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Let's Get It Out Of The Way! 15 Things About Machine Espresso We're Fed Up Of Hearing
How Does Machine Espresso Work?

The machine espresso makes use of precise pressure and filter technology that is awe-inspiring to create the coffee you enjoy. But how exactly does it work?

Espresso is created by forcing hot water under pressure through finely-ground coffee. The process is similar to that of making drip coffee. However, the pressure is the main difference.

The Head of the Group

As the name suggests, the group head is where you place your portafilter while making espresso. It is responsible for dispersing the water into the portafilter, and controlling the pressure that results from the extraction. There are various kinds of group head each with its own advantages and disadvantages. Some are focused on temperature stability, whereas others on pre-infusion features, and others are designed to control the lever. Some are a combination, like the E61. This is a favorite among baristas since it provides multiple advantages in one package.

As you can see from the photo above the group head is equipped with several notches. It is possible to place your portafilter inside these notches, and then twist the head to lock it. There is also a gasket of rubber that is a part of the notches to help create a seal when you insert your portafilter into the machine. The notches allow for precise placement of the portafilter. This is vital for an efficient extraction.

Aside from allowing you to effortlessly insert your portafilter the group head is also responsible for maintaining an even temperature. It does this by cycling hot water through the brew pan and around the portafilter, making sure that it is always at the right temperature to extract. It is important to note that even a small deviation can make the difference between a decent and a excellent espresso.

The Pump

The motorized pumps used in rotary espresso machines supply the nine atmospheric bars of pressure required to extract espresso. This differs from manually operated piston machines that employ a lever. The pressure builds up by removing tap water from a reservoir, and pumping it through a heat exchanger prior being pushed through the ground coffee inside the group head.

Pumps tend to be less expensive and last for longer than piston-driven machines. However, both kinds of machines can deteriorate due to overuse and insufficient cleaning. They also add mechanical complexity and can lead to a high price tag on even the simplest models.

Some espresso machines employ steam pressure instead of a pump in order to brew espresso. This could lead to over-extraction since the boiler that makes steam also heats the water to boil. They also have to constantly rebuild their pressure in between cups. This requires energy and time.

A majority of espresso machines use an rotary or vibrating pump, which has a vibration model using a vibrating disc to generate the pressure, and an rotary model that pushes hot water through the grounds under high speed. Both machines produce great espresso however rotary machines tend to be more stable, quieter and less likely to fail.

The Boiler

The boiler is the element that heats the water to the ideal temperature for extraction. The resultant steam then reaches the portafilter, which contains the ground espresso coffee and is then funneled down into the cup. During this process, the steam creates pressure to push through the grounds of the coffee. This creates a foam on top of the espresso. This is one of the hallmarks of a great espresso.

There are three different types of espresso machines, each having different types of pumps and the temperature of the brew. There are also different ways in which the brew can be controlled as well as the size of the cup that the machine can produce.

The earliest espresso machines were steam-based. The first espresso machines were steam types. This led to the coffee tasting bitter and burnt. This is why the Milanese producers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most commonly used espresso maker is a semi-automatic machine that has an electric pump. These are the images people have when they think of an espresso machine. With a semi-automatic machine you grind the beans and then tamp them by hand. The pump is able to regulate the flow of water and pressure. This is an excellent compromise between human touch and the mechanised accuracy.

The Filter

Espresso machines usually use filters that separate the grounds of the coffee from hot water. The filter is also a vital part of the temperature control system as it prevents the machine from overheating.

Filters also aid in flavor, as it permits an extended flowering time. This helps the beans to release their flavor and gives the chance 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 and the extraction process remain crucial.


It's in this area that the magic occurs. This is what makes espresso taste so delicious. The grouphead, sometimes called the brew head, is where the portafilter (the container you place the ground coffee in) sits when you're making espresso.

Steam-driven espresso machines use hot water heated in an airtight container to create steam. The steam then pushes hot water through grounds of coffee at high pressure. These machines are cheaper and easier for the user to maintain than pumps-driven models. They are however limited to create the ideal conditions for brewing as they only operate with 1-1.5 bar of pressure. The perfect shot requires 9-10 bars.

In recent years, espresso machines powered by compressed air-pump are becoming increasingly popular. They utilize an air compressor to push hot water through grounds and are more portable than electric steam-driven machines.