Coffee grinder: basic types, principles of operation and features

The main purpose of a coffee grinder is to grind coffee beans to a homogeneous consistency, in which all particles will be identical in size.

If the particles are different in size, then during the extraction process more substances will be obtained from the coffee microparticles, and less from the large grains. In the case of small particles, when brewing coffee, water gains free access simultaneously to the entire surface of the grain cellulose. While coarse grinding retains whole cells in the particles, part of the cellulose surface remains inside, and water access to it is limited. As a result, the taste balance is disturbed. One cup of coffee combines an over-extracted blend and a bland, slightly saturated drink.

The possibility of obtaining a uniform fraction is a key indicator that affects the choice of a coffee grinder. Functionality, efficiency, purpose and convenience during operation are also considered important parameters.

How to choose a coffee grinder


When choosing the best option, you need to take into account a number of parameters: a list of functions, additional equipment, device efficiency, and much more.

Overheating protection . The degree of heating of the elements directly affects the particle size, the likelihood of clumping, the intensity of taste and aroma. Therefore, most manufacturers try to balance the heating temperature of the device.

The higher the heating temperature, the more the metal expands, and therefore the size of the resulting particles will be smaller. Moreover, the coffee particles will bake and lose their aroma due to contact with hot parts.

For espresso, temperature consistency is extremely important, as overheating will increase the grinding time by a few seconds, and this will affect the quality of the drink. There are coffee grinders equipped with coolers to help stabilize the temperature.

In order to brew an espresso at home or in a small establishment with a limited number of visitors, the thermoregulation system is not important. However, if the device is intended for a large establishment with a large influx of guests, it is better to immediately purchase a high-quality device with an additional cooling system for the engine and millstones. This will ensure high efficiency and stability.

Remains of ground coffee inside the structure . On some models, the channels and outlets are clogged with ground coffee. This is reflected in the quality of the drink prepared for the next portions.

This problem most often occurs in devices with horizontal burrs. After the completion of the next grinding, some of the coffee remains inside. Until the next portion is prepared, this coffee oxidizes and loses its richness of aroma and taste.

Sometimes about 10 g of coffee remains from the previous portion. Considering that a standard cup of coffee requires 18 g, more than half of the serving will be old coffee.

In devices with an inclined and vertical arrangement of millstones, this problem does not arise.

Grinding adjustment type . There are two types of grinding settings: micrometric and stepwise. The first type provides a smooth transition. In such devices, you can gradually move the millstones, achieving the required performance. With step-by-step adjustment, the elements are adjusted according to the specified parameters. That is, you should choose from several suggested steps. Micrometric adjustment is ideal for espresso brewing, especially for flat grinders.

Dosage . Some grinders can be adjusted to a specific dosage. Usually the dosage is metered on a timer. This is an affordable and effective solution. However, there are also disadvantages. Due to the difference in the density of coffee beans of different varieties, different amounts can be grinded in the same period of time. After changing the coffee type, you will have to re-configure the device.

To solve this problem, it is recommended to purchase a device with a built-in scale.

Also, such structures are often equipped with an additional measuring device.

Key differences between coffee grinders

Further, the device of coffee grinders will be discussed in more detail. There are many factors to consider when choosing a device.

Burr diameter

This indicator affects the uniformity of the particles obtained in the process of grinding the grains. Also, the type of millstones affects the speed and efficiency of the device, the level of heating and clumping during grinding.

The simplest and most common type of device is a coffee grinder with rotary knives inside the appliance chamber.

In terms of functionality, such a device is identical to a blender. As a result of such processing of coffee beans, it is impossible to obtain a homogeneous fraction. Due to uneven grinding, the knife grinder will not be able to prepare a drink according to any specific recipe. You shouldn’t dwell on this option, since the coffee prepared in this way will not taste good.

Coffee beans go through three stages of processing:

  1. Crushing grain.
  2. Grinding of large particles.
  3. Grinding for the final result.

After processing, the coffee mass is collected in a special container.

The cone-shaped millstones crush the grain mainly by pressing rather than cutting.

During the rotation of the lower element, the grains move along helical tubes or grooves and fall on a row of teeth, which, in turn, grind them to the required size.

Differences between flat and conical millstones

A machine with flat burrs produces a more uniform grinding than a machine with conical elements. This makes it possible to prepare a more refined drink without upsetting the balance of taste and aroma. But such devices also have disadvantages. The efficiency and functionality of the design with flat millstones is much lower. Due to the rapid rotation of the parts, the device heats up quickly, and therefore the aroma evaporates and the intensity of the taste decreases. Moreover, you will have to wait a while until the appliance cools down to make the ground coffee again.

