×
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.

# shrinkage formulas

## shrinkage formulas

(OP)
I need to know the functional diffrence between the shrinkage formulas.

1+S

1/(1-S)

(S stands for the shrinkage factor)

By functional I mean where or when to use the proper formula

### RE: shrinkage formulas

The 1+S formula would be used to add shrinkage (or scale up) to a part. For instance, if the shrink is 0.003 in/in, you would multiply the dimension by 1.003 to get the number that would be used for the tool design.

The 1/(1-S) formula is used to take the shrink away (or to scale down) to give the nominal or real dimension. Since shrink is multiplicitive, you don't multiply the above example by 0.997 to take the shrink away...it would actually be 0.99701 due to the formula.

### RE: shrinkage formulas

In the case of some thermoset molds, the shrinkage is very low and the mold steel is heated up. This can affect the part...in extreme cases on large parts, I have had to calculate cavity sizing based on the steel growing more than the part would shrink. In this case, you actually scale the part down. You should also take steel temps in consideration when design molds for extremely high tolerance parts.

### RE: shrinkage formulas

Both formulas are usefull.   With the second one you will have more presicion.  When you need to get the right size you have to leave more material so after the test you can get the correct size.  Make sure where to leave under & over.  Remove from steel is better than weld.
Visit geocities.com/cursogratis

#### 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.

#### Resources

White Paper - PLM and ERP: Their Respective Roles in Modern Manufacturing
Leading manufacturers are aligning their people, processes, and tools from initial product ideation through to field service. They do so by providing access to product and enterprise data in the context of each personâ€™s domain expertise. However, it can be complicated and costly to unite engineering with the factory and supply chain. Download Now
White Paper - Medical Device Design Control
Medical device product development is a highly integrated and regulated process. Implementation of a requirements tracking solution requires attention to a variety of nuanced topics. When presented with the task of tracking the many concept relationships in a project of this type, the initial software solution of choice tends to be a two-dimensional text systems. 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:

• 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!