Cutter types for CNC machines
Continuing the publication of materials from the Bosinzon M textbook.А “Machining of parts on different types and forms of machine tools”. This time we’ll look at the classification of the cutters.
Cutters. are multi-toothed cutting tools used for planes, grooves, profiled surfaces, bodies of rotation, and material cutting. The milling process usually has several teeth in contact with the workpiece, removing chips of varying thickness. In this case thanks to the large total active length of cutting edges the high productivity of milling process is provided which is also promoted by the high speed of milling which is reached at the expense of periodical exit of teeth from a zone of cutting that provides cooling and removal of thermal tension in a cutting wedge.
The kinematics of milling is simple: the mill receives its rotation from the main drive and the workpiece is clamped on the machine table. The feed movement from a separate machine drive is not kinematically related to the rotation of the cutter. It can be straight, rotary or helical, and the cutting edges of the cutter can be straight, tilted to the axis, helical or shaped. This leads to an enormous variety of cutter designs and a wide range of applications.
Cutters can be classified according to the following main features:
According to the design of the cutting teeth and the method of sharpening the cutters
- with pointed teeth;
- with re-sharpenable teeth on the back surface;
- with back teeth that can be resharpened along the leading edge;
Cutters are subdivided according to shape and location of cutting edges in relation to the tool rotation axis:
Cutters are categorized according to the orientation of the teeth in relation to the tool axis:
Cylindrical milling cutters are subdivided according to the way they are mounted on the machine:
- into solid;
- prefabricated with inserted teeth, including those with soldered or mechanically fastened cutting inserts made of carbide or superhard materials (STM).
Fig. 11.1 shows the basic types of milling cutters with different positions of the cutting edges in relation to the tool rotation axis.
11 Cylindrical cutters (Fig. 11.1, а) are used on horizontal milling machines in the processing of planes. They can be made with helical or straight teeth. Helical gear cutters work smoothly and are widely used in the production of. Straight-toothed cutters are only used for cutting narrow planes where the advantages of helical cutters have little effect on the cutting process. Cylindrical cutters are made of high-speed steel and are equipped with carbide flat and helical inserts.
Disc milling cutters (figure. 11.1, б) Available in slotted, tandem and triangular versions, they are used for slot and groove milling. Slot cutters have teeth only on the cylindrical surface and are designed for relatively shallow grooves. Slot cutters are provided with an auxiliary plan angle to reduce face friction. on the order of 30°, t. е. the thickness of the cutter is greater on the periphery than in the center at the hub. an important element of the slot cutter is its thickness, which is performed with a tolerance of 0.04. 0,05 mm. As the teeth are ground, as a result of undercutting, the thickness of the cutter decreases. However, this is of no practical importance, since the magnitude of this reduction is small.
а. cylindrical; б. disk-shaped; в. end faces; d, e. end; f. angular; g. shaped: t. grinding depth; В. grinding width; D ( d ). cutter diameter
Face milling cutters (fig. 11.1, c) are widely used when machining planes on vertical milling machines. Their axis is set perpendicular to the machined plane of the part. In contrast to cylindrical milling cutters, where all points of cutting edges are profiling and form the machined surface, in face milling cutters only the tips of cutting edges of teeth are profiling, and the end cutting edges are auxiliary. Most of the cutting work is done by the side cutting edges on the outer surface.
Face milling cutters provide smooth operation even with low stock removal rates, because the angle of contact with the workpiece is independent of the stock removal rate and defined by the milling width and the cutter diameter. Face milling cutters can be more solid and rigid than cylindrical milling cutters, which makes it possible to place and securely clamp cutting elements and to equip them with carbide. Face milling generally offers greater productivity than cylindrical milling, so nowadays face milling cutters are used for most face milling work on planes.
