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- incisors
- dolbyakov
Proper sharpening of a tool reduces its consumption and accordingly increases its service life. Therefore, it is necessary to carefully monitor the condition of the cutting edges and sharpen the tool in a timely manner, avoiding excessive wear and especially breakage.
Sharpening and manufacturing of hobs
The production complex of the Spetsstanmash plant offers a full range of services for the manufacture and repair of metal parts and structures, including: production and sharpening of cutters for metal, wood, cast iron, aluminum, graphite or plastic.
The cutter is important tool in industry and workshops. It is a part of different shapes, with distinctive feature sharp teeth. Its main function is the mechanical processing of harvested material.
The operating principle of milling is the translational rotational movement of the cutter teeth.
Depending on the type of tool used, the result is:
- small grooves or grooves when using end mills;
- milling large surfaces;
- milling baguettes, window frames, gears, etc. using spiral cutters,
- cutting using a disc cutter (plinth, paneling, lining, wall beams, etc.).
An important characteristic of a cutter is the material it is made of, in particular the cutting part. These can be teeth made of high-speed steel, mineral-ceramic, metal-ceramic or diamond.
Diamond cutters are considered the most durable due to their natural physical characteristics. But, they are the most expensive. All other materials become dull after some time during use, especially if used incorrectly. Buying new tools is expensive, but our qualified craftsmen and high-precision modern equipment allow us to perform such types of repairs as sharpening knives for cutters of any geometry:
- hob sharpening
- sharpening of disc cutters
- core cutters and other types.
Professional work on sharpening cutters increases the durability of the part and significantly reduces the consumption of cutting teeth.
Sharpening hob cutters: from 600 rub. / PC. (depending on wear)
Minimum sharpening time: from 10 working days
Minimum order amount: 3500 rub.
* The exact cost can be found using the form or by phone
2016-11-04
Sharpening cutters - hard work , requiring special training and equipment. The geometry of the cutting edges has a curved structure - this is what main feature process. The grinding wheel must follow exactly the contour of the sharp teeth of the cutter to maintain its shaped profile.
- The backed teeth are sharpened along the front surface.
- Sharply protruding cloves are processed along the back wall.
- Slotting and parting cutters are sharpened on the front and back sides.
How to sharpen cutters?
You can sharpen it by hand or using a router bit sharpener.
Rice. 1 .
The machine ensures synchronization different types movement and fixation of the cutter. For example, to sharpen an end mill, it is necessary to combine translational and rotational movements while maintaining uniform pressure on the tool against the grinding wheel. Great importance has a rotation speed, abrasive grain size, and its material.
- Abrasive wheels made of electrocorundum are suitable for sharpening cutters for metal and wood (manufactured material is high-speed or tool steel of the “Standard” class).
- High-performance high-speed steel cutters are sharpened with CBN wheels.
- Diamond (PCD) and silicon carbide wheels are used to sharpen the teeth of carbide cutters.
It is important to consider that strong heating reduces the hardness of abrasives and leads to a partial loss of cutting properties. Below is a table of the thermal stability of the main materials used for the production of abrasive wheels.
Rice. 2.
To cool the sharpening tool during operation, water alone will not be enough - the machine will rust. Experts advise adding soap to water and soda ash, nitrite, sodium silicate, etc. — electrolytes create a protective film on the surface of the grinding wheel.
There are more than 20 grinding wheel configurations for sharpening milling tools. The back planes of the incisors are ground with disk-shaped or cup-shaped wheels, the front ones - flat or disk-shaped.
Rice. 2.1
Automated sharpening modes
You cannot sharpen carbide tools in “hard” operating modes of the machine - the edges of the teeth may become chipped.
The average peripheral speed of a grinding wheel for processing hard alloys should not exceed 10 - 18 m/sec. This means that for a circle d 125 mm 2700 rpm is the maximum engine rotation rate. For softer materials, it is enough not to cross the threshold of 1500 rpm.
Technology for sharpening cutters on a machine
The cutter is fixed in its original position, then the machine is turned on and the tool is slowly brought to the grinding wheel (until it sparks). The moment comes to set the thickness of the metal layer to be removed, usually no higher than 50 microns and no less than 25 microns.
