When sustainability is discussed in industry, the focus is often on new technologies or completely new systems. Yet significant potential frequently already exists in installed equipment. This is precisely where retrofit comes in: existing systems are modernised, technically optimised and improved in terms of energy efficiency — in a resource-saving way and usually at a significantly lower cost than a new investment. For Venjakob Maschinenbau, based in Rheda-Wiedenbrück, this is part of everyday business.
The topic is becoming increasingly important in coating technology in particular. Painting and coating systems are among the most energy-intensive processes in industry. Drying technology, air handling and exhaust air treatment in particular account for high levels of energy consumption. Large volumes of air have to be heated, moved, filtered and discharged. At the same time, energy costs and regulatory requirements continue to rise.
“The topics and motivations customers approach us with vary,” explains Sören Steegmann, Head of Service Sales at Venjakob Maschinenbau. “They range from technical adaptations for more cost-effective production to modernisation and conversion measures aimed at saving energy.”
The advantage over a new system: production downtimes usually remain manageable, while the required investment is significantly lower. “Whether you invest between 100,000 and 600,000 euros, or two million euros in a new system — that makes a major difference,” says Steegmann. Retrofit projects often pay for themselves within just three to five years.
Heat recovery saves energy
A current example is the retrofitting of heat exchangers on an existing dryer line. The customer’s objective was to reduce energy costs and meet sustainability requirements.
The challenge: in drying processes, warm exhaust air is continuously extracted, while cold fresh air from outside has to be heated again. Especially in winter, this leads to considerable energy losses.
The solution was to make energetic use of the existing exhaust air. Heat exchangers installed on the roof return part of the thermal energy to the process. Venjakob fully integrated the technology into the existing system control, including sensors, visualisation and process monitoring.
“This means the air no longer has to be heated from 20 to 60 degrees Celsius; instead, preheated air is already returned to the process,” Steegmann explains. Initial evaluations show potential energy savings of around 30 percent. What is particularly remarkable: production was able to continue during the conversion, with only a few hours of interruption.
Retrofitting UV technology
At Venjakob, however, retrofit is not only about saving energy. It is also about adapting systems to new production requirements.
For one customer, an existing system was expanded with a UV drying module so that UV coatings could be used in the future. In another project, UV technology was already in place, but via a robot that had reached its throughput limits. The result: reduced production speeds and quality issues.
The solution was a standardized UV module integrated directly into the existing drying process. “For this, we had around one week of downtime. Afterwards, we supported production together with the customer to ensure the required quality was achieved,” reports Steegmann.
Less overspray, lower consumption
Spray technology also offers considerable optimisation potential. With its “Kante Plus” system, Venjakob has developed a retrofit solution for improved coating results in the wood and furniture industry.
Additional spray guns, more precise sensor technology and extended software parameters enable exact control right up to the edge of the workpiece.
This reduces overspray — in other words, coating material that was previously sprayed beyond the edge. This saves material, reduces cleaning effort and improves process stability.
Small modifications with a major impact
Not every retrofit project is immediately visible. Often, benefits are achieved through targeted detail optimisations. For example, in older high-bay dryers, Venjakob replaces wear-prone friction wheels with more durable claw couplings that were only recently developed, improving process stability and reducing maintenance effort.
Another example is the retrofitting of flow measurement directly at individual spray guns. Blockages or material deviations are detected at an early stage — before rejects occur or production batches have to be reworked.
Where retrofit reaches its limits
Despite all its advantages, retrofit is not always the best solution. Limits are reached when production concepts change fundamentally or when significantly higher performance is required that can no longer be achieved with much older coating lines.
“If the transport system is designed for a certain speed, there is only so much you can get out of it,” Steegmann explains.
For Venjakob, retrofit is therefore not an end in itself, but a strategic middle ground between continued operation and new investment — modernising where it makes sense, and rethinking where it becomes necessary.
