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

In the manufacture of professional espresso coffee machines, one of the biggest 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 an issue of limescale buildup, especially when using hard water, and long-term corrosion, which negatively impacts the quality and taste of the coffee, as well as increasing machine maintenance and wear.

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

As an alternative, the use of plastics has been explored to reduce the problem of limescale and corrosion. However, the need to withstand high pressures and temperatures over prolonged work cycles significantly limits the range of compatible plastics, reducing it to a few technical plastics such as PEEK or PPSU.

One of the components that presents the greatest challenges is the dispersion plate in coffee machines. This component is responsible for evenly distributing the hot water over the ground coffee, meaning it undergoes continuous high-pressure and high-temperature cycles, making it one of the parts most subject to wear. Additionally, this component is in direct contact with water and coffee, so using an inappropriate material or allowing limescale or oxides to build up can negatively impact the coffee’s quality, taste, and aroma.

The importance of the material

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

Among these, the material that best suits the application is 316L or 304 stainless steel, as they are corrosion-resistant, easy to clean, and do not affect the coffee’s taste or aroma. However, their high cost means they are reserved for high-end equipment.

Brass is another common material, as it is more cost-effective to machine than steel and withstands heat well. However, it is prone to corrosion and limescale buildup and can release metal oxide particles that affect the coffee’s flavor and quality.

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

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

In the search for affordable and resistant alternatives that do not affect the flavor 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 encountered in this approach is that the more affordable 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 well-known espresso machine manufacturer has explored an innovative alternative in the manufacture of plastic dispersion plates, aiming to create a resistant, durable product that does not affect the coffee’s taste or quality, while keeping manufacturing costs low to make it accessible to all types of machines.

To achieve this, a service bureau was subcontracted to produce the dispersion plates using FFF 3D printing with PEN-HF, a material developed by the manufacturer FLXR Engineering.

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

Polyethylene naphthalate (PEN) is a polyester similar to PET in composition, but with physical, mechanical, and thermal properties closer to other 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 (with elastic moduli exceeding 2 GPa), provides better barrier properties against gases and water vapor, and maintains excellent chemical resistance and food-grade compatibility.

Putting the material to the test

To evaluate the new dispersion plates made from PEN, a real-world test was conducted involving 120 30-second extractions using water at temperatures between 91ºC and 96ºC and a pressure of 9 bar. The same study was also carried out with 3D printed dispersion plates made of PETg, PCTG, PC, PEEK, and PVDF, as well as with machined PPSU plates.

Only three materials withstood all 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 managed 5 cycles.

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

Moreover, the PEN-HF printed parts were not only a functional alternative to PEEK or PPSU dispersion plates but also proved to be more cost-effective, reducing the cost by 33% to 45% compared to PPSU.

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

Advantages beyond cost

The new PEN-HF 3D printing process not only enables the production of durable, cost-effective, inert, and corrosion-resistant dispersion plates but also results in a lower carbon footprint, a more flexible supply chain, and greater optimization and customization potential.

PEN-HF presents itself as a cost-effective, efficient, and easier-to-print alternative to other more common but expensive and complex technical materials. It does not require high-temperature or industrial 3D printers, complies with both EU and FDA regulations for food contact applications, and offers superior mechanical, thermal, and chemical resistance compared to any other material in its price range.