September/October 2023 DefenseAndMunitions.com
Reducing complexity with industry specific functionality safeguards government compliance across a supply chain.
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KYOCERA PRECISION TOOLS’ Next-Gen CVD Coated Carbide
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ANCA’S MX7 Ultra Grinding Machine
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Accurate, easy to use test stands
force equipment specialist to visit their facility. We review the application infor- mation as to what they’re trying to test, and generally spend a day demonstrating how to set up the equipment. During the visit, the technical and force specialist makes sure the equipment is in a suitable, stable spot so that it doesn’t receive interference from external sources. Importantly, we also provide instruction on how to properly set up and design tests. It’s very one-on-one and involved. Also, our personnel are very experienced with setting up unusual tests, including automation if customers want to have the tests in-line with manufactur- ing processes. DAM : What are the bene ts of using the FMS or MMS stands compared to other testing equipment? JM: e advantage with an encoder-driv- en motorized test stand is you can obtain the position and how far parts travel, so you can test more than just the load. If you need to test di erent qualities of di erent components of rearms or muni- tions, you can do that with one test stand. If you require multiple machines to test various items, that’s another area you can add to as well. Since FMS and MMS stands are computer-driven, you can even automate a lot of the processes. Many customers have stated our software is signi cantly easier to use than other programs they have tried. e interface is more streamlined, and the test process is signi cantly easier. DAM : When using the FMS for trigger pull testing, how does the system collect and present the information for quality control?
Jacob Morales, technical support for force measuring and material testing equipment at The L.S. Starrett Co., discusses their FMS and MMS single column motorized force testing stands.
By Grace Koennecke
Defense & Munitions (DAM) : Why is force measurement in rearms and muni- tions important for defense manufactur- ers to conduct? Jacob Morales (JM): Before manufac- turers make a single rearm part, testing materials is a key step for quality control. Tensile and force testers are used to ensure materials meet quality standards based on ASTM or ISO standards, depending on the provider’s requirements for raw materials prior to manufacturing components. Firearm component examples include springs, triggers, and ammunition. All these parts must be assembled, or in some way have force testing applied to them. ere’s typically a requirement need- ing to be met which makes certain a part functions the way it’s expected to without failure. If the equipment fails when you need it, or has a problem in the usage process, someone could get hurt or have an even worse outcome. DAM : e FMS and MMS single column motorized test stands are accurate and easy to use. With this in mind, how are workers trained to use this equipment? JM: When the customer receives the equipment, we schedule a technician and
JM: Often, there’s a standard provided with the components being tested. For example, springs come with spring sheets. e sheets have information regarding what’s considered the spring’s free length, solid height, and the expected load across that entire length. A test setup could include relevant data collection informa- tion regarding those targets, and return an output showing you whether or not it fell within or outside of tolerance. For example, imagine a 6" long spring that can be compressed down three inches before the coils contact each other. e machine can reach that point and measure the loads at di erent heights along the travel length, and again when it returns to the spring’s original height. Importantly, the force system and its integrated software collect data points and present them on a graph. While the system is doing a pull test, the tension values are shown as an X-Y graph where the X-axis is distance and the Y-axis is load. As it travels upward, the line moves
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DefenseAndMunitions.com SEPTEMBER/OCTOBER 2023
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across the X-axis. When it makes contact with the trigger and starts pulling, it moves up along the Y-axis, producing a crest to the value of the load going up until it goes past that point where the trigger sets o the rearm and then
as a comma separated values (.csv) le, which can be read by programs such as Microsoft Excel. Many people will use a spreadsheet format so they can graph- ically represent that data outside of the controller software. ey can see speci c data point targets and the time incre- ments when those samples were taken, and compare the distance, the load, and even the speed at that point. DAM : What inspired e L.S. Starrett Co. to create the trigger pull testing xture? JM: We were approached by a rearms manufacturer looking to test trigger pulls speci cally. ey were looking to signi - cantly increase the ease of running tests compared to their existing method. We designed and manufactured a xture to lock in the rearm in a downward pointing direction with a hook mechanism and magnetic safety so it didn’t damage the rearm. If it pulled
TOP LEFT: Starrett designs and manufactures force systems that match customers’ unique ap- plication requirements. Change Spring Force Fixture allows opera- tors to quickly switch between test springs and load cells, saving time and costs. TOP RIGHT: New Starrett Rapid
ABOVE: Photo shows hook and barrel support on a Starrett Trigger Pull Test Fixture. The tipped cylinder on the bottom-left of the image is the barrel support, ZKHUHWKHƮUHDUPLVDOLJQHGEHIRUHEH - LQJVHFXUHGLQWRWKHƮ[WXUH,WRSHUDWHV pneumatically – the cylinder receives DLUSUHVVXUHWRVHFXUHWKHƮUHDUPLQWKH Ʈ[WXUHDQGWKHDGGLWLRQDOF\OLQGHUVRQ the bottom right can be swapped out to DFFRPPRGDWHGLƬHUHQWEDUUHOOHQJWKV
it goes back down. If there’s something for it to catch after that, it’ll go back up again. ere’s a point that the trigger will come to a hard stop where pulling on it won’t engage any mechanisms, and the load will go back up at that point. However, a test designer would have included a step to stop the test before or during that point, so it doesn’t damage the rearm. Generally, the force system data export
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too far, the magnet separates the hook from the crosshead to prevent damage. e magnet is strong enough to allow the hook to pull the trigger; and the machine reads tensile loads. Please note that while I refer to the hook mechanism as pulling on the trig- ger, if you were holding the rearm, you
would “squeeze” the trigger, compress- ing it between your nger and the grip in the palm. e rearm xture serves similarly, though it reads the forces in terms of tension instead of compression, as the trigger is pulled by the hook while mounting the rearm pointing down, and locking it in by orienting it based on
the muzzle, nozzle, and grip.
DAM : How is force measurement used in forensic application and how does that di er from its use in product testing? JM: ere isn’t a lot of di erence between the forensic application and the testing application. You’re not likely to test the extraction of a piece of ammunition after it’s been used; once it’s left the casing, it’s spent, and it’s signi cantly changed since it left the barrel. Testing forces of its extraction is probably not going to give useful information. Going back and testing unspent, o - the-shelf ammunition would be helpful if, for example, there was still some of the original, new ammunition available. DAM : How do you think these testing standards will impact the future of de- fense manufacturing? JM: Testing standards ultimately ensure that better quality equipment goes out in the eld. If rearms are used for defense, domestically or internationally, then there will be con dence that the equipment will work. No one wants anyone to use a rearm that fails when least expected. DAM : How have these products impact- ed military applications, law enforcement, and the recreational use of rearms? JM: Being able to test trigger pulls and verify functionality of the rearm is certainly useful, especially if you’re going into a situation where either you need to prove the rearm was raised too high so it couldn’t go o accidentally, or lowered to the point where it could. For law enforcement, the forensic application is surely very important. For recreation, safety is top-of mind, so hav- ing con dence in a manufacturer’s quality control is critical. The L.S. Starrett Co. – Metrology Division https://www.starrettmetrology. com/ rearm About the author: Grace Koennecke is the editorial intern with GIE Media’s Manufacturing Group of magazines.
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