Latest news

Being a partner of the industry and as one of the leading innovators of the market, we are continuously developing our products as well as ourselves and we always are implementing new ideas. What’s new? Which patent applications have been made recently? Which technologies are we using?

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Our newly installed test station enables objective quality control at a central location in production. Among other things, leakage and compressive strength tests take place here, which help to minimise human error and improve the efficiency of the processes. Control results can also have a direct impact on production processes that are already running. But our quality control goes even further, as it also includes the analysis of feedback from our customers. By responding quickly, potential problems are quickly identified and rectified. Products are thus continuously improved and customer satisfaction increases.

For us, quality control refers to the process of reviewing and evaluating products and processes to ensure that they meet established quality standards. Quality control is of great importance. By means of suitable test characteristics, this involves checking the structural safety and uniformity of product manufacture, ensuring compliance with our customers' requirements for vehicle doors and windows as well as other vehicle components for road and rail vehicles.

An essential step in quality control is to establish clear quality standards and specifications. This involves defining criteria that must be met for a product or service to be considered of high quality. These standards are usually defined by internal guidelines, external standards or legal regulations. In order to ensure compliance with these quality standards, inspections tailored to the product and the requirements are applied in addition to an initial overall inspection, differentiated random inspections. Here, a certain number of products are selected and checked for their quality. The sample size is determined depending on the significance of the inspection characteristic for the function of the product and, if applicable, other risk factors determined within the scope of failure mode and effect analyses.

Another important aspect of quality control is accurate documentation. Here it is crucial to document all checks, measurements and results carried out in order to ensure traceability and transparency. The documentation also serves as proof of compliance with quality standards to customers, partners or authorities.

Overall, quality control at the new test station is an indispensable part of our effective quality management system. By consistently checking and ensuring compliance with quality standards, we build the trust of our customers, minimise productivity losses due to defects and strengthen the competitiveness of the Cleff brand in the international vehicle market.

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The purchasing department is in the hands of Mr. Kirstein. He is being supported by Mr Brockmann. The purchasing team has numerous responsible tasks in the company.

These include

• monitoring suppliers' adherence to promised delivery dates

• following up and securing delivery dates

• keeping an eye on prices so that they match the customer's order

• working with reliable suppliers to coordinate quotations and deliveries

• using a network of reliable suppliers, including logistics partners and coating companies

• handling enquiries

• Comparing quotations

• Invoice verification

• the dunning and complaints system

Direct cooperation with other departments, especially with the work preparation department, is a basic prerequisite for the successful activities of our purchasing team. Furtehermore, a reliable supplier network, short decision-making channels and quick decisions ensure that even special challenges such as procurement problems or price increases - caused by external factors - can be mastered.

Therefore, the purchasing department is an essential pillar of our company with a high level of responsibility.

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Electricity management refers to the efficient and responsible use of electrical energy. At a time when our energy consumption is constantly increasing and resources are becoming scarcer, effective electricity management is of great importance. Measures have already been implemented or are still being planned.

• The new IT, new ventilation systems for the social rooms and the heating system now have a significantly improved energy balance.

• New compressor stations also consume less energy and their waste heat is used for hall heating.

• In addition, some of the new systems and machines - besides higher production output - offer additional functions for controlling electricity consumption.

• Lighting optimisation: The use of energy-efficient LED lights throughout the plant, motion sensors and timers reduce power consumption. Intelligent power strips minimise standby consumption.

• Load management: Intelligent control of consumers distributes power consumption more evenly and avoids peak loads.

• Renewable energies: Our new photovoltaic system uses solar energy, reduces fossil fuel demand and environmental pollution.

In 2023, the Wuppertal-based company Enteria completed the plant on the shed roof of the Cleff production building.

With 400 additional solar modules, the generator area now totals 3,145 m², providing a planned annual yield of almost 530,000 kWh. The daily energy output is recorded in real time and displayed on a monitor in our foyer.

For us, economy and ecology are not contradictory, because overall we are aiming for an 8 % saving in electricity consumption per year in the near future.

And the energy awareness of the staff must also be further promoted: In the future, targeted measures will encourage employees to use energy consciously in the workplace. Awareness campaigns promote energy-efficient behaviour. Our joint effective electricity management is crucial for the sustainable energy future. - and implementing these measures lowers costs, conserves resources and reduces environmental impact.

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Modern bonding technology has made considerable progress in recent years. It now replaces or complements traditional joining techniques in many companies and also offers many advantages over conventional methods in Cleff. Riveting can be replaced by bonding, especially when a smooth surface is required. Gluing enables full-surface connections and thus better load distribution. It is also an alternative to bolting as it provides a more even load distribution without material penetration. In addition, bonding can replace welding as it joins dissimilar materials without melting or deforming them. In electronics and precision engineering, soldering and brazing can also be replaced by adhesive bonding. Adhesive bonding also makes it possible to achieve tight joints, as required in particular for windows and doors.

Our technical experts have a huge knowledge of industrial bonding technology. This includes the preparation processes such as cleaning, activating and priming as well as the actual bonding process. They are also familiar with different adhesives and know which is best suited for which application. A high standard for this technique has been established, and the employees involved in the bonding processes are of course trained accordingly.  Precise adherence to all previously defined specific requirements and parameters of a project - including specification of the adhesive suitable for all parameters - ensures that the materials used and the adhesive are compatible. Depending on the specified adhesive system and the surface conditions of the substrates, different operations are carried out to pre-treat the surface.  In brief, a typical bonding process includes careful preparation and cleaning of the surfaces to be bonded, activation and, if necessary, priming, application of the adhesive, joining, fixing of the components if necessary and curing - and finally a quality control. The entire process is precisely documented to ensure traceability and compliance with relevant standards.

