Ejector Pin Selection

Set Core on dial Indicator

Place needle on surface of core as close to ejector pin hole as possible

You may want to do multiple readings for accuracy

Read Dial Indicator and record the thickness of your core

The Dial Indicators we have are 2-inch travels and are read by smaller, inner needle first, then longer, outer needle second

Add the number you read to 3.892. (This new number, (X + 3.892) will give you the length of ejector pin).

If this number, (X + 3.892), is not an exact match with the ejector pin lengths, pick the next closest one.

If the ejector pins are longer than (X + 3.892), use a shim or two!

To determine the proper shim(s), subtract the length of the ejector pin from the (X + 3.892)

There are a variety of shims, so you may need to “stack” multiple shims and use more than one

Install the shims on the core side of the MUD Insert

Make sure they are oriented properly with the sprue hole lined up

Don’t forget to snug your fasteners tightly!

Hand ream if pins don’t spin or if you have trouble inserting them. Also, make sure the ejector pin holes are COMPLETELY clean of any chips or debris!!!

The sprue ejector pin should be a little shorter than the core mold so as to allow the tapped sprue hole enough space to accept the plastic

Install the back push-plate

Prior to installing the MUD insert into the machine, lay it on the table to see how far the ejector pins might extend from the surface. You may need to re-measure your part and choose shorter ejector pins or increase the size of the shims

Install the MUD insert with your core mold into the MUD frame of the injection molding machine

Don’t forget to test your ejector pins on the machine! Look to make sure that all the pins extend and the sprue ejector pin has been installed and is extending also!!!