Angle Grinder Test


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Angle Grinder

Our test winner is the Bosch Professional Angle Grinder GWS 18-125: The device is extremely powerful and well suited for heavy work. Our favourite with the test grade 8.8/10!

We have tested 4 angle grinders and paid especially attention to the cutting quality and handling.

Are you a professional craftsman or just a passionate do-it-yourselfer? Not everywhere you want to cut, mill or grind materials, there's a power outlet nearby. A rechargeable angle grinder is a perfect solution: It is transportable, versatile and yet high performance.

We test independently. uses affiliate links. For a purchase via a link marked with a or our price comparison, we may receive a small commission.

last modified: 12.11.2019, 9:53
Winner Best price winner
Our winner: Bosch Professional GWS 18-125 V-LI Angle Grinder Makita DGA452Z Angle Grinder Review Metabo Cordless Power Extreme Grinder Review Einhell Cordless Angle Grinder TE-AG 18 Li Kit Review

Bosch Professional GWS 18-125 V-LI Angle Grinder

Makita DGA452Z Angle Grinder

Metabo Cordless Power Extreme Grinder

Einhell Cordless Angle Grinder TE-AG 18 Li Kit

Test seal: Bosch Professional GWS 18-125 V-LI Angle Grinder, Rating 1.8
Test seal: Makita DGA452Z Angle Grinder, Rating 2
Test seal: Metabo Cordless Power Extreme Grinder, Rating 2.2
Test seal: Einhell Cordless Angle Grinder TE-AG 18 Li Kit, Rating 2.35
  • Extremely powerful
  • Long battery life
  • Small and compact
  • High performance
  • Can be set upright
  • Quick clamping system during the disc change
  • Small and compact
  • Quick clamping system of the protective hood
  • Ergonomic to hold
  • Carrying case included
  • Tool required for moving the protective cover
  • Tool required for moving the protective cover
  • Performance not optimal
  • Disc size maximum of 115 mm
  • Very large
  • No optimal performance

An extremely powerful angle grinder that is well suited for heavy work.

Small, compact and yet powerful. Convincing on all levels!

A small, compact angle grinder for simple, shorter work. In the end, it lacks the final performance.

A practical angle grinder. In contrast to its competitors, however, it lacks the last strength in the end.

Cut quality
Overall impression
Scope of delivery Angle grinder, handle Angle grinder, roughing wheel, side handle, face wrench Angle grinder, handle Case, angle grinder, handle, battery, charging station
Quality impression Excellent High quality Good Good
Packaging Box Cardboard Cardboard Case
Additional warranty 3 years 12 months 1 year 3 years
Quality of instructions Good Satisfactory Excellent Good
Manual language GER, EN GB GER, EN, FR, NL, IT, ES, PT, SV, FI, NO, DK, PL, EL, HU, RU GER, GB, FR, IT, DK, NL, ES, PO, FIN
Width 17 cm 12 cm 11.5 cm 15 cm
Height 35 cm 36 cm 39 cm 37 cm
Depth 29 cm 18.5 cm 29 cm 33 cm
Weight 2,341 g 2,412 g 2,291 g 2,371 g
Volume 1m distance (idle) 90 dB 85 dB 87 dB 81 dB
Idling speed 10,000 U/min 10,000 U/min 8,000 U/min 8,500 U/min
Smooth start No No No No
Lockable switch Yes Yes Yes Yes
Disc diameter 125 mm 115 mm 125 mm 125 mm
Disk change Turnbuckle Turnbuckle Quick clamping system Turnbuckle
Adjustable protective cover Allen key Slotted screwdriver Quick clamping system Quick clamping system
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*All prices include VAT (if applicable, extra charge for delivery. Check the particular online shop to find information about the availability. Changes of indicated prices since the last update remain reserved.

