Werkzeugbau Ruhla develops and manufactures high-precision multi-cavity injection molds with up to 96 cavities for the medical, diagnostics, laboratory, and packaging industries. With in-house design, advanced manufacturing technologies, comprehensive metrology, and dedicated sampling capabilities, the company delivers tooling solutions that combine precision, reliability, and long-term production performance.
We talked to Lena Lüneburger, Managing Director of Werkzeugbau Ruhla GmbH, about the engineering challenges behind high-precision 64-cavity injection molds.
Ms. Lüneburger, 64-cavity molds are often regarded as one of the most demanding disciplines in injection mold engineering. What makes them so challenging?
Lena Lüneburger: A common misconception is that a multi-cavity mold is simply a single-cavity design multiplied several times. In reality, complexity increases exponentially with every additional cavity. A 64-cavity mold is a highly integrated precision system in which every cavity must operate under exactly the same processing conditions. From melt distribution and cooling to venting and ejection, every detail must be perfectly balanced. Only then can manufacturers produce millions of identical parts with maximum process reliability.
Where do you see the greatest engineering challenges?
L.L: The greatest challenge is achieving absolute uniformity across the entire mold. Every cavity must fill simultaneously, experience the same thermal conditions, and produce identical parts cycle after cycle. This requires naturally balanced runner systems, optimized cooling circuits, precise venting, and exceptional manufacturing accuracy. We always look at the mold as one integrated system rather than a collection of individual cavities.
How important is manufacturing precision in achieving this level of performance?
L.L: It is fundamental. In multi-cavity tooling, we work with tolerances in the micron range. High-speed milling, sink EDM, wire EDM, and advanced 3D metrology allow us to manufacture critical mold components with extremely high accuracy. But precision is not just about achieving tight tolerances—it’s about ensuring that every component interacts flawlessly so that all 64 cavities perform identically over millions of production cycles.
How do you ensure that a mold is ready for serial production?
L.L: Tool manufacturing is only part of the process. Comprehensive mold validation is equally important. During initial sampling in our technical center, we evaluate cavity balance, dimensional accuracy, cooling performance, and process stability. Only after every cavity consistently produces identical parts under production conditions do we consider the mold ready for series manufacturing. This integrated approach significantly reduces production risks and shortens the time to market.
Werkzeugbau Ruhla has extensive experience with high-precision multi-cavity molds. How has this shaped your engineering philosophy?
L.L: For decades, we have specialized in multi-cavity injection molds for medical technology, diagnostics, laboratory consumables, and packaging applications. These industries demand uncompromising precision and process reliability. Our experience with molds of up to 96 cavities has reinforced one fundamental principle: productivity is not defined by the number of cavities, but by the ability of every cavity to deliver identical quality—from the first shot to the millionth.
Looking ahead, what trends do you expect to shape the future of multi-cavity mold engineering?
L.L: Demand for higher output, shorter cycle times, and tighter quality requirements will continue to grow. Digital engineering, simulation, sensor integration, and data-driven process monitoring will become increasingly important. However, regardless of technological advances, one principle will remain unchanged: the quality of every molded part begins with the precision of the mold.
Werkzeugbau Ruhla GmbH | Industriestraße 14 | D-99846 Seebach
