In order to be competitive in the global economy, cold stamping plants must provide defect-free parts, reduce waste and downtime. At the same time, they have to deal with rising raw material costs and a limited supply of steel. Since stampers cannot control the supply side of the market, they must focus on the process side.
From the Material Conditions
Many problems in the production process are caused by different material conditions. Some common coil material challenges are:
- Coil set is the amount of curvature present perpendicular to the material width. It can be removed with a straightener.
- Crossbow, in contrast to the Coil set, is the curvature along the width of material. A straightener can improve this situation, but not completely.
- Oil canning, when the center strip is longer than the edges—can be corrected best with a leveler.
- Edge wave is caused by the excessive pressure of the straightening roller on the thin material. Check the straightening rollers to confirm their respective positions and adjust the pressure to eliminate edge waves.
Equipment Problems and Solutions
To remove the coil set, the material must bend beyond its yield point. This can be achieved by bending the strip back on several appropriately spaced rollers.
Depending on a material’s thickness and yield, the amount of material penetration of each coil is different, because the coil group increases as the O.D. decreases. The extension and compression of a 1500 mm O.D. coil is less than the bending extension and compression of a 508 mm I.D. coil.
Each type of material defect usually requires specific equipment. The straightener can only remove the coil set, which is usually sufficient for most applications. And precision straightener can remove edge waves, center buckle, twisting and residual stress in the material and coil set.
A threading device spans the distance between straightener and feeder to provide hands-free material threading. The table prevents materials from falling into the pit and damaging the loop control mechanism. Keeping the material away from the floor and away from contaminants that can damage the mold and equipment. Image attached.
Identifying and correcting potential problems caused by each piece of equipment can help the die to reduce downtime.
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