Plastic Injection Mold Design for Toolmakers - Volume III: Plastic Injection Mold Design for Toolmakers, #3

By Mike Rowe

Do you already build plastic injection molds?

Do you now want to design them as well?

Or do you design plastic injection molds and want to make it easier on yourself?

Help is here!

This is the third in a series of books on Plastic Injection Mold Design.

This book continues with the Checklist Method of designing a Plastic Injection Mold. A method reduces the amount of redesigning needed to complete a mold design.

This book gets into the "what's and how's" of designing more advanced features of Plastic Injection Molds. There are handy guides to make the design process quicker, especially when using the Checklist Method.

• Language: English
• Publisher: Mike Rowe
• Release date: Aug 7, 2022
• ISBN: 9798201101381

Book preview

How this Book is Organized

As introduced in Plastic Injection Mold Design for Toolmakers - Volumes I & II, the chapter titles in this book are also a checklist to follow when designing a plastic injection mold.

(Click on the link in the ‘Links and Resources’ in the back of this book for a printable checklist.)

This book tells you how to design the different elements of a plastic injection mold.

Note:

The chapters are repeated here, from Plastic Injection Mold Design for Toolmakers - Volumes I & II, in order to maintain the mold design checklist format.

The detailed portions of the chapters in the first two books have been removed to save space and avoid repetition.

CHAPTER 1 - Shrink

Don't let Shrink confuse you.

The mold has to be made bigger than the part we want to end up with, so that when the hot plastic cools it Shrinks to the size we're after.

THE END.

The plastic suppliers know how much each of their plastics Shrinks, and they give this to us in the Shrink factor.

We apply this Shrink factor to our part geometry and then design the mold around the part.

Shrink is the first item on the mold design checklist because it is the most important.

If the Shrink factor is wrong, the entire mold will be wrong.

Let your customer, or engineering department, tell you the Shrink factor they want to use. If you assign this and it's wrong, you get to build a new mold for free.

You will see the Shrink factor defined as .xxx/1.000 or x%.

x% is typically used by the plastic manufacturers because it applies to any unit used.

10%/inch is the same as 10%/mm.

If you need .xxx/1.000 from a Shrink factor defined by % do this, for example:

.7% = .7/100 = .007.

Below is a mock up of a typical Shrink Table you might get from a plastic manufacturer.

That difference, between their Minimum and Maximum Values, is the reason you MUST NOT assign the Shrink factor yourself. I think this bears repeating:

Let your customer, or engineering department, tell you the Shrink factor they want to use. If you