Maintaining high quality standards is essential in the production of aluminum beverage cans. Can cleaning is a critical step to remove surface residues remaining from the forming process.  Traditionally, high temperatures were required to achieve thorough cleaning. However, this approach has drawbacks in terms of cost and sustainability, due to its high energy consumption and CO₂ emissions. Fortunately, new technologies are enabling can manufacturers to optimize the cleaning process to reduce production costs and environmental impact without sacrificing high performance.   

Cleaning is one of the essential steps when producing beverage cans. The production of aluminum cans leaves residues of organic soils, oils, and oxides on the surface. These residuals must be removed to create a clean surface for the application of inks and coatings, and thus ensure the quality of the finished can.  

Paving the way for more sustainable and cost-efficient processes 

The foundation of effective cleaning lies in understanding Sinner’s Circle, a concept formulated by Henkel‘s Dr. Herbert Sinner in 1959, which is based on four main factors: chemistry, mechanics, time and temperature. By altering one parameter, developers can compensate for another. Temperature plays a crucial role not only in cleaning efficiency, but also in energy consumption and foam formation. In the past, these two aspects have been significantly increased by using processes that rely on high temperatures.

The traditional cleaning method involves a multi-stage spray process operating at around 60°C to 70°C, resulting in high use of natural gas for heating. Up to 80 % of the energy is required to compensate for evaporation and heat loss from the spraying process and to maintain the bath temperature. As a result, cleaning is one of the largest users of energy and thus cost drivers in metal pretreatment. However, advancements in cleaner formulations and raw materials have paved the way for low-temperature cleaning solutions.  

Solution: Save energy without sacrificing high performance 

The challenge for these new solutions is to clean as effectively as traditional methods, but at lower temperatures. Requirements: The products should have excellent cleaning and degreasing performance, be compatible with downstream processes, and be low foam.  At the same time, they should be compatible with the existing washer equipment with no mechanical changes needed.

With low-temperature cleaning systems such as Henkel‘s Bonderite C-IC 72000 series, cleaning performance can be achieved from as low as 43°C instead of the usual 60°C to 70°C. Initial line tests have shown that for every 10°C reduction in cleaning zone temperature, energy savings of 15% can be expected. This allows can makers to significantly reduce their carbon footprint and is in line with global efforts to combat climate change. Considering that over 400 billion aluminum beverage cans are used worldwide each year, the potential savings are immense. 

Low-temperature cleaning increases operational efficiency and worker well-being 

Beyond the environmental benefits, low-temperature cleaning increases operational efficiency. Maintenance costs are reduced because heaters, heat exchangers, and pumps are operated at much lower levels and at slower speeds.

The use of new low-foaming surfactants means less foam is generated, which reduces carryover during rinsing allowing for optimised water usage. Another benefit is an improved working environment for employees: Reduced heat in the production area results in lower humidity, making it more comfortable for operators. It also lessens corrosive effects on ventilation systems, the washer components, and other steel structures. Further operational efficiencies and time savings result from maintenance crews not having to wait for the bath to cool before performing maintenance, nor wait as long to heat back up to temperature to resume production.  

Seamless conversion of the cleaning plant  

With the various cost and sustainability benefits of low-temperature cleaning, the case for conversion is clear. So why do most companies still use conventional high-temperature cleaning? The main reason is often a lack of awareness of the availability of this new technology and the significant potential water, energy, and CO₂ savings of the new generation of low-temperature cleaners.

In addition, many companies are afraid of downtime during ongoing operations and therefore consider it risky to replace the current solution with a new system. In practice, however, the conversion is straightforward: The old solution must be drained, the equipment cleaned, and the new solution added. The line can then immediately resume production. The technical support teams of suppliers like Henkel can assist in the analysis and setting of the operating parameters. 

Conclusion: Make production economical and sustainable 

In summary, the introduction of low-temperature cleaning systems represents a significant milestone for the metal packaging industry. These systems signify not just a technological advance, but also a fundamental shift towards adopting a more sustainable approach to can manufacturing. Recognizing the substantial energy savings that can be achieved, it is highly recommended that companies consider the low temperature cleaner as a means of advancing toward their goals for a more sustainable future.