Sharpening is done on each tooth separately. The machine needle must constantly be in contact with the surface of the cutter; sharpening begins by placing the needle in the tail groove of the tooth. The machine is turned on and, gradually retracting the spindle with the cutter, the procedure is performed.
The skill of a professional is to maintain a uniform sharpening stroke on all cutting edges. The same movements will need to be repeated several times for each tooth.
Different types of cutters require different movements
How to sharpen a cutter by hand?
A shaped end mill for tough materials (wood) can be sharpened by hand without resorting to expensive equipment. You will need:
- desktop and bar made of steel or hardwood;
- diamond block;
- abrasive wheel;
- solvent;
- water with soap or lye;
- sandpaper.
Rice. 3.
The diamond bar is fixed on the edge of the table, wetted soap solution. The cutter must be freed from the bearing (if there is one) and cleaned of any remaining wood resin. The size of the rake sharpening angle varies in the range:
- 10 - 20 ⁰ for wood cutters;
- - 5 - 0⁰ for tools for metals (mainly for steels).
The range of the sharpening angle of the back surface is wide and is not limited by the indicators.
Sharpening is done with smooth movements along the diamond stone.
You need to try to make the same number of movements of the cutter on the block with the same pressure force. As the cutting edges become sharper, the grain size of the abrasive decreases; the final stage of processing can be carried out with sandpaper.
The sharpening result is assessed visually using a magnifying glass or kerosene. The teeth should not contain even small nicks or cracks. To detect microcracks, the surface cutting edge moistened with kerosene - in the area of the crack the kerosene will appear more strongly. Notches and microchips are determined by eye or through a magnifying glass.
If you manage to obtain the proper quality and know how to use the tool carefully, then the need for sharpening comes much later than in cases with low-quality products. Big choice high-quality cutters (about 20 types) are always available in the Rincom store. It is convenient to select and order tools of the widest profile on the Internet; today it is not dangerous and modern.
Cutting tools sooner or later become dull. If it is disposable, then there is only one way out - to the landfill. But the cutting edge of expensive devices can most often be restored. in this article we will tell you how to give them a “second youth”.
Different cutting tools require a differentiated approach when sharpening. Today we will talk about restoring chisels, planes, wood cutters and metal drills.
Sharpening chisels and planes
Getting a chisel or plane knife into working condition is not that difficult. The procedure for sharpening them consists of only two stages. When working on sharpening a tool, you will need a regular grinder. A chisel or plane knife for soft wood is sharpened at an angle of 250°. For hard rocks– 350°. When sharpening, you should constantly hold specified angle, which is not so simple. The task can be simplified by special devices for sharpening chisels, allowing you to work in the range from 25 to 35°. To avoid overheating, periodically cool the instrument in water.
You should not immediately grind off the edge of the iron until the cutting part appears. When bringing its thickness to half a millimeter with a square, check that the axis is perpendicular to the cutting edge. Final sharpening is best done by hand or on a low-speed water-cooled sharpener, bringing the tool to the required cutting edge sharpness.
When sharpening a round chisel with an outer edge, the tool moves along the block from edge to edge along the entire length of the stone, describing a “figure eight”. Burr with inside The groove, which is necessarily formed during sharpening, is removed using a shaped sharpening stone. The final sharpening of the cutting edge is carried out sandpaper varying degrees of grain size.
Sharpening wood cutters
To sharpen shaped end mills, it is not necessary to have special tools. It is enough to have a diamond block placed on the edge of a table or workbench. The cutter is sharpened by running its front surface along the block, previously cleaned of resin residues, dirt and dust using a solvent.
If there is a guide bearing, it must be removed before sharpening. An attempt to save a couple of minutes will result, if not in its deformation, but quite possibly in a damaged cutter. During the sharpening process, the block is slightly moistened with water, and after finishing the work it is wiped dry. As the front surface grinds down, the edge of the cutter will become sharper and its diameter will decrease slightly.
When sharpening a tool, you should use whetstones of different grain sizes, depending on the desired end result and the cleanliness of the surface being processed. When sharpening incisors, to maintain symmetry, multiple movements are made with equal pressure. Depending on the material from which the cutter is made, abrasive paper mounted on a strip of steel or a wooden strip can be used instead of a block.
