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Learning NC without machines.

New Mexico State University, Las Cruces, NM, is developing an Advanced Manufacturing Center to educate engineers and help small manufacturing businesses compete in the global market. A result of the initiative is the Manufacturing Engineering Teaching Factory (METF), which provides small businesses with modern machine-tool technology and material handling and control systems.

Surprisingly, students at NMSU do not, however, have access to machine tools while learning to develop NC code. In fact, it isn't until they are ready to take their final exam that students have an opportunity to see if their NC program will properly cut chips on a real machine. Instead, students use Vericut by CGTech, Irvine, CA, to check the accuracy of their programs. Does this put NMSU students at a disadvantage? Not so, according to Leon Cox, associate professor, Department of Engineering Technology & Industrial Engineering, and William Burd, Mechanical Engineering Dept, NMSU.

A better way to learn NC

Vericut is software that interactively simulates, verifies, and displays the metal removal process of an NC toolpath--like having a machine tool in software. On a graphics screen, the program displays a solid 3D model of the raw stock, then simulates the full range of programmed cutting motions, and finally shows the finished prove-out part. The software can simulate milling, drilling, and turning operations with up to five-axis simultaneous motion.

Messrs Cox and Burd easily came up with several reasons why it is more advantageous for the students to prove their NC programming on the computer screen rather than a machine:

Time. It takes time to set up an NC operation. With simulation, the student spends time in the classroom learning and improving programming skills rather than out in the shop setting up machines.

Review. The classroom covers all aspects of a system through comprehensive lectures, demonstrations, and hands-on experience. A student can review a process as many times as necessary without having to wait for a machine or interfering with anyone else.

Economics. Simulation is far less expensive than taking away from productive time to observe a machining process. Material costs are reduced, and machine tool expense can be minimized.

Visibility. A major problem in many industrial environments is that machine tools are heavily guarded, prohibiting a clear view of operation. This is especially true if a number of students are involved.

Hardcopy output. If a student runs a project on a machine tool, he/she can see what happened only once. If attention is diverted, having an opportunity to see the error can be missed. By using simulation software, the student is alerted to mistakes and can interactively make corrections until programming errors are eliminated.

Instruction. No instructor would deliberately mis-program an expensive machine tool to show students what can go wrong. However, with simulation software, an instructor can do just that, enabling the students to thoroughly analyze a programming problem without causing harm to any person or damage to any machine.

Off-site demonstrations. Vericut in-process images and playback files can be viewed anywhere a properly configured computer is available. Because Vericut runs on 386 PCs, the training or studying environment can be almost anywhere.

Interrelationships. Programmers must interpret a designer's CAD drawings into NC code. The end result may not be what either the designer or programmer thought it would be. In the classroom, the student can see the importance of cooperation with other engineering and manufacturing disciplines. With Vericut's automatic differencing function, a comparison of the difference between the CAD design model and the NC program model can be shown.

Safety. While we all try to make the industrial workplace as safe as possible, accident potential is higher when inexperienced students who do not fully understand the dangers are present. With simulation software, the dangers of a major programming error emerge as flying pixels instead of dangerous flying metal.


Finals week at NMSU would strike terror into the typical machinist and machine shop, say Messrs Cox and Burd. During the last finals week, 24 students in teams of three had eight different parts ready for machining at the Manufacturing Teaching Factory. They had no prior contact with the machinists or managers of MFT prior to the due date. The students were given an arms-length view of a machining center near the end of the course, but no hands-on machining experience. They had already been graded on the simulated prove-out but were anxious to see parts run on the flexible machining center, which includes an automatic storage/retrieval system and a four-axis NC machining system.

It was surprising, at least to some, to see how smoothly the actual process of getting a part machined was. The teams were able to log-on to the factory computer, utilize their networking prowess, and get their ANVIL 5000 CL file from the Integrated Systems Laboratory (IMSL) database. After prove-out on Vericut, machinists took over and postprocessed the ANVIL CL file for the Cincinnati T-10 machining center (downloaded via the network to the Synchron cell controller), modified the scheduler, loaded the raw material on a pallet, and treated everyone to a good part the first time.

Where Vericut shines as an educational tool is in its ability to simulate the machining process and provide visual and realistic feedback data. When we consider the thrust of manufacturing techniques moving toward the off-line, hands-off, and lights-out computer controlled environments, we need to find a method whereby the student and industry can view the machining process. Simulation software offers us that window.

CNC control retrofit

Hurco Manufacturing Co has announced the Max 32 retrofit package, which makes an Ultimax II control perform like an Ultimax 3.
COPYRIGHT 1993 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1993 Gale, Cengage Learning. All rights reserved.

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Title Annotation:numerical control
Publication:Tooling & Production
Date:Apr 1, 1993
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