Dango & Dienenthal, headquartered in Germany, is a long-standing machinery manufacturer that has a presence in many processes that directly or indirectly involve metal forging. This article offers a sampling of how their machinery is used in forging manipulation, automated thermal-treatment systems and water filtration in steel production.


In 1865, brass foundry worker and lathe operator August Dango teamed up with foundry worker Louis Dienenthal to start the company that bears their name today. What started as a small nonferrous foundry in the iron city of Siegen, Germany, soon began to take on different dimensions. Production was expanded to include blast-furnace fittings and rolling-mill bearings as well as metal castings.

By the turn of the 20th century Dango & Dienenthal (D&D) had become a machine-building company. The World Wars in the early part of the 1900s had their effect on the company, and by the end of World War II the company had to refocus on the restoration of the Siegen works that had been destroyed during the war. As the business climate was restored in subsequent years, however, D&D continued to provide specialized solutions to its customers within the metallurgical industry.

In 1982, D&D, having lost its pre-war subsidiaries, started to expand again with the establishment of subsidiaries in South Africa, North America, Japan and India. In 2003, former competitors D&D and Paul Wurth of Luxembourg merged their activities in the fields of cast-house equipment and blast-furnace measuring technology.

Today, D&D has a presence in numerous metal-processing markets, including open- and closed-die forging, ring rolling, steelworks, thermal treatments and other metal-forming technologies.

This article highlights some of D&D’s activities in select markets.


South Korea’s Largest Open-Die Forging Plant

The last century saw a movement toward larger and larger presses in open-die forging markets. This trend has continued into the 21st century as forge masters have decided to use increasingly large-scale forging manipulators in order to make the production of large forgings more efficient, safer and cheaper.

Recently, Doosan Heavy Industries & Construction Co., Ltd., Changwon, South Korea, invested heavily in its existing forging plant. Based on long-term market studies and a good outlook for market conditions, the company recently invested in an open-die forging press that will be served by a large rail-bound forging manipulator from D&D.

Doosan, a producer of large forgings for markets ranging from power generation to automotive, stands to improve its output significantly. The upsetting speed of the new press will be five times faster than that of the old one. In addition, reheating times can be reduced by about 20%.

Handling this increased output volume will be facilitated by the new rail-bound manipulator. This manipulator will provide for the efficient and safe handling of large, open-die forgings. As shown in Table 1, the one integrated rail-bound manipulator offers double the productivity of a crane-mounted mandrel.


Automated Thermal-Treatment Systems

In 2012, the subsidiary Dango & Dienenthal Hollerbach (DDH) was formed as a merger-and-acquisition process with the former Ortmann Company in Hamm (Westphalia), Germany. The core business of the subsidiary is the manufacture of handling systems for automated heat-treatment plants with capacity of up to 80 tons. The products to be heat treated vary from small forged and rolled pieces – handled in a bundle or box – up to large single components. To ensure the reproducibility of the manufacturing process, an automated control including documentation is necessary.

In one example, DDH, in cooperation with Canadian furnace builder Can-Eng Furnaces International, installed a semi-automated heat-treatment plant for rings at McInnes Rolled Rings in Erie, Pa. DDH delivered the fork quenching system to transfer charges of rings (25 tons) from a loading station to a furnace, from the furnace to a quenching pool and finally from the quenching pool to an unloading station. The machine is able to travel in X, Y and Z directions. The trolley travels in two directions to interact with the furnaces or set-down locations. Local suppliers of electric and hydraulic components completed the system. This offers the best options to the customer for maintenance and integration of the entire plant.

In a second example, also in cooperation with Can-Eng, DDH installed an automated heat-treatment plant for crankshafts (80 tons) at Ellwood Crankshaft Group in Sharon, Pa. The fork quenching system transfers crankshafts from a skid table into quench tanks. The basic transfer is accomplished by using a bridge with driving beams running on rails. The lifting system consists of eight lifting columns and a crossbeam with forks. The forks are manually located on the crossbeam and are adjusted to suit the production run.

There are several important advantages to automated handling technologies in heat treatment.

  • The customer ensures the quality of their product, saves energy, reduces production costs and stays competitive in the market.
  • Human error and inconsistency are removed from required thermal-cycle times.
  • Automation ensures a fast and consistent transport from the furnace into quenching tanks, and cycle times are further optimized.
  • All process data (such as time and temperature) are recorded, analyzed, monitored and documented during all thermal-treatment steps, creating a reproducible process.
  • The results are a customized automation with optimized process solutions and precise handling so that the customer has an efficient material flow.


Water Filtration in the Steel Industry

Starting in the 1950s, the continuous separation of sinter and other solids out of circuit water in the steel industry became increasingly important. In modern practice, large quantities of cooling water for different manufacturing processes are required (e.g., continuous-casting units, rolling mills, etc.). In most cases, river, well or lake water is used. As a practical matter, this water must be filtered to prevent contamination of equipment, clogging of lines, etc.

Compared with the high-ticket, high-profile equipment common to steel production, water-filtration systems tend to attract less consideration and lower budgets. However, this initial oversight often results in substantial but avoidable subsequent expense. Depending on the degree of water pollution at the source, for example, adverse effects may occur on the plant equipment.

Heat exchangers or spray nozzles often get clogged, but seals, pumps and all piping systems can also be damaged or operate at less-than-optimal efficiency. This affects their function and decreases their life cycle significantly. Additionally, process heat generated in plants is dissipated with plate-and-tube heat exchangers. Impurities can reduce the efficiency of a heat exchanger so that it eventually overheats, which makes cleaning of the heat exchanger inevitable.

There are automatic and manual filtering systems used to clean process water. Automatic backwash filters clean themselves automatically after an adjustable differential pressure has been reached. No external medium is necessary for cleaning the filter element. The back-flushing process is activated and monitored via a control panel. This leads to no interruption in operation during the back-flushing.

With manual filters, the screen must be removed from the housing by the operating personnel and carefully cleaned using a water hose or a high-pressure cleaner. This means an interruption in operation.

As an example of an automatic filter, D&D supplied a Filterautomat DDF unit that was installed in 2014 in a steelmaking facility located on Lake Michigan in northwest Indiana. The unit filters 45,000 gpm of water from the lake. The filtering unit is distinguished by a robust design and an excellent back-flushing performance. The complete filter area is cleaned by a reverse back-flush with a rotating filter drum.

The filter system eliminates solids contamination in pressurized cooling- and process-water systems by arresting contaminants across the whole surface of a specially constructed slotted-strainer element in the filter drum, where these retained contaminants then become part of the filtering function (100% surface filtration). Periodic segmental backwashing cleans the strainer without interrupting the filtering process. The backwash is to atmosphere, and a minimum pressure differential of 0.8 bar (11.6 psi) across the strainer is required.

For additional information, visit www.dds-filter.com/us/products/filterautomat/.

For more information on: Forging manipulators, contact D&D Maschinenbau GmbH, Siegen, Germany, at contact@dango-dienenthal.de; Automated thermal-treatment systems, contact D&D Maschinenbau GmbH, Hamm, Germany, at jhb@ddh-hamm.de; Water-filtration systems, contact D&D Filtertechnik GmbH, Siegen, Germany, at filter@dds-gmbh.com.