×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

#### Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

# Questions about helicoil screw assembly strength

## Questions about helicoil screw assembly strength

(OP)
Attached file is an excerpts from HELI-COIL tensile strength of threaded insert assembly.
The parent material is Al6061, and bolt strength is 420MPa, in this case, its intersection is below the 1 dia insert length.
• If I use 1 Dia insert, what’s the strength of assembly?
• If I use 1.5 Dia insert, what’s the strength of assembly?

### RE: Questions about helicoil screw assembly strength

That chart is not designed to tell you the ultimate strength of the assembly- its a guide to selecting which insert to use, so that your assembly strength is controlled by the strength of the fastener and not by pullout of the insert.

### RE: Questions about helicoil screw assembly strength

(OP)
I think what I really want to know is, what if the intersection does fall onto the insert length, then what's the assembly strength?

### RE: Questions about helicoil screw assembly strength

The assembly strength is whatever you calculate it to be.

The point of that chart is not to tell you what the assembly strength is.

### RE: Questions about helicoil screw assembly strength

(OP)
Thanks.
Do you have reference book recommend, or formula I can learn?

### RE: Questions about helicoil screw assembly strength

(OP)
Hi IRstuff, can you explain in more detail?

### RE: Questions about helicoil screw assembly strength

The diagonal lines are the pullout strengths of the inserts, assuming infinite strength fasteners, so ~2.6 kN is the pullout strength of the 1 dia. insert and ~4.4 kN for the 1.5 dia insert, in 6061T. The 420 MPa fastener line is below the intersection, so the graph is saying that ANY insert with that fastener will be limited to ~1.4 kN

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

### RE: Questions about helicoil screw assembly strength

(OP)
Thanks IRstuff, I am getting there.
How about the case that intersection is above the dia. line?

### RE: Questions about helicoil screw assembly strength

If the intersection is above a diagonal, then the chart is telling you to use a different diagonal so that your assembly strength is controlled by the fastener.

The fastener should always fail first.

The strength of the joint is the strength of the fastener.

### RE: Questions about helicoil screw assembly strength

(OP)
Thanks JgKRI

#### Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

#### Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!