𝐓𝐨𝐝𝐚𝐲'𝐬 𝐊𝐍𝐎𝐖𝐋𝐄𝐃𝐆𝐄 𝐒𝐡𝐚𝐫𝐞 : 𝗖𝗮𝗻 𝘆𝗼𝘂 𝘄𝗲𝗹𝗱 𝘁𝗵𝗲𝗿𝗺𝗼𝗽𝗹𝗮𝘀𝘁𝗶𝗰 𝗰𝗼𝗺𝗽𝗼𝘀𝗶𝘁𝗲𝘀 𝘁𝗼 𝗺𝗲𝘁𝗮𝗹?

𝐓𝐨𝐝𝐚𝐲'𝐬 𝐊𝐍𝐎𝐖𝐋𝐄𝐃𝐆𝐄 𝐒𝐡𝐚𝐫𝐞

𝗖𝗮𝗻 𝘆𝗼𝘂 𝘄𝗲𝗹𝗱 𝘁𝗵𝗲𝗿𝗺𝗼𝗽𝗹𝗮𝘀𝘁𝗶𝗰 𝗰𝗼𝗺𝗽𝗼𝘀𝗶𝘁𝗲𝘀 𝘁𝗼 𝗺𝗲𝘁𝗮𝗹? 𝐈𝐭 𝐬𝐨𝐮𝐧𝐝𝐬 𝐢𝐦𝐩𝐨𝐬𝐬𝐢𝐛𝐥𝐞, 𝐛𝐮𝐭 𝐢𝐭 𝐡𝐚𝐬 𝐦𝐨𝐯𝐞𝐝 𝐟𝐫𝐨𝐦 𝐥𝐚𝐛 𝐬𝐭𝐮𝐝𝐢𝐞𝐬 𝐭𝐨 𝐫𝐞𝐚𝐥 𝐩𝐫𝐨𝐝𝐮𝐜𝐭𝐬.

Thermoplastics are weldable. This is one of the core advantages of thermoplastic composites (TPCs). For most engineers, the picture is clear: CF-PEEK to CF-PEEK, CF-PPS to CF-PPS, same material, same polymer family, fusion bonding through molecular interdiffusion.

But what if the counterpart is metal?

At first glance, this sounds impossible. Metals do not melt at thermoplastic processing temperatures, and there is no chemical fusion mechanism as in polymer polymer welding.

Yet it is possible, and it has now moved from lab studies to real products.

𝗧𝗵𝗲 𝗸𝗲𝘆 𝗱𝗶𝗳𝗳𝗲𝗿𝗲𝗻𝗰𝗲: 𝘁𝗵𝗲 𝗯𝗼𝗻𝗱𝗶𝗻𝗴 𝗺𝗲𝗰𝗵𝗮𝗻𝗶𝘀𝗺

When welding TPC to metal, the joint is not based on polymer chain diffusion. Instead, it relies on:

- Local melting of the thermoplastic

- Engineered surface preparation of the metal

- Mechanical interlocking at the interface

The molten thermoplastic flows into micro and nano scale surface structures on the metal. After consolidation and cooling, the polymer is mechanically anchored into the metal surface. No adhesives. No fasteners.

𝗛𝗼𝘄 𝗶𝘀 𝘁𝗵𝗶𝘀 𝗱𝗼𝗻𝗲 𝗶𝗻 𝗽𝗿𝗮𝗰𝘁𝗶𝗰𝗲?

Technologies such as thermal direct joining or induction based joining (for example hyJOIN) combine:

- Optimized metal surface topology (structured, etched, or functionalized)

- Controlled, localized heating of the metal

- Precise melting of the thermoplastic matrix

The result is a load bearing hybrid interface formed in seconds.

𝗪𝗵𝗮𝘁 𝗮𝗯𝗼𝘂𝘁 𝘀𝘁𝗿𝗲𝗻𝗴𝘁𝗵?

Well designed TPC metal joints can reach structural shear strengths unmatched by adhesive bonding, at the same time offering key advantages:

- No cure time

- No added mass from adhesives

- High temperature resistance limited by the thermoplastic

- Recyclability and repairability

Failure often shifts away from the interface into the composite itself.

𝗜𝗻𝗱𝘂𝘀𝘁𝗿𝗶𝗮𝗹 𝗽𝗿𝗼𝗼𝗳

This approach was recently demonstrated in a thermoplastic composite bike developed by fenix composites, Alformet, and hyjoin GmbH, combining thermoplastic CFRP structures with metal elements, and it has won a JEC Innovation Award.

A clear signal that composite metal welding is no longer experimental.

𝗪𝗵𝘆 𝘁𝗵𝗶𝘀 𝗺𝗮𝘁𝘁𝗲𝗿𝘀

Thermoplastic composite metal welding unlocks new design space:

- Metal flanges welded directly to composite pressure vessels

- Hybrid tubes, casings, and housings

- Load efficient transition zones without bolts or adhesives

- Faster, more automated assembly concepts

Thermoplastic composites are not only lightweight and tough. They are weldable, sometimes in ways we did not think possible just a few years ago.

source : Fedor Antonov