August 2008 Edition

CONTROLLING INTEREST

CNC is the Obvious Choice for the Future-minded Shop

CNC offers so many advantages to metalworking shops that it isn’t a case of why to make the switch, but when

Let’s start with the obvious: the benefits of CNC.

Quick setup is easier than ever, as CAD programming translates into the controller faster than ever. Using any number of data transfer, from Ethernet, to wireless, to a memory stick, developers can import programs into the controller. As I’ve written, what once was called the "trial cut" can run right on the machine, using some of the available software. Or, it can be run offline on a PC. In either case, the entire cutting cycle, tool movement, and part articulation can be simulated in real time before the first workpiece is ever loaded into the machine.

Another benefit is that programming is easier than ever, because of the plain language commands on the screens of most CNC models. Extensive G-code knowledge – while always helpful, and something I encourage all operators to master for their own efficiency and strength as machinists in today’s competitive work environment – is not the necessary skill it once was.

Operation is easier because of the improvement in control mechanisms, such as the planogram layout on the control face, as well as the availability of customized screens, either from the CNC supplier or generated from internal proprietary software.

Customizable Advantages

Open architecture and algorithmic flexibility of the onboard computer let shops customize screens for specific industries, work products, or vernacular languages.

"Simplified interface" refers to the ease with which advanced CNC technology has reduced the commands needed to affect a machine operation. Up to 15 lines of code were needed to program a function a few years ago. Now it requires just three lines. Words can also now be used for many functions, rather than complex sequences of code commands.

There are more benefits, such as the way CNC saves offsets and tool information for quick recall. Also, onboard tool management programs are available to assist the shop in proper tool selection for specific functions, tool change sequencing for similar part paths, routine machine maintenance alerts, and program modification for faster implementation of design changes into the control.

Machine, Rinse, Repeat

This helps job shops working with configurable component customers, where slight modifications made to standard programs and delivery schedules are critical. In one folder, an operator can maintain tool table settings for just such cases, where more than 90 percent of the settings are identical for repeat cycles.

Since the math on a CNC is built into the Numerical Control Kernel, there is less step-by-step sequencing required to build programs. While many shops maintain separate files and codes for their subprograms, many CNC models have this functionality onboard. Rather than using numbers from 0001 to 9999, for example, the program and subs can be assigned easily-recognized names for reference, as the CNC software does the ordering of the files. Readers can e-mail me [at pnofel@nelsonpub.com , put Controlling Interest in the subject line], for details.

A tip about program transfer: don’t run programs from memory sticks. While easy and tempting, it will compromise the cycle and could cause serious errors. There is also the hazard of the sticks being disconnected if bumped.

Use compact flash devices instead of PCMCIA cards, as the former are more effective for added memory, have auto-recognition, and don’t require a reboot.

Today’s CNC is not only not your father’s NC tape drive, it’s not even the CNC of 10 years ago. We’ve come a long way and there’s more to come.

Randy Pearson is the Siemens sales support manager for U.S. dealers and OEMs. His special interest is the training aspect on CNC machine tools, through the various seminars and classes the company conducts at votech schools, on-site at shops, as well as the Siemens training facilities around the country.

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