Manual filing of surfaces. filing. Techniques and methods for filing metal Sawing metal with files of various profiles
Filing is the removal of a layer from the surface of the workpiece by means of a file.
The files are cutting tool in the form of hardened steel bars with a notch on the surface. Material U13, U13A, as well as chromium ball bearing steel ШХ15.
They have various shapes - flat, square, trihedral, semicircular, round, rhombic, hacksaw. With a different number of notches per 1 running cm of the working part (bastard, personal and velvet).
Three types: ordinary, needle files and rasps, diamond files and needle files.
Files are:
with a single notch can remove wide chips, they are used when filing soft metals, as well as non-metals.
with double or cross cut, for steel, cast iron, etc. hard materials. In these files, the lower, deep notch, called the main one, is first cut, and on top of it, the upper, shallow one, called the auxiliary, which cuts the main notch into teeth.
the cross-cut cuts the chips, making it easier to work.
The arc cut has large tooth gaps and an arc shape for high performance and good quality.
Rasp notch - teeth in a checkerboard pattern. For soft metals and non-metals.
Choice of files:
For coarse filing up to 0.5 mm, apply bastard files that allow you to remove a metal layer of 0.08-0.15 mm in one move.
Personal– for a cleaner finish by 0.15 mm. Remove 0.05-0.08 mm in one move. 7-8 cells of purity are achieved.
With velvet trim- the most fine finishing, grinding with an accuracy of 0.01-0.05 mm. Remove 0.01-0.03 mm. Roughness 9-12 cells of purity.
Chabers - steel strips or rods with working edges. There are flat, trihedral, shaped with handles, with sharply sharpened working surfaces.
Requirements. A sharp, even shank, a handle with a ring, without cracks, when struck on the anvil, it makes a clear sound.
The handle is first drilled, then burned with the shank of an old file and clogged by hitting the head of the handle on the workbench.
When filing soft and viscous metals, rub with chalk, aluminum - with stearin. Protect them from moisture and oil, so do not wipe with your hand. Periodically clean from chips with steel brushes.
Marriage. The unevenness of the surface and blockages of the edges, the excess was removed or not filmed.
Security. You can injure your hand with a shank if the handle is faulty, or damage the fingers of your left hand when you reverse. Do not clean files from chips with bare hands, blow them off or remove them. compressed air, you can damage your hands and eyes. It is better to work with a headdress. shavings from the hair are difficult to remove.
drilling.
drilling The process of making holes in a cutting material with a cutting tool is called a drill.
Reaming- increasing the diameter of the existing hole.
Purity of processing– 1-3 roughness classes.
Applies to obtain irresponsible holes, a low degree of accuracy and a low roughness class, for example, for mounting bolts, rivets, studs, threading, reaming, and countersinking.
twist drill- a two-tooth cutting tool, consisting of 2 main parts: working and shank. Working part The drill consists of a cylindrical (guide) and a cutting part. On the cylindrical part there are two helical grooves located one against the other. Their purpose is to remove chips.
To reduce friction, the drill has a reverse taper of 0.1 mm for every 100 mm of length.
Tooth- this is the protruding part of the drill having cutting edges.
The angle between the cutting edges has a significant effect. With its increase, the strength of the drill increases, but the feed force increases. With a decrease in the angle, the cutting becomes easier, but the cutting part is weakened. The angle value is selected depending on the hardness of the material.
Steel and cast iron……………………………………….116-118 about
Hardened steel, red copper……………………125
Brass and bronze, aluminum………………….…….130-140
Silumin……………………………………………...90-100
ebonite………………………………………………...85-90
marble………………………………………………..80
plastics………………………………………..…50-60
Shanks
a drill up to 10 mm is cylindrical (usually) and is mounted in a chuck. The shank has a driver for additional transmission of torque.
