Unternehmen : CASCADE
Industrie : Energie - Öl
Geschäft : World leader in quality material handling products for lift trucks
During the past 70 years, material handling has developed into a highly sophisticated and important part of industry. Cascade Corporation, Portland, OR, has played a significant role in this growth and development, from its beginnings as a small machine shop in the early 1940s to the leading worldwide manufacturer that the company is today, Cascade continues to grow as the premier supplier of lift truck attachments and related products.
Cascade Corporation's innovative material handling solutions enable lift trucks to become more versatile and efficient material handling tools. They rely on intricate hydraulic valve designs that make it possible to pull, push, clamp, lift, side-shift and rotate practically any unit load imaginable. These products are made and shipped to Europe, Asia and many other parts of the world from its manufacturing facility in northwestern United States.
Prototypes for hydraulic valve bodies critical to the success of the next generation of Cascade products are made in the same plant and on the same manufacturing equipment as the full production components. Manufacturing prototypes on the same equipment allows the company to transition swiftly and smoothly into production manufacturing when a new design is released. It also means, however, that prototype manufacturing must be conducted in off hours so that it does not disrupt very active production manufacturing schedules.
Also, CNC programmer Stan Wolf explained that running a 5-axis program for one of these complex valve bodies was not a simple matter of posting the CAM program to one of the company's two machining centers and letting it run. To assure that there were no interferences that might cause the tool or its holder to crash into the part or the tightly-spaced work-holders at a feed rate of 350 IPM, someone had to «single block» through a program that consisted of 2000 to 3000 lines of code and up to 40 tool changes.
Since Wolf wrote the program, he was very familiar with it and could get this task accomplished in about eight hours. The two machine operators were also capable of doing this, but since they were not familiar with the code, they would have to run the first piece very cautiously, which could take a couple shifts. This was not an option anyway because the operators were engaged for five hectic 10-hour shifts, loading and unloading parts and deburring them.
Wolf said, «An engineer would send me a new design and he would need his prototype as soon as possible. So as not to interfere with production, I would find myself single-blocking through a new program late at night or during the weekend. We avoided crashes this way but the parts are very complex involving intersecting internal work planes. We had no way of being sure that the part replicated the model exactly until I measured it on the CMM. If something was off, then the part was likely to be scrap, part of the manufacturing program would have to be rewritten back in CAM software, and I would once again be back to single blocking through the code the next late night or weekend opportunity.»
Wolf said that this situation would occur about 20 times a year for him and sometimes he would get two assignments like this in the same week. Mitch David, the lead programmer who works in Wolf's department, was having a similar experience. When logjams like this occurred, production would be interrupted or product development would be stalled while the engineers waited for their prototypes.
The programmers presented their case to management and proposed that the company acquire a seat of simulation software that would allow them to detect interference and design nonconformance issues before the programs were posted to the machining centers. Management was impressed with cost justification and purchased a seat of NCSIMUL MACHINE software from SPRING Technologies because it provides a highly realistic 3D machine model environment within which CNC programs can be simulated, verified, optimized and reviewed based on the G-code that is posted by the CAM software.
The software makes it unnecessary to spend valuable on-machine hours single-stepping through first piece CNC programs to ensure that they will run without encountering interferences. As a result, prototype work rarely interferes with production manufacturing and design engineers get their prototype parts faster. NCSIMUL MACHINE eliminates the need to step through complex first piece to avoid machining crashes while powerful algorithms and embedded process-based intelligence facilitates the optimization of cutting conditions and the standardization of the shop-floor documentation. The NCSIMUL MACHINE package purchased by Cascade Corp included the development of models for its two machining centers and a week of training. One of the first things the programmers did during training was to model some of the most frequently used tools. Since the machining centers accommodate 240 and 308 tools respectively, the modeling of less frequently used tools is still an ongoing project. During training they also used the software to simulate some of the most complex work in progress, immediately recovering the time that would previously have been spent in single blocking through complex part programs. Wolf believes that time savings alone provided a payback for the software, most likely within the first four to six weeks.
After programming a part in his CAM system, Wolf opens the posted code in NCSIMUL MACHINE, which investigates and corrects coding errors, simulates tool movement to locate collisions and corrects motion errors. The software automatically detects and highlights interferences and these can be corrected directly from within the simulation environment without having to go back to the CAM system. Once these corrections are made, he can run the program as it is without hovering over the machine to watch for interferences. This basic application alone eliminates about 160 hours of single stepping through CNC programs for valve bodies annually. There have been no crashes in the year and a half when NCSIMUL MACHINE was utilized. Prototype parts have been manufactured on a fast turn basis without interfering with production manufacturing schedules.
First piece crash detection is not the only area where the simulation software is paying dividends. Scrap is down. NCSIMUL MACHINE compares the simulated part to an STL file replicating the CAD model. Then toolpaths can be fine-tuned from within the software to eliminate non-conformances. Wolf said, «NCSIMUL MACHINE also allows me to create different planes within the part model and the simulated part model and compare the intersections of the deep cavities. This is very useful in making sure my deep cavities intersect where they are supposed to.»
The program's usefulness also extends backwards to CNC valve body programs that are already in production to reduce cycle times. It has analytical tools that allow Wolf to review how often a tool is accessed, the amount of time a particular tool is engaged with the part, how much time the tool is in rapid moves rather than actually cutting. This allows him to rapidly zoom into areas that would benefit from refinement. In one instance he reduced the machine cycle of a long cutting program by 25% because he found that a particular tool was absorbing an unusually large amount of time and switched to a type of tool that could feed faster.
Eighteen months before his NCSIMUL MACHINE training, Wolf was confident that simulation would help reduce his late night and weekend programming tasks. He wasn't that certain about how well it would integrate with his computer aided manufacturing workflow or that it would be useful for improving the quality and productivity of his CNC programs. «However, today,» he said, «I'm a believer.»