| Infiniti Manufacture Milling, Welding, Finishing | Corona, CA | MillingWeldingFinishing | - |
| Inland Marine Industries Inc Milling, Turning, Waterjet, Punching, Bending, Welding, Grinding, Finishing · ISO 9001, ITAR | Hayward, CA | MillingTurningWaterjetPunchingBendingWeldingGrindingFinishing | ISO 9001, ITAR |
| Innovated Metal Fabrication, Inc Turning, Bending, Laser, Welding | Maplewood, MN | TurningBendingLaserWelding | - |
| Innovation Alley Milling, Turning, Bending, Welding | Fresno, CA | MillingTurningBendingWelding | - |
| InSight Manufacturing Milling, Turning, Welding, Forging, Assembly | Murphys, CA | MillingTurningWeldingForgingAssembly | - |
| Integra Cast Milling, Turning, Welding, Casting, Finishing, Assembly · ISO 9001, NADCAP | New Britain, CT | MillingTurningWeldingCastingFinishingAssembly | ISO 9001, NADCAP |
| Integrated Machining Co Milling, Turning, Welding, EDM, Grinding · ISO 9001, ITAR | Albuquerque, NM | MillingTurningWeldingEDMGrinding | ISO 9001, ITAR |
| Interactive Manufacturing, Inc Milling, Turning, Waterjet, Welding, Finishing, Assembly | Central Point, OR | MillingTurningWaterjetWeldingFinishingAssembly | - |
| Interior Metals Laser, Punching, Bending, Welding, Finishing | Staten Island, NY | LaserPunchingBendingWeldingFinishing | - |
| International Precision Manufacturing LLC Milling, Turning, Welding, EDM, Assembly · ISO 9001, AS9100, ISO 13485 | Houston, TX | MillingTurningWeldingEDMAssembly | ISO 9001, AS9100, ISO 13485 |
| Interstate Manufacturing Company, Inc Milling, Welding · ITAR | Agawam, MA | MillingWelding | ITAR |
| IntoMetal Bending, Laser, Welding, Metal AM | Lincoln, NE | BendingLaserWeldingMetal AM | - |
| Iowa Metal Spinners Milling, Turning, Laser, Welding, Stamping · ISO 9001 | Cedar Falls, IA | MillingTurningLaserWeldingStamping | ISO 9001 |
| IPMI Manufacturing & Engineering Milling, Turning, Welding | Buckner, MO | MillingTurningWelding | - |
| IronStrong Metal Fabrication LLC Milling, Bending, Laser, Welding | Lancaster, PA | MillingBendingLaserWelding | - |
| Irwin Automation Inc Milling, Turning, Welding, EDM, Grinding | Greensburg, PA | MillingTurningWeldingEDMGrinding | - |
| ISCO Manufacturing Solutions Milling, Turning, Waterjet, Bending, Welding, Grinding · ISO 9001, AS9100 | Bend, OR | MillingTurningWaterjetBendingWeldingGrinding | ISO 9001, AS9100 |
| Ital-Tech Machined Products, LLC Milling, Turning, Welding, Grinding · ISO 9001, ITAR | Groveland, MA | MillingTurningWeldingGrinding | ISO 9001, ITAR |
| J & L Precision Manufacturing LLC Bending, Welding, Stamping, Finishing, Assembly · ISO 9001 | Brooklyn Heights, OH | BendingWeldingStampingFinishingAssembly | ISO 9001 |
| J & N Metal Products, LLC Milling, Laser, Bending, Welding, EDM · ISO 9001 | Brazil, IN | MillingLaserBendingWeldingEDM | ISO 9001 |
| J B Tool Die & Engineering Co Inc Milling, Turning, Welding, Stamping, EDM, Grinding · ISO 9001 | Fort Wayne, IN | MillingTurningWeldingStampingEDMGrinding | ISO 9001 |
| J E Fifer Sheet Metal Fabricators Inc Bending, Laser, Welding | Richmond, VA | BendingLaserWelding | - |
| J.B. Anderson & Son, Inc Milling, Turning, Welding, Assembly | Irwin, PA | MillingTurningWeldingAssembly | - |