End mills (fig. 11.1, г, д) are used for machining of deep grooves in housing parts of contour recesses, ledges and mutually perpendicular planes. They are mounted in the machine spindle with a tapered or cylindrical shank. In these cutters, the main cutting work is done by the main cutting edges located on the cylindrical surface, and the auxiliary end cutting edges only clean up the bottom of the groove. End mills are normally constructed with helical or tilted teeth up to 30. 45°. Diameter of end mills should be smaller (up to 0,1 mm) than the width of the slot, because the slot is breaking up during milling. A variation of the end mills is the keyed double tooth milling cutters. Like a drill, they can go deep into the workpiece material during axial infeed movement and drill a hole, and then move along the groove. At the moment of axial feed, the main cutting work is done by the end edges, one of which must reach the axis of the cutter to ensure the drilling of the hole. Resharpening of key cutters is carried out along the rear surfaces of the end edges. The diameter of the cutter remains constant, which is necessary to keep the size of the slot constant.
Face-milling cutters offer high productivity in spite of partially severed teeth.
Angle milling cutters (fig. 11.1, f) are used when milling angular grooves and inclined planes of parts. Single-angle milling cutters have cutting edges located on the tapered surface and face. Double-angle milling cutters have cutting edges that are on two adjacent tapered surfaces. Angle milling cutters are widely used in toolmaking applications for milling grooves in various tools. axial cutting forces occur in the process of single-angle milling cutters, because cutting of metal of the workpiece is mostly carried out by cutting edges located on the tapered surface. But in double-angle milling cutters the axial forces of two adjacent angular tooth edges compensate each other to some extent, and in case of symmetrical double-angle milling cutters they are balanced, so double-angle milling cutters work more smoothly.
T-slots, which are frequently used in machine tool construction, are used for the machining of T-slots T milling cutters. They are subjected to heavy loads and break down frequently because of faulty chip evacuation and chip bundling. Each tooth is processed twice per revolution. To improve chip evacuation such milling cutters are made with differently directed teeth and with undercut angle on the ends equal to φ 1 = 1. 2°.
Shaper cutters (Fig. 11.1, g) are very commonly used on a variety of shaped workpiece surfaces. Advantages of such milling cutters are especially advantageous, when processing workpieces with big ratio of length to width of milled surfaces.
Design features of milling cutters equipped with tungsten carbide. Cutter designs and operating conditions allow for the widespread use of high-performance carbide, mineral-ceramic and STM, which, however, have reduced bending strength and brittleness. The following advantages of the milling process contribute to the widespread use of carbide:
favourable chip shape with low thicknesses and lengths, resulting in good transportability;
interrupted cutting process that reduces thermal stress on the cutting elements;
These properties have made it possible to use indexable inserts (SMI) and the large geometry of the cutter bodies enables the location of the securing elements.
The disadvantages of the milling process include:
high probability of working in uneven milling conditions causing vibrations and oscillations;
cutting with zero chip thickness (in cylindrical milling);
■ difficult chip evacuation with end mills, disc mills, and slot mills;
high manufacturing costs for prefabricated milling cutters with strict requirements for axial and radial runout of cutting edges.
However, as practice has shown, by means of eliminating or minimizing the influence of unfavorable factors on durability and productivity of the milling process, in most designs of milling cutters it was possible to achieve wide application of new brands of cutting materials and mainly of hard alloys. Especially good results were obtained in the development of face-milling cutter designs equipped with SMT, which practically replaced the previously widely used cutters with soldered-on carbide inserts.
а. A solid carbide end mill; б. narrow disc cutter
Brazed inserts are used only in the manufacture of small-sized milling cutters, in which it is not possible to place elements of mechanical fastening of inserts. Even in these cases, preference is still given to solid milling cutters made entirely of tungsten carbide and pressed into special molds for cutting hard-to-machine materials.
Methods of manufacturing solid milling cutters or their cutting parts by grinding from carbide blanks with diamond circles, and also by cutting from plasticized blanks with subsequent sintering are also used. Production of solid carbide end mills with a diameter of 3 mm is mastered, for example. 12 mm (Fig. 11.2, a), as well as narrow disc and other types of milling cutters with straight or helical teeth (Fig. 11.2, б). end milling cutters are made either with a cylindrical shank, or in the form of crowns and inserts, connected by soldering with a steel shank.
