The utilization of suitable materials based on specialized engineering and manufacturing know-how makes it possible to integrate several parts and/or functions in a single assembly component. In many cases, this can shorten the process chain and reduce logistics and assembly requirements. In the case of hygienically sensitive applications such as those in the food industry, a reduction of the number of components enhances hygiene and ease of use, as the number of interfaces and joints decreases as well. As a result, the need for long and costly cleaning cycles is eliminated and the frequently necessary partial dismantling of equipment for maintenance and cleaning can be accomplished with much greater ease and in less time.
An Example from the Field:
Development of a Fully Integrated Brewing Piston Made of nobrox® for Professional Coffee Machines
The brew unit is the centerpiece of any fully automatic coffee machine. This is where the key parameters of the coffee’s quality are determined, such as the compaction level of the grounds, water pressure and filtering of the coffee product.
The brewing chamber, the metallic micro-strainer and, last but not least, the brewing piston with the associated sealing and wiping system are the key components of the brew unit.
Conventional brewing piston systems in professional fully automatic coffee machines frequently consist of complex, metallic brewing pistons with sophisticated geometries and failure-prone sealing systems with an average expected lifetime of approximately 50,000 brewing cycles. Afterwards, the brewing piston and the related sealing system have to be exchanged in a time-consuming and costly process.
The sealing system not only has to withstand a pressure of up to 20 bar at temperatures of 95 °C, but also resist the highly abrasive coffee powder and the acidic coffee extract.
The newly developed brewing piston system features two major components: the brewing piston and the portafilter with integrated sealing, wiping and filtering function. Easy connection of the components can optionally be achieved by a threaded connection or snap fitting for ease of assembly and servicing.
The fully integrated design of the nobrox® brewing piston reduces the geometric complexity and number of single components while increasing ease of assembly and servicing.
The piston attachment combines various functions, which helps reduce the complexity and component diversity of the brew unit. This where the non-reinforced nobrox® material can display its advantages. Its high wear resistance makes it possible to combine the sealing and wiping function in a dynamic sealing system. The sealing/wiping lip is preloaded by a TPU O-Ring and ensures consistently good sealing performance between the brewing piston and the brewing chamber across the entire lifetime.
Service life extended on average by 50 to 100 % or to an average expected life of > 100,000 brewing cycles.
Lower heat loss compared with metallic pistons saves heating elements.
Manufacturing cost benefits due to injection molding technology compared with machining of metallic brew pistons.
Unlike solution concepts that enclose the seals in a groove on the outer piston diameter the fully integrated system permits absolutely no dead space. This avoids coffee deposits that impair functionality or flavor. Due to the outstanding tribological properties of the nobrox® material, there is no need for additional lubrication.
- EMG Report 04/2015 Page 7, Universal nobrox Material in Professional Coffee Machines
- EMG Report 06/2017 Page 10, Universal Material nobrox for Food Applications
- Brochure "Materials for the Chemical Process and Food Industries"
- www.nobrox.com - Food Applications
Article contributed by
Stefan Reichle, market unit manager industry
Engineered Materials Group Europe, Prädifa Technology Division