Wear Mechanisms on Injection Molding

[KatrinaStone]

Hi:

Somebody knows about this topic. Anything is good. Thank you!

 

[unclesyd]

I did a lot of testing with different die materials vs different additives, fiberglass, kaolin, carbon, TiO2, fumed silica and others versus various die steels of the time, specifically D2, O1, SI and some different proprietary ones made by Carpenter and others. Again I don’t have my data, but the results were somewhat as expected as to wear. The higher the percentage of small dispersed carbides the greater resistance to wear. On a good wearing steel we saw a precipitous increase in wear at some loading point of each additive. We didn’t explore this as it was considered as a no go. There was one notable one, with an increase from 3.5% to 5% loading with TiO2 on D2. The wear rate tripled in the same temperature range on the change. Some of the worst wear problems were with TiO2 first and fiberglass second. If there is any additive in the compound that is essentially corrosive to the die material this appeared to have an effect even at extremely low moisture levels. We were never able to quantify lubricant additives in our testings.


There were a lot of work that could have been and needed to be done but we weren’t allowed to pursue. This was in a industrial setting. There should be a lot of information available on the net.

You might approach it thru the backdoor by starting with the steel producers and working forward. The extruder people have done a great deal of work with various components of and ancillary.

http://www.specialchem4polymers.com/techcenter/index.aspx

Register and check out their technical section

http://www.feedscrews.com/

These people have a lot leads to information.

http://www.plastemart.com/cimp/publications_injections3.asp

Literature on Injection molding.

 

[rnd2]

Below are some basic wear mechanisms for hard particle abrasion:
Sliding
Impact or angular contact
Grinding
Each influenced by particle:
Size: wear is proportional to size
Shape: spheroid (glass bead) to flat (mica)to acicular (glass, carbon fibre,). Acicular and flat particles that tend to "log jam" can increase pressure and increase wear in one area yet reduce wear in another by layering.
Spheroid particles develop sharp jagged edges if they break when subjected to grinding.
Hardness: increases wear
Edge sharpness: increases wear
Pressure: increases wear

 

[unclesyd]

Since you are beginning in the mold business you might try the following website for surface finishing methods for molds.

http://www.mold-tech.com/index5.shtml