| HP Machine & Engineering Inc Milling, Turning, EDM | San Jose, CA | MillingTurningEDM | - |
| HPR Machine Milling, Turning | Vista, CA | MillingTurning | - |
| HR Machine Turning, Waterjet, EDM | Dayton, OH | TurningWaterjetEDM | - |
| Hub Pattern Corp Milling, Turning, Waterjet, EDM, Grinding, Assembly | Roanoke, VA | MillingTurningWaterjetEDMGrindingAssembly | - |
| Huffman Welding & Machine Inc Milling, Turning, Laser, Waterjet, Bending, Welding, EDM, Grinding, Finishing, Assembly · ISO 9001 | Fort Madison, IA | MillingTurningLaserWaterjetBendingWeldingEDMGrindingFinishingAssembly | ISO 9001 |
| Hughes Machine Shop, Inc Milling, Turning, Waterjet, Welding · ISO 9001 | Bogalusa, LA | MillingTurningWaterjetWelding | ISO 9001 |
| Hunt Design & Manufacturing Inc Milling, Turning, Swiss, EDM, Grinding · AS9100 | Arab, AL | MillingTurningSwissEDMGrinding | AS9100 |
| Hunt Enterprises Milling, Turning, Welding | Santa Ana, CA | MillingTurningWelding | - |
| Hy-Speed Machining, Inc Milling, Turning, EDM | Grants Pass, OR | MillingTurningEDM | - |
| I Auman Machine Co Inc Milling, Turning, Welding | Lebanon, PA | MillingTurningWelding | - |
| I.p. Automation, Inc Milling, Turning, Laser, Waterjet, Bending, Welding, Grinding · ISO 9001 | Colorado Springs, CO | MillingTurningLaserWaterjetBendingWeldingGrinding | ISO 9001 |
| Ibs Machine & Manufacturing LLC Milling, Turning | Ocala, FL | MillingTurning | - |
| Icc Machining, LLC Milling, Turning, Welding, EDM, Grinding, Assembly · ISO 9001 | Alvin, TX | MillingTurningWeldingEDMGrindingAssembly | ISO 9001 |
| Icon Machine Co Milling, Turning, Casting · ISO 9001, AS9100 | Irving, TX | MillingTurningCasting | ISO 9001, AS9100 |
| Img Companies LLC Milling, Turning, Welding, Finishing · ISO 9001, AS9100 | Livermore, CA | MillingTurningWeldingFinishing | ISO 9001, AS9100 |
| Impact Machine LLC Milling, Turning · ISO 9001 | Kaukauna, WI | MillingTurning | ISO 9001 |
| Imr Inc Turning | Prentice, WI | Turning | - |
| Independent Machine Company Milling, Turning, Laser, Welding, Grinding | Escanaba, MI | MillingTurningLaserWeldingGrinding | - |
| Indus Precision Mfg., Inc Milling, Turning, Waterjet, Bending, Welding, Grinding, Finishing, Assembly · ISO 9001, AS9100, ITAR, CMMC | Congers, NY | MillingTurningWaterjetBendingWeldingGrindingFinishingAssembly | ISO 9001, AS9100, ITAR, CMMC |
| Industrial Fabricators Milling, Turning, Bending, Welding, Waterjet | Corpus Christi, TX | MillingTurningBendingWeldingWaterjet | - |
| Industrial Manufacturing Specialties, Inc Milling, Turning, Welding, EDM, Grinding · ISO 9001, AS9100 | Decatur, AL | MillingTurningWeldingEDMGrinding | ISO 9001, AS9100 |
| Industrial Motions Engineering, Inc Milling, Turning, Welding, Grinding, Finishing, Assembly | Wilmington, MA | MillingTurningWeldingGrindingFinishingAssembly | - |
| Industrial Screen & Maintenance, Inc Milling, Turning, Welding, Casting, Grinding · ISO 9001 | Casper, WY | MillingTurningWeldingCastingGrinding | ISO 9001 |
| Infinisys Manufacturing LLC Milling, Turning, EDM | Phoenix, AZ | MillingTurningEDM | - |
