Press fit into nylon 3

[TheMotionGuy]

I need to press fit a metal threaded insert into a piece of nylon. Does anyone have advice on how much interference would be adequate?

I generalize by saying metal because I was thinking of using brass or steel.. is there another material that would be better suited for this application?

It will not be load bearing.. it is a connection point for a handle to a custom chuck for a manual cleaning device.

 

[CoryPad]

Use these:

http://www.spirol.com/library/sub_catalogs/ins-Series_50_and_51_us.pdf

 

[zekeman]

Depending on a press fit in a plastic part for mechanical integrity is a bad idea.

Adding a set screw may help, but is still problematical.

 

[plasgears]

We generally used a diamond knurl on metal shafts to give torque resistance and push out retention. This works best for plastic gears. Research knurls and learn about interferences. We used several thous. on small shafts like 3/8"D. The straight knurl is reserved for metal to metal interferences.

 

[boo1]

consider using adhesive bonding

 

[TheMotionGuy]

adhesive bonding for around the insert? Or an adhesive connection instead of a threaded connection.

I need the parts to come apart because it is a universal handle.

 

[dgowans]

Check out the information here:

http://www.emhart.com/products/dodge/design.asp

Dodge makes a variety of inserts and has good information available on pull-out / torque resistance. If you're not relying on the insert to bear any load, I would suspect that you've got a lot of latitude in what you can do.

 

[loughnane]

If you can, try to use flanged inserts where the pull force is going from the flanged end to the split end. Press fits are nice but nothing helps you sleep better at night than the phrase "infinite mechanical advantage"

Also, if you dig down deeper into dodge ultraserts you see a table like the attached, which should do it for you.



Chris Loughnane - Product Design

http://www.pdnotebook.com

http://www.twitter.com/DesignNotebook

 

[TheMotionGuy]

Dodge has some well detailed info.. I've found everything I need to finish designing the connection.

Thank you for pointing me in the right direction.

-Dale

 

[CoryPad]

The Dodge products are for insertion via ultrasonics, heat or insert molding. You asked for press fit, which means you should use the Spirol product instead.

 

[TheMotionGuy]

I decided to use one if dodge's thermal installation techniques to do an insert. Talked to an applications engineer over there about it.

 

[CoryPad]

Excellent.

 

[loughnane]

if by "thermal installation" you mean using a soldering iron to heat it up, just be sure to let it get niiiiiiiiice and hot before you start GENTLY applying pressure.

It works like a charm, but is easy to screw up.

Chris Loughnane - Product Design

http://www.pdnotebook.com

http://www.twitter.com/DesignNotebook

 

[TheMotionGuy]

Haha yep. Fun times ahead with the soldering iron!