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Unsnarl your shop - with DNC.

Unsnarl your shop - with DNC

Flameco Engineering Inc, Ogden, UT, produces complex sheet-metal parts for the aerospace industry. Made of titanium alloys, Inconel, and other exotic metals, these parts go into engines and airframe structures.

To make these complex shapes, Flameco builds its own dies, punches, and other tooling. Equipment in the shop includes two Cincinnati Milacron CNC vertical milling machines, two Shizuoka CNC vertical milling machine, an Amada CNC turret punch press, and a Westinghouse Unimate 6000 CNC robot that wields a waterjet cutter. Other machines in use here are a Behrens manual turret punch press, a CNC wire EDM, and a CNC lathe.

Until a year ago, programming for the CNC machines was done on manual system (diagram). Programs were stored on 8" floppy disks, and were sent over cables to behind-the-tape readers (BTRs) using an A-B-C-D (4-outlet) switch. Transmission rates were 600 baud to the Milacron mills, and a turtle-like 110 baud to the Shizuokas. An average, 700-ft program for a Milacron mill would take 40 min just to transmit - if everything went right.


Two years ago, to gain improvements in design and NC programming, and to speed communications with its customers, Flameco installed a Unigraphics CAD/CAM system. This software runs on a DEC Micro VAX II minicomputer.

The CAD/CAM system immediately began providing benefits, but communications within Flameco's shop remained slow and complicated. Engineers still relied on the old 4-outlet switch. Programmers transferred data from the Unigraphics system to the old programming system (at 600 baud), and then out to the machine tools.

One reason for maintaining this slow, awkward link was that the MicroVAX II was too small to allow direct NC communications from it to the machine CNC units. Moreover, at that time Flameco lacked expertise to design DNC interfaces. Protocol problems occurred during transmission from the system host to the CNC units.

In addition, programmers liked the editor in the old manual programming system. They had written 80 percent of all existing programs on this system, and it would have been very time-consuming to transfer these many programs to the Unigraphics CAD/CAM computer.

On many occasions, transmission to the machine tools would abort. This generally required resetting the control of the machine, resetting the transmission switch, and trying again. The cycle was usually repeated several times before successful transmission.

Oftentimes, data would be scrambled before it reached the machine tools. Lines of code and numbers would be lost. In one instance, the transmission system dropped 7000 lines of code. Under these circumstances, it wasn't unusual for programmers and operators to spend 30 minutes to an hour sending one program to a machine.

Equally undesirable, machine operators were continuously beating a path between their workstations and the programming office. They had to find an available programmer, and locate the disk containing the program they wanted sent. Then, with luck, the program would be transmitted in 40 minutes.

In one notorious case, a programmer was called upon to help an operator transmit a program down to his machine. They encountered protocol problems that delayed transmission six hours before the program could be sent successfully.

In the meantime, another operator was waiting for a program that the programmer had stopped working on to help the first operator. Thus two operators stood by waiting for work, two machines sat idle, and one programmer went crazy - for six hours.


Finally, a year ago this past winter, the communications snarl proved intolerable, so Flameco began looking around for a solution. After making a thorough search, the company installed a simple, low-cost, PC-based DNC (distributed NC) system.

The designer and supplier of the system is Remex Div, Seymour Electronics and Automation Inc, Fullerton, CA. Installation, including wiring and connections to the CNC units, took two days.

Flameco's new DNC system (diagram) consists of an AST Premium 286 PC, Remex DNC hardware and software, high-speed data transmission lines, and three shop terminals with interfaces to CNC machine tools. The PC uses a 286 microprocessor and runs on MS-DOS. As shown in the diagram, the PC links the CAD/CAM system's MicroVAX II host computer and the three shop terminals.

One shop terminal controls two Milacron CNC vertical milling machines. A second operates two Shizuoka CNC vertical milling machines, and a third controls a CNC turret punch press plus a CNC robot with waterjet cutter.

"The Remex DNC system cost $23,000 installed," reports Gary Olsen, Flameco's supervisor of CAD/CAM and tool design. "This system saved us $39,000 in the production of one large forming die alone.

"We completed the die in just five days, working two shifts. Formerly we would have needed three weeks working three shifts. We estimate the entire DNC system paid for itself about one and a half times in the first five days."