Larger diameter drills have a tapered shank. At the end there is a foot that does not allow the drill to turn in the spindle and serves as a stop when the drill is knocked out of the socket. Dimensions 0,1,2,3,4,5,6 with different sizes cones
Manufactured - U10, U12A, chromium 9X, chromium-silicon 9XC, high-speed R9, P18, metal-ceramic alloys of grades VK6, VK8 and T15K6, with bodies made of steel grades R9.9XS and 40X.
Drills with carbide inserts are used for cast iron, hardened steel, plastics, glass, marble.
There are drills with holes for supplying coolant to the cutting edges of the drill.
When drilling, a dull drill will heat up very quickly, so much so that the steel will temper and the drill will become unusable. Therefore, the drills are cooled.
Steel………………………………….soap emulsion or mixture of mineral and fat is small.
Cast iron………………………………….soap emulsion or dry
Copper…………………………………..soap emulsion or rapeseed oil
Aluminum…………………………….soapy emulsion or dry
Duralumin………………………..soap emulsion, kerosene with castor or rapeseed oil
Silumin………………………………soap emulsion or a mixture of alcohol and turpentine.
Drill wear is detected by a sharp creaking sound.
Sharpening is carried out with cooling with a water-soda solution. Sharpen the drill as follows: slightly pressing the cutting edge against the surface of the abrasive wheel so that the cutting part assumes a horizontal position, with its back surface against the circle. With a smooth movement of the right hand, without taking the drill away from the circle, turn the drill around its axis, observing the correct inclination, sharpen the back surface, while making sure that the cutting edges are straight, have the same length and are sharpened at the same angles.
Drills with cutting edges of different lengths or with different angles of their inclination will drill holes larger than their diameter.
They drill with hand, electric, pneumatic drills and El. machines.
Safety measures for hand drills :
To work in rubber gloves on a rubber mat.
Check wire;
The brushes must be well ground and do not spark during normal operation.
Safety measures for drilling machines:
Work in overalls with a headgear, fasten the straps and sleeves (hanging parts of clothing and hair can be caught by a spindle or drill)
Do not operate the machine with gloves on.
Check grounding
Check for a fence
Check in idle rotation, axial movement of the spindle and work feed mechanism, fixing the table
Firmly fix the parts and do not hold them with your hands during processing;
Conical drills are mounted directly in the conical bore of the spindle or through adapter conical bushings. They are removed with a wedge through a slot.
Cylindrical in chucks
Do not leave the key in the drill chuck after changing the drill;
Do not take hold of the rotary drill and spindle;
Do not remove the broken drill by hand;
Do not press hard on the feed lever when drilling through workpieces, especially with small diameter drills.
Put a wooden lining on the table under the spindle when changing the drill;
Do not transfer items through a running machine;
Do not lean on the machine while it is in operation.
Do not remove chips from the holes with your fingers and do not blow them off. This should be done with a pen or brush, and only after stopping the machine.
Be sure to stop the machine when changing the drill, cleaning or maintenance.
Need for processing metal products and designs arises in a variety of areas. Locksmiths use a wide range of tools to solve such problems, including all kinds of cutters, drills, hacksaws and abrasive equipment. The initial level is represented by a file, which is also used in household purposes and in specialized workshops. Operations of delicate, soft processing allow you to bring the characteristics of the workpiece as close as possible to the desired indicators. However, in order to realize high-quality filing of metal, it is necessary to responsibly approach the choice of a working tool.
Filing purposes
In the process of performing this kind of processing, the upper layer of the metal surface is removed. Depending on the characteristics of the tool used, this layer can be from one to several millimeters. As a rule, plumbing in this direction helps to form the optimal qualities of the workpiece for its subsequent use in structures or as an independent object. The workflow allows you to give the product certain form, dimensions, as well as provide a curved or straight surface for the purpose of subsequent fitting to a part or structure.
