*7.2.7 Torque augmentation*

A liquid thread locking adhesive provides a torque augmentation when the bolt and nut assembly with adhesive was disassembled higher than the tightened torque. As shown in **Figure 10**, the bolt and nut assembly without adhesive showed a lower break loose torque than tightening torque which is 70% only. However, the break loose torque with adhesive showed a higher figure than tightening torque (more than 100%) which can make the assembly more stable, reliable, and ensure a longer life (see **Figure 10**) [1].

#### *7.2.8 Galling*

When using a liquid thread locking adhesive during assembly, it provides a lubrication that reduces the friction between threads, heat buildup, and, consequently, galling.

#### *7.2.9 Thread locker lock and seal*

As mentioned earlier, mechanical fastener assembly is susceptible to a loosening, leak, and corrosion inside. Thread is in an inclined plane and easy to slide down (loosen) with an external transverse impact or vibration. It also leaves an inner space even though how high it was tightened, and it does not provide a sealing against fluids. Such inner space also allows external environment to penetrate and cause a corrosion that makes the easy disassemble very difficult. In many cases, torch has to be used to cut the threaded assembly and use a new one to reassemble. Liquid thread locking adhesives provide a locking and sealing as it fills all the inner spaces to cure and lock it in place against external impact and vibration. It also provides a sealing against fluid such as hydraulic system thread sealing as the cured thermoset plastic has a resistance against various fluids and chemicals. It also protects inner surface against corrosion; therefore, disassembly becomes very easy anytime. So, the life of mechanical assembly and assembly quality image are improved and increased. This also allows easier and cost-effective bolt-hole design as a cured thermoset plastic has a resistance against various fluids.

#### *7.2.10 Cost efficiency*

Liquid thread locking adhesives cut costs by replacing expensive special locking bolts and nuts. Less costly standard bolt or nuts can be used. **Table 3** compares the costs for the "ribbed flange bolt" and "adhesive" locking methods. The costs of normal shaft bolt secured with liquid thread locking adhesive are defined as 100%. The chart shows the relative increases or reductions in cost with surface-compacting


**Table 3.**

*Cost comparison between "ribbed flange bolt" and "adhesive" locking method.*

ribbed flange bolts. The parameter that makes the "ribbed flange bolt" expensive in overall cost is because of its material cost. Over the long years, mechanical designers have tried to find a way to keep the assembly safe against loosening without control, and they have come up with those expensive fasteners, but they could not prevent a complete "loosening prevention" either [2, 5, 6].

As shown in **Table 3**, liquid thread locking adhesive is a less costly method. The cost advantages coming from the simultaneous sealing effect and the use of through holes instead of blind holes have also not been considered. The liquid thread locking can be provided right from the design stage, reducing the costs of overall structure design and providing a guaranteed lock against loosening [2, 5, 6].

#### **7.3 Adhesive application**

Liquid thread locking adhesive can be applied to bolt thread in most of the cases to show an effective locking of threads. But for some critical or special design applications, liquid thread locking adhesives can be applied to both male and female threads to ensure a complete filling of the inner space and to cover an effective thread engagement length. The important factor is that the inner space should be filled completely. All "50-ml" and "250-ml" bottles of liquid thread locking adhesives are equipped with dispensing nozzles for use directly from the bottles. The flexibility of this method can be used to variations in the quantity of adhesive dispensed from one application to another. Dispensing systems allow accurate control of quantity. Liquid thread locking adhesive dispensing equipment has been designed for the specific properties of its adhesives to ensure trouble-free, reliable dispensing. Various dispensing equipment are available according to application requirements. For simple manual dispensing, volumetric hand pump that can be connected to the adhesive bottle directly can be used to dispense a controlled amount to bolt thread or threaded tap hole. For semiauto dispensing, a dispenser with a reservoir and controller can be used, and it can fit various applications in the different mechanical assembly industries. For automatic dispensing, a dispenser with reservoir, controller, and sensor that can be interlocked with a whole assembly line can be used. This automatic dispenser in many cases is used together with three axes or multiaxis robot for precise and accurate dispensing for fully automated production line [2].

#### **7.4 Major products available**

There are also various choices of adhesives according to each product performance as follows:

#### *7.4.1 Go-to product*

This is a first choice product for thread locking applications when a fast fixture time is required not only for active substrates and inactive substrates but also for some oily surface without the need of cleaning and when a high-temperature resistance of up to 180°C is required. This product has both medium strength and high strength.

**133**

*Liquid Thread Locking Solution for Machinery Assembly Industry*

This is a right choice for applications when thread locking of bolt and nut for manufacturing or repairing of equipment used for making food such as beverage, chips, bread, soup etc. It confirms to the requirement of FDA. This product has a medium strength that they can repair by hand tools easily when necessary

This is a product for application when then a threaded assembly must endure an ultra-high temperature environment up to "350°C." This product has both medium

This is a product that carries no warning sign on the product label and material safety data sheet (MSDS) such as no R phrases associated with raw materials, no product hazard symbol, and no product risk phrases, in other words, no skin irritation, nontoxic, etc. This is simply an environmentally green product and the best choice when the assembly site requires a safe health and safety (H&S). This product

Semisolid grade is a compact stick design in a semisolid state just like a glue stick. It can be used mainly for repair application where worker can carry and apply easily to vertical or ceiling area of applications. This product has a medium strength

This is a strength of cured adhesive when bolt and nut were assembled by hand

This is a strength of cured adhesive after breakaway torque was measured and

This is a strength of cured adhesive when bolt and nut were assembled with an on-torque together with adhesive. Measuring of the strength is done the same as the

It is critically important to understand the exact requirements of each application in order to provide a right solution. There are 10 key questions to ask to clarify

the strength after 180° turn. This also measures a strength of adhesive only.

without on-torque. This measures a strength of adhesive only.

and identify the application situation and requirements.

*DOI: http://dx.doi.org/10.5772/intechopen.85090*

*7.4.3 Ultra-high-temperature product*

*7.4.4 Environmentally green product*

has a medium strength and high strength.

strength and high strength.

*7.4.5 Semisolid product*

and high strength.

*7.5.1 Breakaway torque*

*7.5.2 Prevailing-off torque*

*7.5.3 Break loose torque*

breakaway torque.

**7.6 How to identify application**

**7.5 Major terms**

*7.4.2 Food grade product*

anytime.