Tested products

1st place: Bosch Professional GWS 18-125 V-LI Angle Grinder

Test seal: Bosch Professional GWS 18-125 V-LI Angle Grinder, Rating good

The Bosch Professional GWS 18-125 V-LI Angle Grinder can convince in almost all categories. It lies comfortably in the hand, has a very strong performance and the included 6.0 Ah battery ensures a long service life without having to charge the battery. In addition, the device can be placed upright and does not have to be put down.

read review
Makita DGA452Z Angle Grinder - thumbnail Test seal: Makita DGA452Z Angle Grinder, Rating good

2nd place: Makita DGA452Z Angle Grinder

On the whole, the Makita DGA452Z Angle Grinder is convincing. Compared to other models it is very compact and small, but still has a lot of power. It can also stand upright. However, you will need tools to adjust the protective hood and change the discs.

read review
Metabo Cordless Power Extreme Grinder - thumbnail Test seal: Metabo Cordless Power Extreme Grinder, Rating good

3rd place: Metabo Cordless Power Extreme Grinder

The Metabo Cordless Power Extreme Grinder is characterized above all by its simple and practical handling. Both the guard plate and the discs can be exchanged or moved using a quick-release clamping system. However, one has to make sacrifices regarding performance. The cutting process on metal is carried out without any problems. However, if you need to do heavier and longer work, the angle grinder is not for you.

read review
Einhell Cordless Angle Grinder TE-AG 18 Li Kit - thumbnail Test seal: Einhell Cordless Angle Grinder TE-AG 18 Li Kit, Rating good

4th place: Einhell Cordless Angle Grinder TE-AG 18 Li Kit

The Cordless Angle Grinder TE-AG 18 Li Kit by Einhell is a very large machine. The mudguard can be moved with a quick clamping system. However, the angle grinder has to cut back on performance. It performs the cutting process on metal and other materials without any problems. However, if you need to do heavier work for a longer time, the angle grinder is not for you.

read review

Bosch Professional - GWS 18-125 V-LI Angle Grinder

Winner: read review
  • Find out which discs are suitable for which materials
  • Hearing protection, safety glasses and protective clothing are a must
  • Make sure that there are no flammable objects in close proximity
  • A battery with a lot of capacity is very noticeable in the power duration
  • An angle grinder with a quick clamping system helps you if you change your discs very often

In the run-up to the test, we defined practical requirements and the following test criteria:

  • Cutting quality
  • Overall impression
  • Handling
  • Safety and security
  • Ergonomics

In order to evaluate these criteria, we have defined several tests for the battery angle grinders. First, the scope of delivery and functions are checked. In order to be able to compare the devices better with each other, the metal cutting disc Bosch DIY 115 x 2.5mm is used for all of them. In the test sequences, various bicycle locks made of hardened steel are cut through with the battery angle grinders. The test also takes into account whether the devices fit well in the hand and are easy to operate even after long working hours. In further test runs, the batteries were fully charged and checked to see how long the battery life is for several disconnection processes.

In order to rule out errors and to ensure the load of everyday use, each test takes place in several runs.

The test criteria are given percentages depending on their importance. The final score is then objectively calculated from the test criteria using an algorithm.

Product selection

Our product selection is based on an observation of the current market. In addition to popular branded products, we also include insider tips in our selection. Criteria such as price and range of functions are an important factor for us. The test field is also determined by analysis and evaluation of customer reviews and external tests (e.g. Stiftung Warentest).

The devices are purchased anonymously or lent to us by the manufacturer. Dealers and manufacturers have no influence on the tests and our evaluation.

As soon as new relevant products come onto the market, our test field is extended by these. The new products go through the same test as the already tested devices.

On almost all building sites and also in many other crafts enterprises angle grinders are used very often. However, these power tools are also used by numerous DIY enthusiasts. The reason is, of course, the versatility of these tools.

Which work can be carried out with the angle grinders is described in more detail in the following sections. You will also find out why these tools are sometimes referred to as flex.

But first of all, it is advisable to describe the angle grinders with regard to their functionality. This is not only important for understanding but can also be a help if you are thinking about buying such a tool at some point.

