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Ask the Stamping Expert: How can I increase press speed without constant production stoppage

Q: In am a new press operator. We have press lines with progressive dies, electric feeds, a straightener, and a double reel. There are electronic die and press protection sensors to emergency-stop the press. I also set all the coil material guides with a slide fit clearance. However, I have to slow down the press speed below the die’s capabilities to prevent constant stoppage of production. Do you have any suggestions?

A: Your description suggests to me that the centerlines of the press, bolster, feed, straightener, and reel are not in line. Also, the coil material guide settings are incorrect for the coil material edge bow tolerance. To run all equipment at maximum speed, you need to understand the tolerances of all the equipment and material being run.

Check the alignment of the press centerline with the bolster centerline, which should also be square with the feed pads. It is a good idea to dowel the press bolster to the press bed in the correct position. Then use a laser or run a piano wire through the centerline of the press, bolster, die, feed, straightener, and reel to ensure they are all in line.

When you’ve set up the coil material centerline and lined it up with the reel centerline, and the die centerline is set up and lined up with the press and bolster centerlines, these locations become your datums from one end of the line to the other. You can set the stock guides in the die at a slide fit, but you must set them and the straightener with clearance to allow for the coil material edge bow tolerance. This can be considerable depending on the length of the equipment line.

Coils are slit from a master coil and can have an edge bow of 0.25 in. in a 10-ft. length (see Figure 1). If the coil is laid out flat on the floor, you can see the bow easily by putting a straight edge next to it. The bow can go right or left when the material is running in the feed or straightener, so the stock guides must allow for the material bow tolerance.

If the clearance is insufficient, the equipment stock guides will mechanically lock, or the material will ride up over the guide. Misfeed will accrue, and the press speed may have to be reduced.

Understanding die, press, feed, straightener, and reel tolerances is the key to part quality and production speed. Good luck.

Figure 1
Camber must be within die stock guide tolerance.