Flutes and Chipload

Flutes are the helical grooves that wrap around the sides of the end mill. Each flute has a single tooth with a sharp cutting edge (although there can be more than one) that runs along the edge of the flute.

As the tooth cuts into the wood, each flute whisks away a small section or “chip”. The fewer the flutes, the more material that is ejected with each tool rotation.  The overall cutting depth should never exceed the length of the flutes on an end mill. If cutting deeper than the length of the flutes, the tops of the flutes will be blocked and chips won’t clear, building up heat and reducing tool life.

Chipload is the thickness of a machined chip as cut by a specific tool type. More flutes create a smoother surface finish, while fewer flutes remove material fastest, but make rougher cuts.

Proper chipload is important because chips dissipate heat. Hot cutters can lead to suboptimal results, including burned wood, a poor edge finish and dull tooling.

If you’re machining a material like HDPE plastic, you want to use an “O” or single flute bit to clear the chips away as quickly as possible or heat will build up melting the plastic, which will “reweld” to the tool.

To summarize:

More flutes create a smoother surface finish

Fewer flutes are best at chip clearing, keep heat from building up

Two or four flute cutters are the most common.

The direction, size, speed and amount of chips being ejected can also damage the surface of the work piece. We can control how the tooling effects the material through our end mill type selection (upcut, downcut or compression) and speed at which we cut.

Drill Bits vs End Mills

Interested in CNC routing but clueless about tooling? Can’t tell an end mill from a drill bit? Here’s an overview of end mill anatomy, some basic cutter types, and tips on how to choose the correct tooling for basic wood or plastic jobs.

CNC machining is a subtractive process that uses rotational cutting tools called “end mills” to remove material. An end mill, while similar in appearance to a drill bit, is far more versatile. However, in practice the terms “bit” and “end mill” are often used interchangeably.

Here’s the key difference. Drill bits are designed to plunge directly into material, cutting axially and creating cylindrical holes. End mills are typically used for horizontal carving and cut laterally. Additionally, most mills are “center-cutting”, meaning they are able to cut both axially and laterally. This is due to cutting flutes that extend to the end face and enable plunge cutting. To minimize tool breakage and stress on the material being cut, most CNC software will “ramp” the end mill slowly into lateral cuts.

Feeds and Speeds

The speed at which we move a cutter across the material is called the “feed rate”. The rate of rotation is called the “speed” and is controlled by how fast the router or spindle turns the cutting tool. Both feed rate and spindle speed will vary based on the material being cut. A general rule of thumb is that you want to move the tool through the material as fast as possible, without sacrificing surface finish. The longer the tool rotates in any one place, the more heat that builds up. Heat is your enemy and can burn your material or radically decrease the life or your cutting tool. Feed rate vs spindle speed:

 

Spindle speed that is too fast paired with a slow feed rate can result in burning or melting.

Spindle speed that is too slow paired with a faster feed rate can result in dulling of the cutting edge, deflection of the end mill and possibility of breaking the end mill.

A good strategy when selecting a cutter is to attempt to balance feed rate and spindle speed by performing two passes on the work piece. The first pass, called the roughing pass, can be done by using an end mill that will eject a large number of chips at a high feed rate. The second pass, called the finishing pass, then won’t require as aggressive of a cut and can provide a smoother finish at a high speed.

Indexable cutters-Screw drive groove

Screw drive groove type

Drive slot as cross slot with traditional cone (Phillips) to loosen or tighten the screws, tighten the tool often slip. According to the stress analysis, part of the energy is applied to the screw will make a screwdriver or screwdriver head from the screw slot sliding. The operator must be applied in order to prevent the pressure face additional slide effect.

Driver such as Hex groove with vertical sidewalls (six corners), Torx (plum type) and TorxPlus (plum enhanced), the elimination of this slide out basic differences between the effects of.Torx and TorxPlus is the former driver drive slot with an angle of 15 degrees, which is almost 0 degrees, which can ensure the best torque to the screw. Although it has a vertical side wall Torx drive slot can prevent the slide effect, but the 15 degree angle drive prevents fully engaged screwdriver head and a screw groove, and produce a little, can shorten the life of the screwdriver head radial stress.

