Milling is one of the most varied production processes in metalworking. The process creates precise, complex components that are used in many areas. Gühring provides suitable milling tools for machining different materials depending on the application. The range extends from all-rounders to specialist tools, from conventional roughing cutters to modern HPC/HSC strategies such as dynamic trochoidal milling (GTC) or iMachining (SolidCAM). Different cutting materials are also used for the milling cutters.

Roughing cutters for metalworking are subject to high mechanical loads. It is therefore essential to use a high-quality cutting material in this area that is extremely tough and resistant to rapid temperature fluctuations.

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For more flexibility in machining, Gühring offers PCD face milling heads that can be individually aligned to different machining operations. This is made possible by axially adjustable PCD cutting edges. Thanks to the integrated adjustment screws, the cutting edge axial runout of these milling cutters can be adjusted to the exact μm. These can be balanced using balancing screws for particularly smooth running at high speeds.

End mill 6 mmThe Gühring end mill made of solid carbide with 6 mm diameter and AlCrN coating is a new addition to the tool portfolio.

In metalworking, milling heads are mainly used for face milling and have four to 50 cutting edges. In older milling heads, the soldered cutting edges are made of carbide, modern ones have interchangeable inserts, usually made of carbide. Gühring also offers various milling cutters with cutting edges made of PCD, which enable even more efficient face milling.

End mill extra longGühring offers the XL end mill series for machining that requires extra-long milling cutters. These have a total length of up to 150 mm.

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In most cases, end mills with flutes arranged in a spiral shape are used for metalworking. This offers several advantages: The spiral flute ensures a uniform cut, uniform cutting force and smoother running of the machine. Chips are also removed to the side and do not enter the bore.

Finishing often follows roughing, with the aim of improving surface quality as well as dimensional and shape accuracy. In this milling process, smaller quantities of material are generally removed from the workpiece, usually only a few centimetres. Cutting with the finishing cutter produces larger chips, which must be removed from the work area using compressed air or cooling lubricant. An end mill with a roughing profile also generates lower cutting forces compared to a smooth-edged finishing cutter and therefore requires less drive power. Finishing cutters unleash their potential in particular in vibration-free machining on stable, high-performance machines with maximum machining volume, short unclamping and good cooling. Tools with a roughing profile, on the other hand, are also suitable for machining that is susceptible to vibration.

For groove-turning operations, the rigidity of the toolholder is even more important since the forces during groove turning are at 90° to the tool’s strength. So again, using a tool holder with the shortest cutting depth that will do the job is best. For groove turning the insert of choice is the longer two-edge style since the longer inserts are better able to resist the side forces generated in the turning operation. The geometry of the groove turning insert is also critical: it needs to have very good chip control properties in both the radial and axial cutting directions. Inserts for groove turning are designed with the proper chip breaker form around all the cutting edges, although that form may vary significantly from the front of the insert to the sides to handle the different flow of the chip in axial and radial grooving.

A. Without a chip breaker, there really aren’t any good ways to control the chips, and turn-grooving would be extremely difficult. The only option is to use a peck cycle to stop the cutting process and clear the chip. But that reduces productivity, and the chips are still quite long and cause problems. The chip breakers developed for grooving over the last 20 years have been a tremendous improvement to the grooving process.

In metalworking, a distinction is made between solid milling tools or end mills and carrier tools. Carrier tools are milling cutters with exchangeable indexable inserts. They can be converted to other milling processes in just a few simple steps. In the case of end mills, the cutting edge and the shank are made from a single piece. Each tool is designed for a specific task and can therefore only be used for this specific process. Here is an overview of the most commonly used cutter types:

End mills with a roughing profile are usually used for roughing. A high infeed width and depth should remove as much material as possible in the shortest possible time. This rough pre-machining produces a rough surface with visible machining marks. As a rule, the workpiece is finish machined afterwards. Learn more about our roughing cutters here.

In principle, we differentiate between circumferential milling and face milling. During face milling, the cutting edges on the face of the milling tools are responsible for chip removal. In this case, the tool is perpendicular to the machining plane. In peripheral milling, the tool axis is transverse to the workpiece. This means that the cutting movement takes place on the circumference of the tool.

A general rule for all grooving operations is to choose the widest insert possible that will do the job. This provides the strongest insert to handle the widely varying forces during the various phases of the cut, and the insert also has more mass to handle the heat generated especially at the bottom of the groove.

