Post processors make perfect, operators say.
Orbit is a custom-contract machining company that serves the printing press, industrial spraypainting, and hydraulic industries. "We usually have as many as 100 active orders inhouse for everything from little pins, to complicated hydraulic blocks, to brackets and bearing retainers, a variety of both milled and turned parts," says George Zarytsky, Orbit president.
"We don't use a CAD program. We do everything in our CAM software. We either import drawings sent by customers, or we draw them ourselves. More and more, customers tend to e-mail us the prints. We just download them into EdgeCAM and go from there," Mr Zarytsky says.
EdgeCAM, from Pathtrace Systems Inc, Ontario, CA, has direct file loaders that accept files from several leading CAD systems, as well as IGES and DXF files. Because of that, Orbit's CNC Manager, Brian Kowal can open the electronically transferred drawings within the CAM system's environment and save them as EdgeCAM files.
In one example, Messrs Zarytsky and Kowal estimate that receiving a drawing electronically and importing it into EdgeCAM saves between four and five hours of design and setup time over drawing the part by hand.
Then begins the post processing. A post processor is a part of a CAM or NC programming system that takes the toolpath graphics and creates actual G-codes required by most CNC machines. A good post processor will create virtually flawless G-codes, requiring little or no editing, and eliminating the possibility for human error, according to Bill Gibbs, Gibbs and Associates, Moorpark, CA.
How important is post processing? An error as small as a missing decimal point can mean trouble.
Mr Kowal uses the post processors he made with EdgeCAM's Code Wizard to generate code for the machine controls. The Code Wizard is a Windows-style template that guides users through the process of producing machine specific post processors. The post processors translate EdgeCAM files into code that can be read by the shop's machine controls.
The Code Wizard contains templates to walk the user through post processor generation for a variety of common machine controls. The shop's goal using the Code Wizard is to eliminate manual code editing.
"Pure code is what we're shooting for. We want to download the program and have it be perfect so the operator can start running it," says Mr Zarytsky.
However, because of the advanced nature of some of Orbit's machine tools, and the unique method of outputting their code, templates to generate code for its controls are not yet complete. The shop has two different brands of horizontal machining centers, two brands of vertical machining centers, two twin spindle, twin turret lathes with live tooling capability, and one twin spindle, single turret lathe with live tooling.
"Live tooling has given us a new niche market. We do a lot of parts requiring milling that come off the lathe complete. We were really able to save our customers money with the combination of live tooling and EdgeCAM. They're a little more complicated to program, but if you have the talent to program the parts and run the machines, there's nothing better in my opinion," Mr Zarytsky says.
"In addition," he adds, "every machine, whether milling or turning, has different codes. Some machining centers use an M-code for rigid tapping, some use a G-code with a decimal point. No one has written a post that recognizes these differences.
"Some controls give you the Zs and the Xs, and the spindle speeds in the right spot, but don't know you need an M29 or a G84.2. That's something you have to modify based on your equipment," Mr Zarytsky explains. Code Wizard gives Orbit the flexibility to modify the output to the needs of their equipment.
Meet the compiler
Since Mr Kowal wrote the post processors, Orbit has purchased a compiler for the software. The compiler allows the shop to take its use of EdgeCAM to a new level.
Mr Zarytsky says that now, instead of using the Code Wizard, Mr Kowal is using the compiler to program it, making changes in the code behind the template that will allow the shop to reach its goal of generating perfect code.
"He's modifying the foundation behind the Code Wizard to make it even more powerful, which is not something everyone can do. You have to be pretty computer literate," Mr Zarytsky says. Orbit requires the use of advanced custom macros on the control, and the flexibility of the compiler allows them to take advantage of the custom macros.
Mr Zarytsky says the shop's main focus is perfecting its post processors. "We're about 95% of the way there, where when we write a part and post a program, it's going to go out to the machine exactly the way we want it," he says.
Because the Code Wizard gets so close to pure code, all that is usually required of the programs generated with the post processors is to verify the programs before they are sent out to the shopfloor to be tested by an operator. The actual transfer from the PC in the shop office to the machine control is made directly.
Adding the software, Mr Zarytsky notes, also helps save the shop money by improving first-time part accuracy and reducing scrap.
The advanced degree of EdgeCAM use includes plans for the future integration of a gantry crane into the shop and its CAM system to further automate operations. That could take place as soon as next year, according to Mr Zarytsky.
To supplement the standard libraries which are built into the software, Mr Kowal has loaded information from major tool suppliers such as Sandvik, Kennametal, and Carboloy into the software. That information will eventually accompany each job out to the shop floor as part of the operators' setup packet.
"We want to eventually put that in our tooling sheets with a picture of the part. We're going to start taking digital pictures of setups and putting them, right in the job's EdgeCAM file," Mr Zarytsky says.
"We're trying to make some of our routines automatic so we can pick ports on a block and the computer will pick a sequence of tools that will complete that port," Mr Zarytsky says. "What we'd like to do is click on a drawing of that port and have EdgeCAM program the block for us. I foresee us using that quite a bit in the future. I envision engineering departments sending us prints or designs and having us quote them to get a cost very quickly."
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|Publication:||Tooling & Production|
|Date:||Jun 1, 2000|
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