This firearm part is typical of the intricate small parts that can be produced by the metal injection molding (MIM) process.
Firearm sales have increased exponentially over the past few years, especially in recent months, and forecasts are continuing to escalate, reflecting an increase in the popularity of hunting, a rise in the desire for personal protection, and a variety of other socio-economic factors. As manufacturers seek to meet demand while decreasing costs, reducing weight, and increasing durability, the spotlight is turning to engineering and design capabilities in the industry.
Engineered metal solutions, including expertise in such technologies as precision CNC machining, metal injection molding (MIM), laser welding, and stamping, are key to meeting the challenges of this booming industry.
In 2011 and 2012, firearms had strong, record-setting sales. According to the National Shooting Sports Foundation (NSSF), there have been 24 straight monthly increases in the number of the National Instant Criminal Background Check System (NICS) background checks, when compared to the same period of the previous year. The FBI checks are required by all licensed firearms dealers to ensure that a customer does not have a criminal record or isn’t otherwise ineligible to make a purchase.
The NICS statistics are not actual sales data, but since one cannot purchase a firearm without getting one, it is likely that most people getting a NICS check are buying a firearm.
In addition to background-check statistics, the NSSF notes that firearms production and importation, firearm-retailer surveys and on-theground reports from retailers nationwide reveal that interest in firearm ownership is high.
In fact, the increased demand has had major firearms manufacturers struggling to keep up, with some even having to stop taking orders. For example, Sturm, Ruger & Co. resumed taking new orders from its independent wholesale distributors in late May 2012, after temporarily suspending the acceptance of new orders in March.
Ruger had received orders for more than one million firearms in the first quarter; the company said its production and shipments in the first quarter of 2012 increased more than 50% from the first quarter of 2011.
What’s fueling the boom? Experts cite several reasons for the increase, including uncertainty in a presidential election year, warriors returning from the battlefields, the comeback of the hunter, and economic uncertainty.
Personal defense is also seen as a large and growing trend, resulting in a marked increase in compact pistols.
Engineering firms are rapidly expanding to provide the engineering and design capabilities necessary to accommodate the boom in the firearms market. In guns and other projectiles, most branches of mechanical engineering are applied, including wearproperties (tribology) of the moving parts, manufacturing of highly precise machining processes, and system design. A high degree of design collaboration with top gun manufacturers is imperative to meet the needs of today’s firearms purchasers, whether they are for personal protection, hunting, or for the military.
For example, Tracy MacNeal, ATW Company’s director of business development, notes the importance of engineering expertise for helping firearms manufacturers hit tight tolerances, and resolve complex issues.
“Identifying prototyping needs, turning around a prototype quickly, developing the best materials for the application, and providing advice on appropriate designs and tolerances, are services that are essential to supporting today’s firearms industry,” says MacNeal. Warwick, RI-based ATW Companies is a provider of highly engineered metal solutions to the metal component marketplace.
According to Chris Schirmer, quality control manager at STI International, a Texas-based company that manufactures complete M1911 pistols and parts for competition, duty and self-defense, designers must pay careful attention to the application of the firearm. He asks, “What is the intent of the firearm—Is it concealed carry, competition, or law enforcement? Each area of firearm use will have specific requirements that need to be met, which requires decisions on size, material, weight, length, and caliber.” Since most people have very limited budgets, consumers like to buy inexpensive firearms, and most manufacturers are responding by looking for ways to reduce costs. This is why many firearm manufacturers are using molded plastics, aluminum extrusions, and die cast zinc parts in their new designs. All of these processes can be used to make inexpensive, strong, and durable components.
High tolerances and precision function is key to every component in gun manufacturing. For example, Metalform Magazines, a division of A.T.
Wall, produces firearms magazines, a relatively simple device that feeds the rounds into the pistol’s chamber via a spring-loaded follower mechanism.
Although standard magazines tend to cost only $15-75 depending on design/ size, this small component can determine how well a $2000 pistol works.
Kevin Collins, a senior design engineer at Savage Arms, a Westfield, MA-based manufacturer of rifles and shotguns, explains that designing weapons for today’s firearms purchasers depends not only on precision, but also weight.
“Lighter and stronger has been a goal for a long time, and the design mantra has been to look to polymers, aluminum, titanium, and carbon fiber to get just the right combination of durability and weight.” He notes that today’s hunters are looking for lightweight rifles, and designers are responding to the demand by looking at aluminum frames and receivers. This can save as much as 30 to 50% of the weight of the firearm and shipping of the raw material, and also saves on machining costs.
