Tech Briefs

Deep-drawn components are used in breathing apparatus, missiles, and pyrotechnic containers.

In applications where product performance is mission critical, commercial, military, and aerospace companies require technology to manufacture deep- drawn cylindrical product components. Conventional production alternatives such as impact, spinning, and supplemental annealing processes often do not deliver reliable results for certain applications.

Deep-Draw Technology is used to manufacture cylindrical shells, tubes, and other components that are longer in length than diameter.
Deep draw technology originated as a practical option for manufacturing unique parts once considered too difficult or too costly to produce through conventional methods. Through a virtually flawless manufacturing process, deep draw technology creates complex small, medium, and large cylindrical shells, tubes, and other shapes requiring close tolerances.

The deep draw process is actually a reverse draw. On the primary draw, material is pulled or drawn through a ring, forming a cup-shaped cylinder with uniform wall thickness. The cylinder is simultaneously turned inside out, or reversed, thus combining two draws in one operation and saving steps and time. Ironing is also performed during the deep draw process, which allows sections of the material to be ironed down to different wall thicknesses.

Once the part is drawn or shaped, the forming process begins. The necking and expanding processes allow for the creation of multiple diameters in a single part. Diameters can either be expanded or reduced (necked) to create forms that more exactly match the product specifications. The process results in seamless, one-piece parts with multiple wall thickness and diameters created through minimal operations. The multiple wall thicknesses give strength where it’s needed while reducing the amount of material used in other areas of the product, eliminating the waste of raw materials and reducing the overall weight and cost of the product. The multiple diameters also simplify the assembly and positioning of internal parts and O-rings.

Deep draw technology results in refined, highly calibrated products with tolerances in the thousandths, and the accuracy is repeatable via high-volume, high-speed manufacturing. Because the process allows for multiple wall thickness and diameters in a single part, there is no need to weld or otherwise connect separate product components to achieve the appropriate product shape and dimensions. Thus, vulnerable interfaces in the final product are eliminated, resulting in a product that performs more reliably in the field.

Deep draw technology relies on a controlled movement process. Typically, when metal is shaped and formed, the material grains are scattered and the integrity of the material structure is compromised. However, the controlled movement process uses optimum speed to enhance the efficiency of the process while maximizing material grain alignment in the final product.

The deep draw process also results in a better finish than specified by most product designers. With deep draw, the finish is typically 63 micro-inches or less, lending a smooth, mirror-like luster to the final part. This finish allows for the direct application of sealing aspects such as O-rings and gaskets during final product assembly, further eliminating secondary operations and providing a leak-proof seal for harsh field conditions.

Deep draw technology primarily utilizes aluminum of different alloys; however, the process also works well with copper, brass, mild (cold rolled) steel, precious metals, and ductile metal. While steel may make sense for some applications, the use of aluminum in the deep draw process provides significant advantages in the final product. Aluminum is softer and more malleable, making it easier to iron the material down and create multiple wall thickness and diameters. Aluminum provides a uniform grain structure and strong, yet ductile product, compared to the less-uniform quality and brittleness of impact-produced parts. As a result, aluminum deep-drawn products absorb vibration better, which is critical with sensitive electronics and other technology.

Applications include missile skins; high-pressure liners for self-contained breathing apparatus used in firefighting and mine safety units; and high-pressure CNG liners for use with buses, vans, and light trucks.

This work was done by Buckeye Shapeform, Columbus, OH. For more information, visit http://info.hotims.com/22922-519.