Steel Interlock – The Steel Puzzle

On the occasion of SAMUEXPO 2026, Bonomi Acciai presents Steel Interlock, a project created to concretely showcase the world of plastic mould steels and the main steel grades used in industrial applications. Through a mechanical art installation composed of different steels – including 2083 steel, 2343 steel and solutions for die casting steels such as 1.2344 – Steel Interlock highlights key properties such as polishability, photo-etching capability and corrosion resistance, which are essential factors in the selection of steel for plastic injection moulds.

Steel Interlock is a work of mechanical art designed to tell the story of plastic mould steels through the material itself.
A puzzle composed of six pieces made from six different steels, enclosed and held together by a frame made of a seventh steel.

Each piece retains its own metallurgical identity, but finds its meaning only within a shared structure:
a system made of different materials, different requirements and different applications, all working together.

The puzzle pieces are mirror polished.
Not as a purely aesthetic exercise, but to clearly demonstrate the properties required of plastic mould steels:

• polishability
• surface quality
• suitability for photo-etching

All of these characteristics are fundamental in the design of plastic moulds, where the appearance of the moulded part is often just as important as its function.

The surface finishing process was carried out in collaboration with K-One Srl – Masters in Finishing, a leading company in the field of mould polishing and finishing.
Thanks to their experience and expertise, it was possible to fully enhance the potential of each steel, achieving extremely high surface finish levels consistent with real plastic mould applications.

The installation brings together seven plastic mould steels, selected to represent different combinations of wear resistance, polishability, photo-etching capability, corrosion resistance and machinability.

1. Formadur® 320
   Supplied at a hardness of approximately 320 HB, designed to ensure high wear resistance and long-term reliability. Suitable for injection moulds requiring robustness and production continuity.

2. Formadur® PH42 Superclean
   Remelted steel for plastic moulds, precipitation hardenable, supplied at approximately 38–40 HRC. It stands out for its excellent polishability and high photo-etching capability, making it ideal for moulds with high aesthetic requirements.

3. Formadur® 2316 Superclean
   Remelted stainless steel, supplied quenched and tempered at approximately 300 HB. It offers a balanced combination of corrosion resistance, machinability and surface quality, suitable for moulds used with sensitive plastic materials.

4. Formadur® PHX Superclean
   Remelted steel with high corrosion resistance, supplied at approximately 40 HRC, with simplified weldability. Designed for complex moulds requiring high performance and ease of maintenance.

5. Thermodur® 2343 Superclean (2343)
   Remelted Cr–Mo–V alloy steel, characterised by an extremely fine structure and excellent polishability. Supplied in the annealed condition, it is ideal for moulds requiring precision and stability.

6. Formadur® 2083 Superclean (2083)
   Remelted stainless steel, corrosion resistant and offering good polishability. Supplied in the annealed condition, it is a proven solution for moulds used with corrosive or filled plastic materials.

7. Corroplast® (Frame)
   The frame of the installation is made of Corroplast®, a plastic mould steel resistant to corrosion, exceptionally machinable and supplied at approximately 320 HB.
   It was not originally designed to be polished, which is precisely why it represents the core of the project: demonstrating that even steels not intended for this purpose, when of high quality, can achieve excellent surface finishes.
   The reduced carbon content also ensures good weldability, making it ideal as the structural element of the puzzle.

Steel Interlock – The Steel Puzzle is not an isolated exercise.

This installation will accompany Bonomi Acciai at the main industry trade fairs – SAMUEXPO, Fornitore Offresi, MECSPE 2026, Fastener Fair – becoming each time a starting point to discuss:

• plastic mould steel selection
• polishability and photo-etching
• corrosion resistance and stainless properties
• material behaviour depending on the processed plastics

A concrete way to show how technical consultancy and material knowledge, combined with collaboration with specialised finishing partners such as K-One Srl, are central to the design of high-performance, long-lasting moulds.