Corrosion protection becomes recyclable

When it comes to capital goods, quality and durability count: they have to pay for themselves over their entire service life. One example of this are trailers for trucks, which one manufacturer offers galvanized - with a success that the companies involved now want to build on.

Founded in 1892 as a forge, Schmitz Cargobull has developed into the leading European trailer manufacturer today. With more than 45,000 units produced, the family-owned company from Horstmar has consistently achieved a turnover of around 2.5 billion euros in recent financial years. And thanks to its dedicated employees - currently around 6,700 - the company is always able to bring innovations to the market.

One of these advances has proven its worth for almost 25 years: the galvanized chassis. "At Schmitz Cargobull, all vehicle chassis are galvanized, unless the customer requests a paint finish," explains a company spokeswoman. This meets the needs of customers, as the proportion of galvanized trailers is over 95 percent. There are good reasons for this: The particularly good corrosion protection provided by galvanizing increases the longevity, reliability and value retention of the vehicles.

Painted chassis, on the other hand, are only used in special situations. For example, in lightweight construction when high-strength fine-grain steels (S700 and higher) are used, as these materials place special demands on production. "Of course, vehicles are also painted on special customer request in order to meet individual design ideas or specific requirements," reports the company spokesperson.

Sustainability is more than corrosion protection

In 2001, Zinq from Gelsenkirchen implemented hot-dip galvanizing of trailers for Schmitz Cargobull for the first time in series production as an alternative to painting. Since then, almost one million tons of steel have been galvanized as part of this partnership, according to the Gelsenkirchen-based company. Thanks to the long service life and recycling properties, the CO2 balance is positive.

For Zinq, sustainability is about more than just corrosion protection. The focus is on recyclability: a product in circular quality is developed and manufactured in such a way that it can be completely and repeatedly returned to the material cycle at the end of the product life cycle. In addition to the recovery and recycling of raw materials in circular quality, this also requires material-friendly surfaces. They do not emit any microplastics and are maximally biocompatible. The term "circular quality" means that the products are designed and manufactured in such a way that the materials can be returned to the production cycle at the end of the product's life. The aim is to minimize waste, CO2 emissions and environmental pollution in order to ensure resource-efficient production.

"In order to achieve the actual conversion of product design to circular products, two essential aspects must be added to the strategies in order to optimize the products with regard to a longer service life," says Zinq: "Redesign means making products circular. They must be modular, the materials used must be of high quality and processed according to the principle of purity of type, and all material cycles must be closed in recycling at the end of the life cycle. The keyword "replace" revolves around the question of how non-recyclable materials can be replaced. However, if companies only focus on material efficiency, fewer of the "bad", non-recyclable materials are used - but no more of the "good" ones.

Before the trailer chassis were galvanized, Schmitz Cargobull first launched another innovation. With the Modulos modular system, the era of welded chassis came to an end in 1999. They are now joined with locking ring bolts in a force-fit and form-fit manner. Thanks to this joining technology, the individual parts can be prefabricated in segments, coated and joined together without damaging the corrosion protection. Welding, on the other hand, reaches such high temperatures that the zinc melts. This is why a zinc coating normally burns off during this process. As a result, the welding fumes contain a lot of zinc oxide, and these zinc oxide vapors are toxic. The resulting spatter also makes the entire welding process unstable, and the molten zinc layer can create pores in the weld seam.

Repairs are becoming rarer and simpler

Repairs to the galvanized chassis are also comparatively uncomplicated. In the event of damage that also affects the zinc coating, repairs to galvanized components are mainly carried out using cold zinc or zinc dust systems. Corrosion protection is restored by applying a new zinc coating to the damaged areas. The protective effect of the galvanizing and the durability of the components are retained. According to the Schmitz Cargobull spokesperson, cold zinc and zinc dust systems are easy to use and particularly suitable for minor damage. Repairs can be carried out on site without the need for extensive dismantling.

"Hot-dip galvanized trailers have a basic service life of up to one hundred years, while painted models often show the first signs of corrosion damage after just a few years," Zinq also reports. In contrast to paint, which is quickly damaged by stone chips or scratches, the zinc coating remains intact even with minor damage thanks to its cathodic protection and prevents rust formation. This is because the zinc surface has a "self-healing" effect. It also protects edges and cavities.

Galvanizing also significantly reduces maintenance costs. While a trailer's paintwork has to be repaired regularly, the zinc surface remains maintenance-free for decades. This means that the galvanized chassis and body parts of the trailers have proven to be robust and durable right from the start. Schmitz Cargobull's experience speaks for a significantly longer service life.

Digital product passport brings data together

Zinq and Schmitz Cargobull now want to expand their collaboration in order to promote the circular economy. To this end, the trailer manufacturer not only wants to gradually convert its products to circular quality, but also document them in a traceable manner. According to a statement from Zinq, the cooperation between the two companies will begin with the development and implementation of a digital circular product passport (DCPP) for hot-dip galvanized steel chassis for trailers, which was originally developed by the Gelsenkirchen-based company as a prototype for metallic surfaces. The overarching aim of the partnership is to achieve a shared understanding of the relevance of transparent environmental data, its collection within the company and its transfer to downstream companies in the value chain.

With a product passport, the circular quality of a product - as specified by the EU Ecodesign Regulation for Sustainable Products (EU-ESPR) - can be measured and evaluated. The aim of the regulation is to improve traceability, the circular economy, energy efficiency and general environmental sustainability. A digital product passport (DPP) will be mandatory for certain product groups on the EU market from 2026. As a digital twin, the DPP records all relevant data on the environmental impact of a product over the entire product cycle and across the entire value chain.

"In this case, it is the product-related footprint of the steel and zinc used in the life cycle assessment including after-use (Scope 4) based on environmental product declarations," Zinq explains on request. The chassis weight is calculated at around 1.7 tons. According to Zinq, it is important that everyone in all supply chains affected by the introduction of product passports from 2026 is involved in the complete documentation of environmental impacts over the entire life cycle of products.

The entire supply chain is required

With the DCPP, Zinq has developed a product passport approach based on existing, generally applicable standards and presented the prototype to the public at the end of 2023. The Digital Circular Product Passport adds information on the hot-dip galvanized surface to the product life cycle. "The DCPP should be applicable across all industries. It is being developed with a multi-stakeholder network for universal application in all conceivable sectors of the manufacturing industry," says Zinq Managing Director Lars Baumgürtel. In order to drive the DCPP prototype forward, the participation of as many players as possible in the supply chain of hot-dip galvanized steel products is necessary. In Schmitz Cargobull AG, Zinq has gained a partner in this future field with whom it is shaping the circular transformation and implementing the objectives of the EU Green Deal.

At the end of a trailer's life, galvanized steel chassis can be returned to the complete material cycle. "With the development and implementation of a digital circular product passport for trailers based on the DCPP prototype in the value chain of galvanized steel products, we are setting a benchmark towards a circular economy, which is our declared goal," explains Dr Günter Schweitzer, Chief Operations Officer at Schmitz Cargobull.

The commitment to sustainability, not only through galvanizing, is already bearing fruit for Schmitz Cargobull. The trailer manufacturer won the German Sustainability Award Company 2025 in the mobility and logistics category in the automotive industry sector. The expert jury was impressed by the contributions to sustainable production processes and a product portfolio that is designed for longevity and resource conservation, as the company announced. SI

Schmitz Cargobull AG www.cargobull.com

Zinq Technologie GmbH www.zinq.com