This question can actually be answered quite simply. It is a power tool with which workpieces made of metal, stone or ceramics can be machined. Angle irons, tubes, and other steel profiles can be easily cut to size. Other workpieces made of different metals can also be cut without any problems. However, grinding work of any kind can also be carried out. The range extends from derusting and form grinding to the removal of paintwork.

The angle grinders are also suitable for sharpening knives for lawn mowers or agricultural machines. Once you get used to the handling, you will have no difficulty at all in working with high precision. It is just as easy to cut stones or concrete components. Cutting tiles is also possible without any problems.

All work carried out with a Flex always requires high peripheral speeds of the cutting and grinding wheels. The wheels are driven by an electric motor. This is located in stable housing. A handle is attached to the rear of the housing. It also contains the switch that switches the motor on and off. There is no speed control on an angle grinder as known from a drill.

Find out which discs are suitable for which materials.

This is because the discs should always rotate at a constantly high speed. How high it is, always depends on the diameter of the disc. They do not work at a reduced speed. However, modern devices of this type are equipped with an automatic start. When the switch is actuated, the speed of the grinding wheel builds up slowly thanks to this technology. This avoids high starting currents. However, this technology is usually only available in very powerful versions.

Since there are no high starting currents, there is no danger of the fuse jumping out. Such a power tool usually works with a mains voltage of 230 Volt. Therefore, a Flex can be connected to any socket. Meanwhile, devices with a battery drive are also available. These are particularly advantageous when working in areas where there is no power supply.

The drive shaft of the motor ends in an angular gear. Hence the name angle grinder. The grinding or cutting wheel rotates at an angle of 90 degrees to the drive motor. Exactly this aspect is the most important advantage of these power tools. The holders for the discs are standardized. For mounting the grinding wheels a special wrench is required, which is included in almost all angle grinders. Depending on the model, the drive shaft is fixed with a fork wrench or a push button. Fixing with a push button is called spindle locking. This makes it much easier to change the cutting and grinding wheels. In this case, only a key is required. This is much more practical.

However, for safety reasons, the mains plug must be pulled each time the disc is changed. If the power button is accidentally pressed when changing the pane, the hands of the fitter will be seriously injured. Since the discs rotate at a high speed during work, it is important that they are always firmly mounted.

When working with a Flex, sparks spray. The violent flying of sparks is not completely harmless. Therefore it is absolutely necessary to wear protective goggles when working with an angle grinder. The sparks flying at high speed can cause serious injuries to the eyes. There is a spark arrester in a semi-circle around the grinding wheel. This is a mudguard that directs the spark in a certain direction.

With most devices, the position of the spark arrester is freely adjustable. In any case, the protection must be adjusted so that the sparks are not directed in the direction of flammable materials. However, everyone will quickly find out what the optimum setting is.

Typical operations carried out with an angle grinder include cutting steel tools to size. With a correspondingly large flex, pipes with a diameter of three inches and more can also be cut. U-iron, flat iron, and all other types can also be cut easily. Another common job is cutting welds. Even if they are very hard, they can be cut with a flex.

Special stands are also available for precise cuts. These are fixed on a workbench. The angle grinder then only needs to be clamped in the stand. The device is then pressed down with a lever. There workpieces can be fixed exactly so that rectangular cuts or mitre cuts can be made with high precision. Such stands are available in different designs, so that angle grinders of different designs can be clamped in them. The function is then similar to that of a cross-cut saw for cutting wood.

On a construction site, the construction workers cut stones, concrete parts, and tiles with an angle grinder. It is also possible to cut larger blocks of reinforced concrete. If the disc hits a reinforcing iron, it is also cut with a grinder. On a construction site there are many possible applications for angle grinders. That is why the equipment can always be found there. Often the flex is also simply put on the back. Then chisels and drills can be sharpened on the free-running grinding wheel at any time without great effort.

Make sure that there are no flammable objects in the vicinity.

Actually, this should not be done this way, because it is dangerous. However, since this procedure proves to be practical, it is still done this way again and again. It is not possible to process workpieces made of wood or plastic with such a power tool. In order to carry out different tasks, different discs are necessary. In the following section, you will find out which there are and what they are used for. This will also give you an overview of what is possible.

