Tap Bolt Joint Types

[struclearner]

The Tap Bolt Joint has threads in the lower member of the joint and usually the hole is not a through all (a blind hole).
Is there a bolt joint with a member having a through all hole with internal threads and no nut.
Which bolt joint is better, i.e through bolt (with a nut) or a tap bolt (no nut) as the durability, retaining the clamping pressure and resistance to being loosening due to vibration loading.

Thanks for help.

 

[mk3223]

From the machine design point of view without knowing your detail application, I will say the through bolt with nuts are the better way to secure the joints as the adequate space is provided around the joint for tightening the nuts.

Can you share more detail?

 

[BEMPE16524]

Agree witk mk3223. Need more detail on your application.

R.Efendy

 

[dhengr]

Struclearner:
The matched set of nut and bolt, with washers, is really a pretty secure and practical system. The thread geometry and class, the material strength, the thread lengths are all matched to provide an optimized fastening system/pair. Of course, this can be screwed up by picking a weaker nut or bolt, in which case the weaker element will control the cap’y. The tapped hole requires some special design attention because almost certainly the bolt material and the tapped material do not match in yield, tensile or shear strength. Thus, the depth of the tapped hole/thread must be designed to take full advantage of the bolt strength. The main advantage (or need) of a tapped hole is limited access for nut application, but this often means adding a boss to the backside of the pl. to gain enough tapped thread length to match the bolt strength. There isn’t much advantage to the blind hole, it is usually much more expensive to make properly than just using a proper nut. The bolt/nut connection is usually better and more economical for heavier structural connections, and proper/sufficient tightening of the bolt/nut are usually a pretty good method of managing vibration problems and loosening. Sometimes various means are applied which prevent the bolt or nut from turning once tightened. You would do well to do some self-study/reading in Strength of Materials and Machine Design texts and AISC Stds., Machinery's Handbook, to further your understanding of bolted connections.

 

[desertfox]

Hi
Well it really depends on the situation, if a tapped hole is used then the material the hole is tapped into needs to be considered from its strength properties. Whereas a nut and bolt usually have close matching properties and so can develop the full clamping load for the nut /bolt combination providing they don't embed into the clamped part.
So if the tapped hole is of a weaker grade material when compared with the bolt then either the bolt preload needs to reduce or the tapped length of the hole must increase to give a longer thread engagement area, from experience though the increased thread length is only good for a depth of 1.5 times the bolt diameter.
as others have stated can you provide more detail of the situation

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[BrianE22]

Using a nut you would have a longer effective bolt length which is usually a good thing.

 

[CWB1]

Yes, thru-holes are commonly tapped. From a manufacturing standpoint they are usually preferable to tapped blind holes for chip clearance. Comparing a joint with a tapped hole to one with a bolt/nut combination, IME the tapped hole is generally preferable on the basis of cost and quality.

John Bickford's "Introduction to Bolted Joint Analysis" is the standard text most folks start with.