The scope of work may be different depending on the application of the end object. For example, for small elements, vise and abrasive tools are used with minimal mechanical action. Conversely, large metal blanks can be serviced directly at the place of their assembly and even operation.
File device
file by appearance is a small bar provided with small teeth. Notches are made according to different schemes and differ in size. So, single ones are located at an angle of about 80 ° relative to the edge of the tool. A double notch is also used. In this case, an angle of 55° is provided at the bottom and 70° at the top. The teeth determine the effectiveness of the abrasive action that a particular file provides. GOST under the number 1465-80 also provides that the base should be made of tool steel grade U13. In addition to the working part, the file has a shank that can act as a handle. But there are also models in which the entire metal surface is represented by jagged notches.
Varieties of files
Files are divided according to many parameters, including length, shape, number of notches per 1 cm, etc. So, there are bastard models that have large teeth on the surface. Accordingly, such a tool is suitable for performing rough machining of parts. The opposite of bastard models are velvet files, which are distinguished by a fine notch. If accurate supply of workpieces is required for the point introduction of the element into the mechanism, then fine teeth are used. There are tools and types of surfaces. In particular, a flat file can be called the basic model, although the range of tasks it solves is significantly limited. The manufacturing technology of such models is the simplest, which is due to their low price and widespread. However, a spherical file, also presented in different variations, is considered more technological and versatile in application. For example, there are round, semicircular, diamond-shaped and rectangular versions.
Requirements for the manufacture of files
Regardless of the device and the configuration of the location of the faces, there are General requirements to files. quality tool must have sufficient hardness and sharpness of the cuts to provide optimum adhesion to the base plate. There are also regulations governing the layout of the notches themselves. Special requirements apply to narrow files. GOST 1465-80 prescribes to make it in such a way that a single notch has an angle of 65 °. In this case, the number of teeth on the narrow sides should correspond to the number of base notches located on the wide sides.
The large narrow side of hacksaw files is provided with notches only in parallel sections. Individual Requirements touch the round tool. Semicircular models must be made with cut teeth, although there are exceptions when traditional notching is used for this type.
The working process
First of all, the conditions for the technical implementation of the event are being prepared. The main requirement for its organization is the reliable fixation of the workpiece. Most often, a vice is used for this purpose, which makes it possible to give the element a stable position. Work begins with a preliminary cleaning. If there are traces of rust or scale on the surface of the material, they are eliminated with a bastard file. That is, in this part, rough filing of metal is used, in which it is desirable to use old tool, because working with problematic surfaces quickly wears out files.
Next, you can start roughing. Depending on the state of the workpiece at this moment, a more efficient and accurate tool in processing is selected. At the same time, it is worth taking care of the vise, which may suffer during the filing process. Sponges can be protected with special pads made of brass, copper or aluminum. The choice of material also depends on the nature of the processing - the more intense and rough it is, the harder the overlay should be.
The vise is installed so that their jaws are at elbow level. During filing, you should stand half-turned to the equipment - at a distance of about 20 cm from the edge of the table. The body is held straight, but rotated by 45° relative to the longitudinal axis of the vise. The optimal position of the legs is shoulder width apart, while left leg can be turned out in the direction of tool movement forward. This position provides the most stable position of the body, which allows you to perform free filing of metal even with a slight tilt of the body forward to control the quality of work. During the operation, the file is held right hand so that the head of the pen rests on the palm.
Mechanization of filing
Recently, many representatives of the traditional hand tool successfully entered the form electrical devices with higher technical and operational performance. Plumbing was also modernized, as a result of which the craftsmen acquired pneumatic devices for filing metal. The whole concept manual processing was saved, however, the force effect is provided by the electric motor. Nozzles with abrasive surfaces also act as working elements.
In addition to pneumatic tools, cordless and networked devices are also widely used. For example, a band file is equipped with cutting blades, effectively performing accurate and point finishing of various metal surfaces. The advantages of mechanized devices include the quality of processing, high speed and process safety. However, high precision when servicing complex-shaped workpieces is still achieved only when traditional files are used.
