A USER’S GUIDE TO ADHESIVE TECHNOLOGIES
Henkel, whose brands include LOCTITE®, BONDERITE® and TEROSON®, is a market leader in the field of adhesive technology. The company is renowned for its commitment to customer technical support and you can benefit from second-to-none, expert guidance on industrial bonding and sealing without moving a muscle! The new LOCTITE® Success Secured webinar series brings LOCTITE® product specialists into your workplace via the internet during June, July and September 2015. The three subjects covered are: Why adhesives? – optimise the manufacturing process; Instant adhesives – hybrid technology provides strength and speed; Machinery adhesives – ensure high performance and reliability.
The Henkel webinars provide industry with the opportunity to tap into nearly a century’s worth of experience in the use of adhesives for structural bonding, instant bonding and machine construction and maintenance.
For dates and the full registration details visit: https://www.loctite-success.co.uk/en/webinar.html
A structural bond is used to join critical load-bearing parts of an assembly. Adhesives developed to meet this need require a combination of high shear, tensile and peel strength, together with maximum stress, impact and shock absorbent characteristics. They can bond a diverse selection of materials including composite, wood, metal and glass.
Structural adhesives fall into five groups – epoxies, acrylics, polyurethanes, modified silanes and silicones.
When it comes to high strength structural bonding, epoxy resins are the acknowledged leader. Epoxy formulation comes with a huge degree of freedom and virtually any characteristic can be formulated on demand.
Structural epoxies are generally slower to cure than other technologies. It is the ideal choice for rigid bonding where the bonded parts can be considered to be structurally linked, they also have an ability to fill large gaps and provide good chemical resistance.
If a small degree of flexibility is required for the otherwise rigid bond, acrylics are a good choice. They are suitable for bonding a wide range of materials and are regularly used for sheet metal, especially on applications where the substrates might flex.
A key characteristic of the acrylic family is their speed of set. Handling strength is generally achieved in less than 30 minutes at room temperature. Another major benefit of using toughened acrylics on sheet metal applications is their ability to deaden sound when compared to traditionally fastened metal sections.
The key advantages of high performance polyurethanes include high strength, their suitability for bonding and sealing of a wide range of substrates, excellent gap fill capability and low temperature performance.
Elastomeric polyurethanes are best known for their ability to fill large gaps and for resisting flexing, these products have been used in the motor industry for around 40 years where they are typically used for bonding windscreens into vehicles.
For elastic bonding, silicone is king. Products in this class are selected for their ability to absorb and tolerate dynamic stress. They are available in one and two part versions and allow the bonding of a wide variety of substrates.
The key characteristics of silicones are low modulus, high elongation to failure (200-600%) and are generally capable of withstanding temperatures of up to 250°C. Some grades even offer performance up to 350°C. They have a high gap filling and sealing capacity, good durability and are resistant to humidity, ozone and UV radiation.
An ability to bond just about any substrate and compatibility with most paint systems make modified silanes another good option for flexible bonding. Mainly one-component products, they cure by reaction with moisture so no primer is needed to achieve a good bond.
Typically they are used to seal joints and seams on a broad variety of structures including air conditioning and ventilation equipment and they can be used for interior and exterior applications.
The benefit of instant adhesives is clear. They cure very quickly when confined between surfaces and are chosen for bonding small parts to achieve extremely fast fixturing.
Historically this group of adhesives was only suitable for close fitting surfaces but now formulations are also available that are able to gap fill and this extends their potential in maintenance engineering considerably. New high temperature instants will also withstand exposure up to 120◦C for short periods.
Threadlocking and sealing
The main benefits of threadlocking adhesives over traditional mechanical locking devices is that they prevent self-loosening and secure any threaded fastener against vibration and shock loads. They are easy flowing or semi solid formulations which completely fill the gaps between mating threads, eliminating fretting corrosion by creating a unitised assembly.
Thread sealants do a similar job but are primarily designed to create an instant, low pressure seal. The substrates involved are the main criterion when selecting the most appropriate thread sealant for the job. Anaerobic sealants are used on metal fittings and silicones on plastic and plastic/metal combinations.
Gasketing sealants provide an instant seal that resists high pressure when fully cured. Many factors influence adhesive choice but broadly anaerobic products are for rigid flanges where the sealing gap is zero or very small. Silicone gasketing materials are best suited for large gap applications and assemblies where flange movement occurs.
For more information or advice on selecting the best adhesive product for your application visit www.loctite-maintenance.co.ukwww.loctite-maintenance.co.ukor join our webinar series Summer 2015.
If the new Loctite Universal Structural Bonders are strong enough to pull a train, imagine what they can do for your tough repair challenges; the possibilities are endless.
To prove the speed, strength and durability of Loctite Universal Structural Bonders, they were tested by pulling a 208-ton (more...