Manufacturing News

Turning to structural adhesives

As industry continues to battle the effects of economic uncertainty, manufacturers are now looking for cost-effective, safe and sustainable adhesive solutions for a range of applications. Peri Muddle writes.

GROWING economic pressure is forc­ing manufacturers to rethink their bonding strategies as they face the challenge of utilising sustainable and efficient products that offer significant value for the long-term.

As a result, more and more manufacturers are turning to structural acrylic adhesives to replace or augment rivets, bolts, welding and other traditional fastening methods in their assembly processes, primarily because of the savings benefits.

Structural acrylic adhesives are two-part systems that fill large gaps, seal joints, join dissimilar materials and provide a neat appearance. These materials deliver thermal and chemical resistance, and distribute stresses evenly across the entire bond joint, making it stronger.

They also come in the form of high-performance formulations to bond specific substrates such as aluminium, stainless steel, carbon steel or galvanized materials, and boast advanced toughening agents to improve impact and peel resistance.

Henkel’s Engineering Adhesives Marketing Manger, Charles Vint explains that not only do structural adhesives improve product performance and aesthetics, but they also reduce overall assembly time and lower production costs.

“There’s still an argument for traditional metal assembly. But increasingly we’re seeing customers use structural adhesives across a number of applications because they realise Henkel’s new adhesive technology provides long-term durability on galvanized substrates.

Structural adhesives are a sustainable alternative for bonding metal-to-metal, metal-to-plastic and metal-to-composites.”

“They also present additional safety benefits, especially in underground applications, where traditional mechanical fastening methods like welding can be highly dangerous,” Vint said.

Henkel has long pioneered advances in structural adhesive technology, yet it is now more than ever that the real value of innovation – and the potential for cost-savings – has become crucial for forward-thinking manufacturers.

Cost has always been a major limitation of traditional metal assembly methods, particularly in the areas of thermal joining and mechanical fastening.

Thermal joining, which welds, brazes or solders two homogenous materials with similar melting points together, is an expensive process that requires specialised labour.

Mechanical fastening, which secures dissimilar substrates with bolts, screws or rivets, is also labour intensive, requiring the drilling of holes and inserting of fasteners. Both techniques concentrate stress at a single point which can cause premature joint failure and reduce flex or vibration stress resistance.

Vint explains that the use of structural adhesives can reduce overall fixture handling time, therefore generating cost savings for customers. For example, Henkel application engineers recently worked with a leading manufacturer of specialised custom truck bodies, reviewing existing procedures to cut costs and lower production and handling time.

“Our customer was experiencing issues with the bonding of mild sheet metal panels to the aluminium framework on the truck bodies, which was causing bulging of the sheet metals. In turn this made it difficult to seal and paint along the panel edges due to flexing at the bonding points.”

“We recommended Loctite Structural Adhesive H8600 because it reduces bead size and produces a rigid bond line and smooth finish. We ended up saving our customer over 22 hours in fixture time, as compared with their previous bonding process,” Vint said.

Vint expects that welds and rivets will be used less and less in manufacturing processes and instead be replaced by stronger, more efficient technologies such as structural adhesives.

“We’ve been seeing customers achieve great success using structural adhesives to replace rivets and mechanical fasteners in truck body and trailer manufacturing. The difference in the end result is clear – the time and cost of undertaking the riveting process is greatly diminished.

“It’s also a more sustainable alternative. Rivets can cause paint to peel and eventually rust and corrode in extreme weather conditions, but with structural acrylic adhesives, you’re offered long-term performance,” Vint said.

Henkel’s structural adhesive systems have been formulated to bond trusses, joists, shear walls, headers, studs and cantilevered beams.

Similar bonding applications can also be translated to other industries that use galvanized steel, steel and aluminium, such as HVAC and appliance assemblies where corrosion resistance is critical.

“There are myriad benefits to using structural adhesives versus mechanical fasteners.

“For customers it all boils down to savings and product quality. Savings are mainly derived through lower production times and labour costs, while strength, durability, and aesthetics are all important factors that demonstrate superior product quality.”

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