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3-D transfer die simulation eliminates transfer die headaches

Finding problems better sooner than later

Transfer simulation software allows die builders and designers to detect potential problems, troubleshoot and perfect their transfer die stamping runs before they ever go to production.

In today’s extremely fast-paced, lean manufacturing world, on-time and on-budget are more important than ever. Transfer die problems and related problem-solving wreak havoc on production and deadlines and cut deeply into profits. By using transfer die simulation software, stamping manufacturers, die builders, and designers can troubleshoot and perfect their transfer die stamping runs before they ever go to production (see lead image).

Home-line Runoff Disaster All too Familiar

Imagine this scenario: A triaxis transfer die arrives at the stamping plant for a home-line runoff. This final moment is the culmination of weeks of design and months of build time. The questions looming in everyone’s heads are: Will the die run without problems? How long will it take to set up and run parts? Will it meet parts-per-minute (PPM) production requirements?

At first it looks promising. The press ram, with the upper die attached, cycles up and down to the bottom dead center (BDC) without problems. The first few parts are transferred from station to station by hand, just to make sure the actual die stations work. So far, so good. Then the triaxis transfer system is moved into position. The ultimate test is now at hand.

Before long it’s obvious that there are problems! There is not enough clearance for the fingers to pick up the panels. There is not enough clearance for the fingers to drop the panels off in the next station. The upper shoe’s guide pins obstruct the transfer system, so the clamp stroke has to be increased. This slows the production rate. One station is too high, so the part cannot be dropped off properly. Headaches! Problems!


The Blame Game Begins

At this point the blame game begins. Who is at fault? Who has to make the necessary changes to the dies? What exactly has to be changed? Maybe the press operator is using curves with a low PPM rate. Maybe if the transfer system were set up differently there would be no problems. Perhaps the die could have been designed and built differently so the upper guide pins were not in the way. Why didn’t the build shop see this and other problems earlier during design reviews?

Eventually the build shop has to ship the dies back to make changes. Their profit margins are reduced or, worse yet, in the red. The stamper is disappointed with the build shop. The dies will be delivered late, and so the parts will be late also. The home-line runoff has been a failure and everyone loses—both in reputation and in additional costs. Does this sound all too familiar?

What If?

What if there were a way to do a home-line runoff using 3-D transfer simulation software? What if a die designer and die builder could load the dies into the press, position the transfer bars and fingers, identify transfer motion bottlenecks, find crashes and interferences, and create the optimum triaxis motion curves virtually? By running all the checks before building the die, a designer and die builder could get rid of the pitfalls, headaches, blame games, extra back-and-forth shipping, rework, missed deadlines—and the accompanying profit losses.

It sounds too good to be true, right? Yet, 25 years ago the same thinking surrounded proposals for draw forming metal parts using virtual software. Fast-forward to present day, and look at all the benefits forming simulation contributes to the stamping industry.

Transfer Die Simulation Capabilities

Transfer simulation software currently is being used to validate 3-D die designs and their ability to function with the transfer press and transfer system.

Transfer simulation software not only puts the press, die, and transfer system into motion, it also automatically finds crashes and close calls throughout the entire press cycle. The software finds interferences and clearance violations automatically, rather than manually, to reduce the risk of human error.

Because it’s just not possible for the operator’s human eye to create the best transfer motion curves, the software can be used on both new and existing tooling to improve the transfer motion and timing and increase production rates.

Stampers with servo presses need the ability to program both the transfer system motion and the servo press ram motion, so the best motion curves can be created and used in production.

Capabilities include:

  • Acceleration and velocity specifications are factored into the transfer system for accurate production rates.
  • It can run a full kinematic analysis through 360-degree press and transfer motion. Parts can be rotated, tipped, flipped over with grippers, and slid into position with actuators.
  • It finds all crashes, close calls, and inefficient transfer system curves, and makes adjustments.
  • Servo press ram locations and transfer system locations are both fully programmable and associative to each other.
  • Strokes per minute (SPM) can be calculated and improved on-the-fly.
  • Transfer motion can be optimized for best part control and highest feasible SPM.
  • Clamp, pitch, and lift motions are independently adjustable to achieve the best motion possible for a given stamping die and transfer system.
  • Press ram motion is fully programmable so even the most current servo press lines can have their ram motion and transfer system motion programmed simultaneously for the highest possible production rates.

    Case Example: Matcor-Matsu

    Matcor-Matsu, a global supplier of metal stampings, used transfer simulation to validate transfer tooling and optimize motion curves. Program Manager Andrew Szczepanski relayed the results:

    “We’ve had fewer problems and frustrations with home-line runoff on projects run through the transfer simulation. What typically took a few days of press time is now done in a single shift. Our production rates have increased significantly.”

    By the Numbers

    Production rates directly influence profits, so producing the same number of parts in less time obviously leaves more room for profit in a press line; more dies can be lined up for that particular press.

    By the numbers, if a press line runs 20 different dies in production during a year, and each die’s production rate could be improved even a modest 15 percent, the improvements would allow another three dies to be added to that press line.

    For example, on a job stamping gas tank straps, a stamper was getting only 11 parts per minute. Transfer simulation software detected a couple of bottlenecks that were limiting the transfer motion. Once the motion curves and timing were optimized, the speed increased to 15 PPM.

    Moving Forward

    Results show faster setup of the die and transfer system, better success at home-line runoff, increased production rates, and higher profits for everyone involved. If anything has been learned from forming simulation, it’s that it is easier and less costly to make changes when the designs are on the screen rather than when the dies are machined and built. Getting rid of the headaches and problems isn’t too bad either.

  • About the Author

    Mark Hansen

    Transfer Press Simulation Engineer

    642 Byrne Industrial Dr

    Rockford, MI 49341

    616-863-8630