Family Molds

[Suhas]

All,
Thanks for contributing to this forum.
In your company what do you think is the %of molds that are family molds? I need to redesign my software to include this but am having a tough time with some decisions.
Let me know.
Thanks,
Suhas

[Chris]

i would say we run about 40% of family tools at our plant.

And these are MUD base tooling as well, so that probably adds an extra twist.

[tim12871]

It can be cost effective! Just make sure the cavities are balanced.

[pjhall]

We have many family molds (20+%). There are runner shut-offs on all of the latest molds. Some of the older molds do not have shut-offs. I have been dabbling with mold flow on a few of our latest family molds to get the parts to be balanced (modifying the runners). When a new family mold comes in I will first try to run the parts together, but if I'm unsuccessful I'll turn the shut-off(s) and run the parts individually.

As the saying goes for custom molders "We don't sell plastic parts; We sell TIME". Run them together if you can!!!!

[Pilot]

Hello
I have cca 80% of family tools and (except 2 tools) are with shut off nozzles.

[rickbatey]

It is dependent on press size; <800t ~ 40%, 1000-2000t~10%, 3000-4000t=0%. I too have asked for the shut offs and added them to older molds as you couldn't mold BOTH parts good at the same time. Ran one mold at last job one cavity at a time due to shot weight requiring intrusion to fill out ONE part!?
Rick.

[tim12871]

I currently run a four cavity family tool (PMMA material) in a 500 ton. Two parts are 14" long 4" wide the other two parts are4" long 4" wide all hav a wall stock of 2mm. The hot runner system is balanced and pneumatic valve gates were added thinking we might have to delay gates. Fourtunatly we do not considering how sensative PMMA can be!!

[Suhas]

So looks like you are dealing with this quite a bit. As a processor, I do not want the pain of running the parts at the same time. But I understand that it makes business sense. I have also tried to use lot of the 6-Step studies (Sci Mld studies) and DOE for a few of them. The issue is always the balance and therefore the Process Window. The acceptable process is always just one point with no possibility for any adjustments. Usually management cannot understand this 'Well, we made good parts last time!!!' - I am sure you have heard this a few times.
Thanks,
Suhas

[Team JAG]

In my experience, a flow analysis is necessary for proper balancing. That being said, I've been involved with many hot runner systems built for family tooling and heard few complaints regarding balance or process issues when performing due diligence. In one case, a customer wanted a 5 drop 20 cavity family mold and the internal runner paths wound up looking like a bowl of spaghetti based on the flow report. There was no guarantee on +/- balance % but the customer was very happy with the end results.

Go with a reputable supplier that will ensure that balance is taken care of from within the manifold and you will save yourself some grief. A decent design house can perform a flow analysis for a cold runner tool or in hot to cold applications.

Our company has several cold runner family tools, small cavitation in low tonnage presses. No major issues with fill or balance to speak of.