End mill 2 mmGühring offer four-flute solid carbide end mills with a nominal diameter of 2 mm. Different coatings are possible here.Micro milling cutters are available from 0.3-3.2 mm.

For most coating systems there is a trade-off between the higher wear resistance of CVD coatings containing aluminum oxide and PVD coatings that do not. With the Walter Tiger·tec® Silver PVD technology, the best of both worlds is provided – sharp edges and smooth coatings along with the superior heat and wear resistance of aluminum oxide. By providing all these advantages together, the insert has a wider application range, simplifying application for the customer while providing excellent performance.

A cutter continuously removes material from a blank in the form of chips. In contrast to a drill, which only cuts at the tip (main cutting edge), the milling cutter cuts on the circumference, the main cutting edge, the secondary cutting edge and at the end face. This allows the cutter to simultaneously process materials in different directions, also known as axes. During chip removal, the tools rotate around their own axis at high speed and simultaneously move according to the contour to be produced. The shape of the workpiece is therefore the result of the infeed width (ae) and the infeed depth (ap).

Steel, cast iron and hardened steel with tensile strengths of up to 1,400 N/mm² are no problem for the RF 100 U. Due to its unequal spiral angle, the Ratio 3 cutter creates a particularly easy cut even with large feeds.

A. As with most turning applications, tool choice for grooving operations depends on the details. For radial grooving operations, tool choice is straightforward. The toolholder needs to have the proper depth of cut capability to complete the groove, and securely clamp the insert. Choosing the toolholder with the shortest cutting depth that will do the job is best because the rigidity of the tool has an influence on tool life of the insert. The more rigidity and clamping force on the insert, the longer it will last.  Insert choice depends on the workpiece material and the cycle time requirements. By having the appropriate  geometry for the operation, the chip will be controlled and will easily exit the groove. Radial grooving operations can be done very effectively with either short single edge inserts, or with the longer two-edge inserts.

A milling head (also known as cutter head) is a milling tool with interchangeable inserts. Milling heads consist of a base tool with a machine interface and a cutting edge holder.

End mills with cylindrical shanks are defined in the ISO standard DIN 844. The standard contains information on dimensions, cutting materials, designs and identification of the tools. DIN 845 specifies the requirements for end mills with Morse taper shank.

A. It is quite important to select feed rate and speed that is appropriate for the workpiece material. This ensures the best performance of the insert, and the best possible productivity.

PVD coatings are used for most of the grooving and parting operations for a number of reasons. Since PVD coatings are thinner and adhere to sharp cutting edges better, the cutting edges can be sharper than with a typical CVD coated tool. The advantage is that the cutting edge generates lower forces, which in turn create less heat, and therefore less wear; and along with a very smooth surface, PVD coatings are less susceptible to built-up edge that is common in stainless steels and high temperature alloys. The sharper edge also significantly reduces the tool pressure that leads to work hardening of those alloys susceptible to it.

HSS roughing cutters are made of high-speed steel (high-performance high-speed steel) and enable fast and efficient machining of metals and plastics. Gühring offers roughing cutters with fine teeth made of HSS-E with different numbers of cutting edges and different surface treatments, such as the GS 80 roughing cutter.

The RF 100 Sharp solves all these problems: Chip jamming when milling soft and tough materials, difficult machine conditions and slow cutting speeds. The solid carbide milling cutter offers extremely high cutting speeds and metal removal rates.

During upcut milling, the cutter rotates against the feed direction of the workpiece. This creates a thickening chip, and the effort increases significantly from the entry of the cutting edge to the exit. During synchronous milling, the cutting edge rotates in the feed direction of the workpiece.As a result, the force is highest when the cutting edge enters. Synchronous milling is preferable due to the longer tool life and better surfaces on the component. In the following, a direct comparison is made between synchronous milling and upcut milling.

The RF 100 Diver has established itself for customers with high flexibility requirements, because it covers five operations at once. The tool has an innovative coolant supply that perfectly cools and protects both the face and peripheral geometry during drilling and plunging.

Gühring combines several solid carbide end mills in practical sets for different milling applications. For example, these sets include four-flute cutters with diameters of 6 to 12 mm.

End mills for metalworking can be made of different cutting materials. High-speed steel (HSS) and solid carbide (SC) are common.Universal or high-performance solid carbide milling cutters are used on modern CNC machines. They are particularly suitable for series production. High processing speeds make them extremely powerful. They also achieve a long service life as well as cutting depths and cutting widths. All in all, they therefore offer a high level of efficiency. Disadvantages of solid carbide milling cutters include the relatively high purchase price. They are also not suitable for production processes with unstable machine conditions.