At present in the design of medium and large milling cutters the method of brazing of carbide inserts on the tool bodies is used in the case when the cutting inserts have a shaped shape. So, for example, in Fig. 11.3 shows a cylindrical cutter with brazed helical inserts that can only be made in short lengths. Each tooth is a set of such inserts with their joints shaped as chip breaker grooves. The main disadvantage of this cutter is the need to re-solder and sharpen all the teeth in case at least one of the plates is broken. Helical soldered inserts are also used in the production of end mills with short workpiece lengths.
Cylindrical milling cutters, due to their specific design and cutting conditions, are equipped with carbide SMT much less frequently than end mills.
Face milling cutters allow a large variety of methods of fixing the polyhedral inserts and that is why a great number of different types of such milling cutters are produced nowadays, the most complicated of which allow making adjustment of inserts position in the body in order to get the minimum radial and face run-out of cutting edges.
Analysis of modern face milling cutter designs shows that the main trends in the use of SMR are:
mounting of the inserts directly on the body or its component parts;
use of inserts with two or three insert bases;
use of a mechanism for regulating the position of the cutting edges of the inserts in relation to the cutter rotation axis.
The widely used inserts are three-, four-sided, parallelogram-shaped, less often round and five-sided, negative and positive in geometrical parameters, with or without holes for fixing. The inserts are fastened by screws or levers through the hole, as well as by wedges that press the insert to the socket in the body or in the liner.
Shanks of end mills can be cylindrical, conical or special short cylindrical. Until recently, disc milling cutters with tungsten carbide plates were usually used in the soldered-on variant. However, because of the difficulty of sharpening and soldering of the cutting inserts during heating (especially on three-sided milling cutters), milling cutters with mechanical SMF fastening are becoming more and more widespread. The designs of these milling cutters use basically the same methods and securing elements as the face-milling cutters.
L. cutter length; d. cutter diameter; d 1. diameter of the cutter center hole; ω. inclination angle of the teeth
table 11.1. Choice of cutter grades for various processes
|Methods and nature of machining||Grade of tool material when machining|
|Carbon and alloy steel||Hardened steel||Titanium and titanium alloys||Cast iron||Non-ferrous metals and their alloys||Nonmetallic materials|
Choice of cutters tool material depends on workpiece material, machining conditions and performance requirements of the operations. Detailed description of tool materials is given in. 8.3. Table. 11.1 shows grades of tool material of milling cutters for various grinding methods.
Choice of cutters for NC machine
Choosing a cutter for a job is like choosing a tool for a musician. The best results can only be achieved with a reliable and high-quality cutting attachment. It is quite difficult to foresee all the possible nuances that may arise in the course of work, but it is not superfluous to have a classifier of milling cutters for CNC machines at hand. In the assortment of FREZA store.UZ presents all kinds of cutting tools for a modern CNC milling machine.
Depending on the material and type of workpiece to be milled, as well as the specific cutting conditions, milling cutters come in a wide range of designs. Check the choices you need for your power tiller.
The type of operation on the CNC machine is one of the most important parameters when choosing a cutter. Such equipment is characterized by high accuracy and speed of material processing which requires proper selection of cutting tools. Depending on the technological requirements of the manufacturer, not only the type of machining, but also the operating conditions of the machine tool must be considered. Understanding the specialization of the equipment and taking into account the diameter and rotational speed of the spindle head, you should pick up a cutter by the way of attachment, focusing on the final result.
Depending on the project tasks, a distinction is made:
accordingly, an appropriate cutter with a specific geometry is selected for each milling task.
How a mill is mounted on the spindle also influences the selection of cutting tools. Before you buy, you need to find out. whether or not the cutter is suited to your machine tool.
Achieve highest possible centering of the cutters on the milling machine spindle for best possible tooth runout.
Cutting direction, cutting technology, cutting mode and form of the workpiece determine the choice of the appropriate cutting tool.
