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How Does Machine Espresso Work?

The machine espresso uses precision pressure, and a filtering technology that is amazing to make the coffee you love. What exactly is it?

To make an espresso, hot water is forced under high pressure through finely ground coffee. The process is similar to making drip coffee, but the key difference is in the pressure.

The Head of the Group

The group head is the portafilter is inserted when you are making espresso. It distributes water into the portafilter, and regulates the pressure of the extraction. There are numerous kinds of group heads each with its own advantages and drawbacks. Some are specifically designed for stability of temperature while others are built to handle pre-infusion. Some are designed to control the lever. Some come with a combination of both, like the E61. This is a very popular choice for baristas since it provides multiple benefits in a single package.

As you can see in the image above the group head comes with many notches in which you can place your portafilter and then twist it manually to lock it in. A gasket made of rubber is positioned in the notches to make a seal when you insert your portafilter. The notches allow for the precise placement of the portafilter. This is essential for an even extraction.

Aside from allowing you to easily place your portafilter in, the group head is responsible to ensure that the temperature remains even. It does this by cycling hot water through the brew pan and around the portafilter, ensuring that it's always at the correct temperature to extract. It is important to remember that even a few degree difference can make the difference between a good and a excellent espresso.

The Pump

In contrast to piston machines that are manually operated, which use a lever to pressurize water, the rotary espresso machines use motorized pumps that provide the nine atmospheric bars of pressure needed for buy espresso makers extraction. The pressure is created by drawing tap water from a reservoir and pumping it through a heat exchanger prior being pumped through the ground coffee in the group head.

Pumps tend to be cheaper than piston-driven machines, and tend to last longer, however both types of machine can get damaged through overuse and lack of cleaning. They also increase the complexity of mechanical systems which can result in a high price tag on even the simplest models.

Some espresso machines eliminate the pump completely and make use of steam pressure to make espresso coffee machine. The disadvantage of this is that the same boiler that produces steam also raises the temperature of water to boiling, which can lead to excessive extraction. These machines also have to constantly rebuild their pressure between cups. This takes energy and time.

A large majority of espresso machines employ either a vibration or rotary pump. A vibration model employs the vibrating disk to create pressure, whereas the rotating model pushes hot water through the ground at high speed. Both machines can produce excellent espresso, but rotary machines are more quiet, durable and less likely to fail.

The Boiler

The boiler is the element that heats water to an ideal temperature for extraction. The steam that is created gets to the portafilter which holds the espresso grounds. It is then pumped into the cup. During this process the steam causes enough pressure to push the grounds of coffee through. This results in a crema on the top of the espresso. This is a hallmark of a great espresso.

There are three kinds of espresso makers - visit their website -, and they differ in the type of pump they use and the degree of heat that the espresso is. There are a variety of ways to control the brew and the size of cup that can be produced by the machine.

The first espresso machines were steam-type. They employed a single boiler to make both brew and steam, however, the pressure they could create was minimal - two bars of atmospheric pressure at most. This led to the coffee tasting bitter and burnt. This is the reason why Milanese makers Luigi Bezzerra and Desiderio Pavoni created the modern espresso machine.

The most well-known espresso maker is a semi-automatic machine that has an electric espresso maker pump. When people think of espresso machines, they think of these machines. Semi-automatic machines require you to grind and tamp the beans by yourself however the pump controls the flow of water and pressure. This is an excellent compromise between human control and mechanized accuracy.

The Filter

Typically, espresso machines use a filter to separate out the grounds of coffee as they move through the hot water. The filter is also an essential component of the temperature control system, since it helps prevent the machine from overheating.

A filter also helps with flavor, as it permits a longer flowering phase. This lets the beans release their nuances, and allows for better extraction.

It is important to keep in mind that even the most efficient filter could result in a poor cup of coffee. The quality of the beans as well as the extraction, are still very important.

It's here that the magic takes place. This is the reason why espresso tastes so good. The grouphead, often referred to as the brew head, is the place where the portafilter (the container you place the coffee ground into) sits when you're making espresso.

In an espresso machine that is driven by steam, hot water is heated in an airtight container to create steam. This is then pushed through the grounds under high pressure. These machines are less expensive and easier for the owner to maintain than pumps-driven models. However, they are not as efficient in their capacity to create the ideal brewing conditions, because they operate at 1-1.5 bars of pressure, while the perfect shot requires 9-10 bar.

In recent years, compressed air-pump-driven espresso machines have become more popular. They make use of an air compressor to push hot water across the ground and are much more mobile than electric steam-driven espresso machines.