Devices with conical burrs do not make it possible to obtain such a uniform fraction, but their productivity is higher. This is due to the fact that the rotation speed of the elements is half that of a design with flat millstones. Such a device is well suited for preparing espresso, since a wider selection of fractions helps to protect the coffee from the influence of environmental factors.

Materials for making millstones

The duration and efficiency of the device depend on the quality of the material. It also affects the amount of coffee dust produced during the grinding process.

Ceramic parts practically do not grind, thanks to which they last longer. But this is a rather fragile material, so ceramic millstones often break when solid objects hit. And in the process, they produce more coffee dust. Therefore, making high quality coffee is much more difficult in this case.

The main factor that influenced the increase in the production of coffee grinders with ceramic parts is the low cost of materials.

Steel millstones differ in their quality. Over time, they grind down, and their effectiveness decreases. To increase wear resistance, a titanium or tungsten carbide coating is applied to the steel elements.

The cost of such millstones is higher, but the service life is longer. If ordinary metal parts need to be changed after processing 0.5-1 thousand kg of coffee, then metal millstones with a protective coating will last three times longer.

What to choose: steel or ceramic millstones?

Experts recommend giving preference to steel millstones with a protective coating. Such a coffee grinder allows you to prepare a higher quality drink than a device with ceramic elements. True coffee connoisseurs understand that the difference in taste and aroma is significant.

Millstone size

Another important factor is the size of the millstones. This indicator will depend on the grinding speed, the uniformity of the particles and the heating temperature of the device during operation. If the appliance overheats, the coffee particles will bake, and therefore the main aroma disappears and a bitter taste of burnt coffee appears. Moreover, you will often have to adjust the grind, because the size of the grains changes due to the expansion of the metal parts when heated.

Large millstones are preferable. They allow you to increase the grinding speed, reduce the degree of heating of the device and get more uniform particles.

Moreover, this factor also affects the clumping of coffee beans. Involuntary adhesion and compaction of particles is bad for the quality of extraction. This most often happens in structures with small millstones. To reduce the likelihood of clumping, it is recommended to select devices with large burrs (inclined or vertical).

What size millstone is better?

The decision directly depends on the desired cooking speed and the volume of the processed product. If the machine is purchased for home use or making coffee for a small establishment, you can take a device with small millstones. If the device is intended for an institution with a high level of attendance, it is better to give preference to large millstones.

Espresso devices

Espresso models allow you to make fine coffee. Often they are equipped with an additional special holder for a removable holder.

One of the most common varieties is a machine with a special container for collecting ground coffee, known as a hopper. Such a capacity is necessary if the performance of the device is not high, and the volumes of preparation of ground coffee are large. In such a situation, you can prepare ground coffee in advance and collect it in the hopper. And then to prepare the next cup, simply pour the contents into the holder. There are also blades inside the hopper that break up the ground coffee clumps. One of the significant disadvantages of such a device is the oxidation of coffee and the lack of stability in preparation.

There are also designs with the collection of ground coffee in a separate container. One of the clear advantages of this device is that the coffee is ground separately for each cup. Consequently, the coffee does not have time to oxidize, and the rich taste and aroma are preserved. Often, such devices are equipped with a timer that allows you to control the dosage of coffee. But there is also a drawback. With a low productivity of the device, grinding of beans for a standard cup may take at least 15 seconds, which is quite a long time. There is also the possibility of coffee clumping.

In some devices, coffee, after grinding, goes directly to the holder. Most of these models are equipped with a timer. This is the preferred option.

Devices for alternative recipes

In such coffee grinders, you can make coarse coffee without coffee dust. They are equipped not with a holder, but with a removable hopper or a special clamp for a measuring container.

Top tips for choosing a coffee grinder

The quality of the taste and the richness of the aroma of coffee depends on the quality of the grinder even more than on the coffee machine.

The first question to be answered when choosing a grinder is the purpose of the device:

  • For espresso it is recommended to choose devices with micrometric grinding adjustment, removable holder and timer (or scales) to control dosage.
  • It is better to give preference to a coffee grinder with large steel millstones with a protective coating and an additional cooling system. They are significantly higher in quality and, therefore, in price.
  • If a coarse grind is required, additional parameters are not so significant.

The cost of a coffee grinder directly reflects its quality. If possible, it is advisable to choose the most expensive and high-quality device. This will help to save on further repairs and parts replacement. But you shouldn’t skimp on the quality of your coffee.