Espresso Machine: Structure And Working Principle

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Espresso Machine: Structure And Working Principle

Espresso Machine : Structure And Working Principle: We all know an espresso machine isn’t cheap, and sometimes with the most expensive devices on the market, it’s not always easy for a good espresso.

This depends on the structure and operating principles of each espresso machine – And the fastest way not to dismantle a particular device is to see this tutorial to know the basic principles of espresso machines, thereby quickly mastering the operation of the dispenser as well as choosing the most suitable machine possible.

About the main parts of the espresso machine

We’re talking about copper pipes, stainless steel boilers, pumps, programming software, etc. All the mechanical components are shaped in an exact – and sometimes artistic – design. Although the overly sophisticated composition of modern espresso machines makes us feel bad, for most espresso machines a century ago, the principle of operation based on 4 phases has not changed:

Water Source » Pump » Boiler» Extract Cluster (Grouphead)

The article will take turns in order the main parts of the machine:

  1. The Water Source
  2. The Pump:
  3. The Boiler, Bringing the Heat
  4. The Boiler, Control Temperature
  5. The Grouphead

Water sources or water juts

Every coffee machine needs water to function. For home or work dispensers, water is fed into the machine by one of two sources: The container is in the device or directly connected to the appropriate water supply.

Usually, any water source is used based on the requirement to use an espresso machine. For example, espresso machines that only extract a few cups with high-quality daily needs often use built-in containers; this way, you can easily adjust the water quality.

Meanwhile, for commercial espresso machines for coffee shops, which require hundreds of cups per day, it is more reasonable to use water directly from the built-in softening and filtration system (you never have to light water).

Meanwhile, some “hybrid machines” still use containers and can connect water sources directly, such as the high-end E61 series.

In short, in terms of water resources, we will have the following advantages and disadvantages:

Container usage machine

  • Advantages: easy to install, compact
  • Cons: regular cleaning requirements
  • Machine: LUCCA A53 Mini, ECM Classica

Use of direct water sources

  • Advantage: no need for water
  • Cons: Requires separate pipes and filters.
  • Machine: LUCCA A53 , La Marzocco GS3

Pump – The heart of every espresso machine

Pressure – the key to each espresso, the machine needs the same pressure as 9 bars (9.1kg / 1cm) to get water through the finely grated coffee layer.2 ). In the history of more than a century, early espresso machines have moved slowly from using the pressure generated by the steam in the boilerBoilergh traps pressed by the Barista.

However, hand compression is really “laborious” and inconsistent, so in the end, espresso machines use electric pumps, with two main types of pumps: Vibratory pump and Rotary pump.

Espresso Machine – Structure And Working Principle: Vibratory pump & Rotary pump on an espresso machine
  • Vibratory pump – A vibrating pump operates according to the electro-electrodialysis principle. Current runs through the coil, causing the magnet to move the piston back and forth (an average of sixty times per second) to push water through the machine.
  • The rotary pump is a standard pump used at home and on many other espresso machines. But with a more complex pumping mechanism. The motor will drive to a rotating disc placed inside the pump. When the disc rotates, the centrifugal force causes the rotors to press close to the pumping wall and create pressure on the water flow.

There are relative advantages to each type of pump. The vibrating pump is more compact, inexpensive, and easy to replace, which can be caught on the LUCCA A53, Profitec Pro 300series.

Rotary pumps are quieter, provide stable pressure, and often have a longer lifespan – such as the LUCCA M58machine. However, it should be noted that the pump does not entirely determine the quality of the espresso.

Boiler on an espresso machine

The pump has provided the necessary pressure source, but the water needs to be heated for the preparation. Boilers are where water is heated to the required temperature.

Espresso machines have a significant variety of boiler structures, from the number of boilers to the heat stabilization mechanism. And this is easy to confuse the owners as well as the Barista.

The primary function of the boiler boil water and store hot water for espresso extraction, mixing, and steaming milk. Early coffee machines were burned with wood or coal.

On modern devices, electricity is used to bring water to boiling temperatures with many different mechanisms. And to choose an espresso machine with the proper boiler mechanism, you have to consider two factors:

Boiler heating size and mechanism

First, we need to consider boiler capacity every day. We need 3, 5, or 13 liters before investing in an espresso machine. For machines with large boilers (such as La Marzocco GS3), the more continuous espresso shots can be made, the more energy and time it will take to boil.

Comparison of the mechanism of action of espresso boilers and heat exchangers

Second, but very important, is the boiler mechanism, a single boiler pot integrated heat exchanger. These details are complex and should be presented separately in the Espresso Boiler & Heat Exchanger Comparison. Here we will summarize some of the main pros and cons:

Single Boiler

  • Pros: Inexpensive
  • Cons: Temperature control is incorrect; it is impossible to extract and steam milk, and long waiting times simultaneously.
  • Machine: ECM Classika

Heat Exchanger

  • Pros: Less expensive, can be extracted and steamed milk at the same time
  • Cons: Poor temperature control, with Thermoblock style better temperature control
  • Machine: ECM Casa V, Profitec Pro 500, Quick Mill Silvano Evo (Thermoblock)

Double Boiler

  • Advantages: Can simultaneously extract and steam milk, independent and accurate temperature control
  • Cons: More expensive
  • Machine: LUCCA M58, Profitec Pro 700
Espresso Machine – Structure And Working Principle: Double Boiler and Grouphead Saturated on La-marzocco GS3

A temperature control mechanism on an espresso machine

Even after having four times the tires, espresso is still a fine art; baristas have constantly set stricter limits on temperature control. And many manufacturers have entered the technical battle to stabilize the temperature per shot of espresso, which has always been a fascinating topic about espresso machines, as the slightest changes in temperature amplitude can also significantly affect the taste.

