January 2012 / Volume 64 / Issue 1|
Simulating and optimizing multitasking
By Jeff Fritsch, CAMplete Solutions Inc.
More than ever, it is crucial that North American part manufacturers constantly improve their technology and processes to compete globally. As a result, they are increasingly using multitask machine tools, which are engineered to mill and turn complex features with high accuracy and quality. These applications, however, create the challenge of initially obtaining a safe and optimal NC program to reduce machine downtime and program prove out.
Multitask machines typically consist of multiple spindles and turrets, which can operate independently or in synchronization. All six sides of a part can be roughed and finished in a single setup, allowing production batches to be run lights-out. In addition, parallel operation allows a manufacturer to simultaneously perform multiple operations on the part, saving significant time.
All images courtesy of CAMplete Solutions
In traditional multitasking, programmers and operators must optimize the process to take advantage of a machine’s capabilities. This means long setup times on the machine and extensive part prove outs, both of which can be costly. There is always a trade-off between spending more time on optimization—and therefore increasing machine downtime—and the cycle-time reduction that optimization achieves.
To maximize multitask machine utilization, a user needs an integrated software package that “intelligently” post-processes, simulates and optimizes programs, such as CAMplete TruePath TurnMill. The software was developed in partnership with Methods Machine Tools Inc., Sudbury, Mass., exclusively for Nakamura-Tome multitask machines, which Methods distributes.
Programmers use the software to generate NC programs using input from their CAM systems. They can even reuse NC code from other machines. After generating the NC code, the software simulates and optimizes the programs before they are run on the multi- task machine.
However, a simulation platform is only as effective as the level of detail it offers. It must support the specific G and M codes required by each machine. This includes advanced features, such as tool center point control for 5-axis machining, part transfer between spindles and synchronization codes between turrets. For example, all Nakamura-Tome machine models use the exact manufacturing CAD data directly from the builder. This eliminates the approximations and guesses of using a model designed by a third party.
Instead of limiting itself to the basics, simulation and optimization software should control, monitor and simulate every aspect of a machine as closely as possible. For instance, CAMplete TruePath TurnMill simulates and displays the entire tool-change sequence on its virtual controller.
Having a proven and collision-free program is still not enough to get the most out of a multitask machine. With so many different elements moving and the constantly expanding complexity of the machines, such as two or three turrets or a milling spindle mounted on a rotary axis, efficiently managing every machine aspect is crucial. Machine setup is challenging because of the large number of tools that must be allocated to multiple turrets. This complexity can overwhelm even experienced operators. TruePath TurnMill helps programmers reduce setup time by using intelligent tools to automatically detect and assign cutting tools to the proper channel and turret and dynamically try and prove multiple setup options to determine the most appropriate one for a particular part.
A multitask simulation and optimization program should also provide the ability to quickly change a fixture, reposition and reorient parts on the fly and test a new tool. This is essential to achieve a quick and efficient setup. Additionally, the software must offer features to automate the tool assignment to the proper turret, automatically calculate the proper offsets and seamlessly reorganize a program or setup by copying or moving tools or entire operations. An extensive library of premade tools and workholding elements also enables high-quality simulation.
After the proper operation sequencing is done, the software should easily synchronize the turrets and moving axes. Users also want to quickly switch operations around to optimize the process and minimize downtime.
To offer a clear view of how a program will run on a machine, the simulation should enable viewing to the millisecond increment.
The stakes are high, but the appropriate simulation and optimization software helps part manufacturers make complex multitask machines easier to use. CTEAbout the Author: Jeff Fritsch is product manager for TruePath TurnMill for multitask machines at CAMplete Solutions Inc., Kitchener, Ontario. The company also distributes TruePath software for 5-axis milling machines. For more information, call (519) 725-2557 or visit www.camplete.com.
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