Metal stamping is a manufacturing process used to form metal parts based upon a specific design. A metal alloy sheet is used as the stock which is either stamped on a press or drawn into shapes using hydraulic deep drawing machines. Stamping can be applied to metals including aluminum, zinc, steel, nickel, bronze, copper and many other alloys. This process is commonly used for automobile parts, metal components for consumer appliances, aerosol spray cans, and even military tanks.
Metal stamping requires dies and punches to form and cut the metal into the required shape and size. The design and manufacture of these dies and punches are a highly skilled process.
stamping can be a challenging, iterative process, with many physical changes to the tools required before ‘good’ quality parts can be made. The definition of a good quality stamped part includes the dimensional inspection of the part, but can also include other factors such as thinning, wrinkling, cracking and the control of spring back on the part. The metal stamping process is also very harsh process which can be abusive to the tools. As a result, tooling wear must be monitored and repairs are often necessary to allow for high volume production of stamped parts.
3D measurement for the metal stamping process can apply to either the parts or the stamping tools themselves. The goals of each are typically different. If the parts are measured, usually it is for the purpose of checking the part against a known dimensional standard (a "golden part" or a 3D CAD model). For example, the Steinbichler T-Scan laser system; the Steinbichler COMET white light system can be used for 3D digitizing of stamped parts or tooling depending on accuracy and size specifications.
If the tools are measured, usually it is for the purposes of understanding the 3D shape of the tools and using this information for the future repair or replacement of the tools (or a portion of them). 3D measurements can either be for the entire part surface or for specific areas. For example, in the case of high precision 3D digitizing of large tooling the Steinbichler COMET white light 3D scanner can be used in combination with the AICON DPA Pro photogrammetry system.
Advantages of using 3D scanning technology in metal stamping
Both white light and laser 3D scanning offer fast, complete and accurate 3D measurement of both stamped parts and stamping dies. Once the part or tooling has been digitized, the 3D data is processed and aligned using either Polyworks or Geomagic software. Depending on the application, the data is inspected in PolyWorks Inspector or Geomagic Qualify or in the case of 3D CAD updating or reverse engineering, modeled in Polyworks Modeler or Geomagic Studio. Cross-sections (typically in IGES or STP format) or a complete polygon model (typically in STL format) can also be easily exported for use in a 3D CAD package to ‘classically’ model the part or tooling or to make necessary modifications.
Due to engineering changes and the seemingly inevitable hand-worked changes that occur over the life of a metal stamping tool, there are several times where 3D measurements can be required. During tool prove-out and part trials, both the resulting parts and capturing the changes to the tool may be vital. These 3D measurements can be used to correlate and validate simulation results to actual stamped part results. Once an acceptable part has been produced, it is critically important that the 3D shape of the tool be captured at that point in time. This essentially provides an "insurance policy". If anything were to happen to the tool such as partial breakage or loss, there would be a digital 3D record of the shape which is capable of producing the approved part. This 3D record would include the working surfaces of the part and any other features that affect the stamping process, such as the binder and draw bead geometry. And finally, any time a repair or modification is done, that resulting shape should be captured, serving to document and quantify the changes done over time.
The portability and adaptability of today’s advanced 3D scanning technologies such as the Steinbichler COMET and T-Scan, ensures that this required 3D digitizing can be done quickly, accurately and most important, cost-effectively.
As tooling ages, the risk of catastrophic failure increases. Through our many years of experience in metal stamping, the Applied Precision Team has seen broken dies, sometimes in many pieces, and with no record of the proper 3D shape. Unfortunately when this point is reached, all that is possible is to record the shape of the pieces, and it is quite difficult to re-create the whole with high certainty of accuracy. The "insurance policy" is a much more cost and time effective approach if the proper pro-active steps are taken. 3D measurements completed in a well planned approach, over time can even be used to assess tool wear and support predictive maintenance cycles.
Companies often work on tools without full access to all the engineering data for a tool. That missing engineering data may be the original tool 3D CAD, part CAD, or changes done over time. 3D measurements at that time are critical to understand the current state of the tool, and to be able to confidently plan and quantify what changes are made from that point forward.
The 3D inspection process can be used to show 3D deviations from a known reference (‘part to part’ or ‘part to CAD’), investigate alternate alignment results, measure specific check points, quantify springback, thinning, check clearance between die halves, and much more. Colour map results from scanning convey much more information than traditional measurement methods, and can lead to more thorough understanding of the dimensional behavior of the parts in the manufacturing process.
Selecting the right 3D scanning system and software
A wide variety of hardware and software combinations are available to suit your specific manufacturing requirements. The choice of 3D digitizing system is generally determined by the size of the part or tooling and accuracy needs. For example, Steinbichler COMET system is ideally suited for smaller stamped products such as consumer appliance components, while the Steinbichler T-Scan laser system reduces scanning time for larger products such as automotive body panels.
The Applied Precision Team has extensive experience in applying this technology to stamped parts and stamping tooling and is available to assist you in evaluating the best possible combination of equipment and software for your business needs. Our team continues to be recognized by our customers for excellence in technical support and customer training programs to ensure that you get the greatest possible value from your 3D scanning technology investment.