INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • 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.

Jobs

Rubber injection molding questions

Rubber injection molding questions

(OP)
Currently I run a six hundred ton rubber injection molding press.     Mold has six cavities.

How do I go about calculating the tonnage required for a given mold with rubber?  Is it the same "projected area" calculation that thermoplastic molding uses?   Or are there additional factors I need to be aware of.

Ultimate goal is to refurbish some of our "expired" cavities by re-plating them, re-polishing them and building a new frame to house them.    We do not want another 600 ton press,  we are thinking 200 or 400 ton.

Ideal situation would be to find out 1 cavity = 100 tons for our application because then we could acquire a new press on the cheap.   

----
BFL Dreamworks
"If we don't have an answer we'll get one"

 

RE: Rubber injection molding questions

GPB,

I've always used the area at the parting line, which seems to work.  We've never independently verified the internal mold pressure, though.

RE: Rubber injection molding questions

(OP)
Btrueblood:  

Thank you for your help.   I suppose if it works it works, eh?  :D

I tracked down a few good books on the subject, we'll see what they say.

----
BFL Dreamworks
"If we don't have an answer we'll get one"

 

RE: Rubber injection molding questions

GPB,

Let me know what the book says, it's one of those questions I've asked several different rubber mold shops, and can't get a firm answer.  I can see where for transfer and compression molds the answer is only pertinent to the mold designer (me); but for injection molding it would start to affect enough different pieces of equipment that it would become important...

RE: Rubber injection molding questions

(OP)
I know thermoplastic injection molding inside and out.    Rubber... is totally different in many respects.   In fact I think they gave it certain properties just to piss me off.   I mean... making the feed-stock warmer actually DECREASES the flowy-ness (increases viscosity).   And don't get me started on this rapid-onset curing induced by injecting it TOO FAST.    Sheesh.

*laugh*

Seriously it's always great to learn new skills,  I'm having a ball.    So long as the scrap stays below .5 percent I'm free to experiment.  

----
BFL Dreamworks
"If we don't have an answer we'll get one"

 

RE: Rubber injection molding questions

Welcome to the wonderful world of rubber.

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.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


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:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close