Whether you’re designing silencers for muzzle-loading guns or the most efficient AR-15 lower receiver, keep these three ideas in mind to ensure the most profitable approach to firearms manufacturing and design.
1. Design Specifically for the Additive Manufacturing Process
As a designer, you need to have a particular metal additive manufacturing (AM) process in mind when creating your CAD model.
Chalk this up to that Stephen Covey maxim from the 7 Habits of Highly Effective People: Start with the end in mind. Or, to borrow a shooting visual, have the target in view.
You’d be surprised how different 3D metal printers can affect the final part output based on different laser spot size and melt pool variations. And different metal AM process can make a huge difference in part performance.
Did you know that with laser sintering, for example, the longer it takes to print a metal part, the higher the chances it will fail. Repeated heating and cooling creates internal stress that can lead to part distortion during the printing process. The cumulative effect of those internal stresses can express themselves in multiple structural deficiencies in the final part.
To avoid overbuilding underperforming parts, you may need to putz around with your design after a test run, or have your metal AM vendor work with you during design to get ahead of the learning curve.
What are the most likely suspects for design failure in firearm parts manufacturing using metal 3D printing?
- Wall Thicknesses: Thin walls collapse under their own weight during build.
- Holes and Gaps: Specs for gaps and holes vary widely based on the specific metal 3D printing process in play, the metals used, and the part geometry. Smaller gaps run the risk of the sides merging together and filling the empty space.
- Overhangs: Minimize overhangs where possible and try to integrate supports for downward-facing structures at more than a 45-degree angle.
- Part Orientation: Mechanical or structural metal parts created in 3D printing will have anisotropic properties, which means they have different tensile strength levels in different build directions.
- Aesthetics / Surface Finish: Most 3D-printed parts require post-machining to get aesthetically pleasing surface finishes, which can require CNC machining or manual surface work. Down-facing surfaces of printed firearms parts will have a poorer surface finish compared to the top-facing surfaces.
By knowing the specific process that will produce your final parts, you can get ahead of failures in design. Forewarned is forearmed.
2. Design for the Final Gun Part Material
Metal prints present complexities that need to be taken into account during design, but if you’re thinking in terms of prototypes using a material different from the final piece, then you may be setting your design up for failure.
For example, many parts designers design prototypes in plastic just to test the final geometry. They may spend time tweaking the design to make the geometry perfect. In plastic. But just as not all metal AM processes are interchangeable, 3D printing in plastic is definitely another beast altogether.
But you knew that already. You’re more interested in something like the difference between 7075-T6 aluminum and MIM 17-4PH stainless steel. (They both have good anti-corrosion properties, by the way, but 17-4PH has more than double the tensile and yield strength ratings than 7075-T6).
The point is that your design needs to consider the metal used in the finished part.
3. Choose a Cost-Effective Production Process
Many manufacturers exploring metal AM find it difficult to get the numbers to “add up” in their favor. 3D printing metal parts in small to mid-sized volumes can just be too expensive.
3D printing can be cost-competitive with CNC milling when part features are complex or just flat-out impossible with traditional CNC; however, if you can create parts with simple geometries in subtractive CNC manufacturing at a price-per-count that makes sense, then why wouldn’t you? Trying to fight common sense is like trying to fire a .223 round out of a Glock 23.
Additionally, speed can be an issue with metal AM. In the direct metal laser melting (DMLM) powderbed fusion process, laser sintering is the bottleneck. That slows the production of large parts or high volume orders or smaller parts (not to mention extraordinarily high cost-per-part numbers).
But AM does have total cost-saving potential for firearms manufacturing compared to the CNC process. For example, 3D printing metal parts generates less material waste than traditional subtractive methods. In fact, the waste stream from CNC parts can rise as high as 90 percent compared to five percent for metal AM parts.
Now, if only there were an additive manufacturing process that reduced the cost per part even at the low-volume production range and one that allowed for shorter lead times.
Ta-da! Reduce Cost per Part for Firearms Manufacturing with 3DEO
Thanks to 3DEO’s Intelligent Layering® technology, even mid-sized firearms manufacturers can meet industry quality standards like MPIF Standard 35 while achieving the same cost savings per part as with metal injection molding (MIM), casting, or hot-drop forging.
Intelligent Layering® binds the entire layer of metal powder before a CNC micro end mill defines the part geometry. Then, layer by layer, a “green part” is built that is heated in a sintering furnace to fully form.