- End mills are used for machining stepped and flat surfaces. They are made in the form of a cylindrical construction with working blades located at the ends. Here, only the tips of the cutting blades are used. These are solid tools that operate at high rotational speeds.
- Circular cutters are indispensable for creating grooves, recesses, and notches. Depending on the number and arrangement of cutting edges, can perform several operations in one pass. To form shallow grooves use circular milling cutters, to cut narrow grooves and slots use thin circular saws. Disc milling cutters with two- or three-sided blades at the ends are highly versatile and highly productive.
- The scope of application of corner milling cutters is the machining of inclined planes, edges and corner grooves. Angle milling cutters can be both single-angle and double-angle. Cutting edges of such a cutter are at different angles to each other. Single-angle is characterized by the location of the edges on one side of the taper and on the ends, and for the double-angle, the blades lie on two adjacent tapered surfaces.
- End milling cutters have all the workable cutting edges and look rather similar to standard drills. They are suited for demanding milling operations, working perpendicular planes, deep indentations, and recesses. Allow for workpiece machining in all directions.
- Spherical cutters are used for relief surface treatment, for 3D designs and shapes. Most frequently used for wood and plastics, less frequently for metal and steel. Spherical cutters give on an output surface smoothness, minimize vibrations and allow avoiding roughness.
- Routing cutter is used for cutting complicated surfaces. cylindrical or helical. This cutter is used for cutting shaped grooves, straight and spiral chip channels, and for machining edges with complex shapes.
Number of teeth (grooves) of a mill influences the quality of the removed chips and heat production while processing the workpiece. So, when comparing two cutters of equal diameter, a cutter with bigger number of teeth has higher temperature for each tooth than a cutter with lesser number of teeth.
- Large-toothed cutters are more durable. They have a small number of large-pitch teeth and produce coarse chips;
- Small-toothed cutters have a large number of small-pitch teeth. Small chips are produced at work.
Diameter of cutting part and shank affects the depth of machining and the amount of work done. Cutters with large diameter of shank (6, 8, 10, 12 mm) are used for large volume of work, and cut of small relief and processing small area with diameter up to 4 mm is suitable.
An engraver and its bits are also used for machining materials, but they must be distinguished from cutters and other cutting tools. Unlike milling cutters nozzles for graver have no spiral chute for chip evacuation and are designed for simple types of workpiece processing with subsequent back polishing. They are completed with various types of nozzles and used for processing of miniature details and small scopes of work.
The method of chip evacuation is especially important in high volume applications. It is necessary to consider not only the direction of the chips, but also their shape, cross-section and characteristics of education. The parameters of chip separation from the workpiece are controlled according to the selected cutting parameters.
The length of the cutting part is selected depending on the parameters of workpiece processing. Cutter length is always little less than full cutter length and set by cutting parameters.
Selection of cutters by price range and brands allows choosing the most optimal variant of a milling cutter. The Cutter Shop.UR offers both inexpensive tools and products of reputable companies. Cutters of the Chinese manufacturer DJTOL have established themselves as good quality tools at a relatively low cost. American, European and Japanese cutters of well-known brands are distinguished by higher productivity, higher reliability and, therefore, higher cost.
Cutter coating makes the cutting tool more resistant to wear. To choose a coating, you should read its description and properties in the catalogs of manufacturers.
In the Internet-shop of Mill.A handy filter makes it easy to choose the right milling cutter for you. It automatically selects milling cutters by the parameters you specify. In addition, you can leave a request for selection of a tool or contact our managers. Call 8 (800) 777-05-39, they will help you to choose and buy a cutter for a CNC machine tool! The right tool is a guarantee of quality and safe work, a prerequisite for a long and excellent service life of your equipment.
Home CNC mill as an alternative to a 3D printer, Part Two, tools and accessories
The other day I was embarrassed to say that I swear at amateurs, and I do not write anything good, but I promised a “series of articles”. I had to take out an old draft and refine it. For those who forgot. the first part of the choice of machine tools here.
Let’s assume that you have decided on a cutter model, had initial talks with the supplier and began to prepare morally for the purchase. What else do you need to get started?
