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The automotive industry is constantly evolving and seeking new ways to ensure our vehicles are fit for purpose and keep us safe. Implementing powerful and efficient bonding methods is a highly important part of the vehicle production process.

Modern day automotive manufacturers are increasingly using adhesives as their bonding method of choice as they are versatile and offer a huge array of benefits over traditional fastening methods such as welts and rivets. Global car manufacturer BMW produced their streamlined i3 all-electric car using Dowsil (Dow Corning) adhesives in 2014 to overcome any out-dated production issues.

Structural adhesives, hot melt adhesives and adhesive tapes are all commonly used in the automotive manufacturing process and can be found everywhere from the upholstery to under the bonnet. Read on to find out 8 ways that automotive adhesives are revolutionising the automotive industry…

Increase in Eco-Conscience Consumers

There is an increasing demand for cars and vehicles to be produced using lightweight materials to keep the overall weight to a minimum. Traditionally, the exterior material such as steel or aluminium would be welded, and additional weighty mechanical fasteners would be used to join the components. Adhesives reduce interior and exterior weight of the vehicle when used as a bonding method and therefore will maximise fuel economy and lower emissions. This allows for more eco-friendly vehicles to be produced, including all electric cars.

 

Long Wearing

Adhesives offer a stronger bond than welts and rivets as the bonding occurs over the surface area of the joint. As the adhesive distributes its force in a more efficient way, this reduces wear and tear through vibration, impact or contraction and expansion of the material. This is particularly powerful when bonding the exterior or frame work of a vehicle.

 

Optimal Joining of Diverse Material

Modern streamlined cars are composed of a composite mix of materials including glass, rubber, plastics and metal, and the ability to create strong bonds between these is crucial to the robustness of the vehicle. Automotive adhesives such as structural adhesives and hot melt adhesives can effectively bond a wide range of substrates making them a perfect fit.

 

Aethetically Pleasing

Adhesives are highly versatile and can keep up with the latest trends without taking away from the vehicles visual appeal. They are practically seamless once applied and require no drilling or welding. They work particularly well in areas such as the interior fabric seat covers, visors and dashboard components where the bond may be visible to passengers.

 

Faster Production

Increased production and faster processing times are crucial within the manufacturing industry, meaning that traditional methods can simply take too long. Adhesives such as hot melts are a great alternative as they require very little open and setting time. As parts no longer need to be drilled or mechanically attached when using adhesives, the assembly process is simplified and can allow for a greater turnover.

 

Bond Hard to Reach Areas

Traditional welding tools cannot reach certain areas of the vehicle, therefore are limited to which elements they can bond. Structural and hot melt adhesives work particularly well to combat this as they can be used to cover a large surface area as well as obscure or tight areas with ease.

 

 

Effective in Demanding Applications

Hot melt adhesives are commonly used to bond the car interior such as carpets and upholstered seats which face daily rigorous wear and tear. They are also commonly used in areas such as side and door panelling which require a high level of durability. Similarly, structural adhesives can be used in highly heat-sensitive areas such as within electronic equipment.

 

Resilient to External Factors

Welts and rivets can often begin to rust when exposed to air or water, which takes away from the aesthetic as well as loosening the fastening. Adhesive tape has become a key component in the attachment of external finishers such as nameplates, wheel trims and spoilers as they have outstanding resilience to external conditions and provide a long-lasting bond. Adhesive tape can also be used in applications requiring low movement of parts or to control noise from vibration.

 

 

Our Top Picks:

Permabond ES5741	Lord 320	Lord Ap134
3M Scotch Weld Hot Melt Adhesive 3748	3M Scotch Weld Hot Melt Adhesive 3762	3M UHMW Polyethylene Tape 5421

Shop our extensive range of adhesives here.

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Unsure which adhesive would suit your application best? You can ask our Glue Doctor! Simply fill out our enquiry form regarding any product or technical queries you may have.

A hot melt adhesive, also known as a hot glue, is the name given to a polymer-based glue which is solid at room temperature and is applied in a molten state.

