More firearms manufacturers are adopting 3D printing to supply production components. Why?
The internet was taken by storm with the world’s first 3D-printed gun (the classic 1911 .45), leaving many firearms manufacturers wondering how (or when) metal 3D printing (also known as additive manufacturing or AM) was going to impact production in the firearms industry.
Here are the three main reasons why firearm manufacturers are transitioning production to metal additive manufacturing in 2020.
Reason #1: Metal 3D printing is finally cost competitive with traditional
In AM, layers of material are deposited to form an object – the term is synonymous and can correctly be used interchangeably with 3D printing. For comparison, older methods where objects were milled and shaped from a solid block of metal is considered ‘subtractive manufacturing’, since the process works by removing material. Additive, as it sounds, works by adding material as the process goes along. The benefits are ease of design (you don’t have to think about what’s being removed), speed, and a minimum of waste. In practical terms, the only material consumed is what is used to form the object.
Also, AM techniques require far less “setup” than traditional methods. In a traditional subtractive setup, a technician must program massive machines, select the proper drill bits and other tooling to perform the material removal and shaping, and determine the limits of the machine itself. In AM, if the object fits on the “bed” of the 3D printer, it can generally be realized.
Reason #2: Design freedom of 3D printing creates new possibilities by utilizing 17-4 PH powder metal alloy
According to The Truth About Guns, heat is the enemy of accuracy. Gun models that require steady or repeated discharge, as is the case of many automatic weapons produced for the defense industry, produce heat in the barrel. And that heat leads to expansion of the bore, which, in turn, allows the ordnance to spread. Instead of a tight grouping, a shooter will begin to see looser target patterns.
This is where MIM 17-4 PH shines. The “PH” part of the alloy name refers to precipitation hardening, which uses heat to make a metal alloy stronger by hardening it and introducing precipitates into the alloy chemical structure that adds stability and reduces dislocations (sometimes referred to as deformation, plasticity, or warping).
At 17 percent chromium, the 17-4 PH alloy adds the strength of precipitation hardening, and it provides tarnish resistance and the ability to add a high-polish finish. Nickel is a transitional metallic element that also contributes precipitation hardening characteristics as four percent of the 17-PH alloy.
The iron, chromium, and nickel elemental powders form the 17-4 PH alloy during sintering, a process that densifies the powders and produces component densification. After sintering these is no difference between the physical or mechanical properties of the powder metal part compared to traditional “solid” metallurgical sources.
By reducing material dislocations through precipitation within the crystalline structure of the alloy, the 17-4 PH can withstand extremely high temperatures without material dislocation. That means those barrels expand more slowly, allowing shooters to maintain accuracy over long periods of time.
17-4 PH’s strength holds to approximately 572°F (300°C). In fact, with 17-4 PH hardened to 36-44RC, a shooter can fire double or triple the amount of rounds accurately compared to 416R stainless steel, which only hardens to about 28RC.
Reason #3: Metal 3D printing reached a greater degree of precision, offering superior tolerances and standards
In the world of firearms, the watchword is truly precision. Accessories should not adversely affect the point of impact in a gun, and critical components of the weapon such as the barrel should be able to produce an accuracy of 1 minute-of-arc or better. With AM techniques, this can be easily realized, and at a more cost-effective rate, leading to greater profits for the designer, cost savings for the consumer, or both. The precision of AM also leads to a more aesthetically pleasing product as well, with the product being free of the dimples, divots, and tool marks that can plague traditional firearms manufacturing processes.
This is especially notable since firearms reviewers will often judge a product by its fit-and-finish, especially in the domestic market. While toolmarks and imperfections are expected from a $400 Warsaw Pact surplus weapon or accessory, it is generally unacceptable for a domestic product to sport the same defects. With traditional methods, this is difficult to achieve, and requires many man-hours of work and discarded errors before an acceptable final product is finished. After final acceptance of a design, an AM company such as 3DEO can churn out quality product after quality product from the first specimen out of the chamber, and at a cost that is far less than traditional methods.