Since the Hex drive trough not only produces stress concentration at the contact point, but also inevitably causes damage to the head of the screw, the torque is relatively low relative to the applied force

Tighten or loosen the screws in the dangerous high stress concentration. High stress mainly occurred in hex and the head of the screw screwdriver and screw stress. Based on elliptic geometry and no corner of Torx driving groove can reduce the stress concentration, can protect the screwdriver and screws and prolong its life. The ellipse based on the geometry brought little tolerance between the screwdriver head and screw and improved the force closure.

The TorxPlus drive trough further improves force closure by allowing almost 0 degrees of work angle and greater core diameter, allowing higher torque transmission and preventing damage to screws and screwdrivers

Carbide blade manufacturers often use Torx or TorxPlus to tighten the blade. Because it can effectively transfer the torque, so the use of TorxPlus is the development trend. The TorxPlus drive slot, almost do not need to exert face load can ensure the screwdriver engaged with the screw groove, reduce manual assembly operator muscle stress and fatigue. In general, the hard alloy blade manufacturers prefer manual locking mode instead of automatic locking system.

Disadvantages of indexable cutters

Deficiencies

Indexable tool also has shortcomings. The blade is usually in the mold made of powder and binder alloy. After high pressure press forming, and then sintered at high temperature, the alloy powder combined with other materials, and the blade has a certain strength. The press blade is higher than grinding blade strength. Although the blade strength higher. But the blade is not sharp enough, limit the effectiveness of shallow depth of cut, thus finishing more difficult.

The milling cutter with a plurality of blades, the blade and the blade size changes of the socket, will enable the cutting edge of the blade is different in different planes. The result is a poor surface finish or obvious jump line. In this case, only the tool of another type of finishing.

As the tool industry continues to demand modular, low inventory, high productivity, longer tool life and general tool solutions, indexable cutting tools will continue to improve and replace obsolete tooling.

Common applications of indexable cutters

Common applications

Different tool manufacturer of indexable turning tool is very versatile. Turning the blade according to common shapes such as diamond, square and round to manufacturing, the size and shape of the blade with ANSI and ISO standard. This versatility can make the process personnel free choice of blade material and blade groove. Because all the mainstream tool manufacturers according to the relevant standards of production of cutting blade, therefore, to select a best performance of the blade is relatively easy.

Unlike the indexable turning tool, milling cutter with different blade shapes and different groove milling tool manufacturers, users can purchase the corresponding tool manufacturers. Nevertheless, tool manufacturers have the shape of the blade for its proprietary development a series of cutter body, a blade can be used in a series the knife body, thereby reducing the inventory and make use of technology personnel more flexible.

Most tool manufacturers can be customized non standard indexable forming cutter. Effective way of forming milling cutter is complete complex shapes, and can improve production efficiency and reduce tool inventory. Usually, a ladder, the parts required multiple tool joint processing and arc chamfering feature. If the combination of indexable forming cutter to process it can shorten the production time, reduce tool inventory and improve parts quality.

Customized non-standard indexable cutters are expensive and usually require modifications of the blade, so the blade is expensive. For these reasons, custom indexable cutters are usually used for mass production or for expensive parts

A major technical progress of transposition milling tool lies on the large mold cavity plunge milling. Due to the rough machining tool for deep cavity or ladder is very long, in the traditional processing technology, cutting tool flank feeding induced vibration. The rough machining tool inserted cutter according to the axial feed, can make the cutting force the best part of the machine tool spindle taper guide rigid. Need long cutting tool with plunge milling can bring high metal removal rate.

New pics-End mill for steel

Calloytool-cutting

 

Product

                   Roughing end mill

           ball nose long neck end mill

high efficiency machining end mill

               general purpose end mill

 

Application

Video

 

 

Advantages of indexable cutters

From the last century since the end of 20s, the hard alloy cutting tools have been widely used in the field of metal cutting. In 1950, cutting tool with carbide blade is gradually widely used in metal cutting, until it is still an essential tool for metal cutting.

Indexable cutters are usually made of steel knives, etc. the cutter body is machined with a blade slot for accurate positioning of the blade. The steel cutter body needs to clamp the blade, and a combination of the cutter body and the blade is mounted on the machine tool

Advantages of indexable cutters for monolithic cutters

In the use of cemented carbide indexable inserts, need whole tool machine removed from the heavy mill. Due to the heavy grinding workload, large factories are usually built to carry heavy grinding workshop tool regrinding. Therefore, using one of the most significant benefits of indexable tool is not required to remove from the production site the tool can realize the cutting edge. The cutting edge of the blade update updates are usually achieved by using the following methods: loosen the clamping blade, rotate or flip (translocation) blade to a new cutting edge, or install a new blade to replace completely worn blade.

