Bimetal Strip: Component Specs, Materials & Applications

Component Specifications

Definition

A precision-engineered component consisting of two bonded metal strips with different coefficients of thermal expansion, designed to bend predictably when heated by electrical current, thereby actuating the trip mechanism in circuit breakers to interrupt power during overload conditions.

Working Principle

Operates on differential thermal expansion: when current flows through or near the strip, resistive heating causes the metals to expand at different rates, creating mechanical deflection that triggers the trip mechanism at a calibrated temperature threshold.

Materials

Typically composed of high-conductivity copper or nickel-iron alloy bonded to low-expansion invar or manganese-nickel alloy, with specific thickness ratios (e.g., 1:1 to 3:1) and bonding via rolling, welding, or cladding.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Response Time	2-30 seconds depending on overload
Deflection Angle	15-45 degrees at trip point
Electrical Resistance	0.1-10 mΩ depending on design
Trip Current Accuracy	±10% of rated current
Operating Temperature Range	-40°C to 150°C

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

IEC 60947-2, UL 489, ISO 8820-2

Parent Products

This component is used in the following industrial products

Trip Mechanism (Circuit Breaker)

The internal mechanism within a circuit breaker that detects abnormal electrical conditions and triggers the opening of contacts to interrupt current flow.

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Engineering Analysis

Risks & Mitigation

Fatigue failure from repeated cycling
Calibration drift due to material aging
Contamination affecting thermal response

FMEA Triads

Trigger: Material fatigue from thermal cycling
Failure: Reduced deflection sensitivity leading to missed trips
Mitigation: Use fatigue-resistant alloys and design for minimum stress concentrations

Trigger: Corrosion at bonding interface
Failure: Delamination and loss of thermal response
Mitigation: Apply protective coatings and ensure clean bonding surfaces

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

Trip current tolerance ±10%, deflection repeatability ±5%

Test Method

Thermal cycling test per IEC 60947-2, current injection testing with infrared thermography

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

Check the legal entity, factory address, ownership, certifications, and direct contacts.

CNFX does not score or rank suppliers. Buyers must verify all claims and documents with the legal manufacturer before ordering.

Manufacturers of Bimetal Strip

Manufacturer profiles associated with Bimetal Strip.

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Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review

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Frequently Asked Questions

How does a bimetal strip protect against electrical overload?

It bends when heated by excessive current, mechanically triggering the circuit breaker to open and interrupt the circuit.

Can bimetal strips be calibrated for different trip currents?

Yes, through material selection, thickness ratios, and mechanical pre-tensioning during manufacturing.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Bimetal Strip