Sheet Metal Forming Processes And Die Design
Sheet Metal Forming Processes and Die Design, Second Edition is the long-awaited new edition of a best-selling text and reference. It provides an expanded and more comprehensive treatment of sheet metal forming processes, while placing forming processes and die design in the broader context of the techniques of press-working sheet metal.
Sheet metal forming processes and die design
Metal manufacturing is essential for all areas of the economy. Because of their strength, stiffness, and long-term durability, metal components are used in applications from appliances to construction parts and car body panels. Traditional metal manufacturing techniques include forming, casting, molding, joining, and machining.
Sheet metal forming involves various processes where force is applied to a piece of sheet metal to plastically deform the material into the desired shape, modifying its geometry rather than removing any material. Sheet metals can be bent or stretched into a variety of complex shapes, permitting the creation of complex structures with great strength and a minimum amount of material.
Sheet metal forming is the most cost-effective forming procedure today for manufacturing parts in large quantities. It can be highly automated in factories or, at the other end of the spectrum, manually operated in metal workshops for small series parts. It is a versatile, consistent, and high-quality procedure to create accurate metal parts with limited material waste. From metal cans to protective housing for hardware, parts created by sheet metal forming are found everywhere in our daily lives.
In this article, learn the basics of sheet metals, the various sheet metal forming processes, and how to reduce the cost of sheet metal forming with rapid tooling and 3D printed dies. For a detailed overview and the step-by-step method, watch our webinar or download our white paper.
Sheet metal forming includes treatments such as bending, spinning, drawing, or stretching implemented by dies or punching tools. Forming is mostly performed on a press and parts are formed between two dies.
Typically, manufacturers produce their forming tools out of metal by CNC machining in house or outsourcing to service providers. This upfront tooling is expensive and generates significant lead times.
In-house 3D printing enables engineers to prototype metal parts and iterate tool designs in a matter of hours, achieving complex geometries while reducing reliance on outsourced providers. Professional desktop printers are affordable, easy to implement, and can be quickly scaled with the demand.
Manufacturers are already using stereolithography (SLA) polymer resins to substitute metal jigs, fixtures, and replacement parts in factories. In processes such as injection molding or thermoforming, using test molds in plastic is an effective practice to validate designs and solve DFM challenges before committing to expensive metal molds. Savings in material costs from metal to plastic are significant.
SLA 3D printing technology presents some interesting properties for sheet metal forming. Characterized by high precision and a smooth surface finish, SLA printers can fabricate tools with excellent registration features for better repeatability. Thanks to a broad material library with various mechanical properties, choosing a resin tailored to the specific use case can optimize the result of the forming. SLA resins are isotropic and fairly stable under load compared to other 3D printing materials. Plastic tooling can also eliminate a polishing step, as plastic dies do not mark the sheet as metal.
The mechanism is similar to the general sheet metal forming workflow. The difference lies in the design and print of the two-part tool made of upper and lower dies. The blank sheet is then placed between both plastic dies, and pressed with a hydraulic press or other forming equipment.
For large volume production, prototyping the tool in plastic allows verifying the design before committing to an expensive metal tool. For short-run production, printed dies would save hundreds of dollars compared to outsourcing the part.
Rethinking toolmaking is a powerful way for reducing costs in metal manufacturing. Beyond the agility provided by prototyping expensive tools, 3D printed plastic dies can be efficient and affordable substitutes to expensive metal tools. For sheet metal forming, 3D printed tools offer multiple opportunities for applications from bent brackets to embossed parts, louvers, grille, and off the shelf set of dies for a press brake.
In our free white paper, we demonstrate how we successfully fabricated a metallic blade guard with the help of 3D printed plastic dies. We could potentially produce dozens of these parts with a single set of dies, bringing short-run production in house. Download the white paper now for the detailed case study and the step-by-step method and watch the webinar for specific design considerations and application examples.
The science, engineering, and technology of sheet metal forming processes and die design continue to advance rapidly on a global scale and with major impact on the economies of all nations. In preparing this second edition, my goal throughout has been to provide an expanded and more comprehensive treatment of the sheet metal forming processes, while placing forming processes and die design in the broader context of the techniques of press-working sheet metal.
A very large variety of sheet-metal forming processes is used in modern sheet-metal press-working shop practice. Many of these deformation processes, used in making aircraft, automobiles, and other products, use complex equipment that is derived from the latest discoveries in science and technology. With the ever-increasing knowledge of science and technology, future deformation processes promise to be even more complex to satisfy the demand for more productivity, lower cost, and greater precision. However, for all their advantages, the more sophisticated deformation processes of today have not replaced the need for basic sheet-metal forming processes and dies.
The book concentrates on simple, practical engineering methods rather than complex numerical techniques to provide the practicing engineer, student, technician, and die maker with usable approaches to sheet-metal forming processes and die design.
The first part of the book deals with the structures of metals and the fundamental aspects of the mechanical behavior of metals. Knowledge of structures is necessary to controlling and predicting the behavior and performance of metals in sheet-metal forming processes.
The second part of the book covers all aspects of forming sheet metal. It presents the fundamental sheet-metal forming operations of shearing, blanking and punching, bending, stretching, and deep drawing. Mechanics of various drawing processes indicate ways in which the deformation, loads, and process limits can be calculated for press forming and deep drawing operations. The book includes various drawing processes (nosing, expanding, dimpling, spinning and flexible die forming) mostly used in the aircraft and aerospace industry.
Dies are very important to the overall mass production picture, so they are discussed in the last section of the book, which presents a complete picture of the knowledge and skills needs for the effective design of dies for sheet-metal forming processes described. Special attention is given to:
Although the book provides many examples of calculations, illustrations, and tables to aid in sheet-metal forming processes, die design, and die manufacturing, it should be evident that it is not possible to present all the data, tables, statistics, and other information needed to design complicated dies and other tools for sheet-metal forming in one text. However, the book endeavors to provide most of the information needed by a die designer in practical situations.
Sheet-metal forming processes are used for both serial and mass production. Their characteristics include high productivity, highly efficient use of material, easy servicing of machines, the ability to employ workers with relatively lower basic skills, and other advantageous economic aspects. Parts made from sheet metal have many attractive qualities: good accuracy of dimension, adequate strength, light weight, and a broad range of possible dimensions, from the miniature parts used in electronics to the large components of airplane structures.
Notching. Notching is cutting the edge of the blank to form a notch in the shape of a portion of the punch. If the material is cut around a closed contour to free the sheet metal for drawing or forming, this operation is called semi-notching.
Trimming. For many types of drawing and forming parts, excess metal must be allowed; the workpiece can then be held during the operation that shapes the metal into the form of the part. The cutting off of this excess metal after drawing or forming operations is known as trimming.
Parting. Parting is the cutting of a sheet metal strip by die cutting edges on two opposite sides. During parting, some amount of scrap is produced. This might be required when the blank outline is not a regular shape and cannot perfectly nest on the strip.
Bending. Bending consists of uniformly straining flat sheets or strips of metal around a linear axis. Metal on the outside of the bend is stressed in tension beyond the elastic limit. Metal on the inside of the bend is compressed.
Deep Drawing. Deep drawing is a sheet metal forming process in which a sheet metal blank is radially drawn into a cylindrical or box-shape forming die by the mechanical action of a punch. It is thus a shape transformation process with material retention. Drawing may be performed with or without a reduction in the thickness of the material. 041b061a72