Continuation of the 4 Factors… the process

In the last installment we discussed some things about the tool constructions and all. We have progressed to the point of testing out the tool.  This is where the processor actually has a say so, but in many cases is pressed for time and a true evaluation is never done. Especially if everything we have done to date has been followed good parts fall from our tool and everyone goes on their merry way. But as we all know that is usually not the case.

If in fact a mold flow was done for the tool the processor should have the data so they can set up the machine parameters accordingly, at the very least the cycle time and material processing sheets and volumetric calculations for shot should be passed onto the processor. After having set the tool up and hooked up all the cooling lines correctly it is time to dry cycle the mold. By this we open and shut the tool numerous times to see that everything works, sometimes people well set up their machines to do this automatically, I would suggest that it be done carefully and if a complex tool such as one with slides and pins that the sequence should be manually check to prevent any tool damage. After running for a period of time the tool should be inspected for any galling and wear. If the tool is to run hot, above 185 F insulations plates on the mold and platens are suggested, and care should be taken that the tool steels are checked for galling.

Once the tool is checked out and we are ready to process the following steps and or tests should be run.
1- Short shot series, with parts eventually going to full. These parts given to QC just to see if things are close. Don’t want to be making 2” parts when they really should have been only 1.5”.
2- Shear viscosity study, this to determine the fill rate.
3- Pressure drop study.
4- Gate freeze study
5- Determination of maximum packing pressure necessary.
6- Recording of melt temperature and steel temperature
7- Run an optimization of the cycle and record plastic pressure and fill time.
8- Finally run the tool for a period of time for your retained samples. This is the hard part because we have used up so much time. But this is dependent on the production run of parts. If in fact the production run is only going to be 2 to 4 hours than maybe it doesn’t matter.  If in fact it is 24/7 for a year than maybe a sample run of 24 hours is warranted with samples saved at the end.

The above are not in any particular order. The key is to follow or do them so you generate the data to make intelligent decisions on what possible tool changes may be needed, and or to prove or disprove the mold flow data. By generation of data we can over time generate the information to become more productive and optimize our tooling, design, and processing of our parts.

Thanks for the time.

Steven L Silvey
Consultant to the Plastics Industry
360-882-3183
ssilvey643@aol.com

PS: Yes the above is new as after 15 years of employment I face the same fate as others in being let go. Anyway if you need help or know of a position give me a call or send me an e-mail.