile, they begin filing the opposite surface. In this case, it is required to obtain parallel surfaces of a given thickness.

The second wide surface is filed with cross strokes.

The accuracy of the surface treatment and the accuracy of the corners are checked with a ruler and a square, and the dimensions are checked with a caliper, inside gauge, scale ruler or caliper.

When preparing pipelines and manufacturing parts for sanitary systems, the ends of pipes and the plane of parts are sawn off. When filing products, it is necessary to strive to prevent marriage. Marriage during filing is the removal of an excess layer of metal and a decrease in the size of the product compared to the required ones, the unevenness of the sawn surface and the appearance of "blockages".

Therefore, before starting filing, the locksmith must carefully mark the product and choose the right files. In the process of filing, use control and measuring tools and systematically check the dimensions of the workpieces.

To extend the service life of files, it is necessary to clean the file notch from stuck chips in a timely manner and protect it from oil and water. The file is cleaned of dirt or metal particles with steel brushes.

Do not take the working part of the file oily hands and put the files on the oil workbench.

When filing soft metals, it is recommended to rub the file with chalk beforehand. This will prevent it from being clogged with metal filings and will facilitate cleaning from sawdust.

When filing, the following safety rules must be observed: - the handle must be firmly attached to the file so that during operation it does not come off and injure the hand with the shank; - the vise must be in good condition, the product must be firmly fixed in them; - the workbench must be firmly fixed so that it does not swing; - when filing parts with sharp edges, do not press your fingers under the nozzle during its reverse stroke; - shavings are allowed to be removed only with a sweeping brush; - after work, the files must be cleaned of dirt and chips with a metal brush; - it is not recommended to put files one on top of the other, as this spoils the notch.

For the mechanization of filing work, an electric filing machine with a pneumatic drive and a flexible shaft is used. A special device is put on the end of the flexible shaft, which converts rotational motion into reciprocating motion. A file is inserted into this device, with which parts are filed.

- Techniques for filing metal