CAM Means Mission Productivity

The primary mission of NASA's Jet Propulsion Laboratory is the exploration of the solar system and extend outward to the search for extra-solar planetary systems. Tools such as this software system are brought in at ground level.

Case Study From: 2/15/1998 Modern Machine Shop

By John Jordan

Getting into space requires meeting the same objectives as any earthly business venture. NASA's mandate to the Jet Propulsion Laboratory in Pasadena, California is: do it faster, better and cheaper. "Virtual Gibbs CAM software systems have played a role in many of the recent spacecraft we've launched including the recent launch of Cassini to Saturn," says JPL's Darrol Houser, Group Supervisor of the Lab's prototype and R&D machining group. The primary mission of NASA's Jet Propulsion Laboratory is the exploration of the solar system and extend outward to the search for extra-solar planetary systems. Tools such as Gibbs CAM software systems are brought in at ground level.

When Mr. Houser began working for JPL as a contractor seven years ago, the prototype shop had virtually no NC programming software. Even as recently as 1991, all prototype work was done manually. "I was asked to recommend a way to improve on that, and having used the Gibbs CAM system on a previous job I was sure it would make a difference here," recalls Mr. Houser. JPL bought the first seat. Additional seats were quickly added and today, Mr. Houser oversees 18 machinists all using the low cost, high performance CAM system from Gibbs and Associates (Moorpark, California).

At JPL, a NASA facility managed by the California Institute of Technology, a small city is employed to research, design, build and test spacecraft for programs such as Voyager, Mariner, Hubble space telescope, and Pathfinder. 5800 people, including those in medical, firefighting, security, and other fields join the R&D and manufacturing activity to bring what is out in space, a little closer to earth. But however adventurous and grand the ultimate goal, JPL being a federally funded center faces fierce competition for dollars. "Productivity becomes as paramount here as in any other industry," says Mr. Houser.

Tools to do the job, such as the CAM software from Gibbs, rank high with Mr. Houser. Using the Gibbs system, followed by Virtual Gibbs and then the solids-based, 3D SolidSurfacer model, JPL increased proficiency in the main shop by 60 percent. This CAM system improved the machining group's productivity and the very nature of the machinists' jobs. Before Gibbs was put to use, machinists were at the mercy of the programmers, spending a lot of time proofing for errors before running the job. "Now, I program the job myself. I know what it will do before I hit the `Go' button," says JPL's Lyle Zink. Virtual Gibbs cut-part rendering enables the user to preview the part at any stage in the programming process, and watch it being machined, on-screen.

Finding mistakes during the programming process instead of at the machine saves money in reduced machine time, programming time, and scrap. "With Gibbs, the machinists are confident of the part's correctness before it is machined," says Mr. Zink.

Gibbs gives the machinist the ability to program and run the job in the most efficient way for that machinist in those circumstances. The system has the flexibility and capability to let them be more productive. "High end programming used to be done by the system programmer and sent to the floor. Now, I am generating three-axis tool paths myself. At JPL, 50 percent of the work is three axis. With that much opportunity for complex machining, planning the SolidSurfacer capability in the machinist's hands has expanded my job and provides an exciting atmosphere to work in," says Mr. Zink.

Training took place on several fronts. Having used Gibbs previously, Mr. Houser opted for a week of training at Gibbs headquarters in Moorpark. Within a few months of installing the system on his shop floor, Mr. Houser approved an on-site training session conducted by Braden Engineering, a local reseller. He spent the next month using the software in a small group setting before integrating the system with the main shop. Gibbs has always promoted its CAM systems as easy to use and easy to learn. Most users find that with even very little NC background or experience, the gains in productivity are quickly realized.

Machinists from the Prototype and R&D Machining Group work closely with JPL engineers on all phases of spacecraft production from research and design to flight, and Gibbs CAM systems are used throughout. On the Pathfinder high gain antenna alone, 30 out of 100 parts were made with Virtual Gibbs. "The system produces accurate machine code. It allows us take engineered data and from that, accurately produce a tool path for a particular component, quickly," explains Mr. Houser. "Due to the nature of the business, we don't have production runs. We are manufacturing only one or two of each part as components of an instrument package, propulsion module, or the main spacecraft. So we are constantly going back to run a different part and this system's ease of use allows the machinist to get an accurate tool path on the machine very quickly."

The Virtual Gibbs SolidsSurfacer module is used to create, import, and machine solid and surface models. It provides JPL with multi-surface machining functions including fast, gouge-free tool paths, constant Z-step cutting, lace finishing, and corner and ridge clean up capability. JPL machinists can do more to ensure the part is correct before it goes to the machine and that has increased productivity.

"A part called a K-beam was our very first end-to-end solids part with Gibbs," says machinist Gary Keel. The K-beam is an integral part of the mechanical interface structure of the New Millennium Program's Deep Space 2 mission to Mars. The interface structure attaches a soccer ball-sized spacecraft, called the Mars Microprobe, to the cruise cylinder. To reduce the movements imparted to the cruise cylinder, the part has flexures near the interfaces to the cylinder. The K-beam is made of Ti 6A1-4V to achieve thermal isolation from the cruise stage and also for strength. Many of the part's faces are at compound angles from each other because of the interface structure's complex geometry. The part is created on ComputerVision, downloaded to Virtual Gibbs SolidSurfacer on a PC. "I click on the surface and tell the machine how to cut it and it does just that. Most of the time for this part was spent on planning and tooling, cutting the part was easy. If we had to program this part by hand it would be much harder." Mr. Keel also uses the system for tooling to determine hole locations using 4th and 5th axis rotations. "The K-beam is a complicated part and without Gibbs would have been more difficult to machine," says Mr. Keel.

Looking ahead, Mr. Houser would like to equip all the shop's workstations with Gibbs systems. "I don't want any machinist waiting in line to use the SolidSurfacer module," says Mr. Houser. "It is to our advantage to have full capability at each seat."

Even when reaching for the stars, JPL must constantly keep an eye on the bottom line. "Because we use taxpayers' money, we have to be cautious with what we do and how we do it. I wanted something likely to be beneficial and increase our productivity and at the same time be an investment that would pay off quickly," said Mr. Houser. JPL's Mars Pathfinder was produced on time and under budget. This mission, deemed phenomenal by JPL, operated on the surface of Mars three times longer than expected and returned a tremendous amount of new information about the planet. Gibbs has also played sizable roles in manufacturing parts for the small rover on Mars called Sojourner, Cassini's mission to Saturn, and other projects. In these high profile, costly programs, performance is critical. MMS

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