Metal Stamping and etching are essential manufacturing processes for creating a vast array of metal parts for various industrial applications. The two processes aren’t, in any way, similar but are somewhat related. Both play a part in finishing metal materials, making them functional and aesthetically appealing. However, one has the edge over the other in numerous aspects, which this stamping vs. etching article will delve into.
What are Stamping and Etching?
The critical difference between etching and metal stamping is that the latter is more involved in the dynamism and transformation of metals, changing their forms and shapes. Conversely, etching doesn’t necessarily alter the forms and shapes but gives metals a more aesthetically pleasing appearance. The thread tying the two processes determines metals’ finishing quality, with stamping helping with grade and quality and etching going more profoundly with the detailing.
The Stamping and Etching Processes
Stamping and etching are both procedural and follow a chronology of steps. Besides, they utilize quite varied techniques and yield almost similar results. Stamping or stamping is commonly used in engraving metals, imprinting words and symbols often permanent and indestructible. On the other hand, etching also yields similar results but follows a relatively varied approach by laser, chemicals, and acids. Here are the processes of stamping and etching.
Stamping uses dies and mechanical forces to shape metals and eventually engrave them, leaving permanent markings. The process takes quite a long time and has lead times spanning several days to weeks. However, we can safely presume that the results are always fascinating and ideal from prototyping to the finishing phase. Stamping or microstamping involves the following.
Materials and Tooling
Stamping includes using dies, blanks, and forces to shape metals. Different toolings come into play for any supply, determining the lead times and results. Usually, the need for Computer Aided Machining (CAM) is always profound, and design software is used to determine the eventual results. Moreover, the physical use of Computer Numerical Controls (CNC) is always handy in creating the die tooling for shaping and engraving metals.
Metal blanks are sheets from various materials and have properties enabling them to withstand mechanical forces and pressure. Aluminum and steel are commonly used metals since they have the propensity to deform without tearing or wrinkling. Here’s the chronology of the stamping and microstamping process.
Holding the Blank into Position
The blank holder usually holds the blank in position, preparing it for pressing during the stamping. This holding apparatus is found on the lower die, but the pressure holding the blank in position usually emanates from the upper die as it administers the force. That ensures that the blank sheet remains in position and doesn’t wobble, leading to deformities such as wrinkling and tearing.
Administering the Hydraulic Pressure
The upper die usually administers the pressure to shape the metal blank. However, this force is usually metered, and the speed is predetermined for a more successful operation. Stamping can be simple or involve bending and coining per the predetermined results and projected outcome. Some dies have the tooling design to perform several operations on a single thrust, including coining, cutting, or bending. However, other dies, such as in progressive die stamping, may require several stations and operations to complete a series of isolated operations.
Microstamping and Engraving
Die tools mainly feature designs with markings that need engraving on the metals, making it easy to print them at a go. That can happen in a single downward thrust or after a series of steps further away from the first thrust. The markings are usually permanent and can be symbols, letters, or perhaps images that imprint on metals. A typical example of such similar results includes coins bearing markings, numbers, and usually permanent symbols.
Types of Metal Stamping
Metal stamping is quite a diverse procedure using different processes and techniques. And although these processes all yield similar results, the quality and finishing largely depend on the type of stamping procedure. The various stamping procedures include the following.
Progressive Die Stamping
Progressive die stamping uses more sophisticated and complex die with isolated stations that perform different operations. Usually, a metal coil is fed from one end and transforms, popping out from the far end when it’s all shaped and ready for use. Progressive die stamping also includes a micro-stamping station depending on a client’s needs. Therefore, it’s always essential that the consumer communicates and liaises with their manufacturer to design a customized progressive die tooling station.
Transfer Die Stamping
Like progressive die stamping, transfer die stamping uses several stations to shape and deform metal blanks. However, these stations aren’t usually situated in a single die block but different. A conveyor belt usually transfers a blank from one station to the other. And that also includes a microstamping station having customized markings and symbols to engrave the blank.
Four-slide stamping is one of the quickest and most efficient stamping operations. And as much as most stamping operations use vertical stamping, this type uses horizontal alignment to shape metals and blanks. It has four slides with four different tools to achieve multiple bends simultaneously. Every slide is driven by a shaft and controlled by the rotations of a cam. The process is more or less like conventional stamping but performs more complex operations simultaneously, including microstamping and engraving.
Metal Stamping Products
Metal stamping products are everywhere, and more defined, engraved products are available. Metals, including coins, have markings on their surfaces, like numerals and numbers. Some metal stamping products include metal housing enclosures, decorative stamping products, shells, metal cups, and cans.
Like stamping, etching typically yields similar results, leaving marks and engraving symbols, letters, and numbers on metals. However, this process doesn’t use mechanical force like stamping but chemicals and lasers. Unlike stamping, etching is relatively quick and has shorter lead times. Besides, it’s more flexible and doesn’t need expensive or time-consuming tooling of the dies. Here’s how etching takes place.
Etching is a more simplified process of giving metals their permanent marks than metal stamping. The latter uses excessive capital and is time-consuming, besides being incredibly strenuous. Unlike stamping, the process uses a simple electrochemical, photochemical or acid treatment, not only making it efficient but practical and less strenuous. Here are the different etching processes in industrial applications.
