What cutters are needed for CNC machines
Different types of end mills for milling machines. classification, special features
To be able to shape steel workpieces, milling machines are widely used in manufacturing. Metal milling cutters for milling machines allow the end product to be machined precisely in line with the engineering design. The types of milling cutters, presented today in the domestic market, have a great variety, which allows you to choose the most appropriate for a particular case.
Choice of a cutter for a CNC machine
and more companies choose numerically controlled machines. Just one such machine replaces the entire fleet of equipment, the control is not manual, as in previous generations of machines, but by a set program. Numerical milling is one of the most precise types of production. Cutting nozzle or mill is the most important part of the machine tool, and the choice of a milling cutter for a CNC machine determines the efficiency of the whole operation.
Select the type of milling cutter on the basis of what you plan to cut, in what volume.
This type of cutters is suitable for working with “soft” plastics, wood, sandwich panels. Single-twist cutters are easy to cut with:
These types of milling cutters are used in those productions where the quality of the cut edge is not important. But they have another advantage. long cutters do not choke on cutters, so they last a long time.
Another type of milling cutters suitable for CNC machines are double-end milling cutters.
They are used for cutting tougher materials than those cut with single-return burrs:
Different types of plastic (PVC, acrylic, plexiglass);
Spiral cutters, most often they are two-beveled. These cutters are needed when the goal is to remove as much material as possible in one pass, while at the same time getting a fine chip. When machining, compared to other counterparts, the spiral leaves the least roughness. Smoothness is achieved by deeper grooves, less vibration when cutting.
Also, the cleanliness of the surface is related to how many spiral cutters. the more of them, the cleaner the surface.
For example, when working with hard types of wood, it is possible to do without additional sanding of the surface. It already turns out polished.
Machining of objects in 3D with different shapes, degrees of detail.
The choice of cutter also depends on whether it is used for chip removal upwards or downwards. Nozzles that remove material upward are more common than those that cut chips downward. What is the difference between them? If the chips are removed upwards, the surface is rough, but if they are removed downwards, the cut is smooth.
Compression cutters are designed for laminated materials. They avoid chipping, cracking the cladding.
To create three-dimensional images in 3D, you need ball cutters. They are also called spherical. They are versatile and work well with different materials:
You get a smoother surface because you create very little vibration.
Two-tapered taper milling cutters are good for finishing cuts in relief. Tapered spheres have a small tip diameter, but a large safety margin. They are made of tungsten carbide with various additives for hardening.
Cone milling cutters can cut various plastics, wood, model wax and metals.
Cone gravers are also very popular, they can be used for cutting small details of 3D images and engraving texts.
If you are milling through a sheet of paper, choose a fishtail cutter. It has a deep groove, this will prevent chips, burrs, cracks from the underside of the sheet.
Also the “tail” helps reduce vibration during cutting, throw away chips.
Home CNC milling as an alternative to a 3D printer, part four. General machining concepts
Beginning to write about the processing strategies, I realized that I create a “monkey kit”. a step by step guide is not even for dummies, but for idiots, my steps can be repeated, to do theirs by example too, but understanding is not added. At one time, when I suddenly decided to become a routing engineer, having a medical degree, MBA and 10 years of experience in computer retail, it was very difficult to wade through the terminology and completely new conceptual apparatus.
Of course, most CAM software has a good help, but it is still written by technologists for operators and a person in the street can not always understand what is “both in increments”, why do you need “safety area cylinder”, what type of approach to choose and what is it all.
Below is my humble attempt to run through the basic concepts of milling with a brief deciphering. I used Russian terminology from Delcam textbooks, it may not match other CAM software, but I think intuition and Google will save the day. And as always, a little personal experience with machining plastics on hobby machines.
Actually, spindle speed is not a standalone parameter but depends on a tool and material. The documentation for normal adult cutters has a parameter “cutting speed” in m/min for different materials, it’s the speed of the edge in relation to the material.
