Metal Stamping Design Guidelines
The forces required to bend and shape metal leave their marks on the finished piece, especially in thicker materials. A punch wiping by the material to form it will cause tool marks on the outside of the bend. Deep drawn parts will have shock lines near the bottom of the cup. Coining, swaging and embossing will leave impressions in the material surrounding the form. Where the faces of the tooling are used to form the part, holes drilled for fasteners can leave marks on the part. These tooling marks are a normal part of the metal forming process, however, when cosmetics are important these marks can be minimized by the use of creative tooling techniques and careful die design.
Most metal stampings are automatically ejected from press equipment, moved through the manufacturing process in the largest containers possible, mass finished and shipped in bulk form. They are subject to the dings and scratches common to this type of process.
It is most helpful to know what the application is and what the cosmetic requirements are. Whenever possible, cosmetic specifications should be described on the part drawing.