I’ve always been fascinated with metal stamping, and one of my recent light bulb moments has been trying to make metal stamping dies and test them out. Having considerable experience in metal drawing fabrication and a vast array of precision CNC milling, perhaps it was a chance for me to put my skills to the test. I was confident that I could pull it off, but I understood that creating metal stamping dies wasn’t a walk in the park. So I took my time to think it over.
Unlike in industrial-scale manufacturing, I dealt with makeshifts, allowing a slight margin of error and less strict tolerance specifications. Besides, I needed the complete set of tools, software, and material. But since it’s all but a trial, I wasn’t coined to produce large stamp volumes quickly. However, I had a knack for it and was well-versed, so it wasn’t supposed to be entirely complex. Nonetheless, I won’t bore you with the preliminaries, so I’ll jump right into it.
What is Metal Stamping?
If you aren’t well with familiar metal stamping, It’s a process that subjects a metal strip into isolated work stations to shape it. In an industrial-scale operation, metal stamping molds are usually of precise dimension and overly intricate. And that’s what makes them so usable and efficient machine parts and accessories. Therefore I considered the myriad factors, pinning down every detail and considering every production factor.
The material cost me about 6 dollars, and I had to acquire the CNC machines separately at an extra cost. And this being a DIY project, I made sure that it didn’t take most of my savings because it’s only a sampling process. Once I was well-equipped, I got pumped up for the challenge. Here are the tools and materials that I needed and collected.
• A hydraulic press
• A tiny knife (or a flathead screwdriver) for plucking the die shoes apart and flaking the stamping sheet away
• DMG Mori 3-axis CNC mill + 3/8 Inch Flat End Mill, 1/4 Inch, and 1/8 Inch Ball End Mills. (I also included a .100 Inch Drill Bit).
• A heat source – which was a propane burner for me
• 0.020 Inch Alloy 3003 aluminum sheet
• .100 Inch hardened stainless steel bar
• Round mild steel bar of diameter 2.75 Inches
The Process of Forming the Metal Stamping Die
You may find it somewhat intricate if it’s your first time making a metal stamping die and obtaining specific products. That’s why I’ll lay out the steps more coherently. Keep in mind that there are complex measurements you need to make and include in your design, including the offset allowance. Failure to which your dies would suffer some friction and wear out. Here are the steps:
Creating the 3D Models of the Positive and Negative Die
I used the free version of the Fusion 360 software to make the two main die shoes. But, I have to admit that you need sufficient information if you’re new to 3D modeling. Luckily, it’s an intuitive cloud-based software platform designed for startups and students, and there are loads of information to acquaint yourself with. Nonetheless, that was a piece of cake for me since I have vast experience using it in my amateur days.
As I mentioned before, there are other factors you should essentially consider when making your 3D model. That includes the offset and the tooling, which I’ll discuss shortly. Proper measurements helped me minimize my margin of error more remarkably, contrary to what I had expected. So, what’s the deal with the offsets and tooling requirements?
Offsets – An offset is a tiny room that prevents contact between the upper and lower die shoes. It’s the space that the metal sheet fits as the die subject it to pressure for deformation. The alloy 3003 aluminum sheets had a 0.020 Inch thickness for my project. Therefore, I had to include a 0.020 Inch offset by removing an amount of die material corresponding to that thickness from the die shoes – my option was the two upper positive dies.
Tooling – means designing your 3D model while considering the least-sized tools you’d attach to your milling machine. And since my smallest mill measured 1/8 Inches, I had to design my model features to fit that size.
Using Computer Aided Machining (CAM)
With my 3D models ready, the machining followed after. Surprisingly, the process wasn’t that challenging since Fusion 360 has bound CAM software with bells and whistles to make things more seamless. And since I didn’t need any sort of G-code, I created a series of tool paths to vary the speeds for cutting the die blanks.
Remember, my makeshift metal die-stamping project was minimalist and only needed two processes: stamping and trimming. However, I wasn’t going to carry out the two processes simultaneously but feed the aluminum sheet separately. With the suitable offset design and tooling, the CAM fun began!
I then fitted the two blank metals for making the positive and negative dyes on the DMG Mori 3-axis mill to create the four die shoes. Each took considerably long, spanning an hour tops. I matched each steel blank with the corresponding 3D model to create unique die shoes, and after a lengthy period of waiting patiently, it was ready. The results were astonishing since the texture was smooth, and the measurements were correct as intended!
Heating the Aluminum Sheet and Preparing it Before Stamping
In most standard metal stamping processes, there isn’t any heating involved. I’m sure that’s because the manufacturers’ pressing forces are usually on some meter and accurate measurements to compensate for the sheet’s tensile strengths. There’s always the risk of tears and deformity when doing it casually like I did because the pressure can be excess. And aluminum, as we all know it, is overly ductile and malleable, a characteristic making it vulnerable to overboard pressures.