The future belongs to industrial bonding!

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The people of Hamburg love to travel on the red double-deckers - and not only them ...
Because the buses of the "Hamburger Stadtrundfahrt - Die Roten Doppeldecker GmbH" offer different tours to the sights of Hamburg and visitors quickly get to know all the beautiful places of the Hanseatic city. With the hop on/hop off principle (interruption and continuation of the journey with a day ticket) and according to the motto "To experience Hamburg is to experience Hamburg", you can explore the Hanseatic city and even combine the trips with harbour tours.

The striking red MAN SD 200 convertible double-decker buses have 82 seats and a "sliding roof" over the entire upper deck. The buses date back to the 1970s and were converted into convertible sightseeing buses after they were taken out of service as regular service buses in many cities. As double-deck buses, they are particularly well suited for this - due to the good view from the upper deck. Their new engines also meet contemporary and environmentally oriented standards. The fleet includes not only the double-decker buses for tours, but also a playmobile for trade fairs and events, a multifunctional mobile with a living cabin, an infobox for trade fair meetings and a jumbo trailer with a living area - equipped with windows by Cleff. We have been working with "Hamburger Stadtrundfahrt - Die Roten Doppeldecker GmbH" for four decades. Especially when it comes to modernising older bus models such as the MAN SD 200, we demonstrate our expertise: being able to build individual window solutions even for older and modern vehicles. This is demonstrated by the installation of new Cleff windows during the general overhaul as well as the adaptation of windows for special purposes, such as the event kitchen vehicle for the International Tourism Exchange in Berlin, where cooking is done for trade fair guests of honour.

It all started with the "Hummelbahn" in 1980, which took guests across the island of Sylt - and was already equipped with Cleff windows. Then owner Heinrich Schuster shifted his tours to Hamburg's city centre - with sightseeing buses. He gave them an open "convertible roof" and was the first to implement this vehicle principle throughout Europe. In the meantime, the company has developed significantly: In addition to the classic city tours in the Red Double Decker, the Hamburg-based company, which is now also represented in Dresden with its city tours, offers transfer and charter trips, boat tours on the Elbe, excursions into the surrounding countryside, catering and cooking events.

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Cleff has equipped the new PistenBully type 300 Polar Antarctic with vehicle windows. 20 of these tracked vehicles, distinguished by their exceptionally high manoeuvrability, thrust and reliability, will be delivered to the Antarctic in the coming weeks to perform their service under the most extreme conditions. The PistenBully vehicles have been in service in the polar region for more than 30 years. Their overall construction is specially designed for the extreme conditions in the perpetual ice and they have since become an indispensable asset in the Antarctic for expedition and research teams from more than 15 nations.
Not only are the special vehicles, which have been further developed into true "polar all-rounders", used as supply, clearing, towing or construction vehicles, but they can even be used as vehicle for overnight accommodation – and that in temperatures as low as 50 degrees Celsius below zero. This makes it clear what stresses our windows are subjected to in terms of material quality, tightness and insulation in these vehicles.

We have been partnering with Kässbohrer Geländefahrzeug AG, which celebrated its 50th anniversary in 2019, as a supplier for various vehicle series for decades. Kässbohrer Geländefahrzeug AG develops and produces tracked vehicles for a wide variety of applications pursuant to the very highest quality standards - standards that we at Cleff are happy to meet: With the supply of vehicle windows and doors, which must also function reliably under special conditions.

You can find more about the PistenBully 300 Polar Antarctic here:

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... and now it’s ready for use by our customers: the side-hung window has ISO glazing and places high demands on its design due to the heavy weight resulting from its dimensions. The window weighs in at approx. 40 kg – 20 kg of which is accounted for by the glazing alone. The viewing area measures 800 mm x 660 mm.
The weight of the window glass (28 mm laminated safety glass/toughened safety glass ISO) combined with the window’s dimensions could quickly result in imprecise opening and closing if the design wasn’t as sophisticated as it is, i.e. the window snags when opening and no longer closes precisely and tightly.
This problem has been eliminated through the use of a two-point lock and opening via an integrated gas strut. The new side-hung window also offers a latch position at 10°, which can be fixed using the ergonomic rotary handle.
The opening angle is also restricted to 90°.


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This week Cleff produced its largest ever sliding window for use in the rail industry. The dimensions (external dimensions) of 2028 mm wide x 1317 mm high with an opening clearance of 1644 mm wide x 445 mm high are unusual and require complex and extensive preparation work – particularly with regards to the weight of the countersunk part, which weighs approx. 30 kg due to the window’s dimensions.
Ergonomics was the main focus of our development: the countersunk part, in other words the extremely heavy sliding area of the window, had to be user-friendly and easy for passengers to move.
This was achieved through our proprietary “Soft Elevation System” (SES), which significantly reduces the opening and closing forces thereby allows even heavy window elements to open and close effortlessly.
The design and implementation of a large, yet easy to operate window: another exciting challenge we were glad to face.

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A special construction feature was implemented for one of our long-standing customers. The top-hung windows were
intended to be closed by the passengers – but only to be opened by the driver. We complied with this special wish of our
customer with a respective construction feature: now the window can only be opened by the driver with a key tool. The
background of this necessary construction change was the special climatic and safety technical requirements for the
window and its design.