Checking the quality of work
The correctness of the processing performed is evaluated using a ruler or square. Thus, the controlling master checks for gaps. This control option is used if the goal was to obtain a flat and clean surface. If the filing of the metal was carried out for the subsequent integration of the element into the structure with grooves, then the quality of the work can be assessed by comparing the parameters in a natural way.
Conclusion
In a wide range of cutting tools, a file is one of the safest. Nevertheless, in working with it, one should not forget about some rules that will prevent unpleasant consequences. So, it should be performed only under the condition of a stable position of the workpiece. The absence of swings will favorably affect both safety and the quality of work. Also, during processing, do not remove chips with your hands. To do this, use special brushes or industrial vacuum cleaners. By the way, electric belt and pneumatic tools, depending on the modification, may provide for the possibility of additional equipment with dust removal systems.
Filing is a locksmith operation in which thin layers of material are removed from the surface of the workpiece using a file.
A file is a multi-blade cutting tool that provides relatively high accuracy and low roughness of the workpiece (part) surface to be machined. The material for files of all types is carbon tool steel, starting with grades U7 or U7A and ending with grades U13 or U13A.
By filing, they give the parts the required shape and dimensions, fit the parts to each other during assembly, and perform other work. With the help of files, planes, curved surfaces, grooves, grooves, holes are processed various shapes, surfaces located at different angles, etc.
In order to make it more convenient to hold the files during work, a wooden handle (handle) made of maple, ash, birch, linden or pressed paper is placed on its shank; the latter are better, since they do not split.
Sawing allowances are left small - from 0.5 to 0.025 mm. The error during processing can be from 0.2 to 0.05 mm and in some cases up to 0.005 mm.
A file is a steel bar of a certain profile and length, on the surface of which there is a notch (cutting). The notch forms small and sharply sharpened teeth, having a wedge shape in cross section. For knurled files, the cutting angle is usually 70°, rake angle(y) - up to 16°, rear angle (a) - from 32 to 40°.
Depending on the size of the notches and the step between them, all files are divided into six numbers:
For precise special work, files with a very fine notch are used - needle files. With their help, they perform patterning, engraving, jewelry work, cleaning in hard-to-reach places of matrices, small holes, profile sections of the product, etc.
The quality of sawing is controlled by the most various tools. The correctness of the sawn plane is checked with a straightedge "in the light". If a flat surface is to be filed particularly accurately, it is checked with surface plate"for paint". In the event that the plane must be sawn at a certain angle to another adjacent plane, control is carried out using a square or goniometer. To check the parallelism of two planes, use a caliper or caliper.
Locksmith squares
The distance between parallel planes in any place must be the same.
Control of curvilinear machined surfaces is carried out along marking lines or using special templates.
A file is a very fragile tool and deteriorates quickly if handled carelessly. One of the main conditions when working with a file is proper care of it. The smallest chips (sawdust), cut off by the teeth of the file, get stuck in the recesses, as a result of which the file begins to slide over the surface to be treated and stops removing chips, as they say, “does not take”. To restore its performance, it is necessary to remove all stuck metal particles, i.e., clean the teeth of the file.
To clean bastard files with a large notch, a specially sharpened soft iron spatula is used, and hard brushes made of steel wire are used to clean personal and velvet files. Cleaning is carried out only in the direction of the upper notch, since otherwise the teeth of the file will become blunt as a result of exposure to a hard wire brush.
Safety precautions when filing metal:
1. Check the serviceability of the handles mounted on the files; it is not allowed to use a file without handles, with ill-fitting or cracked and split handles. 2. It is necessary to properly fit the handle to avoid injuring the palm of the file shank.
3. Borrow the right working position behind the vise when filing.
4. Follow the correct grip of the file. The fingers of the left hand should be half-bent, not tucked in, otherwise, when the file is reversed, they can be easily injured on the sharp edges1 of the sawn products.
