Compound Bar Bonded Bimetallic Strips with Handle

Description

The Compound Bar Bonded Bimetallic Strips with Handle, 100 mm & 150 mm, also known as bimetallic strips, compound metal bars or thermal expansion demonstration bars, are designed for investigating the different expansion rates of metals during heating and cooling experiments. Manufactured by IEC (Industrial Equipment & Control Pty Ltd), these educational physics instruments consist of two different metals permanently bonded together. Each metal has a different coefficient of linear thermal expansion, causing the compound strip to bend when its temperature changes. The range includes 100 × 12.5 mm and 150 × 12.5 mm variations, allowing teachers to choose between shorter and longer active bimetallic strips. Both models feature a stainless steel handle attached to the bonded metal section.

The two metal layers have contrasting copper-coloured and silver-coloured surfaces, making their different appearances visible to students. This helps illustrate that the compound bar contains two materials with different thermal expansion characteristics. Unlike traditional compound bars assembled using rivets, the modern IEC design uses permanently bonded metal layers. This construction allows the materials to respond together while developing unequal thermal expansion forces. When heated, each metal attempts to expand according to its individual thermal expansion coefficient. Because the layers remain bonded, the difference in expansion causes the strip to curve rather than allowing each metal to extend independently. The metal with the higher thermal expansion coefficient forms the outside of the bend, while the metal with the lower coefficient forms the inside. Students can observe this behaviour and relate it to the properties of the two materials.

The 100 mm variation features a shorter active strip measuring 100 × 12.5 mm and has a manufacturer-listed weight of approximately 34 g. It provides a compact option for classroom thermal expansion demonstrations. The 150 mm variation features a longer active strip measuring 150 × 12.5 mm and weighs approximately 40 g. Its extended length provides an alternative for experiments requiring a larger demonstration strip. Both variations feature a welded stainless steel handle, allowing the apparatus to be positioned during heating. Stainless steel conducts heat, so the handle should not be assumed to remain cool throughout an experiment. As the compound bar cools, it generally returns towards its original shape, provided the metal layers have not experienced permanent deformation or excessive heating.

The apparatus demonstrates the operating principle of bimetallic thermostats and temperature-sensitive switches, which use differences in metal expansion to produce mechanical movement in response to temperature changes. These compound bars are suitable for secondary school physics, university teaching laboratories and practical heat experiments, helping students connect theoretical concepts of thermal expansion with observable material behaviour.

Safety Precautions: Use appropriate supervision and a controlled heat source. Avoid overheating the strip, keep combustible materials away and never touch the metal or handle until completely cooled. Wear suitable eye protection and use heat-resistant holding equipment where necessary. Each selected variation is supplied as one IEC Bonded Compound Bar with a Stainless Steel Handle. Heating equipment and additional laboratory accessories are not included unless specified separately.

LabChoice Australia supplies bimetallic strips, compound bars and educational thermal physics equipment for schools, universities and science teaching laboratories across Australia.