Gas assist?

[moldingppm]

Hi all.

I'm currently working on a new project with a new customer. They're telling me that the annual usage will be high volume. This is leading me to bring up gas assist as a thought. My problem is, I don't know anything about it.

Here's my questions:
Do you ever have to get the gas refilled? I know it's a self-contained system, I'm just making sure.
If you have a machine that has a gas assist system, can you still run regular molds in it?
Roughly, how much extra does a gas assist system generally run?




Thanks in advance

[Jendalf]

Hi,
If its possible, avoid gas assist. For example if you have part with edges where the material is concentrated for gas assist, try to change the concept of that edges on long ribs.

Generally gas assist ins´t bad idea, but has some limitations which can´t be fully predicted (but are predictable) until you have the tool complete for testing. Second thing is that investments are quite high. (N2 gass tank or flasks; compressor, control panel, high pressure hoses and connectors).

You can run regular molds as you want.
the gas assist can be integrated into the machine or stand as a separate equipment. The only comunication what you need is some signal from machine from what you will start to count the opening of the gas into the tool. Recomended is start of the injection or the end of the holding preassure.

J.

[rickbatey]

I worked at a custom molding shop that used the through the nozzle system with tanks/bottles and was stand-alone not fully integrated into the press. Yes you can run molds without it but I agree the results may not be what was expected or required by th customer. You'd be better signing a development contract at the start to work out all the issues. The systems aren't cheap but it is a tool you can charge a premium for and may bring more customers to you plant.
Rick.

[pjhall]

Mold can be designed with "gas channels" in them and gas nozzles to fill those channels and pack out any thick areas. I did a ton of research about systems and royalty fees. Most of the original patents from have expired now, so you can purchase the equipment w/o paying extra for the technology. Contact Rick Goralski at Bauer Plastics Technology Group. These guys wrote the book on Gas assist and I mean that literally.

Bauer Plastics Technology Group
51053 Celeste Drive
Shelby Township, MI 48315

Office Phone 586-247-1900
www.bauerptg.com

[moldingppm]

Good points guys...I might be steering away from it. I was only looking to do it on a speed standpoint, as I thought my customers annual usage would be more, I was told different this morning.

Some other things;
I'm looking to build a mold for these parts (2 different parts) in a hot runner, issue is, Part 1 requires 30% RG and 70% Virgin and part 2 requires 100% RG. I've heard some horror stories about running regrind in hot runner systems. Is hot runner even an option for this? I know they're currently running these parts overseas, and in a cold runner mold, I believe more for cost reasons.

Does anyone know anywhere to purchase reground polypro? I've been looking for the last few days, haven't found much.

Thanks

[rickbatey]

I knew a great place to purchase regrind but I'm afraid they've closed their doors now. Perhaps some resin suppliers have some post consumer regrind resin they can sell for the right price?
As far as regrind goes, if it's not yours and maybe even because you made it, you just need a filter nozzle to keep the chunks out and a good metal separator. I prefer a PPE edge filter nozzle for price, easy cleaning, they work without too much shearing of the melt. Metal separators is a pricey one: S&S (search and separate), ~$5000 but you mount it over the throat. They get ALL metals versus a magnet getting only ferrous ones.
Rick.

[jdlent]

My company specializes in creating parts for gas assist injection molding (jdlent.com). In addition to offering parts, you can certainly contact us there anytime for assistance with your project.