If you have a sharpening machine with a low rotation speed, then installing an appropriate abrasive wheel can reduce manual labor to nothing.
Sharpening a drill for metal
Over time, drills become dull and many people simply throw them away and buy new ones. However, you can almost always give a drill a “second chance” and extend its service life. To do this, it is enough to process the dull surface on a grinding wheel.
Before starting work, stock up on a container of water into which the drill will be dipped from time to time to avoid overheating. Sharpening is carried out sequentially and begins with processing the back surface, gently but firmly pressed against the surface of the grinding wheel until the correct cone is formed.
After this, its cutting part is sharpened and the final finishing of the rear surface is carried out. During sharpening, you must constantly monitor the jumper on the tip of the drill. For drills with a diameter of 8 mm or less, it should not exceed a size of 0.4 mm. For large samples, the size of the jumper varies from 1-1.5 mm. Keep in mind that it is not the tip that does the drilling, but the side blades of the drill!
Electric sharpener
Structurally, electric sharpeners are extremely simple.
They consist of asynchronous motor, grinding wheels and covers. Shifting the conversation to the plane of choosing a specific manufacturer and model, it should be noted that if you are planning to buy a device for personal purposes, then the brand is not decisive. Such equipment is connected to the network for a short time and has a fairly large resource. The price of a sharpener directly depends on its diameter.
The larger it is, the more expensive the device. When inspecting the electric sharpener before purchasing, try moving the shaft. If it not only rotates, but also “walks,” discard it and choose further. Of course, it is best to plug the sharpener into the network, but not every store will accommodate you in this matter.
Electric sharpeners or sharpening machines are divided into three groups:
- High-speed sharpeners equipped with replaceable holders for various types tool.
- Highly specialized machines designed for a specific tool (for example, drills).
- Low speed water cooled machines.
If high-speed sharpeners spin up to 3000 rpm, then such machines rotate at a maximum of 150 rpm and can sharpen any cutting tool. Low speed and water cooling – ideal conditions for a quality cutting edge.
Milling cutter sharpening operations maintain the technical and physical characteristics of parts, thereby extending their working life. There are many approaches to performing such activities, the choice among which is determined by the nature of operation and the design of the element. The wear rate of a cutter largely depends on its design, based on which the technician selects maintenance regimes.
For example, the selection of a method for regrinding high-speed parts is based on the wear of the front surface. On the other hand, flank sharpening of cutters is more suitable for shaped elements. Therefore, it is important to take into account as many operational factors as possible, which will allow you to make the right choice of processing technology.
Types of cutters
Such elements are widely used in the processing of parts on copying, moulding, tenoning, milling and other machines. As a rule, this is woodworking equipment, although there are also parts for working with metal workpieces. Milling cutters vary in size, shape and purpose.
In general, there are two categories of elements - end and mounted. The first ones are distinguished by the presence of a shank, which is fixed in a special spindle niche. Products of the second group have a central hole, which allows them to be mounted on the working spindle and securely fixed. Accordingly, such sharpening of cutters differs more high level quality, not to mention ease of handling of parts for the operator. Attachment elements can be composite, solid or prefabricated.
A special feature of this group is the possibility of forming cutting tool from several milling parts. It is also worth noting the category of end mills, which can be prefabricated or solid. Elements are also divided according to the quality of the backed processing. Thus, sharpening of cutters with backed surfaces is carried out along the front edge in order to maintain the basic angular parameters.
Milling cutter maintenance
Despite the use of high-strength alloys in the manufacture of cutters, long time operation leads to abrasion and deformation of the edges. Over time, worn-out elements are disposed of, but before the working life expires, the master can restore the characteristics of the part with the help of measures Maintenance. It is important to consider that sharpening cutters allows not only to give them the same geometry, which ensures quality work. This procedure also increases the durability of the element, reducing tool consumption. But this does not mean that any cutter can be restored in this way.
