Log In

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!
  • Students Click Here

*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.

Students Click Here


Optimum Injection Speed

Optimum Injection Speed

Optimum Injection Speed

How to find optimum injection speed on electric machine?

RE: Optimum Injection Speed

Injection speed is dependent on the type of material and its ability to shear thin as well as the potential for surface defects caused by filling too fast thru sharp flow transitions. Start by consulting the materials supplier and then let the machine tell you when you are going too fast and limiting out the injection pressure. Slow it down, if you are getting jetting or surface delamination.

RE: Optimum Injection Speed


As you mentioned "let the machine tell you when you are going too fast and limiting out the injection pressure" How to find it that we are going too fast or too slow? Are you referring to any viscosity curver? if so please explain in detail.

RE: Optimum Injection Speed

Injection speed is always a compromise.

Basic rule of thumb is to inject as fast as possible without causing problems.

Filling to fast can cause:-

Burns from shear.
Burns from gas traps.
Poor surface from jetting.
Poor surface from turbulence over sharp edges.
Over pack and flash from hitting the mould full point with to much inertia in the screw.


eng-tips, by professional engineers for professional engineers
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.

RE: Optimum Injection Speed

The question is what the injection speed is to fill the cavities. If it is a hydraulic or an electric machine is irrelevant.

The injection speed depends, as mentioned above on the material rheology. It also depends on the part design and requirements and the mould design, specially the type of gate and dimensions. A mould flow analysis may help.

For the part of "let the machine tell you", I agree, but there should also be a way to determine it theoretically while the mould is in its design face. I would like to see a post with some formulas. When the mould is already built, visit http://www.fimmtech.com/ (no affiliation). They have free and paid stuff to come up with the right injection speed and other set up parameters.

Mauricio Benavides
Injecnet Solution Inc

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!


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