Precision Stampings: A Detailed Guide to Successful Metal Stampings
Precision stampings are recognized as a complex set of metalworking processes that involve the fabrication of small, highly detailed parts. These components have tight tolerances, demanding features such as slots with a minimum width of 0.25 millimeters and an accuracy of +/- 0.05mm. In fact, some manufacturers require even tighter specifications than this! Precision stampings also demand tight surface finishes (measured in microinches), small radius end points, and protruding tabs or tails on the part that must be able to support its own weight while being handled by automated tools. This blog post will explain why precision stampings are becoming more difficult to produce and which challenges you may run into when trying to implement them in your production line.
What is a Precision Stamping?
A precision stamping is a metal part that is shaped by a die or punch to conform to a particular shape. It is a highly automated process that takes a sheet of metal and cuts it to size, then feeds it into a machine that presses it into a particular shape to form the part. The process is very flexible in that it allows for the creation of numerous different parts from a single sheet of metal. Precision stampings are small parts that require minimal finishing operations. Common examples of precision stampings include electrical connectors, printed circuit boards, medical supplies, and automotive parts such as air bag sensors. These products are expected to be robust, reliable, and lightweight.
Why Are Precision Stampings Becoming More Difficult to Produce?
Manufacturers have been using precision stamping techniques for decades. The majority of these manufacturers are located in Asian countries, including China, Japan, and Taiwan. As these companies have expanded their operations, they’ve been able to produce more precision stampings than ever before. This has led to a global surplus of precision stampings, which has in turn caused the cost of the products to drop significantly. Unfortunately, this trend has also caused many manufacturers to shut down. Because the cost of precision stampings has dropped so significantly, manufacturers in the West have struggled to compete in this market. Whether you’re a manufacturer in the West or East, you have likely noticed that it’s more difficult to produce precision stampings than it used to be.
3D Measurement Data is Required
Precision stampings are created to a particular set of design drawings. In order to ensure the part is manufactured properly, these drawings must be converted into a 3D model. There are numerous 3D modeling software packages on the market, including SolidWorks, Inventor, AutoCAD, and Fusion 360. These programs allow you to create virtual drawings of the part that can then be converted into a 3D model that is accurate within a fraction of a millimeter. When manufacturing a part, it is extremely important that the 3D model be identical to what is shown in the drawings. If the software used to create the part is not accurate, the part will not be manufactured correctly either.
Machine Accuracy is Incredibly Important
The first and most obvious piece of equipment that must be accurate is the pressing machine. You may be surprised to learn that, according to the International Standard Organization (ISO), the machine must be accurate to within 0.020 inches. On the surface, this accuracy requirement may not seem so extraordinary. However, due to the small size of the part being manufactured, this margin of error equates to a tolerance that is just over 0.005 inches! This is an extremely tight tolerance, but if the pressing machine isn’t accurate to this level, the part will not be manufactured correctly.
Tooling Tolerance Tends to Be Very Small
Another important aspect of the precision stamping production process is the tooling. The tooling is a particular die or punch that has been designed to shape the metal into the desired part. The tooling is often manufactured overseas, but it should be inspected to ensure it meets the necessary accuracy requirements. If the tooling does not have the desired accuracy, the part will not be manufactured to the desired dimensions. For example, the width of a 0.25 millimeter slot has to be accurate to within 0.008 inches. This is the same as two sheets of standard copy paper (16 sheets total). The tolerance required of the tooling is dependent upon the part being manufactured, but it tends to be very small.
Consistent Quality Parts Are Produced By Consistent Quality Tooling
If the slot width of the part is supposed to be 0.25 millimeters, the die or punch must be able to create a slot that is that width. If the die or punch has a tolerance of +/- 0.005 inches, the slot will be 0.22 millimeters. This is not only a problem for the manufacturer who is producing the part, but also for the customer who is purchasing it. This is why it is so important to select tools with a tolerance of +/- 0.005 inches. If the tooling has a tighter tolerance, the part will be manufactured with the proper slot width. If the tooling has a looser tolerance, the slot width can vary.
Conclusion
Precision stampings are complex processes that require the use of specialized equipment and analytical skills. For example, the pressing machine has to be calibrated to ensure the part is being punch to the die. Because these parts are manufactured to have tight tolerances, it is important to verify the equipment used to produce these parts is accurate. Precision stampings are more difficult to produce than ever before. It has become necessary to use 3D modeling software to create virtual drawings of the part, and convert this data into a 3D model. To ensure the part is manufactured correctly, the 3D model must be identical to the drawings used to create it. Finally, it is important to select the proper tooling to manufacture the part.
