An overhead bridge crane system for DRU Verwarming B.V. (NL)
Guests who visit DRU Verwarming B.V. in Duiven immediately feel at home. Entering the showroom you are met by a delightful scent of crackling fire. DRU shows a wide range of fireplaces in all types and sizes, most of them in operation. They offer fires and stoves. We would like to know how DRU is able to deliver such a wide variety of fireplaces in short time and tailor made. How does DRU maintain the high level of their well-known quality. And...how did Railtechniek van Herwijnen contribute to the change of DRU's operating process?
The history of Dru
DRU was founded in 1754 and now is one of the oldest Dutch industrial companies. The company was well known for producing pots and pans of cast iron. When natural gas was discovered in the Netherlands at the beginning of the 1960s, DRU switched to producing gas fires and wall heaters. DRU exists for more than 267 years and already provides high quality products for centuries. Therefor it's not surprising that they are one of the first Dutch companies with an ISO 9000 quality certificate.
From functional to atmospheric and sustainable
Besides delivering functional wall heaters DRU started delivering two kinds of fireplaces. Earlier the gas fires and wood burners were assembled in series. To be able to quickly supply from stock in the wintermonths DRU used to produce more fireplaces in summer period. The assembly was done on conveyor belts. At that time this working method was okay. But over time the consumers' demand changed. On the one hand central heating became common and the market demand for traditional gas fires dropped. On the other hand, the attention for atmosphere and intererior was growing and the fire place as an atmospheric and stylish element became more important. That is why the market demand switched more and more from serial to custom made fireplaces. Enlarging the storage capacity would not be the right solution. A complete change of operational processes was necessary. One of these was the assembly process.
The proper logistical solution
To find the right logistical solution DRU did comprehensive research. At first they looked into the possibilities of jib cranes. However, because the six assembly lines are placed very near to each other the jib cranes would stand in each others' way during assembly operations. During reference visits the name and overhead transport systems of Railtechniek van Herwijnen repeatedly popped up. And the stories about Railtechniek were very positive. This was an important reason for DRU to ask Railtechniek for professional advise. Actually, it was not the very first time that Railtechniek installed a system for DRU. Diving into our archives we found out that our daughter company Stewart Gill Conveyors already installed a STS 550 M for a spray-painting facility of DRU.
The first lay-out
After detailed analyses Railtechniek deliverd their first lay-out. With this lay-out Railtechniek immediately hit the nail on the head. The working area was planned in a very practical, efficient way, taking account of DRU's wishes and objectives. Railtechniek designed a bridge crane transport system with in total six overhead cranes. The overhead crane system is situated directly next to the existing platform, where the burners are tested and fine-tuned.
After some detail adaptations Railtechniek started with the installation of the overhead crane system. To avoid any downtime of the production Railtechniek did the installation of the crane system in two parts. The first part was installed in only a few weeks from order date. The second part followed shortly after. Now several fire places can be assembled custom made in six lines at the same time. Every 45 minutes a custom made fireplace is delivered per assembly line.
The process from burner to complete product
The assembly process starts on the first floor, where the burners are carefully fine-tuned and tested. After approval the burners go downstairs for further assembly. Each fireplace has it's own work order, so the assembly worker can immediately see which components are required to customize the fireplace. Now the fireplaces can easily be guided along the different assembly places. Every bridge crane can be operated manually with a control pendant. This way the employees are able to stop the fireplaces at different positions at the assembly line, where they can raise or lower them to the desired height.
Technical details Railtechniek flexible bridge crane system
The bridge crane system is a design where the bridges are flexible suspended under the trolley sets. Every bridge crane consists of two parallel rail tracks of 10.500 mm each. The bridges cranes are equipped with an electricity supply for the electro chain hoist. Every bridge crane has a length of 4.650 mm each, with a maximum capacity of 250kg. The hoist height per electro chain hoist is 3.000 mm. The velocity varies from 2 to 8 meters per minute, multiple speeds (high and low) are possible too.



