Getting Ideas for Energy Management Opportunities
2.3.2 Process and material flow
Time is money. Time losses caused by a poor layout of process equipment, cumbersome operating procedures, a multi-layered organizational structure, delays in transporting materials, molten metal and parts, also incur productivity losses and additional energy costs. Even in established and well-managed foundries, opportunities may be found for process streamlining and simplification, with attendant savings and productivity benefits.
What are the tools to use? An experienced foundry worker may have an instinctive feel for the existence of process bottlenecks in the foundry. In other circumstances, a “rough and dirty” time and motion study will uncover likely shortcomings. In the search for solutions, keeping an open mind and challenging established practices help. So does simple flowcharting of the processes. Pencil, paper and input from knowledgeable operators and staff are all that are needed. When examining a process flowchart, shortcomings, redundancy, duplication of effort and waste may become readily and visually apparent. Consider each activity and process step in terms of supplier-customer relationships. In large foundries, and for complex projects, the use of process simulation software could be employed to find optimum solutions.
Is it really more profitable to rush off with a ladle of poured metal from an electric arc furnace than to have it charged first for the next heat? Do we have to transport the charge bucket over a furnace to reach the next one? Is using the pneumatic system for transporting moulding sand a smart way to do it, considering the high maintenance and high energy costs? Can transporting distances and timing sequences be optimized?
Once we come up with ideas for process improvement, let us subject them to critical evaluation, described in Sections 3.2 to 3.5 (pages 91-101).
Monorail transport system
Foundries with ladle transport by gantry cranes can learn from a galvanizing foundry in the Netherlands. For transporting large parts to be hot-galvanized, a single 5-t gantry crane system was used. This was causing considerable waiting times (and hence heat/energy losses). A new monorail system with a bypass and carrying three gantry cranes was installed. The new arrangement allows the products to be moved independently and simultaneously, and allows the gantry cranes returning to the beginning of the line to pass the other ones. Energy savings alone allowed a 3.5-year payback, but operational advantages (e.g., productivity improvements) reduced it to 1.7 years.