| J.i.t. Manufacturing, Inc Milling, Laser, Punching, Bending, Welding, Finishing, Assembly | Cowpens, SC | MillingLaserPunchingBendingWeldingFinishingAssembly | - |
| J'evac Machine, Inc Milling, Turning, Swiss, Waterjet, Bending, Welding, Finishing · ISO 9001, AS9100, NADCAP | Magnolia, AR | MillingTurningSwissWaterjetBendingWeldingFinishing | ISO 9001, AS9100, NADCAP |
| J&D Custom Finishing | Holden, MO | Finishing | - |
| J&M Machining Milling, Turning, Welding, Casting, Finishing · ISO 9001 | Norton Shores, MI | MillingTurningWeldingCastingFinishing | ISO 9001 |
| Jaffa Precision Engineering Inc Milling, Turning, Swiss, Welding, Grinding, Finishing · ISO 9001 | Riverside, CA | MillingTurningSwissWeldingGrindingFinishing | ISO 9001 |
| James Tool Machine & Engineering Inc Milling, Turning, Welding, EDM, Grinding, Finishing · ISO 9001, AS9100 | Morganton, NC | MillingTurningWeldingEDMGrindingFinishing | ISO 9001, AS9100 |
| Jars Inc Milling, Waterjet, Bending, Welding, EDM, Grinding, Finishing | San Fernando, CA | MillingWaterjetBendingWeldingEDMGrindingFinishing | - |
| Jenkins Machine Inc Milling, Turning, EDM, Grinding, Finishing | Bethlehem, PA | MillingTurningEDMGrindingFinishing | - |
| Jet Helseth Manufacturing Inc Turning, EDM, Finishing, Assembly · ISO 9001, ITAR | Deland, FL | TurningEDMFinishingAssembly | ISO 9001, ITAR |
| Jetsons Precision Cleaning LLC Finishing, Assembly · ISO 9001, AS9100, ISO 13485 | Garner, NC | FinishingAssembly | ISO 9001, AS9100, ISO 13485 |
| JG Innovations, Inc Finishing | Janesville, WI | Finishing | - |
| JMG Tool LLC Milling, Turning, Laser, Welding, Finishing · ISO 9001, AS9100, ITAR | Loxahatchee, FL | MillingTurningLaserWeldingFinishing | ISO 9001, AS9100, ITAR |
| John J Steuby Co Milling, Turning, Swiss, Welding, Stamping, Casting, EDM, Finishing · ISO 9001, ITAR | Hazelwood, MO | MillingTurningSwissWeldingStampingCastingEDMFinishing | ISO 9001, ITAR |
| Johnson Brass & Machine Foundry Inc Casting, Finishing | Saukville, WI | CastingFinishing | - |
| Jolar Machine Shop Milling, Grinding, Finishing · ISO 9001 | Dickson City, PA | MillingGrindingFinishing | ISO 9001 |
| Jones Metal, Inc Milling, Laser, Waterjet, Bending, Welding, Finishing, Assembly | Mankato, MN | MillingLaserWaterjetBendingWeldingFinishingAssembly | - |
| Just One More Part, LLC Bending, Welding, Finishing | Pottstown, PA | BendingWeldingFinishing | - |
| Justified Performance LLC Laser, Bending, Welding, Finishing, Assembly · ISO 9001 | Rocklin, CA | LaserBendingWeldingFinishingAssembly | ISO 9001 |
| Kammerer Dynamics Inc Laser, Bending, Welding, Casting, Finishing, Assembly | Kendallville, IN | LaserBendingWeldingCastingFinishingAssembly | - |
| Kaydek Machining, Inc Milling, Turning, Finishing · ISO 9001, AS9100 | San Jose, CA | MillingTurningFinishing | ISO 9001, AS9100 |
| KB Sheetmetal Fabrication, Inc Turning, Bending, Welding, Finishing · ISO 9001 | Fountain Valley, CA | TurningBendingWeldingFinishing | ISO 9001 |
| Kennley Corp Milling, Turning, Grinding, Finishing | North Chesterfield, VA | MillingTurningGrindingFinishing | - |
| Kilgore Manufacturing Co Inc Milling, Swiss, Bending, Welding, EDM, Finishing, Assembly · ISO 9001, ITAR | Columbia City, IN | MillingSwissBendingWeldingEDMFinishingAssembly | ISO 9001, ITAR |
| Kineo, Inc Milling, Turning, EDM, Grinding, Finishing · ISO 9001, ISO 13485 | Colorado Springs, CO | MillingTurningEDMGrindingFinishing | ISO 9001, ISO 13485 |