There are three main stages to the process of a hot melt adhesive bonding together materials. Firstly, the solid adhesive is heated until it reaches its softening point, at which stage it will turn to liquid. The molten adhesive is then applied and wets the substrate. The period available to make the bond between applying the thermoplastic adhesive and bringing in the secondary material is called the open time. Lastly, cooling time will then occur. This typically varies from just a few seconds to up to 5 minutes, and during which the hot melt will solidify and very quickly build up strength and stability. This fast turn around allows for a quick processing time and rapid assembly.

 

Main Components of Hot Melt Adhesives:

Polymers: These help to give the adhesive strength and flexibility, as well as heat and impact resistance.

Resins: Control the wetting of the adhesive (how long it remains a liquid whilst in contact with the substrate).

Wax: Primarily controls the open time, and how long the bond takes to form. It also helps thin the adhesive for application. The higher the wax content present within a hot melt, the higher viscosity and greater flexibility the bond will have. High levels of wax also allow for a quicker bond.

Antioxidants: These are used primarily to help preserve the material during its shelf life.

 

 

Equipment required for hot melt adhesives:

The equipment which accompanies the hot melt glue is just as important as the adhesive itself, since without the glue gun there is no way of heating the adhesive to the correct application temperature. The glue gun also allows for accurate and precise application onto the substrate. Each gun is specifically made to suit a different need, such as the 3M Hot Melt Low Temperature Applicator LT which maintains a temperature of 129ºC making it an ideal choice for heat sensitive surfaces such as foam and plastics. If a higher temperature is required, the 3M Hot Melt Touch Control Adhesive Applicator TC dispenses up to 196 ºC and is great for more detailed work.

 

 

Advantages of Hot Melt Adhesives:

Good for hard to reach areas:  As the adhesive is applied in a purely liquid form, it allows for easy application to more obscure places or surfaces which other glue or adhesive products cannot do as well. Many glue guns and nozzles are manufactured to distribute the glue into these small complex places ensuring the entire chosen surface is reachable and covered which in turn, allows for stronger bonds.

Speed and ease: As the whole process of using hot melt adhesives is quick, this lowers assembly time and allows for optimum productivity with a fast turnaround.

Bonds variety of substrates: Hot melt adhesives are specially formulated for specific tasks. A wide variety of materials can be bonded, such as wood or corrugated cardboard. Heat sensitive materials such as foam or even some plastics and metal can also be bonded using hot melt adhesive when dispensed at a lower temperature. They can also bond both porous and non-porous surfaces.

Neat Application: The bond which forms from a hot melt adhesive is practically invisible which gives an overall pleasing aesthetic. This is particularly useful when used for items such as signs, displays or even furniture.

Long shelf life: Hot melt adhesives have excellent moisture resistance and do not need refrigeration meaning they remain firmly bonded for an extensive period. 

Challenges of hot melt adhesives:

As with most adhesive products, alongside the benefits, hot melt adhesives have a few limitations. The temperature at which hot melt adhesives are set at is crucial to the application process.

• Once molten, the adhesive must be hot enough for assembly. If the adhesive is not hot enough at this stage, a weak bond may be formed which is also known as a cold bond.
• However, if the hot melt adhesive is applied in a molten state at too high a temperature, it will remain in a liquid state for too long and result in a soft bond being formed. Any stress or weight on this bond will cause a weakening which could fail immediately.
• Unlike other adhesives, if hot melts bonds are re-heated to their softening point temperature, the previous adhesion caused by the cooling process can be reversed. Although this does make hot melt adhesives more flexible and easier to repeatedly change, it can cause a hindrance should this be applied to a substrate which will undergo or survive in an environment with higher temperatures. However, many hot melts are now being manufactured with higher levels of heat resistance to combat this.

 

Common Industries:

Packaging Industry	Electronic Industry
Automotive Industry	Bookbinding Industry
Furniture/Woodwork Industry	Retail Industry

Shop our range of Hot Melt Adhesives here. 

Additional links:

At Ellsworth Adhesives, we supply a wide range of hot melt adhesives and glue guns from leading brands Henkel Loctite and 3M. View our complete range of hot melt adhesives here. 

Unsure if hot melt adhesives are right for you? Our Glue Doctor is available to answer any technical questions you may have. Simply fill out our enquiry form.