In 1986, Jan Stokman, the 3rd generation in the family business, started to focus on an interesting growth market, that of heavy-duty bulk handling. Soon, the first major order was signed for the delivery and installation of conveyor belt rollers for a leading transshipment company in a port. The rollers that the firm was going to produce were of the same quality as those that were used in this market at the time. And if we’re completely honest, they were a mere copy of what was for sale in the market then, but made available at a lower price. The price was therefore a decisive factor when opting for a conveyor belt roller from Stokman.
It soon became apparent that Stokman rollers lasted just as long as those that had been on the market before them. It was of course quite annoying that the first rollers already started showing signs of failure after a few days or weeks. Mind you, they were the same signs of failure as those from other suppliers. The weakness of our product was in the bearings (quality and construction) and in the wear of the roller itself. In short, we had delivered a product that was just as good, or rather just as bad, as that of our competitors.
We weren’t happy with our performance. We were convinced that this could and should be better and so we started to explore the market. On our quest, we came into contact with a renowned German research agency. This agency, affiliated to the government, specialised in underground mining. After various exploratory discussions, a shared ambition emerged, which was to design and realise a product that was a cut above the rest. The condition for the collaboration was therefore that Stokman did not want to produce the cheapest roller, but the best. Soon, the comparison was drawn with a German car make that used the slogan: das beste oder nichts!
The result of our collaboration, which was to lead to the best roller ever made, was that we could in fact destroy all stock we had already produced. It hurt to do so, but we knew it was for the best. Soon, the construction drawing of the ideal roller was realised and the conditions for quality laid down.
The bearings are of course vital in the overall quality of the product. The market generally worked with bearings of a certain quality. These were often bearings from former East Germany. Stokman used bearings from a brand by the name of DKF. The quality was often found to be insufficient for heavy-duty applications in the toughest conditions (for example, in the outdoors and at sea). A search was started for a better quality. That search led Jan Stokman to a factory in Japan and a visit was planned. Following a convincing visit to the factory, the choice was made for these bearings.
One of the unique features of the Stokman conveyor roller is that it consists of cast bearing pots. The market, as well as the first batch of conveyor belt rollers that we produced, used deep-drawn bearing pots. The cast bearing pot has a number of advantages over deep-drawn bearing pots. The biggest advantage: precision and material strength. Deep drawing modifies the molecular composition of the material, which can cause the material to tear much quicker. Nor can deep drawing be done with the same precision, thus resulting in much lower tolerances, inferior fits and less balance. They are all aspects that have an adverse effect on the lifespan and quality of the product. After a search, we came across a supplier for casting bearing pots, i.e. cast bearing pots. This was a Dutch company specialised in high-quality fittings. It must be noted that they were highly experienced in working with weldable cast steel. Their knowledge in the field of heat treatment and carbon composition led to weldable cast steel in close consultation with Stokman, which steel is vital when applied in a conveyor belt roller where the weld construction between the tube and the casting pot forms an integral part of the overall quality. It should also be noted that Stokman bearing pots have a minimum thickness of 5mm, whereas other (often drawn) bearing pots come with a wall thickness of 2mm.
A quest was set up for the metal tubes as well. The tube is of course a wear-sensitive part, so a search was made for steel compositions that would show little or no wear, even under the toughest conditions. This ultimately led us to a supplier in Switzerland, who could not only supply the correct steel composition, but also produce at an exceptionally high level of quality. The production of a tube involves rolling (a flat piece of steel) and subsequently welding it to create a closed tube. This supplier did that with Swiss precision! Yet another competency was the machined weld seam. This means there is hardly a visible weld on the inside of the tube. This may sound like an insignificant detail, but this step in the production process too contributes to less imbalance and a longer lifespan.
We had a construction drawing, the bearings, the tubes and the cast bearing pots. We had the means of production to actually create the best conveyor roller ever made. However, there was another challenge, the sealing. A long lifespan cannot be guaranteed without a good seal. In fact, in really tough conditions, such as on sea-going ships, even a bearing of the highest quality would quickly fail. A long search eventually took us back to a supplier we already knew. And that was a manufacturer of wheelbarrows! They had helped us a lot in the production of our first (poor-quality) batch of conveyor belt rollers. They had supplied us with the deep-drawn pots. We of course no longer needed these, but it turned out that this manufacturer was also big in the field of injection moulding. They moulded the seals for us as prototypes. These were made of plastic (POM), which is very resistant to weather influences and salt water. Ultimately, we teamed up with another supplier, specialised in small products, for the final production of our unique double bearing seals.
As far as records can tell, the Stokman conveyor belt roller is still unique in its kind,
although different from back then or from what is still available in the market now. We think there may be one other supplier in the world that comes close in terms of quality. Most manufacturers still supply rollers of inferior quality. The fact that these cheaper rollers are suitable for certain applications only is clear. So if you really want the best of the best, with moulded bearing pots, double bearing seals, manufactured using the best materials and with a perfect fit for demanding conditions, it’s Stokman every time.
The roller that was conceived during the co-creation phase back then is in fact still the roller that we manufacture today. New production techniques have of course been introduced, such as CNC turning of the pots and other (robotic) production processes. This has further increased the consistent quality and driven down the cost price.
Is there a market for this extremely high quality? In our meetings with clients, a quick calculation tells you all you need to know. Suppose your total business process depends on your system, for example on a (dredging or gravel) ship. And suppose you can equip your system with conveyor belt rollers for half the purchase price. On a ship measuring 100 metres in length, this quickly adds up to 900 rollers. And say you can buy those rollers at € 50 (instead of € 100). You will easily save € 45,000 on conveyor belt rollers! Now, that does of course sound like a considerable saving. However, a gravel vessel that is not operational for two days equates to a loss in turnover of € 100,000 or even € 200,000. Do we need to go on? All we can do is keep making conveyor belt rolls of the highest quality. The fact that our rollers always come with a 3-year warranty is a given. Truth is, we’re no longer surprised about the fact that our rollers often continue to run for up to 3 decades, as previously explained in this article. The proven track record of a long operational lifespan is mere confirmation that we made the right choices back in 1986. Das beste transportbandrol oder nichts!