| J W Machine & Fab LLC Milling, Turning, Welding, Grinding | Fountain Inn, SC | MillingTurningWeldingGrinding | - |
| J.V. Manufacturing Co Inc Stamping, EDM, Grinding · ISO 9001 | Natrona Heights, PA | StampingEDMGrinding | ISO 9001 |
| Jaco Engineering Milling, Turning, Bending, Welding, EDM, Grinding, Finishing, Assembly · NADCAP | Anaheim, CA | MillingTurningBendingWeldingEDMGrindingFinishingAssembly | NADCAP |
| James Tool Machine & Engineering Inc Milling, Turning, Welding, EDM, Grinding, Finishing · ISO 9001, AS9100 | Morganton, NC | MillingTurningWeldingEDMGrindingFinishing | ISO 9001, AS9100 |
| JMS Machine, Inc Milling, Turning, EDM, Grinding | Columbia City, IN | MillingTurningEDMGrinding | - |
| Johnson Manufacturing Milling, Turning, Grinding · AS9100 | Huntington Beach, CA | MillingTurningGrinding | AS9100 |
| Johnson Manufacturing Systems LLC Milling, Turning, Welding, Grinding | Miamisburg, OH | MillingTurningWeldingGrinding | - |
| Jolar Machine Shop Milling, Grinding, Finishing · ISO 9001 | Dickson City, PA | MillingGrindingFinishing | ISO 9001 |
| K & B Machining Inc Milling, Turning, Laser, Grinding, Finishing · ISO 9001, ITAR | Claremore, OK | MillingTurningLaserGrindingFinishing | ISO 9001, ITAR |
| Kam Tool & Die Milling, Turning, EDM, Grinding · ISO 9001 | Zebulon, NC | MillingTurningEDMGrinding | ISO 9001 |
| Kennebec Technologies Milling, Grinding, Assembly | Augusta, ME | MillingGrindingAssembly | - |
| Kennley Corp Milling, Turning, Grinding, Finishing | North Chesterfield, VA | MillingTurningGrindingFinishing | - |
| Kent Machine Milling, EDM, Grinding | Indianapolis, IN | MillingEDMGrinding | - |
| Keystone Machine & Fab, Inc Milling, Turning, EDM, Grinding | Grafton, OH | MillingTurningEDMGrinding | - |
| KLH Industries Inc Milling, Turning, Waterjet, Bending, Welding, EDM, Grinding, Finishing · ISO 9001, AS9100, ITAR, NADCAP | Germantown, WI | MillingTurningWaterjetBendingWeldingEDMGrindingFinishing | ISO 9001, AS9100, ITAR, NADCAP |
| Kuhn Tool & Die Co Milling, Waterjet, Welding, Stamping, EDM, Grinding | Meadville, PA | MillingWaterjetWeldingStampingEDMGrinding | - |
| L.a. Martin Company Milling, Turning, Bending, Welding, Grinding, Finishing · ISO 9001 | Dearborn, MI | MillingTurningBendingWeldingGrindingFinishing | ISO 9001 |
| Lakes Area Manufacturing Co Milling, Grinding | Shafer, MN | MillingGrinding | - |
| Larkin Precision, LLC Laser, Grinding | Kent, WA | LaserGrinding | - |
| Lathrom Manufacturing Inc Milling, Turning, Bending, Grinding · ISO 9001, ITAR | Wichita, KS | MillingTurningBendingGrinding | ISO 9001, ITAR |
| Lawruk Machine & Tool Milling, Turning, Welding, Grinding · ISO 9001 | Altoona, PA | MillingTurningWeldingGrinding | ISO 9001 |
| Layne West Manufacturing LLC Milling, Swiss, Welding, Grinding | Boise, ID | MillingSwissWeldingGrinding | - |
| Lean Industrial LLC Milling, Casting, Grinding · ISO 9001 | Eugene, OR | MillingCastingGrinding | ISO 9001 |
| Leiss Tool & Die Co Milling, Turning, Bending, Welding, Stamping, EDM, Grinding | Somerset, PA | MillingTurningBendingWeldingStampingEDMGrinding | - |
| LHM Engineering LLC Milling, Swiss, Laser, Waterjet, Stamping, EDM, Grinding, Finishing, Assembly · ISO 13485 | Manchester, MA | MillingSwissLaserWaterjetStampingEDMGrindingFinishingAssembly | ISO 13485 |
| Liberty Precision Company Milling, Turning, EDM, Grinding, Assembly · ISO 9001 | Houston, TX | MillingTurningEDMGrindingAssembly | ISO 9001 |
