Rethinking Espresso Hardware: A Better 3D-Printed Dispersion Plate

In the manufacturing of professional espresso machines, one of the greatest challenges is finding materials that can withstand intensive use, constant heat, and contact with hot water and steam without degrading. For years, manufacturers have relied on machined metal components such as brass or stainless steel; however, the use of metals presents issues with scale buildup, especially when using hard water, and long-term corrosion, which negatively affects the quality and taste of the coffee, in addition to increasing machine maintenance and wear.

Image 1: Professional espresso machine. Source: electroluxprofessional.com.

Alternatively, the use of plastics has been explored to reduce the problem of scale buildup and corrosion; however, the need to withstand high pressures and temperatures during prolonged work cycles greatly limits the range of compatible plastics, reducing it to a few technical plastics such as PEEK or PPSU.

One of the most challenging components is the dispersion plate of coffee machines. This component is responsible for distributing hot water evenly over the ground coffee, which means it undergoes continuous work cycles at high pressure and temperature, making it one of the components with the highest wear. In addition, this element is in direct contact with water and coffee, so the use of an unsuitable material, or the accumulation of scale or oxides, can negatively affect the quality, taste, and aroma of the coffee.

The importance of the material

Traditionally, the most commonly used materials in the manufacturing of dispersion plates have been metals, mainly brass, stainless steel, and anodized aluminum.

Of these, the material that best adapts is stainless steel 316L or 304, as they are corrosion-resistant, easy to clean, and do not affect the flavor or aroma of coffee. However, their cost is high, so they are reserved for high-end equipment.

Another common material is brass, as its machining cost is lower than steel and it withstands heat well. However, it is prone to corrosion and scale buildup, and can release metallic oxide particles that affect the taste and quality of coffee.

Currently, many mid- to low-range manufacturers have opted to use anodized aluminum in the manufacturing of dispersion plates due to its low cost and good resistance. However, like brass, it can release metallic particles that affect the taste and quality of coffee.

Image 2: Dispersion plates made of brass and stainless steel. Source: shadesofcoffee.co.uk.

In the search for cost-effective, resistant alternatives that do not affect the taste or quality of coffee, some manufacturers have explored the use of technical plastics as an alternative to metals in the production of dispersion plates. The main problem found with this approach is that cheaper food-grade injection plastics, such as copolyesters, polycarbonate, or PVDF, withstand very few work cycles before deforming due to temperature and pressure, while technical plastics such as machined PEEK or PPSU often exceed the cost of machined steel.

PEN-HF and 3D printing: a simple, cost-effective, and efficient solution

Compared to traditional approaches, a renowned espresso machine manufacturer has explored an innovative alternative in the production of plastic dispersion plates, aiming to achieve a resistant, durable product that does not affect the taste or quality of coffee, while maintaining a low manufacturing cost to make it accessible for all types of machines.

To this end, it subcontracted a service bureau to produce dispersion plates through FFF 3D printing using PEN-HF, a material developed by manufacturer FLXR Engineering.

Image 3: 3D printed dispersion plate with PEN-HF. Source: FLXR Engineering.

Polyethylene naphthalate (PEN) is a polyester similar in composition to PET, but with physical, mechanical, and thermal properties that bring it closer to other more technical materials such as polyamides, PPSU, or even PEEK. PEN can withstand working temperatures close to 170 ºC, has higher tensile strength and stiffness than other polyesters, reaching elastic modulus values above 2 GPa, offers better gas and water vapor permeation barrier, and maintains excellent chemical resistance and food-grade compatibility.

Putting the material to the test

To evaluate the new dispersion plates made of PEN, a real-life test was conducted through a series of 120 extractions of 30s with water at a temperature between 91ºC and 96ºC and a pressure of 9 bars. The same study was also carried out with 3D-printed dispersion plates in PETG, PCTG, PC, PEEK, and PVDF, as well as with machined plates in PPSU.

Only three materials withstood the 120 cycles without deformation: PPSU, PEEK, and PEN-HF. Other polyesters such as PETG or PCTG withstood only 1 and 5 cycles respectively, while PC barely resisted 5 cycles.

Image 4: Number of successful cycles before deformation. Source: FLXR Engineering.

In addition, the parts printed in PEN-HF were not only a functional alternative to PEEK or PPSU dispersion plates, but also more cost-competitive, reducing costs between 33% and 45% compared to PPSU.

Table 1: Manufacturing cost comparison. Source: Filament2Print.com.

Advantages beyond cost

The new manufacturing process through 3D printing with PEN-HF not only makes it possible to obtain durable, cost-effective, inert, and corrosion-resistant dispersion plates, but also implies a lower carbon footprint, a more flexible supply chain, and greater optimization and customization capabilities.

PEN-HF proves to be an economical, efficient alternative that is easier to print than other more common but more expensive and complex technical materials. It does not require industrial or high-temperature 3D printers, complies with European and FDA regulations for food-contact applications, and offers superior mechanical, thermal, and chemical resistance compared to any other material in its price range.