Materials

Together at last – device quickly bonds metal to plastic

Together at last – device quic...
A rendering of the HPCI gun
A rendering of the HPCI gun
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A rendering of the HPCI gun
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A rendering of the HPCI gun

Ordinarily, if you want to join metal and plastic items together, you have to use either adhesives or rivets. Engineers at Germany's Fraunhofer Institute for Material and Beam Technology, however, have developed a bonding "gun" that they claim makes for a much faster and cheaper joining process.

One of the problems with adhesives is the fact that the joined items have to be left alone while the adhesive sets, delaying further steps in the production process. Riveting, on the other hand, can damage plastic objects. Additionally, using either approach, manufacturers have to continually pay for more adhesives or rivets.

The Fraunhofer device gets around these problems, utilizing what is known as the HeatPressCool-Integrative (HPCI) process.

It starts by pinching metal and thermoplastic items together, at the spot where they need to be bonded. Targeted inductive heat is then applied to the metal, causing the plastic that it's in contact with to partially melt. This allows a surface layer of the plastic to penetrate into an array of tiny anchoring structures that were previously laser-etched into the surface of the metal at that spot.

Once the plastic cools and contracts, it forms a secure fit with those structures, thus bonding the two objects together. The whole process takes only a few seconds.

Fraunhofer states that the HPCI gun could be integrated into existing production lines, perhaps being mounted on robotic arms in place of spot-welding guns. Possible applications include the assembly of automobile bodies, or the bonding of stainless steel panels to dishwashers or refrigerators.

The device (incorporated into a larger assembly platform) can be seen in use, in the video below.

Source: Fraunhofer

Direct joining of metal to thermoplastic composites by point-shaped induction heating

5 comments
paul314
Not so much the gun as the previously-machined locking bits on the metal. Still pretty cool if it could ever be generalized. I wonder if you could make a lockable surface on an extrusion.
seewind
hand-held for DIY and prototyping?
Bob Stuart
Heating the metal works, too. Ultrasonics would waste the least heat, just doing the interface.
bullrun
This is not new. Plastic Flowing into metal parts making a bond has been used for decades. This process may be relatively new but the concept not.
amazed W1
Tue bullrun, but concepts are easy-come, easy go. The realisation of the concept relies on science that may not have been studied, technologies that may not yet exist and are unrelated to the concept, and then on the engineering use of the technologies to produce something. Moon travel was conceptualised at least 100 years before it happened and it took two world wars with their frantic research and technology development to allow rockets to be built and capsule design to advance sufficiently for it to happen.