| Jonaco Machine Inc Milling, Turning, Swiss, EDM, Grinding · ISO 9001 | Chaska, MN | MillingTurningSwissEDMGrinding | ISO 9001 |
| Jonesboro Tool & Die Co Inc Milling, Turning, Laser, Waterjet, Bending, Welding, Stamping, EDM, Grinding · AS9100, ITAR, CMMC | Jonesboro, AR | MillingTurningLaserWaterjetBendingWeldingStampingEDMGrinding | AS9100, ITAR, CMMC |
| JV Precision Machine Co Milling, EDM · ISO 9001, AS9100, ITAR | Seymour, CT | MillingEDM | ISO 9001, AS9100, ITAR |
| K & B Machining Inc Milling, Turning, Laser, Grinding, Finishing · ISO 9001, ITAR | Claremore, OK | MillingTurningLaserGrindingFinishing | ISO 9001, ITAR |
| K C Machine Milling, Turning, Waterjet · ISO 9001, AS9100 | Excelsior Springs, MO | MillingTurningWaterjet | ISO 9001, AS9100 |
| K&S Machining Milling, Turning | Madison, AL | MillingTurning | - |
| Kap Manufacturing, Inc Milling · ISO 9001 | San Dimas, CA | Milling | ISO 9001 |
| KCSP Machine LLC (formerly Kansas City Screw Products) Milling, Turning, Welding · ISO 9001, AS9100 | Kansas City, MO | MillingTurningWelding | ISO 9001, AS9100 |
| KD Precision Machining Inc Milling, Turning · AS9100 | Corona, CA | MillingTurning | AS9100 |
| Ketco Inc Milling | Beavercreek, OH | Milling | - |
| Kihm Metal Technologies Laser, Welding | Brazil, IN | LaserWelding | - |
| Kinetic Engine Systems Milling, EDM, Grinding | Phoenix, AZ | MillingEDMGrinding | - |
| King Tek EDM & Precision Machining Milling, Bending, Welding, EDM · ISO 9001, AS9100, ITAR, NADCAP | Anaheim, CA | MillingBendingWeldingEDM | ISO 9001, AS9100, ITAR, NADCAP |
| KN Machine & Tools, Inc Milling, Turning · ISO 9001, AS9100 | Jupiter, FL | MillingTurning | ISO 9001, AS9100 |
| Krametech, Inc Milling, Finishing, Assembly | Lake Zurich, IL | MillingFinishingAssembly | - |
| Krisalis Precision Machining Milling, Turning | San Andreas, CA | MillingTurning | - |
| KW Products, Inc Milling, Turning, Finishing · ISO 9001, AS9100 | Oldsmar, FL | MillingTurningFinishing | ISO 9001, AS9100 |
| L.F. Industries, Inc Milling · ISO 9001, AS9100 | Carlsbad, CA | Milling | ISO 9001, AS9100 |
| La Gauge Co Milling, Turning, EDM, Grinding, Finishing · ISO 9001, AS9100, ITAR | Sun Valley, CA | MillingTurningEDMGrindingFinishing | ISO 9001, AS9100, ITAR |
| Lai International Inc Milling, Laser, Waterjet, Welding, Metal AM, EDM, Finishing · NADCAP | Westminster, MD | MillingLaserWaterjetWeldingMetal AMEDMFinishing | NADCAP |
| Lakeview Forge Co Forging · ITAR | Erie, PA | Forging | ITAR |
| Lakota Industries Milling, Turning · AS9100, ITAR | Marysville, WA | MillingTurning | AS9100, ITAR |
| Land Sea Air Manufacturing Inc Milling, Turning, Waterjet, Assembly | Westminster, MD | MillingTurningWaterjetAssembly | - |
| Lark Industries Turning, Waterjet, Welding, Assembly · ISO 9001, ISO 13485 | El Paso, TX | TurningWaterjetWeldingAssembly | ISO 9001, ISO 13485 |
| Laser Cutting Co Milling, Laser, Bending, Welding, Grinding, Finishing · ISO 9001 | Harrison Township, MI | MillingLaserBendingWeldingGrindingFinishing | ISO 9001 |
| Latva Machine, LLC Milling, Turning, Stamping, Casting, Forging, Finishing · ISO 9001 | Newport, NH | MillingTurningStampingCastingForgingFinishing | ISO 9001 |