Although many vendors include a “starter kit”, for comfortable home use it is clearly not enough. So immediately start looking/buying/doing the following:
And yes, I should say at once: this article refers to home milling machines with spindles like Kress or chinks with collet Er11, so firstly assume that the shank of the cutter we have a cylindrical to 6 mm (Kress has 8, but his work with 8koy not normal. weak he did), and secondly, the mechanical tool makes no sense. not enough power, and thirdly, drills, reamers, markers-flycatters are not available, because the minimum speed. 6000 RPM.
Our machine is a milling machine, so it’s about cutters in the first place. Cutters are subdivided by:
1.1. End mill. a cutter with a cylindrical working area, ideally producing a groove with a perfectly rectangular bottom
1.2. Ball mill. a cutter with a working area ending in a radius, ideally producing a groove with radius walls
1.3. Bull nose mill. a straight mill with a rounded edge, giving a slot with a straight bottom, but a radius transition between the bottom and the wall.
1.4. Cone mill. a mill with a tapered working area ending in a radius or straight area
1.5. Profile mills. cutters with a specific profile that can be useful for CNC milling, either to make the work faster or to create undercuts.
1.6. slot cutters. cutters that create undercuts like T-slots, swallow-tails, O-slots, etc.
1.1. Spiral with upward removal of chips. works on most materials.
1.2. Straight, aka half-pipe mill, aka engravers in russian literature. without chip removal, suitable for laminated materials like plywood, laminate, etc., or for cutting plastic sheets, when the spiral mill can lift material over the table
1.3. Spiral with chip evacuation downwards. for laminates, if it is important to have the flattest possible cut of the laminate surface
1.4. Spiral compression cutters. cutters with variable spiral, bottom part evacuates chips upwards, top part. downwards, for double sided laminates, most often for cutting alucobond/dibond.
To work with plastic/wood is usually sufficient one or two perekuyu cutters in the full size range, with non-ferrous metal 4-6 mm may need 3-4 perekuyu.
Relation of the working part to the shank
4.1. Equal. equal working part and shank.
4.2. Lowered. the shank is wider than the working part. Relevant for small cutters.
4.3. Widened. often for shaper cutters, I did not see such on sale, but I made it myself, the shank is narrower than the working part.
Material, sharpening angle, helix angle, coating, etc.д.
There is probably no point in going over the list. the technologies are endless. It’s just worth noting that the manufacturer usually writes a recommended material and quality of processing (roughing / finishing), if you buy it on Ali, where the seller has spared to give recommendations or recommendations are obviously fey (“super finishing titanium / diamond / sausage / plywood”), try to find a similar looking cutter (spiral, one start, yellow) from a reputable manufacturer in the catalog and take that data.
Special attention should be paid to boron milling cutters. milling cutters with a large number of very small cutting elements and a relatively powerful core. Such milling cutters are designed for finishing or superficial processing of materials, like grinding, removal of thin layer, engraving of hard materials, etc.д.
Different Types of Milling Cutters & Operations Explained
Theoretically, you can use drills with the machine, but do not forget to take into account the speed. After all, drill bits are usually designed for a drill where RPM rarely exceeds 800 RPM, and the discussed spindles have a 6000 minimum. However, for small bits it will be more of a plus, but if it comes to 3 mm or more, first, try to buy coated drills, and second, build a path for drilling so that the drill has no time to overheat.
Collets and adapters
As our supplier is at best a Russian reseller, and at worst a Chinese, you should expect to minimize set. And more or less serious work with the machine requires some number of cutters, most likely with different shanks. Theoretically, there are adapters on sale. additional collets allowing to insert a mill with 3 mm shank into 6 mm collet, but it is necessary to remember that, firstly, it will lower rigidity and, secondly, it will lower mill setting accuracy.
Of course, a set of collets is secondary to a set of cutters used. If you already know a set of cutters then you should not overthink and collect the collets for your set. Nevertheless collets are usually less available than cutters and you may find yourself in a situation where you have a cutter and have to wait 3 weeks for a collet under it from China, so I recommend to take at least 3 tools: 6 mm (maximum), 4 mm (often under it go small cutters and small bevel cutters) and 3 mm (smooth finishing cutters).