For small, cheap coffee machines, the brewing temperature is pre-programmed and made by simple heating sets. The problem with heating factors is that they give users less control over water temperature, making it more challenging to extract inconsistently.

Boilers with digital temperature control (PID) are used for more precise control over the concoction temperature. Both allow the user to change the machine’s temperature in the most detail and keep that temperature with few abettings.

PID and Digital Control

PID (abbreviated for Proportional Integral Derivative controller) – This is a heating unit control system to keep the water temperature as low as possible.

To do this, a PID is connected to the heating unit, and the temperature probe inside the boilerBoilercontinuously reads data from the heat probe. It turns the heating kit on/off continuously based on a pre-programmed algorithm.

With the essential nature of being magic, before being present in the espresso machine, PID was used to control industrial systems and aerospace. And until its presence in espresso machines, PID was one of the most significant technological advances of the past twenty years.

Espresso Machine – Structure And Working Principle
Espresso Machine – Structure And Working Principle: Photo The PID device used by Kees Van Der Westen

Digital temperature controls do the same. There are only two main differences: First: the digital screen on PID provides more information and control options on the DT panel. Second: users can adjust the algorithm on a PID but can’t do the same with a digital temperature controller.

Grouphead (head extract) on an espresso machine

Grouphead is the “last station” of water as it moves through the espresso machine. Whether your espresso machine has 1, 2, or 3 groups, all groups are made up of four essential parts: the Portafilter or filter; filter lock (mount) latch; Activate the pump valves and water pipes from boilers to filters.

With countless espresso machines on the market, there are still only three main group heads: Grouphead E61, Saturated Grouphead (Saturated Grouphead), and Semi-saturated Grouphead or semi-saturated Grouphead.

Grouphead – E61

In historical improvements on the Espresso machine, Ernesto Valente credited himself with introducing the E61 Espresso Series (in 1961), from which the grouphead E61 has become a “classic” set on espresso machines to this day.

The entire grouphead on the E61 is copper-made and weighs 4kg. Although it will take about 15 minutes for the whole group head to heat to the concoction temperature, it retains heat better in the long run.

Simply put, the grouphead-E61 is a three-dimensional valve that operates on mechanical principles, meaning the Barista has to brush off the trap manually to activate the pump.

There will be a valve to let water from the boilerBoilerthe group, a valve to move the water from the group to the Portafilter, and a third valve to release pressure from the Portafilter. The mechanism of group head E61 is quite complex, so I do not mention it here, but we can summarize the pros and cons of grouphead – E61.

  • Advantages: Firmly processed with high heat retention, relatively easy to repair, manual control, Allows to perform the Preinfusion process (when brushing the trap), so the coffee in Portafilter is turbocharged slowly to stabilize before increasing the maximum pressure.
  • Cons: Long heating time, only manual operation
  • Machine: ECM synchronika, ECM Classika

Grouphead – Saturated, and Semi-Saturated

With extract heads as on the Marzocco GS3machine, the group head is welded directly with the boilerBoilergroup hets as an extension of the boiler boilers saturated with hot water (hence the saturated group head).

So, instead of waiting for the hot brass to come up slowly, the group head-saturated will quickly heat up to the same temperature as the water in the boiler.

Boiler grouped semi-saturated principles of operation, the most significant difference is that instead of welding the group head into a boiler, the area above the group is separate.

This reduces the cost of semi-saturated group processing and is easier to repair than grouped saturated. It should also be added that, unlike the largely manual E61 group, both group head-saturated and semi-saturated operates according to the program.

Different models will offer various programs and control capabilities, depending on how “smart” they are. Here’s a look at these two types of “good” extracts.

Grouphead saturated

  • Pros: Of the most advanced type, programmed automatically
  • Cons: High cost, requires highly specialized Barista
  • Machine: La Marzocco GS3

 Semi-saturated group

  • Pros: Durable, easy to repair, and also programmed automatically
  • Cons: Poorer temperature stability
  • Lucca A53, Profitec Pro 300

About Portafilter

The Portafilter is shortened from “Portable-Filter” or what some baristas call “Phase Hand”; however, Portafilter one is a perforated metal funnel placed inside the handle. Finely grated coffee is fed into Portafilter, then compressed with tamping, before inserting and locking into the group head (see also technical manipulation when making espresso).

Simply put – Portrafilter is where the water fired from the espresso machine dissolves the coffee to enter the cup. It may sound simple and not an espresso machine, but Portafilter is the most critical bridge between espresso machines – coffee and baristas.

  • See also An Overview of espresso machines’ filters to better understand Portafilter.

Source of reference:

  • How Do Espresso Machines Work?
  • A Brief History of the PID
  • – Máy Espresso – Cấu tạo và nguyên lý hoạt động

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