5. Metal shavings and sawdust from the surface of the product or vise must not be removed by hand or blown off by mouth. When blowing sawdust with your mouth, you can easily clog your eyes, pollute your hair. Sawdust and shavings should be swept away with a hair brush.
6. When filing products, especially from cast iron, it is recommended to cover your head from metal dust and sawdust; it is convenient to work, for example, in berets. Girls must wear kerchiefs, as shavings are more easily clogged in long hair.
Improving conditions and increasing labor productivity when filing metal is achieved through the use of mechanized (electric and pneumatic) files.
Filing is an operation for processing metals and other materials by removing a small layer with files manually or on filing machines.
With the help of a file, a mechanic gives the parts the required shape and dimensions, fits the parts to each other, prepares the edges of the parts for welding, and performs other work.
With the help of files, planes, curved surfaces, grooves, grooves, holes of any shape, surfaces located at different angles, etc. etc. Sawing allowances are left small - from 0.5 to 0.025 mm. The accuracy of filing processing is from 0.2 to 0.05 mm, in some cases up to 0.001 mm.
Manual filing has now been largely replaced by filing special machines but completely manual filing these machines cannot be forced out, since fitting work during assembly and installation of equipment often has to be done manually.
A file (Fig. 134) is a steel bar of a certain profile and length, on the surface of which there are notches (cuts) that form depressions and sharpened teeth (teeth) that have a wedge shape in cross section. Files are made of steel U13 or U13A (alloyed chromium steel ШХ15 or 13Х is allowed), after notching they are subjected to heat treatment.
Files are subdivided: by the size of the notch, by the shape of the notch, by the length and shape of the bar, by purpose.
Types and main elements of notches. 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- milling cutters grinding machines- special grinding wheels, as well as by rolling, pulling on broaching machines - broaches and gear-cutting machines. Each of these methods incised its own tooth profile. However, regardless of the method of obtaining a notch, each tooth has a back angle a, a sharpening angle p, a front angle y and a cutting angle 5 (Fig. 135).
Files with knurled teeth (Fig. 135, a) with a negative rake angle (γ from -12 to -15 °) and a relatively large back angle (α from 35 to 40 °) provide sufficient space for chip placement. The resulting taper angle β = 62 (up to 67°) ensures the strength of the tooth.
Files with milled or ground teeth (Fig. 135, b) have a positive rake angle γ = 2 (up to 10 °). They have a cutting angle less than 90° and, therefore, less cutting force. The high cost of milling and grinding limits the use of these files.
For files with teeth obtained by pulling (Fig. 135, c), γ \u003d - 5 °, β \u003d 55 °, α \u003d 40 °, δ \u003d 95 °.
The outstretched tooth has a cavity with a flat bottom. These teeth cut into the metal being processed better, which significantly increases labor productivity. In addition, files with such teeth are more resistant, since the teeth do not become clogged with chips.
The fewer notches per 1 cm of file length, the larger the tooth. There are files with a single, i.e., a simple notch (Fig. 136, a), with a double, or cross (Fig. 136, b), point, i.e. with a rasp (Fig. 136, c), and arc (Fig. 136, d).
Single cut files can cut wide chips, equal to the length the entire notch. They are used when filing soft metals (brass, zinc, babbitt, lead, aluminum, bronze, copper, etc.) with low cutting resistance, as well as non-metallic materials. In addition, these files are used for sharpening saw blades, as well as for processing wood and cork. A single notch is applied at an angle λ = 25° to the file axis.
Files with a double (i.e., cross) notch are used for filing steel, cast iron and other hard materials with high cutting resistance. In files with a double notch, the lower one is first cut - a deep notch, called the main one, and on top of it - the upper, shallow notch, called the auxiliary one; she cuts the main notch into a large number of individual teeth.
