The bolts that are classified as M16 bolts are generaly used in applications in which the bolt experience high levels of load and in which the bolt must remain tight despite changes in an environment in which it is installed. Because those installing the bolts use these M16 bolts in these types of environments, it is important for them to understand the different thread options that are available for M16 bolts. M16 bolts has three different thread pitches: coarse, fine, and extra fine threads.
Each of these different type of threads will affect the way in which the threads of the bolt seat within the material that it is securing, the amount of clamping force that the bolt exerts, and the care that must be taken when installing the bolt. Coarse threads are generaly the preferred option for those who are looking for bolts that can handle the errors that can occur during installation, or who are looking to use the bolts in applications that does not experience any movement. Fine threads, however, are preferred for applications that experience constant movement, or for those that require more precise adjustments.
How to Choose and Install M16 Bolts
Fine threads distribute the load over a larger area than coarse threads, and have the ability to resist loosening from movement more better than coarse threads. Consequently, fine threads require the holes to have cleaner threads, and require more care to install the bolt correctly. Thus, before purchasing taps or M16 bolts of either type, you should of made these considerations.
The torque values that are provided for M16 bolts are associated with the thread data of the bolts. The values are provided for scenarios in which the threads are dry, but if you lubricate the threads with oil or anti-seize compounds, the clamp load that is placed onto the joint will be higher. In many cases, failures of bolts occur due to the individual installing the bolts ignoring the difference between dry threads and lubricated threads; therefore, it is important to account for lubrication in the installation process.
In order to avoid creating these potential problems, it is important to use a calibrated torque wrench and to utilize that wrench each time that the bolts is installed. The depth in which the threads of an M16 bolt engage with the material that it is installed into is another critical variable in the installation of these bolts. If the engagement depth of the threads is insufficient, the threads of the bolt can strip as it is installed.
For bolts of M16 sizes that people are installing into steel, one diameter of thread engagement is generaly all that is required for the bolt to reach its full strength. For softer materials, however, more depth of thread engagement will be required to avoid damaging the threads of the material into which the bolt is being installed. Additionally, materials like plastic or composite materials will require inserts to be installed into the materials, as the materials themselves will not provide the level of strength that is required.
A chart that provides information about the minimum depth of thread engagement that should be allowed will help to ensure that the bolt is installed correctly prior to drilling into the material. The reason for applying torque to the bolt is to achieve the proper pre-load for the bolts. By applying the proper amount of torque, the M16 bolt will stretch just enough to ensure that the joint remains compressed when subjected to external loads.
If the stretch of the bolt is too little, the parts of the joint will move relative to one another. If, however, the applied torque stretches the bolt too much, the M16 bolt may begin to yield as a result. The percentages provided within the reference provide a means of ensuring that the bolt is installed so that it remains within these limits.
The dimensions of the head, nut, and washer of the bolt are another consideration in the installation of the bolt. The size of the bolt head is important in situations in which the bolt must fit within a tight space, or in situations in which other parts of the assembly must be added to the bolt. In instances in which you use an anti-seize compound, it may be beneficial to replace the hex head of the bolt with a socket cap version; this type of bolt is useful in situations in which the profile of the bolt is to be lowered, or in situations in which a wrench will not be able to fit the bolt.
These dimensions do not impact the thread pitch of the M16 bolt, but they do have an impact upon the ease with which the bolt can enter the hole in the material that it is to be installed into. Another consideration is the use of locking methods after the installation of the bolt into the material. Locking methods like spring washers are inexpensive, but can lose their effectiveness after the joint has been tightened.
Other methods, like wedge-style lock washers or anaerobic compounds are more effective in locking the joint, particularly if the joint will be exposed to vibrations. Other locking methods, like nylon-insert nuts are effective in high-temperature situations, but only weakly lock when experiencing vibrations. Thus, the type of joint that will be created and the amount of vibrations that the bolt will experience will impact the choice of locking method.
The majority of failures in bolts occur due to improper installation of the bolts. Applying too much torque, installing the bolt with incorrect starting forces can lead to failures. Additionally, under-tensioning the joint will lead to failures.
While failures due to corrosion and fatigue will occur later in the life of the joint, these issues will be made worse by improperly installing the bolt initially. Thus, if attention is paid to the details of the chart, it is possible to reduce the likelihood of these types of failures. To ensure that the M16 bolts are installed in a way that will ensure that the joint will remain tight, each of the considerations described above should be made prior to the installation of the bolt.
By taking the time to ensure that the proper type of thread is selected, that the bolts are properly torqued with consideration to lubrication, that the threads are deep enough for the type of material that is to be joined, that the pre-load is properly installed, that the dimensions are correct, and that appropriate locking methods are selected, the bolt will be installed in a way that will ensure that the joint created by the bolt will remain tight.