Therefore, my subtle way of dealing with the problem was heating it just below its melting point and letting it cool. Surprisingly, it sort of “annealed” the aluminum and made it incredibly malleable and soft to resist tearing and cracking when under hydraulic pressure. But, reasonably enough, I should have used some steel sheet because I believe it has what it takes to resist the pressure and not result in dented edges.
The Stamping Process
Unlike standard metal stamping, I had to subject my aluminum sheet to a series of isolated hydraulic presses to give it a sense of “progression.” But as I already told you, mine was pretty simple and involved stamping and trimming – since it’s only for my experimentation. Besides, I cared more about the “process” and not way too much about the “results.” The best part is that the procedure isn’t overly intricate but pretty straightforward. Here’s my process:
• Punching the 0.020-inch thick aluminum sheet – or creating a significant slot – in the middle. However, the hole had to fit on the positive die’s protrusion. So again, precision was the key. Lucky for me, I had my milling machine on the side, which did all the legwork.
• Placing the 0.020-inch thick aluminum sheet on the positive die and afterward, stamping. That was straightforward since the sheet’s slot fitted the positive die’s protrusion and the negative die sandwiched it.
• Placing a rigid metal rod on the opposite side of the top un-milled negative die’s surface and engaging the hydraulic press.
That was it for the stamping part! And now, I had to repeat the entire process for the trimming. Again, no intricacies of complexity are involved. But first, I had to pluck the two dies apart using my tiny knife. And I also noticed that the aluminum sheet has stuck on the positive die, so the knife was useful once more. Carefully, I slid the knife under the sheet and gave it a slight pull upward to detach it, and it was out.
Trimming the Mold
The mold had dents around the edge, so I had to trim it to give it a smooth lining. Besides, I had to remove the scrap (the metal part outside the shape). That wasn’t an uphill task either since its shape outline was a line of weakness for easy trimming with a tin snip. But still, there was a problem: the edges weren’t entirely even, and the tin snip hadn’t done much satisfactory work. So, I had to get creative. But how?
Don’t forget my little friend – the CNC machine. It was perhaps heaven-sent when it came to rounding the edges. However, I had to devise a way to hold it against its rotating mills without shaking and making unnecessary dents. Nonetheless, that was the least of my worries. There were the vices to provide a firmer grip, and all I had to do was place it on the tight-grabbing vices and smooth the edges. Easy peasy! I was through with it in a few, and the results were virtually the most of what I had expected, but not entirely.
I have to admit that the results weren’t as impeccable as I had pictured but were beyond the ordinary. Remember, I kept everything straightforward, and the process was only minimalist. And unlike industrial-scale manufacturing, my CNC machining and designing weren’t entirely intricate. Nonetheless, there was a lot to savor and some positives to take.
The product piece had its edges slightly scorched, but other than that, everything was perfect. My wild guess was, perhaps I had miscalculated the die dimensions, or the sheet wasn’t fitting. There were a few scratches on the dies and the aluminum stamp, meaning that some friction resulted from the rubbing. I’m therefore thinking of using some sort of lubricant the next time I create a stamp. That’s because the hydraulic pressure can be way overboard sometimes, unlike the metered pressures in industrial production. The lubricant should ease the minor tears and scratches and provide quality results.
In all fairness, these results pleased me big time. However, there were a lot of takeaways and lessons to learn, ideal for my future projects. This process wasn’t so varied from standard manufacturing. The only difference was that I used makeshift CNC milling machines and an unmetered hydraulic pressure, which resulted in the scarring.
The Key Lessons and Takeaways
There’s usually a lot going on with industrial-scale metal stamping. And while it may not be more like it in DIY projects, the processes are almost similar. Creating the dies is some homework, and it takes a well-versed individual to design them. However, there is a lot of information to verse you about the entire process. Besides, the CAM software is usually intuitive with simple user interfaces. So, using them should be your cup of tea.
Precision is the key to designing 3D models using CAM software. It’s tricky getting everything right if you miscalculate your positive and negative dies’ dimensions. That can lead to unnecessary pressure on the stamping sheets and may pan out to scarifications and dents. And unlike industrial metal stamping, the hydraulic pressure can be uneven and non-uniform, leading to unwanted results.
Above all, there’s always room for improvement. Do-It-Yourself metal stamping requires numerous trials to be perfect, and that never comes easy. If you’re venturing into a metal stamping business, it’s worth considering the experience and skillset, which means you need practical know-how. Otherwise, the results won’t be as pleasing as your competitors; however, if you’re doing it for the fun, fret-not because it’s all for play then.
Making metal stamping dies isn’t overly complicated. However, it helps to have the proper know-how since it tags along with some difficulties you can solve well if you’re well-versed. As a startup, it’s typical to start small, but ensure that you learn the procedure and get a considerable amount of knowledge in using the CAM software and CNC milling machines. I’ve issued away my experience in making metal stamping dies, which I won’t rate highly for now. However, I hope you’ll find my lessons valuable and incorporate them into your craft. Good luck, my fellow DIYers!