The panes usually consist of a synthetic resin mixture reinforced with glass fibres. This makes it resistant to high forces and temperatures. Basically, the grinding and cutting wheels are divided into metal and stone. With a stone wheel you can also process concrete, marble and other special materials of this class. A metal disc can be used to process steel, cast iron and many other metals.

Cutting discs for metal, however, are not very suitable for cutting copper pipes. This creates a lot of burr which narrows the pipe opening. When laying heating pipes, the constriction is usually noticeable in the form of noise or other unpleasant noises.

An angle grinder with quick-clamping system helps you if you change your discs very often.

However, there are not only differences in the materials that can be machined. Different disks are needed for cutting workpieces than for grinding. Discs that are used for grinding have a slightly different composition. In principle, it is possible to carry out grinding work with a cut-off wheel. This, however, results in very heavy wear. The reason for the high wear is that the glass fibre reinforcement on the surface dissolves during grinding.

Then the cut-off wheel loses its hold and wears within a few minutes. Therefore, grinding wheels are much thicker than cutting wheels. They are also colloquially referred to as rough grinding wheels. They are suitable for high material removal. It is therefore easy to remove rust or old layers of paint from the workpieces. Roughing discs are also suitable for removing surface irregularities.

There are also extra thin flex discs. These have a thickness of about one millimeter. Since they only make very narrow cuts, they are highly efficient. Such cut-off wheels are ideally suited for precision cuts. When working with thin cut-off wheels, it is only necessary to ensure that the angle grinder is not held in such a way that the wheel cants. It cannot withstand high bending forces.

When choosing the right disc, however, the diameter also plays an important role. There are basically these four standardized sizes:

  • 115 millimetres
  • 125 millimeters
  • 178 millimeters
  • 230 millimeters

Of course, there are also larger cut-off wheels with diameters of up to 400 millimetres. However, these are no longer used with angle grinders, but with special equipment driven by combustion engines.

The different disc sizes are suitable for angle grinders in different performance classes. Smaller angle grinders often referred to as one-hand angle grinders, are equipped with discs with a diameter of 115 or 125 millimetres. These machines have an output of about 600 to 800 watts. A medium-sized Flex works with a disc that has a diameter of 178 millimeters. A cut-off wheel with a diameter of 125 millimeters can also easily be clamped on such a device.

The motor power of these devices is about 1400 to 1800 watts. Angle grinders that are suitable for grinding and cutting wheels with a diameter of up to 230 millimeters achieve an output of more than 2000 watts. It is advantageous to use two angle grinders of different sizes. Since the discs are subject to wear as a result of work, the heavily worn disc can still be used on a smaller flex. In this way, the grinding wheels can be used much better.

The holes for the mounting are identical for all wheel sizes. This makes it easy to change to another machine at any time.

Discs of different sizes are also operated at different speeds. In the smaller models with 115 and 125 millimetre diameters, work is usually carried out at around 10,000 revolutions per minute. If the cutting disc has a diameter of 178 millimeters, it rotates at an average of 8,500 revolutions per minute. In the largest versions with a diameter of 230 millimeters, only about 6,500 revolutions per minute are achieved.

The slightly more expensive diamond discs represent a special form. These are coated with diamond dust and therefore very wear-resistant. They are particularly suitable for cutting different stone materials and especially tiles. You can also cut tiles with a conventional stone disc, but then due to the hard ceramics high wear arises. So if you have to cut a lot of tiles, the purchase of a diamond cutting disc is definitely worthwhile. The additional costs for such a disc are lower than the purchase price.

For angle grinders, wire brush attachments are also available in addition to the cutting, grinding and roughing wheels. These are mounted on the spindle to which the discs are otherwise attached. Wire brush attachments are ideal for derusting or cleaning extremely dirty equipment. The advantage of working with a wire brush attachment is that hardly any material is removed. This is extremely important if a workpiece is to retain its original dimensions in any case.

