Page 62 - Australian Paint & Panel March-April 2020

Bonding
62
PAINT&PANEL MARCH / APRIL 2020
JOINT STRENGTH FROM 3M
ADDING ADHESIVES TO AN EXISTING
joint design can dramatically increase strength, without adding much weight, cost, or cycle time, and has other added benefits.
Hence the development of 'hybrid- joining', in this context it is the process of using an adhesive in conjunction with spot attachments (such as rivets, screws or spot welds) to create a stronger, more efficient structural connection.
The addition of significant amounts of adhesives have had other benefits to vehicle design, resulting in overall stiff- er body structures and providing im- proved ride dynamics making the vehi- cle more responsive. It also offers a reduction in noise, vibration and harsh- ness and allows better crash energy management.
Adhesives provide 'built-in' intra-pan- el sealing with fewer water, dust and air leaks.The use of adhesive also offers bet- ter corrosion protection and improved vehicle longevity.
3M has developed a structural repair adhesive specifically for the collision re- pair industry. 3M Impact Resistant Struc- tural Adhesive PN 07333. It features a bal- anced adhesive performance profile which provides outstanding shear, peel and impact strengths and allows OEM’s to write more structural joint repair pro- cedures, allowing for a less-intrusive re- pair that closer matches the original de- sign intent for the joint and allows repairers to have a choice in 'body in white” structural repair adhesives.
3M's PN 07333 cures at room temper- ature and does not require heating the
bond to achieve the quoted per- formance values. It’s not neces- sary for repairers to take up floor or booth time to heat a joint, although the adhesive can be heated to accelerate the final cure. The adhesives col- our changing chemistry from silver to purple gives the tech- nician feedback that the adhe- sive was mixed and dispensed properly, and that the product has started curing.
3M PN 07333 employs a cor- rosion inhibiting formula to provide corrosion protection to bare metals in the joint. This allows repairers to simply re- move all coatings down to bare metal as a surface preparation step. No complicated primers or wipes. It will bond to prop- erly prepared steel, alumini- um, magnesium, and compos- ites in all combinations with the added benefit of preventing galvanic corrosion in multi-ma- terial joints. The inclusion of glass spacer beads, pre-mixed with the adhesive, maintains the optimum minimum bond- line thickness which allows parts to more easily slide across
each other during positioning and re- pairers to securely clamp or fasten parts together without the concern of 'starving' the bondline and reducing bond performance.
Combining welds or rivets with 3M's PN 07333 allows repairers to restore complex connections between mixed and/or sensitive materials in a manner that preserves strength and durability.
While the terms “hybrid joining, rivet bonding and weld sealing sound compli- cated, the process is straightforward and approachable.
Most automotive OEM are using body structure adhesives in manufacturing and some OEM’s are writing repair pro- cedures that call for 3M PN 07333 in- cluding; General Motors, Tesla, Jaguar Land Rover, Honda and Hyundai.