Product Overview

MI Cable Thermocouples for Rugged Probe Assemblies

MI cable thermocouples, also referred to as mineral-insulated metal-sheathed or MIMS assemblies, use compacted MgO insulation inside a continuous metal sheath. The result is a bendable, durable thermocouple construction for high-temperature service, tight routing, vibration, and custom probe geometry.

MI Cable and MGO Probe Construction

For direct-insertion probes, MGO-style assemblies, compact sheath builds, threaded fittings, connector terminations, and OEM replacement work, the specification starts with the MI cable: sheath alloy, outside diameter, junction style, insertion length, bend profile, lead transition, and termination.

Thermometrics can build MI cable thermocouple assemblies around customer drawings, installed hardware, or sample parts when the probe needs to match an existing bore, fitting, connector, or mounting envelope.

Mineral-insulated metal-sheathed thermocouple probe with realistic cutaway showing sheath, MgO insulation, and conductors

Mineral-Insulated Sheath Construction

Use this construction when the application needs a rugged sheath, electrical isolation, bendability, and stable sensing performance in high-temperature or tight-routing service.

In-House MI Cable Manufacturing Capabilities

Cut-to-Length & Straightening

Cable is cut to the customer-specified length with a precision abrasive cutoff. Straightening is performed on a roller-leveler for assemblies that require tight positional tolerances in fixtures or test hardware.

Tip Formation & Junction Welding

Tip swaged to close-ended or open-ended profile. Hot junction formed by TIG or resistance welding of thermocouple conductors. Grounded junctions welded to the inner sheath wall. Ungrounded junctions left insulated within MgO.

Bending & Forming

Assemblies can be formed to customer print geometry using controlled hand-forming over mandrels. Annealing may be performed after tight-radius bends to relieve residual stress and restore ductility.

Termination & Head Attachment

Cold end stripped, conductors identified, and terminated per customer requirement: flying leads, miniature connectors, standard connectors, or transition to extension wire in a connection head.

Final Inspection & Calibration

100% dimensional inspection, insulation resistance test, continuity check, and EMF verification. Calibration certificates issued per customer requirement. Full AS9100D first-article documentation available.

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