×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

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!

*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

ceramic injection molding gating help

ceramic injection molding gating help

ceramic injection molding gating help

(OP)
I am in need of a little help in the design of a gate system for a ceramic part that we are injection molding. we have tried various gates to try and elimante a cracking problem. the cracks occurs when the material flows around a core in the mold but does not "weld" at this point, after debinding and sintering a "crack" appears at this point. does anyone have any suggestions on what type of gate would help to fill the cavity better.

TIA

RE: ceramic injection molding gating help

As you certainly understand already, the interaction of the gate with the core is creating the problem with the weld line.  Without understanding more about the geometry, injection parameters, etc. I cannot give you anything exact, but things to consider include the following:

1. Reducing the severity of the core geometry.  Is the core round?  Square/recatangular?  The more it departs from round, the worse the problem will be, due to residual stresses, etc.

2. Introducing multiple gates, in order to modify the flow regime around the core.  Depending on the size of the part, this may already exist.  Another option to consider is modifying the geometry to form a flow leader, which is basically a build-up in section size near the feature of concern that allows additional molten material to flow into that area.

3. In general, gating for CIM & MIM require much larger gates than for PIM.  Also, gating should be designed such that injection takes place along cavity walls, and does not directly impinge upon a mold surface or a core pin.  Although typically used in PIM, this causes particle/binder separation, and leads to poor weld lines.

A good article on the subject of tooling for MIM (very similar to CIM) appeared in a supplement to Injection Molding Magazine in December 1999.  I have included a link to the on-line article, which unfortunately does not include the figures.

http://www.immnet.com/articlelibrary/archive/getOneArticle.php3?getArtID=1057

Feel free to post additional details, and maybe we can help you further.  What would be most helpful is if you can post some photos on a website.  Then we can more specifically what to try.

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! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

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