| Infinity EDM, LLC Milling, Turning, EDM, Grinding · ISO 9001 | Jackson, WI | MillingTurningEDMGrinding | ISO 9001 |
| Infinity Precision Inc Milling, Turning, Waterjet, Bending, Grinding · ISO 9001, AS9100 | Simi Valley, CA | MillingTurningWaterjetBendingGrinding | ISO 9001, AS9100 |
| Infinity Precision Machining LLC Milling, Turning | Buffalo, NY | MillingTurning | - |
| Infocus CNC Machining, Inc Milling, Turning, Swiss · ISO 9001, AS9100 | Fountain Valley, CA | MillingTurningSwiss | ISO 9001, AS9100 |
| Inland Marine Industries Inc Milling, Turning, Waterjet, Punching, Bending, Welding, Grinding, Finishing · ISO 9001, ITAR | Hayward, CA | MillingTurningWaterjetPunchingBendingWeldingGrindingFinishing | ISO 9001, ITAR |
| Inno Tech Manufacturing Inc Milling, Turning, Laser · AS9100 | San Diego, CA | MillingTurningLaser | AS9100 |
| Innov8 Manufacturing LLC Milling, Turning, Welding, Grinding · ISO 9001 | Farmington, MI | MillingTurningWeldingGrinding | ISO 9001 |
| 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 | - |
| Insource Design & Manufacturing Technologies, LLC Milling, Turning, Assembly · ISO 9001, ITAR | Manchester, NH | MillingTurningAssembly | ISO 9001, ITAR |
| Inspirnetics, Inc Milling, Turning | Rancho Cucamonga, CA | MillingTurning | - |
| Integrated Components Inc Milling, Turning | Wichita, KS | MillingTurning | - |
| Inter-Precision Mold Inc Milling, Turning, Welding, EDM, Grinding, Assembly | El Paso, TX | MillingTurningWeldingEDMGrindingAssembly | - |
| Interactive Manufacturing, Inc Milling, Turning, Waterjet, Welding, Finishing, Assembly | Central Point, OR | MillingTurningWaterjetWeldingFinishingAssembly | - |
| International Precision Machining, Inc Milling, Turning, Grinding · ISO 9001, AS9100 | Waite Park, MN | MillingTurningGrinding | ISO 9001, AS9100 |
| International Precision Manufacturing LLC Milling, Turning, Welding, EDM, Assembly · ISO 9001, AS9100, ISO 13485 | Houston, TX | MillingTurningWeldingEDMAssembly | ISO 9001, AS9100, ISO 13485 |
| Intrepid Machine, Inc Milling, Turning · ISO 9001, AS9100 | Brooksville, FL | MillingTurning | ISO 9001, AS9100 |
| Inventery Precision Milling, Turning, Swiss, Finishing, Assembly · ISO 9001, AS9100, ITAR, CMMC | Pasadena, CA | MillingTurningSwissFinishingAssembly | ISO 9001, AS9100, ITAR, CMMC |
| 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 | - |
| Iridium Manufacturing Milling, Turning, Waterjet, EDM, Grinding · ISO 9001 | Washington, MI | MillingTurningWaterjetEDMGrinding | ISO 9001 |
| Irwin Automation Inc Milling, Turning, Welding, EDM, Grinding | Greensburg, PA | MillingTurningWeldingEDMGrinding | - |
| Ital-Tech Machined Products, LLC Milling, Turning, Welding, Grinding · ISO 9001, ITAR | Groveland, MA | MillingTurningWeldingGrinding | ISO 9001, ITAR |
| J & R Machine Works Milling, Turning · ISO 9001, AS9100 | Lancaster, CA | MillingTurning | ISO 9001, AS9100 |
| J and J Custom Machining L.L.C Milling, Turning · ISO 9001 | Camarillo, CA | MillingTurning | ISO 9001 |