Like the main cutting edge, the rake angle is located on the circumference on the milling tool. The rake angle is between minus 15 and plus 25 degrees depending on the materials to be machined. Tools with a positive rake angle cut the material with a soft cut and create a flowing chip. Tools with a negative rake angle create a scraping cut. Large rake angles of 10 to 25 degrees produce a sharp cutting edge and are suitable for milling very soft and sticky materials. The clearance angle is produced in two variants: With radial relief grinding, it produces a very quiet cutting behaviour and a stable cutting edge, which is why it is suitable for machining stainless and heat-resistant steels, for example. The clearance angle with facet cut produces a sharp to aggressive cutting behaviour.Milling tools are also designed with different helix angles – from zero to 55 degrees. The smaller the helix angle, the fewer contact points are created between the tool and the workpiece. Tools with a smaller helix angle therefore only achieve a low level of smoothness and are more suitable for roughing. Tools with a larger helix angle impress with their smoother running and are used for finishing.

Slotting is used to create elongated recesses which optionally pass through the material as an elongated hole or do not completely penetrate as a keyway, for example. This milling process is particularly demanding because the tools are fully enclosed by the material at 180 degrees.

A. Bad things. Depending on how far the cutting parameters are from the recommended values, there can be a wide range of effects. At the very least the tool life will be reduced. Improper parameters can also lead to chipping of the cutting edge, severe chip control problems, poor surface finish, and other issues; at its worst it can cause insert fracture and damage to the workpiece and the toolholder.

End mill 12mmLarge diameters are mainly used for high-performance milling because they can achieve higher machining volumes. Gühring offers solid carbide end mills with diameters of 12 to 32 mm.

With an end mill, the cutting face and clamping face are made from a single piece. The integrated shank is clamped into the receiver of the machine. The design of the clamping shank can be cylindrical or conical. End mills come in many different designs and are suitable for producing slots, grooves, pockets, recesses, dies and hollow shapes. Gühring offers various products in the end mill segment, such as roughing and finishing cutters.

During ramping, the cutter plunges into the materials obliquely. Slots, pockets or other shapes are then milled into the component. This plunging strategy creates elongated cavities.

A. For most situations, a chip breaker geometry is very useful. The only materials that don’t need chip breaker geometry are cast irons since the material naturally forms only small chips. The chip breaker folds the chip so that its width is less than the width of the groove – important to minimize contact of the chip with the walls of the groove so they can be ejected easily. This contraction of the chip prevents scratching of the groove walls to maintain a good surface finish.

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The choice of cutter depends, among other things, on the material to be machined. Gühring has a new chamfer cutter for metal processing: SpyroTec. The solid carbide tool ensures efficient milling thanks to its spiral cutting geometry and TiAIN coating.Learn more about the SpyroTec chamfer cutter here.

During helical plunging, the tools move into the component in a spiral. A circular pocket larger than the tool diameter is created.

Another significant factor is the higher toughness of PVD coated tools. This becomes quite important for parting operations that cut to the center of a solid bar. As the insert cuts to center, keeping the cutting speed constant requires higher rpm on the spindle. The maximum rpm for the machine is reached, and at that point the cutting speed drops quickly, eventually reaching zero at the center. The slower speeds generate high forces on the cutting edge, making it more susceptible to chipping. By using tougher PVD coated inserts, edge reliability is improved significantly.

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HSS milling cutters are made of high-speed steel. The main advantage of HSS milling cutters over solid carbide milling cutters is their lower purchase price. The disadvantages, on the other hand, are the low processing speed and short service life. HSS and HSS-E milling cutters are therefore rarely used in series production.

A particular challenge when milling aluminium is the heat generation of the material. With the Alu RF 100 A Ratio milling cutter, Gühring offers a new roughing cutter especially for machining aluminium with reliable internal cooling.

A. The cutting edge geometry determines the shearing action during the metal cutting process, as well as the strength of the cutting edge. A sharp and positive cutting edge will shear the workpiece material with low cutting pressure, and as a result generate less heat and also have less tendency for work hardening of the workpiece material. The trade-off is that the sharp edge is more susceptible to chipping from interruptions in the cut or higher feed rates. A stronger and more negative cutting edge geometry will better withstand higher forces and interruptions, but the price is higher cutting pressures, more heat generated, and a higher likelihood of work hardening.