Technologists do not recommend bringing the tool to a state of complete wear. Manufacturers of cutters indicate in the markings technical and operational values that are limiting for a specific element, and after they are overcome, the cutting edges cannot be restored.
sharpening process
To perform sharpening, special milling machines, equipped with spindles with an average rotation speed of up to 24,000 rpm. Before starting work on them, the master balances the cutters. It can be carried out in two ways - dynamic and static. In the first case, the procedure is performed on a special machine, which provides not only balancing of the force, but also the moment acting on the cutter during rotation. This technique is especially relevant for cases when sharpening a cutter for metal.
Balancing machines using the static method only involves balancing the force acting on the cutter. The element is fixed in the frame, after which it is balanced through a device consisting of two horizontal guide knives. Direct sharpening is carried out on special high-precision equipment.
The machines are produced in different configurations, involving both manual and automatic control. Common to all units of this type is the presence of a working surface on the guides. This design solution makes it possible to achieve high accuracy of element movement, usually with an error of 0.005 mm.
equipment requirements
To ensure high-quality sharpening of cutters, you should not only use equipment suitable for this task, but also prepare it correctly. First of all, equipment spindles must have sufficient vibration resistance, rotate freely and have minimal runout. Next, the feed mechanism must operate stably in all directions provided for by the design without delays and with minimal gaps. The elevation angle settings are of great importance - this parameter should also include high accuracy. For example, sharpening a hob cutter, which is performed on automatic machines, requires setting both a certain helix angle and a helical groove pitch. If grinding wheels are used, it is important to ensure a reliable fit of the replaceable washers and spindles, due to which the working element is accurately seated.
End mill machining
Processing of end elements is most often done manually using universal sharpening equipment. Typically, this technique is used to update the performance of a helical tooth tool. In many ways, sharpening end mills resembles a similar update cylindrical cutters using a cup circle. This applies to operations that require the end mill to be centered seat. Also, similar sharpening is performed on semi-automatic models. In this case, they can be serviced end mills diameter from 14 to 50 mm. In this case, the treatment is suitable for both the back and front surfaces.
Sharpening end mills
Mills made of and some elements equipped with carbide plates are sharpened in assembled form. The main flank surface of the end mill is sharpened with a grinding cup wheel. Before performing the same operation on the plane of the auxiliary rear side, the element is first installed so that its cutting edge is in a horizontal position. After this, the cutter axis rotates horizontally and at the same time tilts in the vertical plane. Unlike the scheme for sharpening end mills, in this case the position of the workpiece is changed several times. Work with the front surface of the tooth can be carried out with the end part of a grinding disc wheel or with a disk wheel from the peripheral side.
Working with disc cutters
On the rear main surface, the processing of the disk elements is carried out using a cup circle. The auxiliary back surface is made by analogy with end mills, that is, by turning the cutting edges horizontally. At the same time, the peculiarities of processing the end teeth of such a tool are noted. In this case, sharpening of disk cutters is performed along the front surface so that the teeth being processed are directed upward. The cutter itself at this moment should occupy a vertical position. The vertical inclination angle of the element axis must correspond to the position of the main cutting edge.
Features of sharpening wood cutters
End shaped parts are sharpened without special tools, usually using a thin diamond whetstone. This element either rests on the edge of the work table, or, if the cutter has a deep recess, it is fixed additional tool. The cutter is inserted along a fixed block. During processing, the block is periodically moistened with water. When the procedure is completed, the master thoroughly washes and dries the product. As the front surfaces grind down, the edge becomes sharper, but the diameter of the tool decreases. If the cutter has a guide bearing, it must first be removed and then the operation can be continued. The fact is that sharpening a wood cutter together with a ruined bearing can lead to damage to the element. It is also necessary to clean the tool from any remaining wood resins using a special solvent.
Features of sharpening cutters for metal
Such elements are less common and at the same time require less effort in preparation. Processing is done using grinding wheels suitable grain size. The materials may be different, in particular, it is common to use parts made of ordinary or white electrocorundum. If you plan to sharpen end mills for metal made from tool steel, then it is recommended to choose electrocorundum discs. For products with more high performance It is advisable to use CBN wheels. The most productive and efficient sharpening parts are made of silicon carbide. They are used to service cutters made of hard alloys. Before work, the abrasive is cooled, since high temperature loads during the operation can negatively affect the structure of the wheel.
