Invar
Invar (Fe-Ni ~36% Ni) is a low-expansion precision alloy used for composite tooling, optical jigs and metrology frames where dimensional stability across temperature cycles is critical.
Overview
Invar (typically Fe–36Ni, Invar 36) is a controlled-expansion iron-nickel alloy with a coefficient of thermal expansion near 1.2 ppm/°C around room temperature — far below steels and aluminium. In automotive CFRP programmes, Invar tooling maintains mould cavity dimensions through autoclave or press cure cycles, reducing spring-in and tolerance stack-up on Class-A and structural composites. It is also used for optical alignment jigs for ADAS cameras/LiDAR and precision metrology frames. Alternatives include carbon-fibre tooling and other low-CTE alloys (Super Invar, Kovar for glass sealing), selected by temperature range and cost. Density (~8.1 g/cm³) and material cost mean Invar is reserved for high-value tools rather than high-volume stamped parts. This entry covers Fe-Ni precision alloy plate/bar for tooling and fixtures.
Automotive Applications
Similar Materials
Carbon Nanotubes (CNT)
Advanced Carbon Nanomaterial
Carbon nanotubes (CNTs) are cylindrical graphene nanostructures used as conductive additives and experimental structural reinforcements. This entry covers structural/functional CNT materials — not Vantablack or decorative ultra-black coatings.
PVC / SAN Foam Core
Structural Foam Core
PVC and SAN (styrene-acrylonitrile) rigid foam cores used in structural sandwich composites for automotive closures, floors and battery enclosures — a cost-effective alternative or complement to PMI cores.
Brass / Copper Alloys
Copper Alloy
Brass and copper-alloy strip and rod for busbars, terminals and connectors, distinct from pure copper.
Magnesium Alloy AZ31
Magnesium Alloy
AZ31 is a widely-used wrought magnesium alloy (approx. 3% aluminium, 1% zinc) valued in automotive engineering for its exceptional strength-to-weight ratio.
Properties
Category
Type
Fe-Ni Precision Alloy
Available Colors
Available Forms
Key Properties
- Extremely low CTE near room temperature (~1.2 ppm/°C)
- ~36% Ni iron-nickel alloy (Invar 36)
- Excellent dimensional stability for tooling
- Machinable and weldable with care
- Higher density than aluminium tooling
- Higher cost — used where CTE matching justifies it
Technical Specifications
Density
~8.1 g/cm³
Tensile Strength
~450–620 MPa depending on condition
Temperature Resistance
Useful low-CTE window roughly −100°C to ~200°C for Invar 36; higher-Ni/Co variants for other ranges
Sustainability
Sustainability Rating
Nickel content and primary melting dominate embodied impacts. Invar tooling is long-lived and fully recyclable as Fe-Ni scrap at end of tool life. Extending tool life multiplies sustainability benefit versus disposable aluminium tools.