CNC machine tools are used for milling in the metalworking industry in particular. This state-of-the-art control technology enables automated and therefore cost-effective production of workpieces with high precision. The machine uses Computerised Numerical Control (CNC) technology and initially designs the desired workpiece using a CAD program. A CAM system then provides this model with parameters such as speed, feed rate or cutting depth and transfers them to the CNC software. Series production is particularly economical on CNC milling machines because cutting speeds of up to 18,000 revolutions per minute can be achieved, and even over 50,000 revolutions per minute on high-speed machines.

Copy milling is carried out with a radius cutters. A distinction is made here between full-radius and corner-radius milling cutters, also known as Torus cutters. This allows complex shapes to be processed.

A. The coating provides heat and wear resistance to the tool, and provides a barrier to the highly reactive chips that can quickly wear away unprotected carbide. By keeping the heat away from the core of the insert, it prevents deformation of the cutting edge that creates higher forces and ultimately insert failure.

Milling is a machining production process with geometrically determined cutting edges and interrupted cutting. The aim of milling is to produce defined workpieces. Milling tools have one or more cutting edges and enable both vertical, horizontal and oblique machining of the materials to the rotational axis.

Milling tools can be used to machine components made of metal, plastic and wood. Cutting materials and geometries must be matched to the materials to be processed and the production process in order to achieve optimal results and a long tool life.

A. The multi-functional chip breaker has a form that varies around the insert cutting edge. The geometry on the front edge is designed for optimum chip form in radial operations and provides short, tight chips that are easily evacuated even when cutting low carbon steels like 1018. The chip breaker geometry on the sides of the insert comes into play during the axial turning phase of groove turning. Because the forces and material flow are different than in radial operations, the edge geometry and position of the chip breaking elements need to be different to get proper chip control. Finally, the corners of the insert are also different in form so that the insert leaves a good surface finish during axial turning operations.

A. Work hardening occurs during metal cutting due to the deformation of the workpiece material below the cutting edge of the insert. Use an insert with a relatively sharp edge preparation so the cutting edge creates as little pressure as possible. Ensure that the feed rate is larger than the minimum recommended for the insert geometry and width.

The RF 100 Speed is the fastest Ratio cutter in our range. Especially when machining extremely tough materials, the solid carbide milling cutter can be used to achieve high machining volumes with stable process reliability.

How do you find the right solution for your specific application from among 100,000 Gühring tools? It is easy, fast and convenient – with our “Gühring Navigator”. The intuitive product finder guides you to the ideal tool solution and associated cutting data.

A chamfer cutter is used to break sharp edges on workpieces and to machine chamfers. V-cuts, undercuts, deburring along the workpiece edges and the preparation of tools for welding are also common chamfer milling operations. Chamfer cutters are available in various angles, 45° is usually suitable for simple edge breaking.

Aluminium has a low weight and high conductivity, which makes it a popular material in the electrical industry, for example. However, milling aluminium is a very demanding process, because the material softens due to the heat generated during milling and the chips stick to the cutting edges of the milling tools. A single tooth cutter is best suited for machining aluminium, as the risk of chips “sticking” is lowest with this solution. Double tooth and multi tooth cutters can also be used for medium-hard aluminium alloys. Learn more about end mills for aluminium machining here.

A distinction is made between different types of milling heads:A face milling head with an angle of adjustment between 45° and 90° is used to machine surfaces. A corner milling head is used for face-peripheral milling and has an adjustment angle of 90°. Round cutting inserts are usually used in form milling heads, which make free-form milling or copy milling possible. Helical milling cutters are suitable for milling with extremely high cutting depths, which is why their interchangeable inserts are arranged one above the other and offset. Milling heads are also differentiated according to the number of interchangeable inserts that can be used and the different requirements for long or short-chipping material.

The roughing cutter cuts as much material as possible from the workpiece in the shortest possible time with large infeeds. This creates a rough surface.

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Walter AG is one of the world's leading metalworking companies. As provider of specialized machining solutions, Walter offers a wide range of precision tools for milling, turning, drilling and threading applications. Walter works together with its customers to develop custom solutions for fully machining components for use in the aviation and aerospace industries, as well as automotive, energy, and general engineering. The company demonstrates its Engineering Kompetenz at every stage of the machining process. As an innovative partner capable of creating digital process solutions for optimal efficiency, Walter is pioneering Industry 4.0 throughout the machining industry.