Article From: 2/15/2011 Production Machining, Chris Felix, Associate Editor
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The 3DVM software offers manual and MDI modes to check clearances for tools and work envelopes. A measure function is also provided to verify that a given part will fit the machining capabilities.
Okuma’s 3D Virtual Monitor (3DVM) software is a verification program that provides virtual confirmation of an Okuma machine setup while emulating the accuracy of Okuma metalcutting NC programs. Many programmers and shop owners question whether verification machining is really worth the time or money. Programmers often consider verification machining an unnecessary step in CNC programming and CNC machine setup. When questioning the value of verification machining, the following points are important:
Lost Production Time During Machine Setup
Programmers should have some level of confidence in their CAD/CAM programming system. However, they must consider the lost time involved in the setup for “prove-out” of the NC programs and the uncertainty of how the machine on the shop floor will interact with the NC program. 3DVM will verify the accuracy of the G and M code language required for OSP control. If there are any G and M code language errors, the same NC alarm that occurs on the machine tool will occur at the programmer’s desk. 3DVM will also help establish tool lengths and chuck clearances, create setup procedures and verify cycle times, all offline while the machine remains in production.
Repair Costs for a Crashed Machine
Beyond verifying NC programs, 3DVM will detect costly collisions that may occur during NC program prove-out. One collision on any CNC machine could easily exceed the cost of the software. Path verification and collision detection software allows simulation and part program editing offline in a 3D environment, helping to detect trouble before it shuts down the machine.
Cost of Scrapped Parts
The virtual machined workpiece can be measured to verify the NC program geometry. To avoid geometry errors, the design-level 3D model can be compared with the virtual machined model. By checking the virtual work, real scrapped parts can be avoided.
Value of Accuracy
3DVM provides machine models with dimensions accurate to within 0.001 inch, which in most instances, sufficiently matches the requirements of the part on the machine.
Model Updating
A built-in utility program allows the user to interact with the machine model, selecting the portion of the (base) machine model that needs to be accessed/modified.
Flexibility with Chucks and Fixtures
The user defines chuck and jaw models. Wizards within the program can assist in creating most items. Definitions for an individual tool can be adjusted, as well as the tool’s active offset.
The Library area facilitates organization of all data files while allowing access to pre-installed cutting tools, chuck bodies, tailstock centers, and so on.
The programmer can import STL model data formats, but there is a size limitation for the STL files, and they must be free of errors. Checker software is available for model correction and size analysis.
Multitasking Protection Beyond the PC
For similar verification protection after the setup has been proven on the computer, the collision avoidance system (CAS) incorporates 3D modeling of Okuma machines, blanks and tooling, along with the power of the THINC control, to create a virtual machine.
By running the realtime virtual application seconds ahead of the actual cutting, interference can be detected early and the machine can be safely stopped before a costly collision occurs.
Both CAS and 3DVM use the same modeling software, allowing for seamless 3D tool and chuck migration to the THINC control. All of the tasks regarding the chuck, jaws, workpiece, tooling, and so on can be performed offline.
3D Monitoring and Part Verification
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Atlas Copco uses 3D monitoring and part verification software designed specifically for its lineup of CNC machines. The company has five MacTurn multitasking machines similar to this one and is looking to add another this year.
The company also uses the Okuma Multus multitasking machine for parts such as these rock drill bits for drilling oil wells.
Robert Hershey uses 3DVM to program the Okumas prior to part production.
To meet the need for highly optimized machine programming, programming systems for machine tools continue to become more flexible, with useful tools for optimizing cycle times. Simultaneously, machine tool manufacturers continue to add power and flexibility to their products. The pairing of these improved systems has brought shopfloor productivity to new heights as machines can be programmed faster and more efficiently while part quality advances as well.
Clearly, the types of parts a shop needs to produce, and therefore the machining operations it needs to perform, help to determine the most suitable machine for the job. These factors also play a significant role in the requirements for the programming system. For instance, the problems a shop faces with Swiss-type lathes are not the same as with a three-axis machining center. Synchronizing the different operations is one of the biggest challenges in Swiss. The programmer needs to balance the operations on the various spindles and turrets in order to reduce dead times and maximize productivity. Machine simulation can help to optimize this process.