The Er11 standard calls for a full range from 0.5mm to 7mm in 0.5mm increments, t.е. collets come in 0.5-1, 1-1.5, 2-2.5 mm and so on.
the Kress spindle has a proprietary collet, but thanks to the wide availability of spindles and clones/fakes, getting hold of collets is not a problem. There are usually 3,4,5,6 and 8mm 3 collets available in stores.175 mm “American standard” in which we have borers and engravers. The collets themselves are four part collets, t.е. the clamping range is unlikely to be much greater than a couple of tens, so that a mill with a shank of 3.There will simply be no 5 mm. However, this is unlikely to be a problem in home use.
I almost forgot: collets are usually sold separately from the nuts. In principle, there is no problem to flip the collets in one nut, but I am lazy, and there is a small, but probability that the flipping will bring some debris into the threads, and it is dangerous for the thread.
Most home routers are equipped with either a table with T-slots or tables with a grid of tapped holes. In both cases, the most common fastener looks like a steel or aluminum clamp with one threaded hole and a second smooth hole. A T-bolt is inserted into the T-slot and goes through the hole in the clamping plate and is secured with a nut, the second bolt pushes the clamp off the table. The machine usually comes with 4 clamps, which under intensive use rather quickly fail: the threads on the screws and clamps are cut. Sometimes Chinese set have usual bolts and T-nuts instead of T-bolt, I recommend to take care of replacement of T-bolt at once.
Instead of rear (stop) screws it is possible to adapt pieces of material or special stepped wedges, but in the case of slippery plastic it can be of no good service: the fastener will “slide away” from the fixed material.
As an alternative to clamps can serve as a machine tool vice. a special vice with a minimized height and adapted for installation on the table handle (or even under the key). Plus. less hassle installing the material, repeatability, relative accuracy. If you work with similar small workpieces, you can set the vise once in a lifetime, write down their coordinates and further refer to them. Disadvantages. most of the finished vise eats a minimum height of 20-30 mm, and discussed the machines rarely have more than 70 mm under the portal, well, with large dimensions vise incredibly expensive.
Another option is to stick the workpiece to the table. Strangely enough, the holding power of a good double-sided adhesive tape is enough even for gentle engraving of color metal, not to mention the plastic. In the not-to-speak-of-the-moment Roland, there was even something about scotch tape in the manual. The disadvantages are obvious: variable reliability, and most importantly, to tear off the finished product, and then clean it from the tape.
And finally. exotic for home machines, vacuum clamping. In principle, not such a complicated thing, but it requires additional vacuum pump and it eats 10 mm of height minimum.
Isolation and chip evacuation system
One of the most common problems with using a router at home is noise and dust. And if you can put up with the noise, the dust really pisses you off. And in the case of processing stone/getinax/glass/composites. the dust is also harmful.
There are 2 possible ways of fighting: an active suction vacuum cleaner with a brush mounted on the spindle, and the creation of a “cabinet” for the machine.
The brush seems nice, but with many hours of trajectories the roar of the vacuum cleaner creates a unique atmosphere in the house. And if you’re deep-picking, the brush head is constantly bending and deteriorating rather quickly. So we left the aspiration system only on the largest cutter, and the small ones we stowed in the offices of transparent polycarbonate and laminate. Not so compact, of course, but the cabinet dampens a little sound and dust.
My personal set of “young soldier”
And finally. a little bonus. My personal “young fighter” kit that I buy/make for every new milling machine (the main job is 3D milling molds on PP, POM, PET, composites):
- 6 mm single pass straight long. edge 40 mm, total length 75, chinaman.
- 6mm bead good (Widia/Makestag/SGS)
- 4 mm single pass straight long chinaman
- 3 mm two-hole straight long good
- 3mm double ball long good
- 1.5 mm with an extended neck straight is good
- 1,5 mm with ordinary ball-joint good
- 0,8 mm with normal ball-joint or conical with 0,8 mm round heel.