| LD Redmer Milling, Turning, Swiss, Welding, Finishing · ISO 9001, ITAR, NADCAP | Bensenville, IL | MillingTurningSwissWeldingFinishing | ISO 9001, ITAR, NADCAP |
| Liberty Precision Manufacturing LLC Milling, Turning, Swiss · ISO 9001, ITAR, CMMC | New Berlin, WI | MillingTurningSwiss | ISO 9001, ITAR, CMMC |
| Lightsout CNC Manufacturing Company Milling · ISO 9001, ITAR, NADCAP, ISO 13485, CMMC | Beverly Hills, CA | Milling | ISO 9001, ITAR, NADCAP, ISO 13485, CMMC |
| Linda Tool & Die Corp Milling, Turning · ISO 9001, AS9100, ITAR | Brooklyn, NY | MillingTurning | ISO 9001, AS9100, ITAR |
| LNT Machining Inc Milling, Turning | Santa Clara, CA | MillingTurning | - |
| Lodolce Machine Co, Inc Milling, Turning, Laser, Welding, EDM, Assembly · ISO 9001, AS9100 | Saugerties, NY | MillingTurningLaserWeldingEDMAssembly | ISO 9001, AS9100 |
| Longleaf Machining LLC Turning, Finishing · ISO 9001, ITAR | Brewton, AL | TurningFinishing | ISO 9001, ITAR |
| Loper Machine LLC Milling, Turning | Edgewood, MD | MillingTurning | - |
| Lorraine Machine Inc Turning, Welding · ISO 9001 | Greenville, SC | TurningWelding | ISO 9001 |
| Loutech LLC Milling, Turning, Swiss, Finishing · ISO 9001, AS9100, ITAR | Chino, CA | MillingTurningSwissFinishing | ISO 9001, AS9100, ITAR |
| LP Precision, Inc Milling, Turning, Grinding, Finishing | Santa Clara, CA | MillingTurningGrindingFinishing | - |
| Lucas Industries Milling, Welding | N Springfield, VT | MillingWelding | - |
| Luna's Sheet Metal Inc Milling, Turning, Bending, Laser, Welding | Santa Clara, CA | MillingTurningBendingLaserWelding | - |
| M & B Machine, Inc Milling, Turning, Swiss, Welding · ISO 9001, AS9100, CMMC | Carlisle, PA | MillingTurningSwissWelding | ISO 9001, AS9100, CMMC |
| M & H Machining, Inc Milling, Turning · ISO 9001 | Georgetown, TX | MillingTurning | ISO 9001 |
| M & M Sheet Metal, Inc Milling, Laser, Bending, Welding, Forging · ISO 9001, ITAR, CMMC | Williamsport, PA | MillingLaserBendingWeldingForging | ISO 9001, ITAR, CMMC |
| M-Tech Machining LLC Milling, Turning, EDM · ITAR | Edgewood, NM | MillingTurningEDM | ITAR |
| M'kaddesh Group LLC Milling, Turning · AS9100 | Cerritos, CA | MillingTurning | AS9100 |
| M&M Machining, Inc Milling, Turning, Welding, Finishing | Ventura, CA | MillingTurningWeldingFinishing | - |
| Mac Machine Company Milling, Turning, Welding, EDM, Grinding · AS9100, ITAR, NADCAP, CMMC | Baltimore, MD | MillingTurningWeldingEDMGrinding | AS9100, ITAR, NADCAP, CMMC |
| Machina Labs Inc Stamping · ITAR, CMMC | Chatsworth, CA | Stamping | ITAR, CMMC |
| Machine Incorporated Milling, Turning, Swiss, Assembly · ISO 9001, AS9100 | Stoughton, MA | MillingTurningSwissAssembly | ISO 9001, AS9100 |
| Machine Specialties, LLC Milling, Turning, Swiss, Welding, EDM, Grinding, Finishing, Assembly · ISO 9001, AS9100, NADCAP | Whitsett, NC | MillingTurningSwissWeldingEDMGrindingFinishingAssembly | ISO 9001, AS9100, NADCAP |
| Machine Time Inc Milling, Turning, Bending, Welding · ISO 9001, AS9100 | Nicholasville, KY | MillingTurningBendingWelding | ISO 9001, AS9100 |