Processing of backed cutters
Relief elements are used in cases where it is necessary to increase the stability of the cutting part and reduce surface roughness. The teeth of the backed cutter are processed along the front surface in such a way that after regrinding in the radial section, the profile of the functional edge retains its original parameters until the part is fully used. Sharpening of such cutters is also carried out in compliance with a strictly established rake angle. When processing sharpened elements, it is necessary to maintain a constant sharpening angle.
Finishing of cutters
In essence, this is an operation designed to correct the result obtained during the main sharpening process. As a rule, fine-tuning is carried out in order to ensure optimal performance roughness or in cases where it is necessary to adjust the sharpening angle of the cutter with the working edges. Abrasive and diamond finishing techniques are quite common. In the first case, it is assumed that fine-grained wheels made of silicon carbide will be used, and in the second case, diamond discs on a bakelite bond will be used. Both techniques allow you to handle, among other things, carbide tools.
Sharpening quality control
During the inspection process, the master evaluates the geometric parameters of the cutting surfaces for compliance technical requirements. In particular, the runout of the cutter is determined, as well as the degree of roughness of the finished or sharpened planes. Auxiliary devices can be used to control parameters directly at the workplace. For example, if you sharpened an end mill according to wood material, then the specialist can measure the angles along the working edges. For this purpose, a protractor is used, the scale of which is presented in the shape of an arc. Special ones are also used to evaluate other parameters; again, most of them are focused on checking the geometric data of the cutter.
Conclusion
The need for machining of cutting tools continues even in the century high technology. The only change in this regard has been with the milling equipment control systems. Appeared automatic devices, allowing you to optimize the process of handling workpieces. However, cutters, bits and other processing metal elements still done with abrasives. Of course there is also alternative technologies, allowing you to restore the geometry of parts, but there is no talk of their widespread use yet. This applies to laser technologies, hydrodynamic machines, as well as installations that have a thermal effect. At this stage of their development, for economic reasons, many enterprises still give preference traditional methods sharpening.
Today there is enough production a large number of cutters of various sizes. They can be classified according to functional and design qualities.
Sharpening of end mills is carried out using special devices for such tools. In some cases, sharpening can be done manually.
The cutters have a relatively large length and uneven teeth for cutting. During the sharpening process, you will need to take care of the movement of the base of the wheel along the edge. In this case, you will need to sharpen shaped cutters that have a backed corner. You should know that sharpening is quite difficult. To preserve the profile of the structure and facilitate the sharpening process, the backed teeth will need to be sharpened exclusively along the front base. Sharp teeth, which have a straight or curved shape, must be sharpened exclusively along the rear base. Slotting and parting cutters can be sharpened along the front and back bases of the teeth.
Geometry of cutter teeth
Geometry of the cutter teeth: a - sharpened tooth, b - backed tooth.
To sharpen correctly, you will need to know the geometry of the cutter teeth. The design of the teeth distinguishes between cutters with backed and sharp teeth. In the latter, the part of the rear base, which is adjacent to the cutting edge, is a plane. Teeth with sharp ends are in most cases sharpened along the back base, but they can also be sharpened along the front base of the tooth.
The backed teeth that come with the end mills have a back base that follows an Archimedes spiral. It is quite difficult to process a shaped base technologically, so you can sharpen cutters with backed teeth exclusively on the front base.
Regardless of the number of teeth in the cutter, each of them can be considered as a separate tooth, which is characterized by typical parameters for the tooth - the angles of the front and back, the size of the sharpening area, and the angle of inclination of the teeth.
The sharpening platform is an element of the rear base of the tooth, which is subjected to grinding during the sharpening process along the rear base. By this basis maximum tooth wear will occur. Its size affects the magnitude of the friction force between the tool and the workpiece, so the base must be maintained in a specific range.
Scheme for sharpening prefabricated cutters on a universal sharpening machine.
The main rake angle is the angle between the tangent to the front base and the base of the axis. It can be measured in a plane that will pass through a given point perpendicular to the main cutting edge.
The main back angle is the angle between the tangent to the back base at given point the main edge for cutting and the tangent to the plane of rotation of this point. This angle helps reduce friction between the tool and the workpiece.
