Quick Switch for Faster, Larger Mold Production

Leda Werk, a foundry in Leer, Germany, that manufactures cast-iron stoves, fireplace inserts, and similar products, recently completed a thorough modernization, the centerpiece of which is the world’s first installation of a new, automatic green-sand molding system for large-dimension castings. The Disamatic D5 replaced an earlier-vintage DISA machine and completed Leda’s recent capital-investment program.

Installation and commissioning were completed on schedule from late December 2020 into January 2021, notwithstanding the travel and working restrictions imposed on Leda and DISA crews due to the coronavirus lockdown in Germany and Denmark (where DISA is headquartered.)

High-quality, short-run casting. Leda has been producing castings in Leer for nearly 150 years, and DISA molding equipment has been in use there for over 40 years. While iron castings for fireplace inserts and stove units are produced under the Leda brand, the plant also operates as a jobbing foundry for various other ferrous castings. Its product quality standards are an important element of its customer-service strategy.

Accordingly, Leda Work has been conducting an extensive modernization of its production systems in recent years, including the melting and sand-mixing system. In 2019, the foundry replaced a smaller molding line with a Disamatic D1 line – leading to the installation of the larger-dimension Disamatic D5 late last year.

“Efficient and high-quality casting production is key for us,” Leda Work managing director Folkmar Ukena explained. “We produce (castings) in small series, so we need molding lines that deliver an extremely stable process despite multiple pattern changes per shift. Disamatic molding lines deliver consistent, repeatable, and high-quality (performance) right from the first mold – exactly what we need.”

The man charged with operating the molding process confirms that evaluation. “With this latest upgrade, we have now replaced all our vertical molding machines with the latest D-series Disamatics and have future-proofed our processes,” according to Rochus Hiller, foundry manager. “The investment in new, state-of-the-art equipment has enabled us to reduce our operating and maintenance costs, improve our energy costs, and achieve high machine availability.”

Efficiency and complexity. Leda’s new Disamatic D5 is the latest in DISA’s flagship ‘D’ range of vertical molding lines, which started with the D3 and the various innovations that followed from it in the D1 (smaller) and D5 (larger) mold sizes. For DISA, as well as for Leda Werk, the D5 replaces the older DISA 240 and 250 machines. The D5 range now comprises three machines with mold sizes of 600 × 775 mm, 600 × 850 mm, and 650 × 850mm, and achieves speeds of up 450 uncored molds per hour.

“The high degree of automation on the D1 and D5 offers us the features and settings to make more complex molds efficiently,” Rochus Hiller detailed, in reference to the foundry’s upgrade. “An example is adjustable squeeze distribution, a new feature we have not had before.”

Adjustable squeeze distribution ensures squeeze distances are optimized across the pattern, for swing plate and pressure plate molding, to adjust for asymmetric patterns or very deep pockets. This achieves the most consistent and even molds, and optimizes the mold surface. The resulting castings exhibit excellent surface quality and require minimal extra finishing work or machining.

“Similarly, both the D1 and D5 have automatic core setters that enable us to produce more economical and save resources,” Hiller continued. “We use the automatic core setter to place not just cores but also the exothermic risers and filters. The efficiency gains we get through the higher level of automation and precision mean we maintain our competitive edge, but this also enables us to pass the benefits of more productive and sustainable production on to our customers.”

Sustainability is an important factor for Leda Werk, where a plant-wide energy-management system has already been put in place, and the managers and operators continue to look for ways to reduce annual energy consumption. The new molding lines consume less energy, directly and indirectly. Indirect energy savings result through scrap reduction as a result of the highly accurate castings that require minimal finishing work, but also through short cycle times, with less idle time between molds required for core setting and other manual tasks. In addition to the energy savings, the requirements for other consumables (e.g., hydraulic fluid) also are reduced.

The new line is a D5-Z, capable of producing up to 355 molds per hour – a high-speed operation that completes up 30 quick pattern changes in a day, giving Leda both flexibility and responsiveness as it runs lower-volume series in a five-day, two-shift operation.

The smooth transition. Leda’s old DISA 250-C was replaced by the new D5 between mid-December 2020 and the start of this year. A team of Leda and DISA staffers, along with transport and crane suppliers, worked in shifts to complete the change-over smoothly. The switch happened on schedule, with the old molding line still running reliably up to “the end.” (It was returned to DISA in Denmark for reconditioning, awaiting reinstallation elsewhere.)

At Leda Werk, DISA technicians reused the old line’s synchronized belt conveyor, rebuilding it on-site to work with the new automatic mold conveyor.

The new D5 was designed to be slotted into the space vacated by a DISA 240 or 250, maintaining the critical dimensions that made for an easy transition to the new technology. Leda’s new D5 line produced its first mold on December 31 and started series production on the January 4, 2021. “We are proud to welcome the second of our two new Disamatic molding lines into the Leda family,” Hiller declared. “Both are at the heart of our production and will ensure the highest quality castings are delivered reliably and responsively for our customers.”

While the design and installation have been important aspects of the story, Leda Werk also gained a new production system that is ready for Industry 4.0 operating standards. The digital capabilities available with the two Disamatics mean that Leda can continue its digital progress, ready for future requirements.

 “Digitalization is an important tool in the continuous improvement of our products and processes,” explained Folkmar Ukena, the managing director. “It’s therefore important to us to capture the digital ‘state of the art’ when we buy any new equipment. DISA molding lines are digitally enabled, allowing us to introduce digital tools in a way and at a pace that suits us.

“For us, that means combining digitalization with the incredible wealth of knowledge and experience we’ve got in our workforce. That’s the winning formula for staying ahead of the competition,” he concluded.