Although in some occasions the use of the whole drill, tap and other tools in the turning process of overall, modern, indexable turning tool has been in a dominant position. With the popularity of the CNC machine, indexable tool has effectively replaced the high-speed steel cutting tool, hard alloy brazing tool and special forming cutter. With the help of CNC tool and multi axis linkage almost without the use of special cutting tool, indexable turning tool can simplify the generation of complex shapes.

In addition, the use of indexable drill than whole high-speed steel or hard alloy bit using the traditional advantage in the lathe. Usually with indexable drill, the drill bit deviated from the center hole to hole, so there is no need to use boring for boring. Because of the CNC lathe turret is usually caused by wear. Damage in the standard drill, the indexable drill will be more adapted to the right.

Like indexable drill, the cutting blade cutting blade turning function diversification, represents a tremendous progress in turning tool. Only the old feed groove cut in one direction, and the groove cutting blade can be used to cut in radial and axial direction.

Application of end mill-automotive industry-2

While choosing the appropriate tools and process seems to be quite difficult, but the use of valuable resources available, processing can help manufacturers do most small parts. Due to the increasingly fierce competition, can choose the most advanced tools and technology to improve the productivity, in order to maintain the leading position in technology, manufacturing enterprises may decide and select the appropriate business success or failure. The tool partners, but also to ensure the success of the processing.

Machining know-how

Although different micro cutting processes require different cutting strategies and processing sequences, there are still some technical know-how and machining guidelines that are applicable in many cases:

(1) in Swiss style lathe processing, should first in the main spindle for drilling and internal turning, because the guide sleeve can play a supporting role on the bar, therefore, can improve the processing stability

(2) the second step should be to cut the outer circle on the main spindle. If possible, it is better to use a knife to complete the cutting depth at the same time to shorten the cutting time so as to improve the machining stability

(3) the third step should be the milling process. The end face milling is preferred. Because the stability and power of the rotating spindle are limited, the cutting force is smaller, the better, and the end face milling can meet this requirement

(4) in order to finish the final stage of the outside diameter of the workpiece before the cutting process, the highly productive reverse machining is adopted, and it is helpful to reduce the vibration once a knife is finished

(5) cutting is the last step in the main shaft. The closer the two spindles are, the smaller the part overhang and the better the surface finish is

(6) finish the finishing process on the sub spindle at the end. The process is usually done with an inner diameter, but it can also be an outside diameter machining

Application of end mill-automotive industry-1

Automobile industry

Many auto parts with a metal sheet through the die formed body parts (such as doors, hood, fenders and other small car parts). But there are also many large batch processing (such as transmission shaft and gear). To reduce the cost per piece is the main object of mass processing of these parts. The key factors to achieve seamless production including process safety, processing cycle and product quality.

The transmission shaft and gear machining, steel turning to occupy the dominant position. However, careful selection of appropriate insert brands is crucial for turning steel, because this will pave the way for hard turning higher efficiency, if the work still needs grinding, can reduce the grinding allowance, resulting in lower processing costs per piece.

After optimization of the scraping blade and the cubic boron nitride (CBN) model tool combination can meet the grade of hard turning transmission parts requirements. After optimization of the scraping blade for high speed machining fine car surface hardened transmission parts. It uses a knife head locking technology, realize mechanical interlock multiple cutter the brazing position of high temperature zone away from the cutting knife head, compared with the traditional design, safety has higher strength and better. The mechanical interlocking cutter head can bear by the feed, cutting depth and intermittent cutting stress, which is able to maintain a reasonable choice of balance between satisfying the surface quality and dimensional accuracy and improve productivity.

Selecting tools and processes

Micro machining presents a unique set of challenges, not only because the workpiece size is very small, but in need of these small parts of the industry, most of the work hard processing materials, and has a complex geometry. With this kind of challenge, medical devices, aerospace and electronics industry increasingly fierce competition, the technical requirements have become the higher the need for large batch processing, and a large investment in the tool and blade.