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Do You Think Machine Espresso One Day Rule The World?
How Does Machine Espresso Work?

Machine espresso uses precision pressure and mind-blowing filter technology to create the perfect cup of coffee. How exactly does it work?

To make espresso, hot water is pushed under pressure through finely ground coffee. The process is similar to making drip coffee. However the pressure is the primary difference.

The Group Head

As the name implies, the group head is the place you place your portafilter when brewing espresso. It disperses the water into the portafilter, and then regulates the pressure of the extraction. There are many different types of group heads, each with its own advantages and drawbacks. Some are focused on temperature stability, others on pre-infusion capabilities, while others are designed to control the lever. Some come with a combination of both, like the E61. This is a preferred choice for baristas as it provides a variety of advantages in one package.

As you can see in the image above, the group head is fitted with several notches. The portafilter is placed in these notches, then twist the head to secure it. A gasket made of rubber is placed in the notches to create a seal as you insert your portafilter. The notches on the head allow for an exact position of the portafilter which is crucial to ensure an efficient extraction.

In addition to allowing you effortlessly insert your portafilter the group head is responsible for maintaining an even temperature. It does this by cycling hot water through the brew basket, and around the portafilter to ensure that it is always at the correct temperature for extraction. It is important to remember that even a few degree variation can mean the difference between a good and great espresso.

The Pump

Unlike manual piston machines, that use a lever to pressurize water, the rotary espresso machines use motorized pumps to deliver the nine atmospheric bars of pressure needed for espresso extraction. The pressure builds by drawing tap water from a reservoir and pumping it through a heat exchanger prior it is shot through the ground coffee in the group head.


Pumps are generally less expensive than piston-driven machines and tend to last longer, however both types of machine can get damaged through overuse and lack of cleaning. Pumps are also more complicated mechanically, which could increase the price of even the simpler models.

Certain espresso machines utilize steam pressure instead of a pump to make espresso. This can cause over-extraction because the boiler that produces steam also heats the water to boil. The machines must also constantly rebuild their pressure between cups. This takes energy and time.

Many espresso machines utilize an rotary or vibrating pump, with a vibration model that uses a vibrating disc to create pressure and a rotary model pushing hot water through the grounds under high speed. Both models can produce an excellent espresso, however the rotary pumps are quieter, and more durable than vibration pumps.

The Boiler

The boiler is the element that heats the water to the optimal temperature to extract. The steam created is then directed to the portafilter, which is a container for espresso grounds. It is then poured into the cup. In this process, the steam causes pressure to push through the grounds of the coffee. This results in a layer crema on top. This is a sign of a great espresso.

There are three types of espresso makers. They differ in the type of pump they use and the degree of heat that the brew is. There are various ways in which the brew could be controlled as well as the dimensions of the cup the machine can produce.

The first espresso machines were steam-types. They employed only one boiler to make steam and brew, however the pressure they were able to produce was not very high - two bars of atmospheric pressure at most. This resulted in the coffee tasting burnt and bitter. This is the reason why Milanese manufacturers Luigi Bezzerra and Desiderio Pavoni invented the modern espresso machine.

The most common espresso maker is a semi-automatic machine that has an electric pump. These are the images people have when they think of an espresso maker. Semi-automatic machines require you to grind and tamp the beans by yourself while the pump controls the flow of water and pressure. This is a great compromise between the human touch and the mechanized accuracy.

The Filter

Espresso machines usually use filters that separate the coffee grounds from the hot water. The filter is also a vital element of the machine's temperature control, since it helps to prevent overheating.

A filter also helps with flavor, as it permits an extended flowering time. This allows the beans to release their flavors, and allows for better extraction.

However, it is important to remember that even a great filter can produce a bad cup of coffee as the quality of the beans and extraction are important.

This is where the magic happens. It's what makes espresso taste great. The grouphead, often called the brew head, is where the portafilter (the thingy you put the ground coffee into) is placed when you're making espresso.

In a steam-driven espresso machine, hot water is heated in an airtight tank to create steam. Steam then pushes the hot water through the grounds at a high pressure. They are less expensive and easier for the owner to maintain than pumps-driven models. However, they are not as efficient in their ability to create the perfect brewing conditions as they only operate at 1-1.5 bars of pressure. While discover this requires 9-10 bars.

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