| J.i.t. Manufacturing, Inc Milling, Laser, Punching, Bending, Welding, Finishing, Assembly | Cowpens, SC | MillingLaserPunchingBendingWeldingFinishingAssembly | - |
| J&M Machining Milling, Turning, Welding, Casting, Finishing · ISO 9001 | Norton Shores, MI | MillingTurningWeldingCastingFinishing | ISO 9001 |
| Jacksonville Machine, Inc Milling, Turning, Welding, Grinding · ISO 9001 | Jacksonville, IL | MillingTurningWeldingGrinding | ISO 9001 |
| Jaffa Precision Engineering Inc Milling, Turning, Swiss, Welding, Grinding, Finishing · ISO 9001 | Riverside, CA | MillingTurningSwissWeldingGrindingFinishing | ISO 9001 |
| Jars Inc Milling, Waterjet, Bending, Welding, EDM, Grinding, Finishing | San Fernando, CA | MillingWaterjetBendingWeldingEDMGrindingFinishing | - |
| Jax Fab Shop LLC Welding | Jacksonville, FL | Welding | - |
| JBC Machine Inc Milling, Turning, Welding, Finishing | Hortonville, WI | MillingTurningWeldingFinishing | - |
| JC Custom Machining & Design Inc Milling, Turning, Welding, Grinding | Hillsboro, OR | MillingTurningWeldingGrinding | - |
| JC Machine, Inc Milling, Turning, Swiss, Laser, Bending, Welding | Lakeland, FL | MillingTurningSwissLaserBendingWelding | - |
| JD Machine Milling, Turning, Bending, Welding, EDM · ISO 9001, AS9100, ITAR, CMMC | Ogden, UT | MillingTurningBendingWeldingEDM | ISO 9001, AS9100, ITAR, CMMC |
| JDM Machining Inc Milling, Turning, Swiss, Bending, Welding, EDM, Grinding · ISO 9001, AS9100 | Staples, MN | MillingTurningSwissBendingWeldingEDMGrinding | ISO 9001, AS9100 |
| Jeglinski Group Inc Milling, Turning, Welding, EDM, Grinding, Assembly · ISO 9001 | Meadville, PA | MillingTurningWeldingEDMGrindingAssembly | ISO 9001 |
| Jep Manufacturing LLC Milling, Turning, Welding · ISO 9001 | Rosenberg, TX | MillingTurningWelding | ISO 9001 |
| Jergens Inc Milling, Welding · ISO 9001, AS9100 | Cleveland, OH | MillingWelding | ISO 9001, AS9100 |
| Jerl Machine Inc Milling, Turning, Welding, Casting, EDM, Grinding, Assembly · ISO 9001 | Perrysburg, OH | MillingTurningWeldingCastingEDMGrindingAssembly | ISO 9001 |
| Jet Machine & Mfg Milling, Welding | Hamilton, OH | MillingWelding | - |
| Jet Speed Metals Bending, Welding | Westbrook, ME | BendingWelding | - |
| Jetfab LLC Milling, Turning, Laser, Waterjet, Punching, Bending, Welding | Lowell, MA | MillingTurningLaserWaterjetPunchingBendingWelding | - |
| Jewett Machine Milling, Turning, Welding · ISO 9001 | Richmond, VA | MillingTurningWelding | ISO 9001 |
| JK Pulley Co Inc Milling, Turning, Welding | Saint Louis, MO | MillingTurningWelding | - |
| JMC Acquisition LLC Milling, Turning, Swiss, Welding · ISO 9001, AS9100, ISO 13485 | Sanford, NC | MillingTurningSwissWelding | ISO 9001, AS9100, ISO 13485 |
| 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 |
| John W. McDougall Co. Bending, Laser, Welding · ISO 9001 | Nashville, TN | BendingLaserWelding | ISO 9001 |
| Joined Alloys Welding, EDM, Assembly · ISO 9001, NADCAP | Phoenix, AZ | WeldingEDMAssembly | ISO 9001, NADCAP |
| Jones & Lockhart Fabrication LLC Bending, Welding | St. Louis, MO | BendingWelding | - |
| Jones Co Machining Milling, Turning, Welding, Assembly | Hannibal, MO | MillingTurningWeldingAssembly | - |