Part Containment

Hi all,

I'm new to the forum, and new to injection molding. I wanted to introduce myself and reach out to the community for ideas / advice / testimonials / etc. about an issue we have where I work.

First, my name is Kevin and I have been in injection molding for about 3 months now. I'm an Industrial Engineer so process improvement falls under the scope of my position and is the motivation for my question.

Now on to the question. We mold a lot of parts that are fairly small and we have a devil of a time getting the parts to drop onto the conveyor below our mold rather than scatter and end up all over the inside of our machines. We have some magnetic skirts that are sometimes used but they don't keep the parts from scattering above the bottom of the mold. Most of these molds make 10 or more parts per shot so the inside of the machine gets filled with scattered parts pretty quickly. To make it worse, many of the parts are very similar is appearance and size so a part from a previous job falling into the new job is a big issue...

Any of you who have faced similar situations what sort of containment strategies or containment aids have you used? Any that you found worked particularly well? Any that were failures that I shouldn't even look at? There are a few places that make various guards and shields but I can't find any reviews from people who have actually used them.

Thanks in advance and thanks for the forum, I'm sure I'll learn a lot.

Kevin

Are the parts ejected or unscrewed from the mold? I have had allot of success by just playing with the speeds of the rack or ejector system. I make pharmaceutics closures, 64 at a time, so I have had the same problems. we also use side shields, the ones I like the best are clear plastic that roll up as the mold closes.
Hope this helps.

I've seen some air knives triggered by the ejector and de-ionizing air used to keep small parts contained. Since my time in automotive, I can't recall a single machine running without a robot and end of arm tooling. I've seen some EOAT even be as simple as a small catch pan with an air cylinder that opened and dumped them on belt. Also seen 120vac muffin fans used to blow parts down out of a mold.
Rick.

Thanks for the replies!

@sublime1: The parts are ejected from the mold. some of the parts use a robot to pick the spru before ejection, others drop the whole thing and use a separator at the end of the conveyor. I will have to talk to our setup guys about playing with the eject speed but we'll have to be careful that we don't end up increasing cycle time.

Do you have a source for any examples of the side shields you're talking about (not sure about the product placement rules on this forum, just looking for examples)? I've been thinking that something on the sides of the mold would help tremendously. We make about 63 million parts a year which comes out to a lot of shots so the longevity / price of such a shield is important.

@reckbatey: You've given me a few good things to think about. Thanks for the input. Just a quick question, what does EOAT stand for?

Thanks for the input folks, I really appreciate it!

Kevin

IPS mold shields are a good example. As far as ejecting the caps, if you need to slow the ejection, you could be able to compensate with higher mold speeds due to the uniformity of falling parts. ( it takes a while to master but once you figure out how to balance ejector and mold speeds to have them work together your cycle time can increase.) I also use bags the we bolt directly to the bottom of the mold, I like for it to be wider than the mold to help catch any strays. Hope this helps.
Kenny

EOAT = End Of Arm Tool. It is attaches to a robot to extract parts from the mold. I worked in the caps and closures industry for a while and I had containment issues. I ended up buying conveyors that have stainless catch bins shaped like a "square-Cone" and I also used de-ionizing air knifes to help the parts fall.

Check out Crizaf Convyors, EMI Convors, and Exair Air knives.