To calculate the spindle speed, divide the recommended speed by the circumference. But there are two problems: first, we cut “homemade” materials like plastics and wood, and second, we use hobby milling cutters that don’t have any templates written on them. So the speed is calculated empirically: we draw a simple trajectory like a slot, start the mill in the material at a small (700-1000 mm / min) feed and start from 6000 slowly to lift. If it starts to fuse/burn. reduce it by a couple of steps. By my experience, for a cutter with 6mm diameter the speed in ductile plastics (caprolon, PP, PE) is 6-8K, in hard plastics (ABS, PS, PC) is 8-12K, in wood is 15-18K, in non-wood is 10-20K. Increase speed if diameter is reduced and also increase speed on finish cuts.
Feed speed is also a derivative, but here everything is even worse. if on one hand it depends on readable/documented numbers like “feed per tooth”, on the other hand. on rigidity of machine-tool-tool-detail system (aka AIDS). The feed rate per tooth Sz or Fz can be found in the documentation of the cutter, it is described in mm/tooth (mm/t). Multiplied by the number of teeth of the cutter and the rotational speed it will give the maximum theoretical feed rate.
But it’s hard and unreasonable to measure the stiffness of the AIDS system, so, as always with self-made people, the feed rate is selected by experience: we try different feed rates, starting with 500 mm/min (we’re talking about plastics, yes) when we stop liking the sound (or the mill breaks, or the workpiece flies out). we reduce the speed. Don’t forget that the feed rate will be different for different cutters and different processes. The general rule is: Increase feed rate when you decrease feed per tooth and decrease it when you increase it. Although in plastics sometimes paradoxical effects occur, for example, the quality of vertical surfaces of POM is higher at higher speeds. When machining plastics on my machines I usually use speeds of 1500 to 3000 mm/minute and the surfaces come out fine.
The safety area
The safety area, also called the OB, is a set of areas of the machine where CAM thinks it is guaranteed that it will encounter neither a workpiece nor a fixture. This is the area where you make transitions and are allowed to walk around at rapid feed by default. During normal 2.5D machining this is the plane. we clamp the part so that it is clear and unclouded over the entire machining zone. However, sometimes it makes sense to set the OB differently, for example, if we are milling only the sides of the workpiece and are fastening through holes in the workpiece in the center. Besides, some milling cutters do not allow vertical or even oblique plunge cuts in material and it is necessary to explain to CAM that transitions and leads should be from the side only. Most normal CAMs have “block”, “cylinder” or even “model” OTP types for this, setting the OTP accordingly.
Leads and taps
Many materials and processes let you not bother with the concept of leads in general. PVC, PS, soft woods can be cut in any direction by any cutter in the normal cutting mode. You set the plunge feed and go. Nevertheless, the moment of entering and leaving the material is different both for the cutter (uneven load on the plane, operation of the cutter center with vertical plunge cutters) and for the material (hanging burr, knocking out a chip). That’s why CAM programs usually have a possibility to set separate modes for feeds and taps.
- Vertical arc approach
- Retracting “straight”
- Transition “both in increments.”
- The approach. moving at an accelerated
- Ascending. moving at an accelerated rate
In fact, the heights are relatively simple. There is an absolute safe Z determined by the OB. But imagine that you are working the lettering on the bottom of a box offset in very small increments. There are a lot of shallow transitions, and at each one CAM guides the cutter to the OB, moves it a couple of millimeters, and then painfully drives it down. To avoid this, they invented a relative safe Z-height at which you can walk during finishing work after the past picking. But remember, if the picking is not made in reality, for example, if the operator messed up the order of trajectories, the tool will try to move between segments in the material and at the same time it will turn the workpiece and break.
My personal values for small parts Absolute Safe. 5-10 mm, Relative. 2-5 mm.
