Problems and Solutions in Metal Deep Drawing Process

While the finished product may look simple, no doubt experts make it look simple, the cylinder shell pulling process is actually one of the most complex manufacturing methods. The act of forcing metals into a given shape poses a number of possible problems and concerns. For the trained eye, the finished product illustrates very clearly the quality of the deepening process.Most deep flushing problems stem from a combination of design and molds. 

Here, the five most common reasons are listed.

Metal fracture

This is one of the most common cylinder shell deepening problems. Despite the most common clearance between the punch and the mold, the fracture of the metal during the pulling process may be caused by several problems. If this is too small, too large, or uneven, the material may break during stretching.

Wrinkles at the top edge

This problem is usually due to rim-pressing problems. If the holder is too tight, unbalanced, or if the blank has burrs on the grip edge, the metal will fail to flow properly and create significant folds along the upper edge.

Unsmooth upper edge

The upper edge of the part shall be flat and concentric. If not, the problem is usually attributed to poor die alignment. This condition can cause excess material being sucked into the mold and prevent the formation of a homogeneous upper margin.

The bottom of the cup fracture

This deep flushing problem is also attributed to the billet and pressing conditions. If there are gaps or abrasions on the surface, it will reduce the flow of material into the mold, causing cracks at the bottom of the cup.

Pull the excess material from the top of the housing

This problem occurs when the material is too thick or the mold gap is too small. Both cases prevent the normal flow of metal during processing, which thickening the top area.

Detailed knowledge of the deep pull method and how to check the finished parts is very important in the decision-making process. This information can prove invaluable at both the conceptual and design stages of the project and can ensure correct results for the first time.

How to solve it?

1. The size of the metal stamping drawing drawing should be marked on one side as far as possible, so that the designer can clearly ensure that the size is internal or external size, and the internal and external sizes can not be marked at the same time, can not be unified, it is necessary to mark whether the assembly relationship between the deepening parts and other stamping parts is reasonable;

2. For the last process of drawing parts, the size of the workpiece is external, mainly the concave mold, the gap is obtained by reducing the size of the convex mold, the size of the workpiece, mainly the convex mold, and the gap is obtained by increasing the size of the concave mold;

3. When judging the causes of tensile parts, we can refer to: the cracks caused by material quality problems are mostly serrated or irregular shape, and the cracks caused by the process and mold are generally neat;

4. In order to ensure the wear resistance of the tensile mold and prevent tensile scratches, the convex and concave mold and the pressure edge ring must be hardened, and can also be coated with hard chromium or TD treatment to ensure the strength of the mold.