He believes that, conservatively speaking, the DNC system will save Flameco $247,000 a year. Nobody at Flameco has even begun to estimate the savings that have resulted from a general increase in shop productivity.

Olsen estimates that before installing stalling DNC, the CNC mills often cut metal during only one hour out of eight in a shift. "This resulted in horrendous order backlogs," he says. "Today, we have a much different situation. The CNC mills cut metal seven hours out of eight in a shift. We've cleared up the backlog, and can bring in more work."

Flameco now considers use of DNC essential in many applications, because of their workpiece complexity, long tapes, or frequent part changes. For example, the large, triangular forming die mentioned previously has numerous, precise hemispheres machined into one surface. This measures about 80" long by 36" wide.

Saves time

Flameco's part programmers formerly said that programming ate up half their time. They spent the other half sending programs to the machine tools.

Today, programmers waste almost no time on data transmission. After completing a program, they simply transfer it to the appropriate DNC directory on the PC's 80-MB hard disk.

Later, when a machine operator needs a program, he can easily call it up from hard-disk storage. He simply keys in the program number, and pushes one button. This action loads the program into the proper CNC controller. Transmission takes just 90 seconds, and is virtually 100-percent reliable.

What's more, the system checks each program after it's sent, to see if any transmission errors occurred. The two Milacron CNC mills now permit transmission rates of 9600 baud, and the two Shizuoka CNC mills accept code at 2400 baud. The Remex system moves data between the DNC host computer and shop terminals at 19,200 baud.

Productivity in the shop has risen in a number of ways. For instance, machine operators don't need to come up to the programming office when they want programs transmitted. Moreover, now there's time to make little improvements in programs, and to easily determine which version of a program is in use.

The DNC system recognizes when it has two versions of a program on file. The original version is placed in a "locked" directory, the modified program in an "unlocked" directory. Until a qualified programmer decides which version to keep, machine operators are denied access to both versions.

Coming: Electronic

shop documentation

Remex DNC provides not only a network for transmission of NC programs, but also the basis for a complete system of electronic shop documentation. Flameco sees their DNC system as an ideal vehicle for eventual transmission of operations sheets, travelers, setup sheets, and other alphanumeric and graphic data needed on the shop floor. Both types of data would appear on a graphics terminal plugged into the Remex shop terminal.

Right now, Flameco is experimenting with recording run-times as a means of job cost-estimating. By using the keyboard on the Remedex shop terminal, operators enter actual times it takes to run a job. These data are sent to a Lotus 1-2-3 spreadsheet program stored in the DNC computer's hard disk.

"We consider this the early stages of electronic timekeeping," Olsen says. "It will remove a lot of guesswork in estimating costs of tooling.

"Eventually, the DNC system will help keep track of actual times on each job and each work-order number, thus giving us much more accurate estimates of costs. We can even plug a barcode reader into the shop floor unit, and read barcodes on the parts themselves. This will aid in accurate recording of run-time data."

In addition, Flameco will be able to transmit NC part-program data to another company facility in Ogden. There, the data will be used to prepare NC tapes. Flameco feels DNC is not practical at this facility, because part programs for its production operations seldom change.

Whatever Flameco does with its DNC system in the future, however, company owners, managers, and other personnel are highly satisfied with what it has done for them already, and with the service Remex has provided. "By the time Remex invoiced us," Olsen says, "the system had paid for itself several times over."

PHOTO : Schematic diagram of Flameco's old, manual programming system and local area network. Note the slow transmission rates, and the use of 8" floppy disks for program storage.

PHOTO : Schematic diagram of Flameco's new Remex DNC system and local-area network. Note the fast transmission rates. Because this system "talks shop," Flameco's machine operators were able to learn how to use it in just one 30-minute training session.

PHOTO : Gary Olsen, Flameco's manager of CAD/CAM and tool design, examines one of three Remex DNC shop terminals. This particular unit operates two Cincinnati Milacron CNC vertical milling machines. The terminal receives programs at 19,200 baud from an AST Premium 286 PC - the DNC system computer - in the company's engineering office.
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Title Annotation:programming for direct numerical-control machine tools
Publication:Tooling & Production
Date:May 1, 1990
Previous Article:Communication is key to die-casting success.
Next Article:CAD/CAM - capturing the master's expertise.

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