Transitions and Gaps
Transition. part of the trajectory between the working strokes of the cutter. As already mentioned, can be done at absolute or relative safe height, in powermill the corresponding settings are called “safe” and “both in increments”. But sometimes, especially on finishing or finish paths, it makes sense to arrange the transition differently, so options are provided in CAM programs:
- By surface. Despite the fact that correctly adjusted leads and taps practically do not leave traces of tool separation on the workpiece, sometimes, for example, if the transition distance is short, it makes sense to make the transition without tearing off the cutter at all. alt=”image”/
- Step by Z. The right choice for trajectories with permanent closed vertical walls, e.g. constant Z
- Right. A real hardcore variant, CAM ignores everything and stupidly draws a straight line between diverter and approach. And woe to the material that was in the way, minus the operator’s salary that blocked both the cutter and the workpiece. But respect and respect to the hero who skillfully used the tool and reduced the time of changes by hours (no joke, it happened).
Allowances and tolerances
A very simple, intuitive item.
Tolerance. the size you don’t care about and within which CAM can play around as it wants. On the one hand, more tolerance means more freedom for CAM, smoother trajectory, fewer direction changes, etc. On the other hand, in some rare cases CAM can, for example, place the offsets in the middle of a vertical surface and regardless of the fact that you do not care about the size of this area, the surface will be ugly. In our age of large memory and powerful computers that calculate the trajectory, let CAM think a little longer and write a couple of extra megabytes in the program, than to scratch its head about what to do with flaws. I put a tolerance of a hundred on plastics, I think I’m happy with everything.
The allowance is initially a concept of roughing. At CAM level, the allowance looks like the construction of equidistant (evenly offset) from the original model. The general rule I gave above. the size of allowance should be certainly greater than the size of the potential defect processing, then even with the unpleasantness you can correct the flaw with the further processing. The allowance can be used in addition for other purposes, for example, for model scaling when matching grooves/slots. On plastics in the roughing, I put an allowance of 0.3-0.7 mm, it is enough.
In general, it looks like this. Now you can begin your article about CAM machining without being distracted every minute wondering if I wrote it clearly enough and without overloading the article with footnotes. If I forget something or have not understand something. write your Комментарии и мнения владельцев, ask questions, I will try to answer them.
What cutters do you need for your tapping machine?
When selecting a cutter for a CNC machine, you should know what the different types of cutters are used for and where they are best used. Mill types and applications. for easy selection of the right milling cutter for your purposes.
In order to choose an appropriate cutter type, it is necessary to proceed from 2 parameters: the material to be processed and the type of the product you want to produce.
One pass milling cutter for NC machines
1-turn burrs are suitable for soft materials such as plastic, wood, plastic and aluminum panels, plexiglass, PVC, acrylic, Plexiglas, foamed plastic, etc. The advantage of this cutter type is that it is very wear resistant. Since the basic parameters of grooves allow for long chips, the cutter does not get clogged. So, dulling is more important here than breakage or spoilage of the milling cutter.
Very often 1-turn milling cutters are used for creating layouts in the advertising industry, when the quality of the machined surface is not so important.
Two RPM cutter for CNC machines
2-turn burrs are used for hard materials like hard plastics, chipboard, acrylic, PVC, polystyrene, etc.д., as well as for sandwiches. aluminum and plastic panels. Two-way cutter produces finer chips. Two-start milling cutter removes less material in one pass compared to a single-start milling cutter. Cleaner, more precise operation.
Two or more passes in a spiral cutter guarantee better debris removal in a single pass. Number of teeth and groove depth help best shred debris.
Use a two-feed circular spiral cutter if you want to get the best out of your cutter. Perfectly smooth and high-quality processing. This effect is achieved by reducing vibration during cutting.
Where the two-start cutter performs best
Engraving and adding intricate elements on the workpiece with a two-step cutter is great for putting the finishing touches to three-dimensional drawings. The result is a perfect, polished, smooth surface that does not require any additional machining. Double-round spiral cutter is suitable both for sketching and for putting the finishing touches to 3D style drawings.
Ball or spherical cutters are most effective when used on CNC machines during complex 3D sketching and volumetric shape work. They are great for machining plastic, wood surfaces, metal and steel, without roughness.
