Conventional methods used for joining metals structures include thermal methods (like welding and brazing), mechanical methods like riveting and bolting, and double-sided tapes. The process costs (skilled labor, equipment, material, grinding/polishing, scrap) and time involved in these methods impact profitability and productivity of the assembly line. Also, irregular distribution of load in case of mechanical & thermal methods and lower adhesion performance of double-sided tapes affects end-product reliability. In addition, many local epoxies, adhesives and sealants tend to be very slow curing and result in lesser strength than required.

Limitations with conventionally used methods:

  • Specialized equipment for thermal processes
  • Welding and brazing are high skill and time intensive – reducing productivity
  • Singular stress concentration around bolts/rivets leads to failure
  • Double-sided tape application involves multiple steps that slows down assembly process
  • Double-sided tapes don't bond well in case of oil contamination or chemical exposure
  • Double-sided tapes have low bond strength and degrade during operation
  • Need for extremely expensive activator to get adequate strength from double sided tapes
  • Realignment is difficult without rework for double-sided tapes
  • Mixing required in local 2-component epoxies which also result in lower strength
  • Conventional methods are not effective in terms of time and cost.
  • With double-sided tapes, no automation is possible and it is labor intensive.
  • No repositioning possible.
LOCTITE Solutions
Conventional methods can be replaced with LOCTITE Structural adhesives with Acrylic, 2-component Epoxy and Silane modified polymers (SMPs). These increase productivity, reduce assembly cost and improve product reliability. Here are some of the features:
  • Bond strengths are comparable to overlap welding and at half the cost

  • Most adhesives cure at room temperature – no special equipment needed

  • Application is simple and can also be fully automated

  • Tolerance to slight oil contamination

  • Good chemical resistance

  • Offer ease of realignment and part adjustment

  • Improved shear and peel strength

  • Design freedom with adhesives of multiple strengths and cure mechanisms available

Some areas where LOCTITE has come in handy for bonding purpose:
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Case Studies

Increase the output of your production line

Increasing the output of your production line

Increasing productivity with better bonding solution

Cutting down the cost of manufacturing with better bonding

An emergency exit stairs manufacturer used LOCTITE to improve the reliability of their stair handrails while reducing the overall production cost.

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frequently asked questions
Here's list of queries with responses that might help you.

We have been using welding for our structural requirement. Will structural adhesives be able to achieve the right strength?

LOCTITE structural adhesives have been proven to be able to take almost as much load as overlap welding and that too at only half the cost. LOCTITE adhesive also offer other advantages like making the process simple, and providing sealing along with bonding.

We use adhesive tapes. It is not messy. Wouldn’t using LOCTITE adhesives increase the process time and cost?

While double sided adhesive tapes are not messy, their application process is definitely very long and complicated – what with the need to cut to specific dimensions and expensive activators. LOCTITE adhesives are mostly applied through static mixers that ensures precise application without any mess.

We are using polypropylene and we have tried to use multiple methods and adhesives before, but they didn’t work. Which LOCTITE adhesives would be suitable?

There are many suitable LOCTITE structural adhesives based on acrylic, epoxy, modified silane and hybrid technologies that would be ideal for bonding polypropylene. Drop a query to our LOCTITE experts with the specifics of the application requirement and they will be able to recommend the right solution.

Replacing rivets is out of question – if we use adhesives, it will take longer to bond but with rivets we would be able to assemble instantly.

Rivets offer the advantage of instant assembly, however result into concerns of reliability because of uneven stress concentrate points that become fatigue and failure points and also lead to corrosion. Instead, LOCTITE structural adhesives offer better reliability and come in various cure types which can be further accelerated with the help of activators.

Can LOCTITE products withstand loads under extreme humidity and temperature conditions?

Yes, LOCTITE structural adhesives have been designed to withstand heavy loads under various ambient conditions. Especially, LOCTITE structural adhesives based on modified silane technology which cure in the presence of humidity, are excellent for outside applications where high temperature, UV resistance etc. features are preferred.

Which LOCTITE structural adhesives can bond rubber to metal?

LOCTITE structural adhesives based on acrylic, epoxy, modified silane technology and hybrids are excellent for bonding rubber to metal. Drop a query to our LOCTITE experts with the specifics of the application requirement and they will be able to recommend the right solution.

Is it possible to bond glass to glass or glass to metal with LOCTITE adhesives?

Yes, bonding dissimilar substrates like glass to metal or even glass to glass is possible with LOCTITE adhesives. If optical clarity and aesthetics is a must, choose clear epoxies like LOCTITE E-30 CL. Otherwise LOCTITE acrylics are also a great choice for bonding glass to metal or glass to glass. Prefer modified silanes if glass has to be fixed to a metallic frame. Drop a query to our LOCTITE experts with the specifics of the application requirement and they will be able to recommend the right solution.

Is any surface preparation needed before applying LOCTITE structural adhesives?

Removal of dirt, dust or other surface impurities from the surfaces to be bonded is important before adhesive application as they can interfere with the effectiveness of the bond strength. This can be achieved through either degreasing or abrasion. Chemical treatments like primers, corona discharge, flame and plasma treatments can also be used to modify the surface properties to further enhance bond strength.

What is meant by open time/working time/pot life of an adhesive?

Open time is the time within which parts should be assembled post application of the adhesive to ensure proper surface wetting and achieve maximum strength.

What does on part life of adhesive signify?

This term is relevant for adhesives where activator is used on one of the parts. On-part life is the time within which activator or primer provides full performance.

What is the difference between fixture time and full cure time?

Fixture time of an adhesive is the time needed to achieve enough strength to hold the parts together without additional support or to achieve lap shear strength of 0.1 N/mm2 whereas full cure time of an adhesive is the time needed to achieve full performance.

What is a hybrid adhesive?

Combination of two different adhesive technologies, which are normally stand-alone technologies and at the outset cannot be manually mixed. A Hybrid combines the positive attributes of both technologies which provides new performance parameter. LOCTITE Hybrid adhesives combine the speed of cyanoacrylates (commonly known as instant adhesives) with the strength of epoxies/acrylates to give universal that can bond anything in seconds providing high strength.