The cross cut cuts the chips more, making the job easier. The main notch is made at an angle λ = 25°, and the auxiliary one is made at an angle ω = 45°.
The distance between adjacent notch teeth is called step S. The step of the main notch is greater than the step of the auxiliary one. As a result, the teeth are located one after another in a straight line, making an angle of 5 ° with the axis of the file, and when it moves, the tooth 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 work very soft metals and non-metallic materials(leather, rubber, etc.).
The arc notch is obtained by milling. The cut has large tooth gaps and an arc shape for high performance and higher quality processed surfaces. These files are used in the processing of soft metals (copper, duralumin, etc.).
To Category:
filing metal
Bench filing
Filing is a method of dimensional processing of workpieces with a file. Sawing is intended to obtain the required shape, size, roughness and surface location. Sawing such surfaces of workpieces, the processing of which on machines is technically impossible or economically impractical (working cavities of dies, molds, etc.). Filing is also used to fit the mating surfaces of parts at the assembly site of the product.
Types of sawing. Sawing can be done by hand or by machine. Sawing to improve surface finish is sometimes referred to as deburring.
Filing is based on the destruction of the surface layer of the workpiece material by the cutting elements of the tool (file), made in the form of a wedge. Each cutting wedge cuts a layer of material from the workpiece and converts it into chips, which are placed in the chip space.
Rice. 1. Cutting elements of various types of files: a - filing process, b, c; g - double, single and dotted (rasp) notches, respectively; 1 - file, 2 - workpiece, 3 - auxiliary notch, 4 - main notch, 5 - cutting edge; y - rake angle, a - back angle, fi - taper angle, 6 - cutting angle
When filing, the file is moved manually forward (away from you) at the speed Tsr.x. working stroke and back (toward yourself) with a speed of v0.x. reverse motion (Fig. 1, a). Horizontal force is applied both during working and idle strokes, and vertical (with two hands) - only during working strokes. To ensure that the file is always parallel to the surface being processed, at the beginning of the working stroke, the file is pressed harder with the left hand, and as it moves, the pressure with the left hand is reduced, and with the right hand it is increased.
Cutting tool for filing. A file is a multi-blade cutting tool whose teeth are located on the surfaces of hardened steel bars with different cross-sectional profiles and lengths. The file has a working part and a shank. The drawn part is called the toe. On the working part, a narrow side, a wide side and a rib are distinguished.
File teeth are obtained by notching, milling; grinding and other technological methods. The most widespread is the notching of teeth on notching machines with special chisels. The cut teeth are more durable.
Files are made with different lengths and shapes. cutting edges. A short edge in the form of an irregular triangle is obtained with a double notch, a long (straight or radius) edge with a single notch. A short edge is also obtained with a rasp (point) notch.
Locksmith's files general purpose usually have a double notch - the main one (at an angle of 65 °) and the auxiliary one (at an angle of 45 °). The latter divides the main notch into numerous teeth, which allows, with the same expenditure of forces, to increase the amount of chips removed.
Rice. 2. Rod file (a) and burr (b): 1 - toe, 2 - working part, 3 - shank, 4 - shoulder
The step of the main and auxiliary notches is made different. As a result, each subsequent tooth is displaced relative to the previous one in a direction perpendicular to the file axis. Without such a displacement, each subsequent tooth would follow strictly the previous one and grooves would form on the machined surface. Overlapping of the teeth ensures low surface roughness.
The size of the chip space has big influence on the quality and productivity of filing. The volume of the chip space is determined by the notch pitch, i.e. the number of main notches over a length of 10 mm. This number is determined by the notch number. General purpose locksmith's files have six cut numbers ranging from zero (largest pitch) to 5 (smallest pitch).
According to the cross-sectional shape, general-purpose files are: flat, flat pointed, square, trihedral, round, semicircular, rhombic and hacksaw. General purpose files are made in length 100; 125; 150; 200; 250; 300; 350 and 400 mm.