Industrial vacuum cleaner. Basically, I’ve now come up with a bottomless cabinet where the shavings will pile into the box themselves, so a vacuum cleaner won’t be much needed. But before that. bought in each new place where we put the machine, without a vacuum cleaner from the cabinet shavings get very hard. This set is sufficient in 99% of cases.
At this point I must say goodbye, next time. a little about the software, the general concepts of machining and machining strategy.
- End cap. With it, the material is milled along a series of lines. Often, diamond CNC machining cutters, which have two cutting edges and resemble a drill.
- End mill. In this type, the tool is shaped like a cylinder, and the derived threads protrude on the ends. Suitable for even surfaces and frequent machining.
- disc-shaped. Used for grooving and notching. The multi-tasking tool performs most operations, depending on the number and position of cutting edges.
- Angular. Used for edge milling. With two cutting edges at different angles to each other.
- Shaped. Used for curvilinear milling operations and forming multi-level patterns. The shaped cutter blades for machine tools have the highest performance, and are used already in the finish machining, where the cut comes out extremely neat.
Profile working tool, which is processed can be subdivided into types:
- For routing work in wood;
- for milling workpieces made of abrasive metals;
- for the manufacture of plastic elements and polymer elements.
Before you start working with milling cutters, you should understand that all milling cutters for plastic and wood are not used for finishing metal products, because the milling cutters for metal products have a completely different technology of cutting and they are made from different raw materials. Wood is much easier to process than metal.
As mentioned, a cutter is a cutting tool, and it is installed in the spindle head of the machine.
The entire machining process is carried out through the rotation of this element, namely: its edge touches the workpiece, after which a part of the machined material is removed.
Cutter types according to machining features
We can consider such varieties of CNC machine tool according to shape and design:
- End mill, thanks to it material can be milled in all axes. Most often they are diamond cutters for CNC machines. Their shape is similar to an ordinary drill bit and provides a pair of cutting edges.
- End mill. Cylindrical shape with cutting elements on the ends. It is suitable for flat work surfaces, e.g. for cutting sheet material.
- Circular. This type is specially designed for shaping grooves and various recesses. Multitasking rotary cutter: it can perform several operations, their number depends on the number and location of cutting edges.
- Angular, which is used for milling of surface edges. It has a pair of cutting edges at different angles to one another.
- Shaped. Quite specific tool, which is used for shaping surfaces of complex shapes. Bevelling cutters for CNC have high quality indicators, because they are used in the finishing process and the cut is received as pure as possible.
Classification of milling cutters by application
It is also necessary to classify the tool by the area in which it is used. Generally, the use of milling cutters implies the pursuit of certain goals, especially if we take industrial machines as an example.
Let’s take a look at the following varieties of CNC machine tool cutters depending on the application:
- for roughing. This type of milling can include removing a large layer of material, shaping the initial shape, cutting or slicing;
- For drilling grooves. These NC cutters can perform operations such as creating grooves, slots, notches, and hollows;
- For precise work in corners and edges on top of the workpiece;
- for finishing (finishing). This is most commonly done with a diamond. This tool creates hollows of different shapes and configurations. After that, all that’s left to do is clean the part and remove the chips;
- for the formation of various artistic drawings.
Types of cutters depending on the material to be machined
One of the important criteria in determining the necessary milling tool is the material to be processed. This also affects the material from which the cutting parts are made, the configuration as well as the technical qualities. It is necessary to allocate such types of profile working tool according to the processed material:
- For the milling of wooden products;
- for milling non-ferrous and ferrous metals;
- for the production of plastic and other plastic materials.
Please note: milling cutters for wood or plastic are not suitable for milling metal, because metal cutters are designed differently and are made of different material.
The size of the end mill
Besides the number of teeth, there are several other sizes and characteristics of the end mills you should pay attention to: cutter diameter, cutting depth and length, and the tool profile.
