Injection Molding with Epoxy Material

I don't understand, " shot fill in the same area.".

short fill?
I once knew a bloke called Phill Short...
Del

OK,

Short fill: material freezing before fill:

Mold may require venting: Shot size may be too small

NEED Details

Agreed. Significantly more details required.

Shot size versus barrel stroke and diameter.

Melt temperature and die cooling.

Wall section and die temperature.

MOLDFLOW (Finite element analysis) will give them a good indication.

Yep, more details needed. What is the size and make of the machine, also what is the part you are trying to mould?

Josh.

Absolutely. Give us more details.

Then one by one we'll copy the first correct answer to prove ourselves that we are smarter than we think, and blow all that frustration away.

Ok Guest - I'll start by copying this;

lynlynch Guru Join Date: Oct 2008 Location: Arizona USA 33.422N. -111.821W. Posts: 3505 Good Answers: 91	# 5 In reply to #4 Re: Injection Molding with Epoxy Material 01/29/2010 1:12 AM
	That's OK. It's a real term. So is dieseling. It occurs when the mold isn't properly vented and the plastic burns due to compression in the unvented area. Most times venting isn't required. But if you discover little black patches in the same area on the part, chances are you are injecting too quickly or the halves of the tool fit so well that air can't escape from the mold as the plastic is injected. More that you wanted to know, I'm sure. __________________ Only in America ......do we buy hot dogs in packages of ten and buns in packages of eight.....
	Off Topic (Score 4)

Thanks. I try to ignore jerks like #9 as much as possible.

One final word before departing: screw compression ratio.(if it's really epoxy)

Without info, I'm done.

Cheers.

No problem Lyn.

Just had a thought "on existing info" - 10 oz machine - 20 oz part?

Hi Lynlynch,

No critics to no one. It was an amusement to read all comments until the expression "we are smarter" and "jerks like #9". In every blog we have deviations, high percentage, which means absolutely nothing to no one. Why is that way? If we have nothing to say about the subject, it's not necessary to attack the write. Make a joke about the subject and pass your time on something else. Wish you a good weekend, Gil.

Gil,

I think you may be admonishing me for my remark. But, honestly, I cannot understand anything you wrote.

I don't see the expression, "we are smarter" anywhere, so I am at loss to understand what it is that you are trying to say.

Cheers.

Hello Lynlynch,

No, I don't argue with you! The comment is disappeared but was there, who said that they realized that they are smarter than. It's diminishing the collaboration of someone, and it's personality, isn't it? It's not necessary to do in a friendly conversation. Oh, probably this is the cause of un-friendliness!!!

Also, I said that I read with amusement. If you read many comments, here and there, you will realize that it's funny at place of being collaborative or instructive.

It's hard to focus on the subject and harder to collaborate, Gil.

Thanks Gil,

What we need now is for the OP to return and provide more information. Till then it's useless to go forward.

Cheers.

Thanks for your kind reply

I have provided some more details below,

Barrel size:Dia 55MM and L/D ratio: 20:1

Melt temperature:100C

Machine size:160ton

Part:Epoxy Endcapsulation moldind

Thanks

Kumar

Kumar,

The "dent" that you talk of might be due to two separate but possibly related issues.

Firstly, it might be just "shrinkage" where the hot material in the die cools and the last area that sets has material "sucked away" to those areas that cool fastest. The part surface will match the tooling for surface finish, but be generally depressed relative to where you think it should be. The real solution to this usually relates to part design and wall thickness, but there are some options using your cooling temperatures for the tool and the maintenance of appropriate pressure on the material until the gate "freezes" off that can reduce the effect. (There is also consideration of other parameters like propper gate design cross section.)

The other option is that you have a gas bubble trapped inside the plastic as you inject and that collapses as the part cools. This is easily confirmed by cutting a cross section through the parts and looking to see that they are solid. This is often caused by turbulence of the plastic coming through the gate, trapping gas that should go out through the vents.

I suspect that these are more likely than "short shot" since you specifically commented that you have checked the tools and also tried with different material.

Good luck.