Stronger bonding thanks to plasma

Surface treatment is indispensable for the secure bonding of plastic parts. Activation with cold atmospheric pressure plasma is an equally simple yet elegant solution. Relyon Plasma, a subsidiary of TDK Electronics, offers the piezobrush^® PZ2 – a handy plasma source based on the TDK CeraPlas™ piezo plasma generator.

3D printing has now become established as a manufacturing technology in both industry and the private sector. Due to the increased importance of this additive manufacturing process, the demands on quality, diversity of materials and robustness of the products are growing accordingly. 

Relyon Plasma has been researching surface activation with cold plasma for various applications including 3D printing for years. In turn, Creabis – a 3D printing service provider – manufactures large and complex parts with dimensions of more than 600 mm. To make use of 3D printing for these larger formats, they are printed as individual parts and then glued together. In practice, predefining joint geometries with maximum bonding areas and the gluing itself pose challenges that should not be underestimated. In particular, the strength of the bond is especially critical for long narrow parts where the available bonding surface is minimal. The strength of the bond can be optimized through surface activation by cold plasma before the adhesive is applied. 

This surface activation using plasma treatment is based on two main effects: Fine cleaning of the surface from organic contaminants and increasing surface energy for improved wettability by adhesives. 

The piezobrush PZ2 – an efficient and compact handheld plasma device from Relyon Plasma that requires no special technical knowledge or complex infrastructures – is excellently suited for preparing 3D printing parts for bonding. The core of this handheld plasma device is the CeraPlas piezo plasma generator – a high-voltage discharge device for generating cold atmospheric pressure plasma.

Figure 1:

The handy piezobrush PZ2 from Relyon Plasma for activating plastic surfaces.

Figure 2:

The TDK CeraPlas is the key component of the piezobrush PZ2 and is used to generate cold atmospheric pressure plasma. 

Improved bonding through plasma activation of individual parts

Two applications at Creabis highlight the potential of using the piezobrush PZ2 in processing 3D printed parts. The interior door trim of an innovative small electric series vehicle is printed by Creabis in four individual parts from unfilled PA12 by selective laser sintering (SLS). These parts are then activated with cold plasma and spotted with cyanoacrylate (superglue). About an hour later as a final step, while the parts are still activated, they are structurally bonded with a two-component adhesive.

Figure 3:

From left to right: The four individual parts of the door trim produced in 3D printing; surface activation with the piezobrush PZ2; finished glued trim.

Ralf Deuke, owner of Creabis, sees the use of plasma technology as extremely advantageous: "Using the piezobrush PZ2 now opens up possibilities for bonding individual parts that were previously unthinkable." This is particularly the case with the second application example, in which motorcycle fairing for racing is made from 12 individual parts using 3D printing and then glued (after pre-treatment with the piezobrush PZ2). Due to the adhesive strength achieved, the fairing on the motorcycle can even withstand speeds of over 200 km/h. Internal tests reveal that the components treated with plasma technology have an adhesive bond that is three times stronger than that of untreated parts.

Figure 4:

This motorcycle trim consists of 12 individual parts manufactured in 3D print. Thanks to the activation of the bonding surfaces with the piezobrush PZ2, the bond is three times stronger than without surface activation.

Both Relyon Plasma and Creabis are convinced that there are many more applications for plasma technology in 3D printing and will continue to intensify their cooperation in the future.

Technical data of piezobrush PZ2