Using the auxiliary relief angle, you can characterize the large gap between the milled base and the body of the tooth. Sharpen the tool according to additional angle necessary for a specific amount of damage to the tool and an increase in the sharpening area. The purpose of this action is to reduce friction between the tooth and the workpiece being milled. You should be aware that not all tools of this type have this angle.
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How to sharpen end mills for woodworking?
The shape of the teeth can be straight or helical. The inclination of the tool teeth can be characterized as the angle between the developed edge of the screw type and the axial part of the tool.
The values of the tooth angles will depend on the type of tool, the grade of alloy and steel from which it is made, as well as the type of material for which the tool is intended for milling.
When milling viscous materials, the main rake angle should be selected in the range of 15-20° or more. Carbide tools for milling steel will have an angle of 0° or -5°. The clearance angle varies over a wide range.
Items you will need:
- Diamond beam.
- Table.
- Water or soap and water.
- Solvent.
- Abrasive paper.
- Hardwood plank or steel strip.
- Abrasive wheel.
It is possible to sharpen shaped end mills without special sharpening devices, along the front base, with a diamond bar of small thickness. The beam must be installed on the extreme part of the table. If the tool has a large recess, then the tool must be secured along the table.
Heat resistance table various materials, °C.
When sharpening, the beam will need to be wetted clean water or a solution with soap. After sharpening, the tool will need to be washed and dried.
As the front base is sharpened, the edge will become sharper, but the diameter of the tool will not decrease much.
If a bearing is installed on the tool, then the first step is to dismantle it and then sharpen it. An attempt to save time in this case may result in a damaged bearing and a non-functioning cutter.
It is imperative to clean the cutter from excess resin from the trees. It is best to use a solvent for this.
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In the process of sharpening tools, you will need to use bars of different grain sizes. The grain size will depend on the thickness of the layer of material being removed and the required cleanliness of the base. Before sharpening, you will need to make sure that the beam has the appropriate shape.
Figure 1. Shapes of grinding wheels.
If the cutter teeth are made of relatively soft material, instead of timber, you can use abrasive paper, which is glued to level base. As a base, you can use a hardwood plank or a steel strip.
End mills for milling wood are sharpened on a special device with a low rotation speed of the wheel. In this case, you will need to use a suitable abrasive wheel.
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Sharpening wheels
Sharpening of modular cutters can be done with wheels made of white or ordinary electrocorundum, diamond and others. For example, using electrocorundum wheels, you can perform high-quality sharpening of cutters for working with metal and wood, which are made from tool or other steel of standard performance. CBN wheels make it possible to sharpen high-performance steel structures. Silicon carbide and diamond wheels are used for sharpening cutters made of hard metals.
By increasing the temperature, the hardness of such a device decreases. A temperature of 1000°C can reduce the hardness by almost 2 times. At a temperature of 1300°C, this indicator will decrease by about 6 times.
Figure 2. Sharpening the end mill: a - the main cutting edge, b - the auxiliary cutting edge, c - installation diagram of the cutter for sharpening the teeth of the auxiliary cutting edge.
Using water to reduce the temperature in most cases leads to rust on the workpieces and corners of the machine. To eliminate corrosion, you need to add soap and some electrolytes to the water, which can form films for protection. When sanding, a solution with soap or soda is almost always used. If fine grinding is performed, a low-concentration emulsion should be used.
To increase the quality of grinding with an abrasive wheel and reduce significant damage, it is recommended to select the maximum grain size that can provide the required cleanliness class for the base of the cutter used.
The peripheral speed of the wheel when sharpening hard metal teeth should be approximately 15-18 m/s. For example, when using a wheel with a diameter of 12.5 cm, the engine rotation speed should be approximately 1600-2700 rpm. If you need to sharpen more brittle materials, the actions need to be performed at a lower speed. When using hard metal tools, harsh conditions result in high stresses and cracks, and in some cases, damage to the cutting edges. In this case, wheel wear will increase.
The shape of the wheel for sharpening the back angle of teeth on a cylindrical base should be cup or disc-shaped. To sharpen the front corner, you need to use a disc-shaped or flat-shaped wheel.
Existing shapes of grinding wheels can be seen in (Fig. 1).