18 Important Differences between Deep Drawing and Stamping

With the development of metalworking, it is essential to have the correct process for making a part. Deep drawing and stamping are two different processes that can produce parts depending on the product’s needs.

Deep drawing is a sheet metal forming process that produces high dimensional accuracy and a smooth surface finish. Stampings are made by striking a sheet of metal with a die to create the desired shape. Stampings are typically less accurate than deep drawn parts and have a rougher surface finish. The following information will help you determine if deep drawing or stamping is more suitable for your needs.

The following points illustrate the differences between deep drawing and stamping.

Accuracy

The accuracy of a deep drawn part is measured by the thickness of the material and the radius of an inside corner. Deep drawing typically produces parts with more accuracy than stamping. A high degree of dimensional accuracy can only be achieved using single-point deep drawing. Stampings will always have a rougher surface finish and less dimensional accuracy than deep drawn parts.

Surface finishing

Deep drawn parts typically have smoother surfaces finishes than stamped parts because there is only one deformation process during the manufacturing of the position. Stamping requires two processes (forming and debossing) to produce a part, leading to a more complicated and rougher surface finish. The embossing process can be added to enhance the appearance of a formed sheet metal piece. Still, it does not improve its structural properties, since it only increases material thickness without changing the shape or dimensions. The embossing process does not provide structural support for the part.

Bending

Deep drawn parts are typically formed using a two-piece bending system to create sharp angular bends. The single-point extrusion die is the best type for deep drawing because it provides maximum dimensional accuracy and produces an accurate bend angle. Stampings cannot produce tight bends or angles that would be suitable for many functional components. However, it is possible to stamp certain parts to the desired shape, then transfer them to another assembly fixture where they could be produced by bending, thus eliminating any additional operations while ensuring that quality remains high.

Production costs

Deep drawing has higher equipment costs than stampings because of the need for two presses to perform operations. The main press is required for deep drawing, while the second press will be used for stamping. However, since deep drawn parts are more precise than stamped parts, they need less post-process work, which leads to reduced costs due to scrap reduction and labor expenses.

Material thickness

On average, deep drawn parts have thinner cross-sections than stamped parts because of the metal flow during the forming process. The material is redistributed throughout, eliminating material accumulation on the die wall, resulting in a uniform distribution. This redistribution also enhances metal grain flow throughout the part, which enhances mechanical properties. When designing for consistent strength, deep drawing provides better results because of its ability to redistribute the material. While stamping can also produce parts with a uniform thickness, it is not as reliable and uniform thickness is difficult to achieve.

Design

When designing a part for deep drawing, the designer must consider that the process is constrained by the sheet metal’s bending and stretching limitations. These limitations need to be considered when determining wall thickness, corner radii, and other features to ensure that the part can be successfully deep drawn. Complex components that have tight bends are not suitable for deep drawing. Stamping does not share this limitation and can be used more freely without taking into consideration the forming process.

Ease of manufacture

Parts designed for deep drawing can be quickly and easily produced on high-volume production lines. The process is simple and does not require a lot of tooling changes. Stampings are more challenging to produce and usually need more setup time. This results in longer lead times and higher production costs.

Volume production

Deep drawing is better suited for high production rates. It is a fast and cost-effective means of producing large quantities in a short period. The embossing process also plays a role in mass production because it allows for better control over the surface finishes of formed parts. Stampings are limited in volume production because of their low speed, making them less efficient for large runs.

Strength

Deep drawn parts are more robust than stamped parts because the stretching of the metal during the deep drawing process results in greater flexibility, which leads to increased strength. The stamping process does not have the same ability to stretch the metal, which results in less flexibility. This lack of elasticity makes stamped parts more susceptible to failure when subjected to high-stress levels. The increased strength of deep drawn components is a significant advantage over stamped ones. It is the preferred choice for applications requiring high reliability.

Appearance

One disadvantage of deep drawing is that it can sometimes cause surface deformations, such as wrinkles, stretching, and tearing. While these deformations are not always visible, they can lead to a less pleasing appearance. Stampings produce smooth surfaces with no deformations. This makes stamped parts more desirable from a purely aesthetic standpoint.

Formability

Deep drawing is considered a formable process because it can easily deform a sheet of metal into complex shapes. Stamped parts are not as formable as deep drawn parts because the metal is not stretched, limiting its ability to deform into complex shapes. A part that needs to be deep drawn will have higher formability than a stamped part.

Application considerations

Parts that need to be lightweight and have a high strength-to-weight ratio are better suited for deep drawing. The deep drawing process results in parts with thinner cross-sections than stamped parts, while sacrificing no mechanical properties. Parts that need to be corrosion resistant should also be produced using deep drawing, as this process results in a higher quality surface finish and dimensional accuracy. Stampings are not as good for producing parts with a high strength-to-weight ratio and/or corrosion resistance.

Volume

Deep drawing is more suitable for high-volume production, while stamping is the preferred method when the number of parts is low. This is because stamping cost less than deep drawing and is better suited for small batch sizes. Deep drawing requires extensive setup costs but can quickly produce large quantities, making it best suited for mass production. Stampings make use of lower-cost equipment and require little labor to produce many pieces.

Material

Most deep drawn parts are made from steel, aluminum, and copper alloys, while most stampings are made from low carbon or alloy steels. However, there is no hard and fast rule for this, and both processes can be used with a wide range of materials to produce a variety of components.

Form

The final shape of the part depends on the method used to form it—deep drawing or stamping. As stated above, deep drawn elements have thinner cross-sections than stamped parts, meaning they can be formed into more complex shapes. Deep drawn components also have tighter tolerances than stamped parts.

Manufacturing process

The forming process for stamped components is usually a single step. In contrast, deep drawn part forming can comprise many steps that include die design, material preparation, blanking, drawing, trimming, and inspection. This means that stampings can be processed in less time than deep drawn components, which can significantly reduce costs. Also, stamping requires less machine maintenance because it uses lower forces than deep drawing, reducing operating costs for this process.

Post-processing

Once stamped parts have been produced, they can be immediately used since no additional processing is required, unlike deep drawn components, which need to go through several post-processing operations, including deburring, surface finishing, and painting.

Lubricants

When deep drawing parts, they may come into contact with lubricants and fluids. Therefore, it is essential to use materials that are resistant to these substances. This can be achieved by either hardening or coating the material or using less susceptible materials such as plastics and ceramics because they do not readily react with water and other chemicals.

Summing Up

Deep drawing is a metal forming process that uses a punch and dies to stretch the metal into the desired shape. The stamping process uses a point and anvil to deform the metal. Stampings are less formable than deep drawn parts and are limited in volume production. Deep drawn elements are stronger than stamped parts because the metal is stretched during the deep drawing process. Stampings are not as strong as deep drawn parts because they do not stretch the metal. Design features requiring high formability are best suited for deep drawing. The cost of a deep drawn part is typically more than a stamped part, but this cost is offset by its higher strength-to-weight ratio and corrosion resistance.