One shop has found a marriage of machine tool and software that has provided consistent, reliable results across its lineup of lathes and machining centers. Having the same supplier for all of the above has played a key role in this success.
A Closer Look
Atlas Copco Secoroc, LLC, manufactures products in 20 different countries for applications such as compressed air and gas, generators, construction and mining equipment, and industrial tool and assembly systems. The company’s Ft. Loudon, Pa., facility has been in operation for more than 20 years, serving the well drilling, mining, construction, oil and gas, and water industries. With 49 employees, this location runs three shifts, 5 days a week, maintaining production on a full line-up of Okuma CNC machines including a Multus 400W multitasking machine, an MA500 machining center, and lathes that include three MacTurn 550s, a MacTurn 550W, a MacTurn 50, a Captain L370, an LR45 and an LU25.
In 2005, working through its Okuma distributor, Gosiger, Atlas purchased its first MacTurn 550 multi-function lathe. At the same time, company management made the decision to try Okuma’s 3D Virtual Monitor (3DVM), a software package designed to provide accurate 3-dimensional machining simulations based on the Okuma machine and the cutting program provided to it.
Software at Work
“We use 3DVM for program prove-out,” explains Robert Hershey, quality assurance manager and CNC programmer at Atlas. “But we also use it for evaluating the performance of our programs to reduce cycle times by evaluating tool paths and rapid moves for the optimal cutting time. Operators also use the software to run programs through. This allows them to see up-front what will be happening during cutting operations, giving them more confidence, particularly on the more complex jobs.”
Prior to purchasing the software, programmers at Atlas needed to prove out programs by going to the machines and testing in “machine lock.” They had found that while typical CAM systems that they used could show machine simulation, they could not do it after the code was made. “While helpful and powerful in their own right, these systems will not show certain errors such as those for tool nose radius settings, incorrect tool offset settings, and incorrect M or G codes, and will not recognize variable programming macro codes for the Okuma control’s capabilities,” Mr. Hershey adds.
Chris Young, an applications engineer for Gosiger in Pennsylvania, who is Mr. Hershey’s local Okuma distributor, says the 3DVM software allows full machine simulation, with tool fixture modeling capabilities to simulate tools and fixtures as they are used in the machine on the floor. Manual and MDI modes are also available to check clearances of tools and work envelopes, as well as a measure function for checking to see if various parts will fit in the machine’s capabilities. “Robert and I have used 3DVM to check the fitting of fixtures and part combinations on the virtual machine to make sure things will fit before we proceed with the machine setup.”
Mr. Young also adds that the software also offers tool offset screens, work offset screens, and parameter setting screens, all of which are set up exactly as they appear on the machine. All models made in the software can be transferred into the machine’s collision avoidance system (CAS) for use in auto, MDI and manual modes, saving setup time at the machine.
The CAS generates the actual and exact shape of the materials after a cut to confirm that no interference will take place. Accurate virtual applications can be run prior to actual cutting, allowing the programmer to produce the most efficient and accurate cuts while avoiding costly collisions that damage
productivity.
Sparking Growth
Since adding the first MacTurn, Atlas has brought in five more similar machines as well as several other Okuma lathes and machining centers, each of which uses the 3DVM software for process prove-out. As the machines become more complex, involving additional axes, automation and setup changes, there is more room for human error to occur. Mr. Hershey explains, “The only limitations we’ve experienced with the software have been because of operator error, such as mistakes in data entry, incorrect tool number codes or incorrect wait codes for two-turret lathes. But each of these instances can be proved out prior to bringing the program to the machine.”
In 2011, the company plans to expand production by adding yet another MacTurn 550 and an MA500H with automation. The software has played a significant role in allowing Atlas to quickly bring machines into the production process by bridging the gap between the virtual machining world and the real-world shop floor.