Files of small sizes are called needle files. The produced needle files have ten notch numbers: 00; 0; one; 2; 3; 4; 5; 6; 7 and 8. The cross-sectional shapes of the needle files are the same as for general purpose files. In addition, trihedral unilateral, oval and grooved needle files are produced. Each type of needle file is produced in three sizes. The total length is respectively 100; 120 and 160 mm; the length of the working part, respectively, 50; 60 and 80 mm.
General purpose locksmith files and needle files are made from steels U12, U12A, U13 and U13A. It is allowed to manufacture files from steels 13X and SHKH15. The files are hardened to a hardness of 54 HRQ.
Files for difficult-to-cut materials are made from 14HF and 13X steels, as well as from high-speed steel. They differ from general purpose files in the number and angle of cuts. Their wide surfaces have a radius shape, due to which fewer teeth are involved in the work at the same time.
In machine filing, core files and burrs are used. The core file, unlike the bench file, has a shank with which it is attached to the machine. When filing dies and molds, end and extension burrs (diameter 3 - 32 mm) of cylindrical, angular, disk and other shapes are widely used. Burr cutters are made of high speed steel or U12A tool steel and hardened to a hardness of 66 HRC s. Burrs are made with extra large, large, medium, small and extra small teeth.
Equipment and devices for sawing. Filing by hand is usually done at a locksmith's workbench. The workpiece is placed in a bench vise equipped with aluminum or copper tips and wooden spacers protecting treated surfaces from damage.
Processing the workpiece with burrs is performed using electrical machine with flexible shaft. Filing with core files is carried out on stationary filing machines. The use of devices such as copiers makes it possible to increase the productivity of filing, since in the process of work it is not necessary to control the deviation of the shape and location of the surfaces to be processed.
The sequence and methods of performing work when filing. The surface of the workpiece is cleaned of dirt, oil and scale. The hard surface crust of castings and forgings is previously removed with an old file or chisel. Then the workpiece is marked.
When choosing a file, it is necessary to take into account the physical and mechanical properties of the material being machined, the dimensions, the shape of the machined surface and its location relative to other surfaces of the workpiece, the size of the machining allowance, the required accuracy and surface roughness.
Flat and flat pointed files are used for processing flat and convex surfaces, grooves. Square and rectangular slots and the holes are filed with square files. Triangular files are useful for processing sharp corners in grooves, as well as triangular and polygonal holes. Round and oval holes, concave surfaces are filed with round files; concave and flat - semicircular; narrow shaped surfaces, slots and grooves - rhombic.
The length of the file is recommended to be chosen 150-200 mm longer than the length of the surface to be filed. Needle files are used for very precise processing of small surfaces and hard materials. Rough filing soft materials, plastics and wood it is rational to carry out rasps.
Filing is carried out sequentially with each type of file (starting with the coarsest and ending with the most accurate). The workpiece is placed in a vice so that the marking mark is clearly visible, and the sawn surface is horizontal.
To increase the productivity and quality of processing, cross filing is used: first, the entire surface is filed with an oblique stroke from left to right; then - with a direct stroke; then - with an oblique stroke from right to left.
As a result of improper use, files lose their cutting properties. If oil gets on the working part of the file or chips clog its depressions, then it becomes unsuitable for work. Greasy files are cleaned with a hard piece charcoal. The file is cleaned of chips with a pointed spatula made of soft iron (or brass) and a steel stiff brush. Cleaning is carried out in the direction of the upper notch. Before filing aluminum alloys the file should be rubbed with stearin to reduce clogging.
When filing, control the roughness, shape, size and location of the surface. Roughness, as a rule, is controlled by reference samples. Deviation from flatness (the most common type of marriage when filing) is controlled by a straightedge (through the light). Mutual arrangement surfaces are controlled by squares, templates and goniometers; linear dimensions are checked with calipers.