Global Cement recently visited the renowned cement process fan manufacturer Ventilatorenfabrik Oelde at its headquarters and main production facility in Oelde, Germany. Managing Director Thomas Gandt, Sales Manager Peter Herrmann and Marketing Manager Inge Teich were keen to talk about the company’s history, growth, manufacturing methods and markets.
Global Cement (GC): Can you please provide a quick introduction to the company Venti Oelde?
Thomas Gandt, Managing Director (TG): Venti Oelde is a family-owned company, established in 1930. It originally made fans, cyclones and filters to remove sawdust from the inside of furniture factories. Over the years the company has always looked for new customers and industries to deliver its fans to. In the 1960s it moved into the cement industry, which is very significant in this area of Germany. It was often asked by the local major equipment producers for advice on industrial fans and air transport.
Peter Herrmann, Sales Manager (PH): The company manufactured small and medium size fans for the cement sector initially, before moving into larger pieces. Initially we worked closely with Polysius, supplying clinker cooler fans and airslide fans. Now our cement sector business is mainly concerned with large process fans. We employ 265 people here, 50% in administration and 50% in fabrication and engineering. There are around 70 engineers
working to develop our products to keep up with future demands.
GC: Does the company have any production bases other than in Oelde?
TG: We manufacture the major rotating parts of the fans in Germany only but also manufacture fan casings and other less complicated parts in partner facilities around the world. These are licensee companies authorised to produce our parts for us.
GC: How important is the cement sector to the company today?
PH: The cement sector is 35-40% of our total order intake. It is our largest sector, the second being steel and the third being chemical processing. We also supply to around 6-8 other sectors, for example power and wood pulp and paper.
GC: What are the most common requests from cement producers?
PH: The main fans we make are the main process fans, which have to deal with high temperatures and abrasive environments. These days a typical order is for a fan in excess of 3000mm in diameter with a drive rated at more than 1MW rotating at 740-1500rpm. We supply fans of 800-4100mm to the cement sector. We make up to 100 cement fans in a good year.
In quality terms, what the customer is looking for is a long lifetime with high performance and high efficiency. Low noise is an increasingly important
factor too.
GC: How do your 70 engineers improve the fan with time?
TG: First we look to the process, because a mill fan is not the same as a kiln fan. Once we know the type of fan that is needed, we use CFD calculations to see what might work well for the exact system in question. We can then choose the best and refine them in our testing lab using scale models. We enter the calculation figures and use our software to extrapolate from a 500mm diameter fan up to a fan that is 5000mm in diameter. It is important to combine the calculations with our near 80 years of experience.
PH: Using this experience and modern technology we can see the critical areas for heavy wear or build up of material. It might be a case of changing the blade angle or altering the speed, the air velocity. It’s about 50/50 experience to calculation.
GC: Once the fan is designed, how is it produced?
PH: We start with a blade sheet and cut them out, bend everything according to the design and weld it together. Then the impeller goes for stress relieving in a big oven. After that, we machine it and balance it on the shaft, which is forged material from elsewhere. We then add the bearings and may also add the casing here, if it is not being produced at one of our partner factories. The finished product is then put in a container and sent to the client. We send out most of our fans via ship.
From cutting the blade to sending out the finished item takes around 3-6 months, depending on the size of the fan. It is not often that we get the same order twice so everything is a ‘one-off.’ I don’t think two fans we have made have ever been the same.
GC: Does Venti Oelde test the product before it is sent out?
PH: It is not common that a cement sector client would request testing before delivery, although we have that capability. Usually we provide guarantee figures and test on site following installation.
TG: We have delivered hundreds of fans and each time we check the accuracy of our figures against the real test. They match to 1-2% in every case.
GC: Which parties are responsible for installation at the client’s site?
PH: The client is usually responsible for installation because we usually deliver as part of a larger project by one of the large original equipment manufacturers (OEMs). They are responsible for incorporating the fan into their system. We then come to site to perform cold and hot commissioning. Sometimes we also perform performance tests if the client requires. We might also be asked to be present during some of the installation steps.
GC: Where are the most orders coming from at the moment?
TG: Africa is big at the moment but we also have strong recent orders from the Middle East. It varies year-on-year though. 2017 was big for Egypt in particular but that probably means that 2018 won’t be. We listen hard to the OEMs and read the news in Global Cement Magazine to position ourselves well for future trends.
On the other end of the spectrum we have places like Europe, where there is only the occasional upgrade order. It is also hard to sell in China but that is due to the prevalence of local suppliers and the dominance of cost in purchasing decisions.
GC: How have client demands changed from a technical standpoint over the years?
PH: The technical demands are not as strong as before because our main customers are now the OEMs rather than individual plants. The OEMs include the fan as part of a much larger whole and are under price pressure. They have simplified the demands placed on the fans and want them to be lighter (i.e. cheaper).
GC: Does that mean that the fans are less interesting for your engineers?
TG: On the contrary. We are being asked to do more with less and run closer to the edge with respect to the tolerances. This is more interesting for us. A fan is typically 80-85% efficient. Achieving this is harder with less material and simpler designs. To improve performance requires subtle changes to the designs, as well as more accurate production techniques.
GC: Does the company have anything new in the pipeline for OEMs and / or cement plants?
PH: We will continue to offer a wide range of fans to both categories of customer and we are also taking steps to reduce our costs. This is very important at the moment. We will buy a new machine to weld the fan impellers automatically, although we will still retain highly-skilled welders to ensure the quality of the most difficult welds.
We have also changed our production system to reduce the number of man-hours required per fan and are looking at new wear protection systems to upgrade older fans and protect them against wear.
GC: Are there any plans to expand production?
TG: We are always looking to extend our capabilities. The robotic welding will be a big step. There is quite a lot of space still available here, even though we have already expanded our production areas by 50% in the past decade.
GC: Thank you for your time today!
TG/PH/IT: You are very welcome indeed!