| Lomar Machine & Tool Co Milling, Turning, Laser, Bending, Welding, Casting, EDM, Grinding, Finishing · ISO 9001 | Horton, MI | MillingTurningLaserBendingWeldingCastingEDMGrindingFinishing | ISO 9001 |
| Long Machine Milling, Turning, Grinding | Temecula, CA | MillingTurningGrinding | - |
| Louis C Morin Co Inc Milling, Turning, Swiss, Welding, Grinding, Finishing, Assembly | North Billerica, MA | MillingTurningSwissWeldingGrindingFinishingAssembly | - |
| Lowery's Job Shop Milling, Turning, Laser, Welding, Grinding, Finishing | Saint Louisville, OH | MillingTurningLaserWeldingGrindingFinishing | - |
| LP Precision, Inc Milling, Turning, Grinding, Finishing | Santa Clara, CA | MillingTurningGrindingFinishing | - |
| LV Swiss Inc Milling, Turning, Swiss, Grinding, Finishing · ISO 9001, AS9100, ITAR, ISO 13485 | La Verkin, UT | MillingTurningSwissGrindingFinishing | ISO 9001, AS9100, ITAR, ISO 13485 |
| M-1 Tool Works, Inc Milling, Turning, EDM, Grinding, Finishing, Assembly · ISO 9001, AS9100 | Mchenry, IL | MillingTurningEDMGrindingFinishingAssembly | ISO 9001, AS9100 |
| M&M Full Service Machine Shop Milling, Bending, Welding, Grinding, Finishing | Satellite Beach, FL | MillingBendingWeldingGrindingFinishing | - |
| Mace Machine LLC Milling, Turning, Swiss, Grinding · AS9100, ITAR, NADCAP | Exeter, NH | MillingTurningSwissGrinding | AS9100, ITAR, NADCAP |
| Machine Tool Engineering Milling, Turning, Swiss, Laser, Waterjet, Stamping, EDM, Grinding, Finishing · ISO 9001, AS9100, NADCAP | Charles City, IA | MillingTurningSwissLaserWaterjetStampingEDMGrindingFinishing | ISO 9001, AS9100, NADCAP |
| Machine Works, L.L.C Milling, Turning, EDM, Grinding · ISO 9001, ITAR | Phoenix, AZ | MillingTurningEDMGrinding | ISO 9001, ITAR |
| Magna Machine & Tool Co Inc Milling, Turning, Waterjet, Welding, EDM, Grinding | New Castle, IN | MillingTurningWaterjetWeldingEDMGrinding | - |
| Magnolia Machine Company Milling, Turning, Welding, EDM, Grinding | Auburndale, FL | MillingTurningWeldingEDMGrinding | - |
| Marinette Machine LLC Turning, Welding, Grinding, Finishing | Marinette, WI | TurningWeldingGrindingFinishing | - |
| Marion Mold & Tool Inc Milling, Turning, Waterjet, EDM, Grinding · ISO 9001, AS9100 | Marion, VA | MillingTurningWaterjetEDMGrinding | ISO 9001, AS9100 |
| Mars Engineering Milling, Turning, Waterjet, EDM, Grinding, Finishing, Assembly | San Leandro, CA | MillingTurningWaterjetEDMGrindingFinishingAssembly | - |
| Master Machine & Tool Co Inc Welding, EDM, Grinding | Newport News, VA | WeldingEDMGrinding | - |
| Master Tool & Manufacturing Inc Turning, Bending, Welding, EDM, Grinding · ISO 9001, ITAR | Hiawatha, IA | TurningBendingWeldingEDMGrinding | ISO 9001, ITAR |
| Masters Machine Company Milling, Turning, Swiss, Grinding, Finishing · ISO 9001, ITAR | Bristol, ME | MillingTurningSwissGrindingFinishing | ISO 9001, ITAR |
| McKenzie Machining Inc Milling, Turning, EDM, Grinding · ISO 9001, AS9100, ITAR | San Jose, CA | MillingTurningEDMGrinding | ISO 9001, AS9100, ITAR |
| Mdi Manufacturing Inc Milling, Turning, Welding, Grinding, Assembly · ISO 9001 | Lakewood, NJ | MillingTurningWeldingGrindingAssembly | ISO 9001 |
| Mennie's Machine Co Milling, Turning, Welding, Grinding · IATF 16949 | Mark, IL | MillingTurningWeldingGrinding | IATF 16949 |
| Merit Industries Milling, Turning, Laser, Waterjet, Welding, EDM, Grinding, Finishing · AS9100, ITAR, NADCAP, CMMC | Erie, PA | MillingTurningLaserWaterjetWeldingEDMGrindingFinishing | AS9100, ITAR, NADCAP, CMMC |
| Merritt Preferred Components Inc Milling, Turning, Waterjet, Grinding | Kilgore, TX | MillingTurningWaterjetGrinding | - |