The application of the firearms determines much of the desired weight requirements. Collins notes that in hunting applications, in which the hunter might be making only a few shots in a given day, a lighter gun is easier to carry and the extra recoil is not much of a problem. By contrast, in a shooting range application, in which the shooter might be firing many rounds, the recoil associated with a very lightweight rifle will cause fatigue fairly quickly. Engineering design seeks to resolve these polarized requirements.
Reinforced plastic with steel ribbing is another design innovation being pursued, though Collins acknowledged the downside of polymers, especially where the weapon may be used in areas with a large temperature fluctuation, as steel components may expand when plastic does not. The variation in these temperature coefficients will eventually cause loosening of the gun’s components, which is not desirable.
Metal injection molding Metal injection molding is a popular choice for relatively high precision at a low cost. MIM combines powder metal with a low melt polymer to create a feedstock that is molded using conventional injection molding equipment and molds. After molding, the plastic, which is known as the binder, must be removed in a step called debinding. After debinding, the parts are placed into high temperature sintering furnaces and sintered. The result is a solid metal part created from powder metal to near net shape at 96 percent density of wrought metal.
There is little waste in the MIM process compared to other competing technologies, making MIM a green technology. MIM is a low cost, high volume manufacturing process that produces geometrically complex metal parts that are difficult or near impossible to produce using other conventional metal fabrication technologies.
This means MIM can be used to produce complex shapes that can cost 20 to 50% of a machined part, producing far less material waste, with high production rates.
Key major firearms manufacturers have adopted MIM widely, and new projects are likely to include MIM parts, due to the cost and consistency of the process. Depending on volume requirements and part complexity, MIM can significantly reduce the component cost and in some instances yield parts that could not be made using any other method. Manufacturing of metal components using MIM technology has enabled US companies to stay within the US for sourcing components, due to MIM’s high manufacturing capability and competitive pricing.
John Lewinski, director of supplier management at Springfield, MA-based Smith & Wesson, notes that any of the company’s new projects are likely to include MIM parts, due to the cost and consistency of the process.
“MIM has allowed us to take cost out of the product while maintaining quality and therefore pass the savings on to the consumer,” says Lewinski.
Collins agrees, calling MIM the modern replacement to investment casting, especially for small parts. He says that MIM is a fairly new technology that is being used more and more for making firearm components. The parts are dimensionally consistent, fairly inexpensive, and the surface finish is smoother than machined or investment cast (IC) components. To save on costs, especially for entry level guns, designers are looking to save on costs by designing guns with less than smooth mirror finish on mating parts, or where parts are not super close fitting, but which are utilitarian and result in a perfectly functional firearm.
In his view, the main drawback of current MIM technology is the material designation and selection. Most engineers are not familiar with the materials used for MIM parts. He explains, “Most MIM parts are not made from common AISI materials such as 4340 and 8620 alloy steels, and this is certainly a drawback for anyone wanting to make parts for existing military rifles such as the M14 and M16.” According to Collins, the rifles purchased by the US military use lots of parts made from AISI 8620 alloy steel, and they don’t have options for similar or equivalent materials.
“Getting new materials approved for military use can be a hassle.” Also, he notes that at this point, IC still has a distinct advantage over MIM in that the cast parts can be bigger or heavier than the MIM parts. Next to stocks and barrels, receivers are the largest and most complex components for firearms. “Making a receiver with the MIM process would be a good test to validate the strength and durability of MIM components and materials,” said Collins.
Basically, Collins believes that creative designs and manufacturing methods will be key, similar to the way firearm manufacturers during WWII found the most economical and least time consuming ways of manufacturing firearms. In his view, there is no reason to make a firearm component any stronger or more complicated than it needs to be. This would drive up its manufacturing cost, but it wouldn’t necessarily improve its quality.
Chris Schirmer of STI International, also believes that that the introduction of MIM components to the firearms industry has had a significant impact.
“MIM allowed the manufacturers to create a ready to use, high detail metal part in high volume at low cost,” said Schirmer. “Unfortunately the early MIM process left a lot to be desired and the manufacturers using these parts experienced failures.” Schirmer explains that, over time, the process has improved to the point that it is a perfectly acceptable method of manufacture for most manufacturers, including STI. He does acknowledge that there is still concern in the public about the early failures and its use may never be accepted by some consumers or 100% by manufacturers.
According to ATW’s Tracy MacNeal, designers must also pay careful attention to the identification and management of complex secondary operations that are performed on the MIM part, which may include laser marking, subassemblies, post machining operations, and coating and plating requirements. Tooling design expertise and use of the latest analytical tools, for example SolidWorks and MoldFlow software, are the final piece of the design puzzle.
Companies with consolidated and broad capabilities are often a good solution for firearms manufacturers seeking to meet demand in today’s boom, while ensuring the best balance of design and production are satisfying the market.