Fishtail cutters are needed for double-sided surface treatment. Thanks to their specific design, they prevent the appearance of defects, chips and snags, both on the front side of the product, and on its back side. Another advantage of this shape cutter. is a deep recess in the groove, which assures consistent high feeds during high-speed machining. This effect is possible thanks to a clever geometry that minimizes the appearance of vibrations. It helps eliminate accumulated shavings better.
On our site you can buy cutters for CNC machines of any shape and with any number of starts. Here you can choose high quality solid cutters from such brands as Watzo Tools, Dress, FREUD and others. Store “Petrovsky” is a direct importer of equipment from Europe, so our retail are much lower than in many domestic stores. If you need consultation on milling cutters selection for different materials and types of work please contact our managers by phone or come to our store and you will get qualified assistance.
Types by application
The worse the condition of the workpiece, the harder the cutting edges work. Roughness of the allowance hits the cutting edges with force and they can be damaged. This is why such workpieces are machined with two tools, a roughing and a finishing tool.
Roughing cutters are made of high-speed steel R18, R6M5 and others. Steel absorbs shock better. Roughing tool removes the major part of the allowance and prepares the surface for further processing. Often it is monolithic, but there are also cutters with soldered inserts.
Finishing tool works on a smoother surface. It gives high accuracy, but costs more. Blades are usually fixed mechanically. Finishing cutters achieve an accuracy grade of 8 to 9. If the workpiece surface is smooth, e.g., after a lost wax investment casting, it can immediately be milled clean.
But if they are rolled or cast in sandy clay molds, you can’t do without roughing.
Rolled or pressed tools are most often used in series production. The shape of the workpiece only vaguely resembles the finished product. Then, in order to simplify the technology of making the part, it is advantageous to take a specialized cutter.
For machining large planes, the cylindrical cutter is the right choice.
CNC Basics. What You Need To Get Started
Finger and disc modular cutters make gears.
Thread cutters quickly and accurately cut external threads on shafts.
Routing cutters carry out other specialized workpieces.
And since the workpiece materials are different, the cutters for them must also be different.
Types of router bits for the wood router
In order not to make a mistake when choosing a mill, it is necessary to know about their classification. So, there are five types of tools we are considering (this classification is based on such a criterion as shape):
Disk. 2. End mills. 3. Angular. 4. End mills. 5. Shaped.
The first cutters, disk type, were designed to make various recesses. They can be called multifunctional, as they are able to perform not one, but several tasks. it all depends on the design features, more precisely, the number and location of the edges.
The second cutters, the end type, are best if you are dealing with a thin and flat surface. They look like a cylinder, the edges are located on the ends.
The third milling cutters, angular type, are indispensable for trimming edges. They have two edges placed at different angles to each other.
Fourth, end milling cutters allow to work with all axes. As a rule, end mills are diamond end mills.
The fifth cutters, shaped type, are unusual and are used for unique, complicated workpieces. Cutters of shaper type are characterized by high technical characteristics, because it is used in the final machining. No inaccuracies in the cut. With the types sorted out, now let’s move on to the types of wood router cutters.
Scope of application
Number of operations, which can be carried out with a mill, is enormously high. That explains their high demand.
- Rough machining of metals and nonmetals. cutting, cutting, drilling, roughing.
- Drilling of grooves of different shapes. slots, grooves, helical channels, hollows of helical gears, etc.
- Corner and edge machining.
- Finishing and cutting, making parts with complex geometric shapes: dies, blades, molds.
- Artistic milling. with the help of cutters milling complicated elegant elements out of wood, form 3D images and ornaments on the plane.
The shape determines how the cutter will be used in the business. Several basic types are distinguished:
- DJTOL end mills. including straight, spiral, plate drills. for drilling and engraving;
- single/corner. milling grooves;
- disk keyed, double-sided, triple-sided. cut;
- face. remove layers, clean, reshape;
- Bevel cutters. making complex 3D shapes.
Industrial numerically controlled bandsaws use several cutting tips in a single cycle.