| Kinross Fab & Machine Inc Milling, Turning, Laser, Welding, Grinding, Finishing | Kincheloe, MI | MillingTurningLaserWeldingGrindingFinishing | - |
| Kirsh Manufacturing Inc Milling, Turning, Welding, Grinding, Finishing · ISO 9001, ITAR | Tucson, AZ | MillingTurningWeldingGrindingFinishing | ISO 9001, ITAR |
| KLH Industries Inc Milling, Turning, Waterjet, Bending, Welding, EDM, Grinding, Finishing · ISO 9001, AS9100, ITAR, NADCAP | Germantown, WI | MillingTurningWaterjetBendingWeldingEDMGrindingFinishing | ISO 9001, AS9100, ITAR, NADCAP |
| KLM Machining, Inc Milling, Turning, Welding, Finishing | Sussex, WI | MillingTurningWeldingFinishing | - |
| Korzan Enterprises Inc Milling, Turning, Waterjet, Welding, EDM, Grinding, Finishing | Orchard Park, NY | MillingTurningWaterjetWeldingEDMGrindingFinishing | - |
| KP Manufacturing Milling, Casting, Finishing, Assembly | Spencer, IA | MillingCastingFinishingAssembly | - |
| Krametech, Inc Milling, Finishing, Assembly | Lake Zurich, IL | MillingFinishingAssembly | - |
| Kte Holdings LLC Milling, Turning, Welding, Grinding, Finishing | Mableton, GA | MillingTurningWeldingGrindingFinishing | - |
| L. E. F., Inc Milling, Laser, Bending, Welding, Stamping, Finishing | Tulsa, OK | MillingLaserBendingWeldingStampingFinishing | - |
| L.a. Martin Company Milling, Turning, Bending, Welding, Grinding, Finishing · ISO 9001 | Dearborn, MI | MillingTurningBendingWeldingGrindingFinishing | ISO 9001 |
| Lakecity Industries Holding Inc Finishing | Lake City, PA | Finishing | - |
| Lakecraft, Inc Turning, Bending, Welding, Grinding, Finishing | Port Clinton, OH | TurningBendingWeldingGrindingFinishing | - |
| Laserbend, LLC Laser, Bending, Welding, Finishing | Tujunga, CA | LaserBendingWeldingFinishing | - |
| Laserform & Machine Inc Turning, Laser, Punching, Bending, Welding, Finishing, Assembly · ISO 9001 | Columbia, SC | TurningLaserPunchingBendingWeldingFinishingAssembly | ISO 9001 |
| Latitude Corp Milling, Waterjet, Punching, Bending, Welding, Stamping, Grinding, Finishing · AS9100 | Verona, WI | MillingWaterjetPunchingBendingWeldingStampingGrindingFinishing | AS9100 |
| 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 |
| Leading Edge Manufacturing, L.L.C Welding, Finishing | Youngsville, LA | WeldingFinishing | - |
| Lemmatic Precision LLC Milling, Turning, Finishing · ISO 9001, ITAR | American Fork, UT | MillingTurningFinishing | ISO 9001, ITAR |
| LHM Engineering LLC Milling, Swiss, Laser, Waterjet, Stamping, EDM, Grinding, Finishing, Assembly · ISO 13485 | Manchester, MA | MillingSwissLaserWaterjetStampingEDMGrindingFinishingAssembly | ISO 13485 |
| Liberty CNC LLC Milling, Turning, Finishing · ISO 9001 | Cocolalla, ID | MillingTurningFinishing | ISO 9001 |
| Linear Machining Technology LLC Milling, Turning, EDM, Grinding, Finishing · ISO 9001 | Irwin, PA | MillingTurningEDMGrindingFinishing | ISO 9001 |
| LNP Machining Milling, Turning, Welding, Finishing · ISO 9001, AS9100, ITAR, ISO 13485 | San Jose, CA | MillingTurningWeldingFinishing | ISO 9001, AS9100, ITAR, ISO 13485 |
| Louis C Morin Co Inc Milling, Turning, Swiss, Welding, Grinding, Finishing, Assembly | North Billerica, MA | MillingTurningSwissWeldingGrindingFinishingAssembly | - |
| LP Precision, Inc Milling, Turning, Grinding, Finishing | Santa Clara, CA | MillingTurningGrindingFinishing | - |
| M&M Full Service Machine Shop Milling, Bending, Welding, Grinding, Finishing | Satellite Beach, FL | MillingBendingWeldingGrindingFinishing | - |