Acid Metal Etching
Acid metal etching uses an acid bath for dipping or flow coating. It’s typically used for coating more etchable metals like bronze and copper as opposed to steel and nickel, which take longer. Other metals that can be etched using acid metal include titanium and aluminum. Besides, molybdenum’s high strength, thermal properties, and electrical conductivity make it ideal. Acid retching occurs in the following steps.
Cleaning the Metals
Dirt and other substance can compromise the quality, and cleaning the metal before etching should be handy. Alkaline solutions and oxidizing agents are the most commonly used, but it’s also a typical finding that some manufacturers use specific solvents to remove contaminants.
A maskant is an inert substance protecting the surface of metals during metal etching. Its chemical properties usually don’t change even after exposure to chemicals since it contains neoprene elastomers and isobutylene isoprene copolymers.
Creating the Image Impressions on The Metal
The pattern of the component can be carved into the maskant coating, basically applying the image on the metal sheet. The image can be recessed when carved into the maskant but raised when the maskant shape the image.
The image should be emblazoned in a little while before putting the metal in an acid bath. Ferric chloride is a standard chemical used, which can also be sprayed instead of dipping. However, the time it takes depends on the intricacies needed and the type of metal being etched.
Removing the Maskant
Removing the maskant presents a challenge, mainly maintaining the quality and preventing damage. Therefore, bathing the workpiece in water is always ideal, and following it up with a bath in an oxidizing agent can round things up, removing any remaining oxides.
Photochemical Metal Etching
Photochemical etching is the selective metal removal from its surface using a chemical reagent. It uses photoresist technology and a chemical reaction to transfer the required pattern or image onto the metal surface. However, the chemical reagent mainly becomes more helpful in removing the metal. The following occurs in photochemical metal etching.
Using Computer-Aided Designing (CAD)
The rendering process is mainly possible using CAD, the thickness determined and the number of pieces that’ll fit on the sheet known.
Preparing the Metal
Cleaning the metal ensures better results and a more seamless process. Impurities and contaminants on the metal’s surface can compromise the outcome, leading to low-quality prints. Usually, scrubbing removes any physical contaminants and dirt. But a mild solvent or water can do the work better.
Using Photoresist Films to Laminate Metal Sheets
Rollers are usually the best at applying the photoresist coating and laminate, but that best happens in a room lit with yellow light to prevent exposure to UV light. Moreover, vacuum-sealing the sheets helps prevent possible bubbles, preventing potential misformations.
Sandwiching the CAD rendering between the metal prints the images initially created. Afterward, exposing the images created to UV sunlight makes them more permanent by making them hard and firm. However, areas that aren’t exposed to UV light remain soft and easily removable.
Developing the Sheets
The developing machine typically applies an acid solution, washing away the soft photoresist film, leaving the parts that need etching more exposed. This process removes the soft resists while maintaining the hardened parts of the photoresist.
The sheets then move along a conveyor machine, pouring an enchant, dissolving the exposed metal, and leaving the protected part. Ferric oxide is usually the substance sprayed from the conveyor’s bottom and top. Keep in mind that some metals can take longer than others in this step, so they should be timed and carefully monitored.
Removing the Remnant Resist Film
A resist stripper is sufficient enough to remove the remaining resist film. That leaves the finished part intact and untouched. That should complete the process, leaving an embroidered and patterned metal sheet. These markings are usually permanent and mainstay existing as a part of the metal.
Other types of etching processes include laser and electrochemical etching. Both processes result in permanent markings on metals, with laser electroplating utilizing a laser beam at controlled and monitored intervals. The lasers are usually high-current, reaching about 100W and releasing 100,000 pulses. Laser etching uses a vast array of lasers, including gas, liquid, solid state, metal vapor, and semiconductor lasers, which yield similar results.
On the other hand, electrochemical metal etching is virtually similar to photochemical metal itching, utilizing similar CAD designs. However, it uses an electric current and combines sodium-based solutions with low-voltage pulses of electricity. Standard techniques include deep and shallow etching, with the latter yielding darker images, depending on the type of material. Deep etching uses a direct current in removing metal ions, with parts and component depths ranging between 0.001 and 0.003.
Metal Etched Products
The standard metal etched products include metal covers and lids, electrical connectors, medical instruments like surgical blades, automobile manufacturing, microphone diaphragms, micro springs, and bipolar plates. The process also has much use in other industries, including aerospace, automobile, and electronics.
What materials can be chemically etched?
There is a wide range of materials that can be chemically etched, from pure metals and hard to machine alloys. Some examples of common metals we etch are:
- Stainless Steel
Which Between Stamping and Etching Results in Better Metal Finishing Quality?
Etching is quicker and more efficient and results in better quality metal prints. Stamping isn’t suitable for high-volume runs at an industrial scale since the lead time is high. Besides, it’s costly due to the need for die tooling and, perhaps, altering their designs to create newer prints.
Metal etching and micro stamping help print metals, a task that not so many processes can do with utmost precision and efficiency. But as it stands, etching is inarguably the best since it’s quicker and more efficient. Hopefully, this stamping vs. etching guide will help you discern the two, understand their result, and become more familiar with their processes.