When working with such an attachment there are usually no sparks flying, but for safety reasons you should never work without safety goggles. Small metal splinters or rust particles fly through the area like small projectiles. If these particles hit the hands or arms, it is a bit unpleasant. In the sensitive eyes, however, they cause serious injuries that lead to impaired vision.

Instead of a wire brush attachment, a serrated washer can also be used. This usually achieves a slightly higher abrasion so that it can also be used to carry out various preliminary work. It is particularly advantageous that the diamond cutting disc, the serrated discs and also the wire brushes are all provided with standardised mounting holes. Therefore, all discs and brushes can be used on all angle grinders. There are no manufacturer-specific standards for these power tools.

Any disc can be used with any flex from any manufacturer.

First, it should be made clear that the term Flex is based on a company name. This company was founded in the 1920s. There the first angle grinders were developed and marketed. Because this company was the only supplier of such power tools for many years, the angle grinders are still called Flex today and everyone knows immediately which tool it is. It is particularly interesting that working with an angle grinder is also referred to as flexing.

In the course of time, the verb form flexen was derived from the company name Flex. This name has been established over the decades and is still used today. It is already very unusual that a tool was named after a company and even a verb developed from it. Something comparable will probably be hard to find.

Another interesting aspect is that both the cut-off wheels and the grinding wheels are called flex wheels everywhere. It doesn't matter which manufacturer the wheels come from. In addition, many craftsmen simply refer to the protective goggles required at work as flex goggles. There is hardly any other power tool that has influenced the world of work to such an extent.

The history of these special power tools begins in 1922 when the two entrepreneurs Hermann Ackermann and Hermann Schmidt founded the company Ackermann & Schmidt. Until that year there were only stationary grinding machines. The two company founders wanted to change this because they saw great potential in a flexible and portable grinding machine. The two inventors, therefore, designed a hand grinder with the sober designation MS6. This consisted of an electric motor to which a flexible shaft was attached. At the end of the shaft, there was a grinding attachment. The greatest advantage of this invention was that it could be transported to any location to carry out grinding work on larger machines.

At the end of the 1920s, the two inventors came up with the idea of installing an angular gear instead of a flexible shaft. The first devices of this type were still working at low speeds. At that time, there were no modern cutting and grinding wheels that worked at high speeds. It was not until 1954 that the first angle grinders with high speeds appeared on the market. At that time, the name Flex had long been a widespread name for angle grinders. It was not until years later that other manufacturers started producing angle grinders.

In 1996 the company became Flex-Elektrowerkzeuge GmbH. The product range was extended to include polishing machines and long-neck sanders, which are mainly used in dry construction. In 2004 the company was taken over by Black & Decker. Meanwhile, more precisely since 2013, the Flex electrical appliances belong to the Chinese company Chervon Holding. Nevertheless, various polishing machines and angle grinders of the Flex brand are still available. These power tools have never lost their good reputation. They continue to enjoy great popularity. This applies not only to do-it-yourselfers but also to many professional craft businesses.

How do we test at

Live and authentic: We get the devices into our Hamburg test laboratory. Here we take a close look at everything.

Each test is preceded by an extensive search:

  • Which suppliers are on the market?
  • What current products are there?
  • What are the comparison criteria?
  • What tests are we going to run?
  • What is the test procedure?

When everything's settled, we'll bring the devices to us. For each product the test procedure, the measured values and product properties are documented in detail. We create photos and videos. We evaluate the results for you, summarize everything in a test report and calculate the test grade.

Have fun!

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What is the best angle grinder?

Our test winner is the Bosch Professional Angle Grinder GWS 18-125: The device is extremely powerful and well suited for heavy work. Our favourite with the test grade 8.8/10!

We have tested 4 angle grinders and paid especially attention to the cutting quality and handling.

Are you a professional craftsman or just a passionate do-it-yourselfer? Not everywhere you want to cut, mill or grind materials, there's a power outlet nearby. A rechargeable angle grinder is a perfect solution: It is transportable, versatile and yet high performance.


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