Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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Annual waste volume discontinuous operations: Figure 3: In traditional discontinuous operation, long-life sulfate-free processes reduce concentrate waste. Between the three available continuous technologies, ENfinity® SteadyState is the lowest waste alternative. Basis for calculation: Mid Phos, bath life: 8 MTO Sulfate type, 16 MTO ENfinity, Electrodialysis at 4 MTO, "Bleed & Feed at 3 MTO, SteadyState at 10 MTO, 1000 kg Nickel deposition per year; 1000 L bath volume." er increase in specific gravity and solution viscosity. In addition to the bath life extension up to 20 MTO, these processes provide compressive deposit stress at any bath age and phosphorus range. Particularly for high phosphorus deposits, where compressive stress is essential, bath life can be extended by a factor of 2 to 5. The real challenge for electroless nickel technology is to provide a simple and low- cost solution for continuous operation, overcoming the fundamental problem of being a discontinuous technology. The automotive industry and its quality demand are the main drivers behind the movement to improve today's operation mode, and to create endless, consistent deposition and identical deposits at any time. It can be expected that only technologies fulfilling these demands will ben- efit from future high-volume and long-term plating jobs. Until today, basically two technologies for continuous EN operation have been available: 1. Operation in "Bleed & Feed" mode, or 2. Electrodialysis. By rather simple means, "Bleed & Feed" uses dilution to keep the process at a typ- 372

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