The diameter of the cutter determines the width of the slot you can create with your end mill. It also affects the chip removal rate for side milling. So before you buy and/or install a cutter, make sure you choose an end mill with the proper diameter so that the resulting piece will meet the specifications.
The largest contact length required determines the depth of cut required for your end mill. Ideally, you should choose a length that is long enough to prevent overhang and provide a stiff and accurate cutting process. A simple trick is to multiply the cutter diameter by five. If this number is greater than the required depth of cut, the overhang option can be considered.
Your cutter probably has a helix angle of about 30 degrees. If you want to reduce cutting force to minimize heat and vibration, you need to use cutters with a large helix angle. These end mills will also give you a better surface finish. However, you will have to make some compromises in terms of the feed rate at which you can cut and the depth of cut.
Finally, let’s look at the tool profile of the end mill. Square, fishtail, ball-end milling, etc.д. are used for many purposes. This is just a reminder, since we reviewed each type above.
Conventional milling is also commonly known as surface milling. It uses a horizontal cutter, which means that the axis of rotation of the cutting tool is parallel to the cutting surface.
Different milling cutters can be used for surface milling. wide or narrow, depending on the desired result. Using a wide cutter can result in fast material removal, combined with low cutting speeds, high feed rates and large cutter teeth. Of course, the surface finish of such a cut may not meet the requirements.
Consequently, the second step may involve changing tools to use smaller cutters. It also requires higher cutting speeds and lower feed rates, so the amount of material removed per unit time is less. At the same time, the final finish is more accurate. So the combination of these two factors is a good choice from an economic point of view.
Cutters for CNC woodworking machines
Milling is a fast and reliable way to shape the wood. The working tool of CNC machines is the cutter. Structurally, it is a rotating part with sharpened teeth. Cutters for CNC woodworking machines are made of different alloys and are divided into categories. The choice depends on the surface to be milled, the type of work and the hardness of the wood. It is also necessary to take into account not only the correspondence of the cutter type to the task performed and the milling mode, but also the design features of the cutting area. Our article will help you to choose the right tool for the program machines, which will acquaint you with the types of milling cutters and their purpose.
Types of diamond cutters
It is the technical diamonds with different gradations that are used in the milling machine.
With increasing the grading index, the quality and fineness of processing improves. Cutters with diamond working element are subdivided into:
- profile. their purpose: changing the relief of the stone, in particular, polishing, creating shaped ends in products. One of their varieties of milling cutters. pressed, which has a continuous diamond-bearing layer (to work with granite and marble workpieces);
- Cylindrical. with the advantage of diamond spraying, they create round holes (e.g. in marble sinks or bathtubs. for mounting faucets and connecting elbows);
- Finger cutters. are involved in the process of making a volumetric drawing. bas-relief and inscription, are used for engraving on the stone. In addition to diamond spraying, which takes precedence, the working element can also be tungsten, cobalt and nickel, for which tungsten, cobalt and nickel are used.
Pobedite cutters are shock resistant, good for high temperature applications, but wear out faster than diamond cutters.
The performance characteristics of cutters on cnc stone machines consist of:
- in the great speed of the cutting process;
- in an exceptionally high quality surface after milling;
- in the longer use of the tool.
Stone cutters usually come in sets of six. Most of them have a conical attachment to the milling machine (according to ISO-40 standard).
Differences in diamond cutters by manufacturing technology
Equipping milling and engraving machine on a stone with milling cutters with diamond working element, it is necessary to know the differences in technology of their manufacture and purpose of this equipment. There are three such technologies:
- Polycrystalline structure. plates are made in the form of cones (straight and radius), cone pyramids. They are used in finish machining of granite, marble, ceramics and glass. Have high durability and productivity, but suffer from shock and vibration. They are used for finishing the elements of relief. Have applications in engraving.
- Vacuum sintering. designed for engraving and carving on granite, marble, ceramic and glass. Used to remove more material at the time of roughing the workpiece, prepare it for finishing.
- Solid sintered metal bonding with diamond powder. These cutters work well on all hard rocks on a CNC milling machine. They can be used for material sampling or engraving process.