How to Make a Flange For this Part

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#1

First different views of the part:



I need to make a mold that will not shrink or distort in any way. The mold is going to be used for production purposes it needs to hold up to at least 20 runs but 40 runs would be preferred.

I have a mold created for me from several different people in several different ways, but none have worked properly.

So my first question is: What should i do to fill in the spacing so that i can make the mold?

I was thinking of welding some sheetmetal from the inside to make a large lip, but matching the radius would be difficult

#2



the rest of the pictures. I know that two of the mould makers used clay to fill in the spacing.

#3

i would just use cardboard and foil tape for the flange, that is the practice I use on a daily basis. it seems pretty starit forward. Are you needing to do the underside as well and attach the 2 pieces?

#4

Is .001 shrinkage to much?

Epoxy Casting resins have very little shrinkage and can be cast up to three inches in a single pour.

An aluminum filled version is what I was thinking.

#5

The underside is not necessary to mold. I am just going to make a mold for the outside.

How exactly would you use cardboard and foil tape?

JRL: is there really such a thing and aluminum filled epoxy resin?
my tolerance would be about .005" so .001" shrinking would work.

I am a bit more interested on filling those gaps PROPERLY. I dont see how card board and aluminum foil tape would make a sturdy flange?

#6

Is there an inexpensive foam that i can purchase that i could cut to the shape of the inside of the panel? That way i could glue or bolt the foam to the inside of the panel, place the assembly onto a large piece of sheet metal, Seal the foam pours up and then lay down my material and resins onto that.

some foam sites i found were:
http://www.foambymail.com/ specifically: http://www.foambymail.com/EPS2.html

has anyone ever used foam? what are some other options with some more details as to how it is all done?
What about balsa wood? this seems to be a very time consuming material and would still be flimsy.

#7

The foam your looking for is a polyurethane foam board. I use it often when shaping plugs. You can spray duratec directly on it with out sealing it.

Heres the aluminum filled epoxy I was talking about:
http://www.freemansupply.com/Freeman801Aluminum.htm

Probably a little pricey for what your doing though.

EDIT: The reason why I recomend foam board vs. the stuff you mix on your own is the consistancy. The bubbles will be extremely small and uniform (easy to seal).

If you do decide to go the a/b foam route and mix it yourself make sure you mix it with a drill and a paint mixing attachment. Then have a bucket of acetone handy to clean the mixer.

The results of mixing with a drill is night and day vs. mixing pour foam with a mixing stick.

#8

I decided to give the cardboard and tape method that was recommended a try.

heres what i used:
White duct tape
Cardboard from a cardboard box

Keep in mind that this section will be excess material removed BUT, a bad flange could make removing the part a nightmare. here are my concerns using card board tell me what u think:

this image shows how a long strech of cardboard would cause a problem because the cardboard leans over. This would create a skirt on your part once it is layed up. Maybe not a direct problem but, when the plus is vacuumed the cardboard is likely to move all over the place.

My concern here is that the tape would essentially change the dimension of the mold slightly because of the thickness of the tape, this is not so crucial. What i see a problem occuring it being able to coat the tape with a release agent (wax or a spray liquid).

In this image the cardboard does not shape well with the radius. this is obviously not a noticeable problem because this amount of material will be cut off. But, this mis shape could affect the area of the radius on the plug. A larger concern would be the mold would have an angle on the edge creating a very difficult time to remove the part.

This image is to show that i taped the front, the back and stuck the cardboard on with double sided tape.

#9

Where do u purchase your polyurethane foam board from?
Would i be able to secure the foam to the inside of this panel causing the foam to take the same contour (large radius) of the panel?

Again my concern is:
putting the foam inside of the panel will make a negative region mkaing it very difficult to release the part once it has been layed up inside of the mold.

To avoid this you would have to sand a recess into the foam so that when the foam piece is inserted into the panel the widths are the same creating little to zero step.

I am referring to a cross section of the mold looking like this on once side

LLL
II
JJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJ

the J’s represent the bottom of the mold. The I’s rep. the mold edge that would touch the panel.
The L’s Represent what would happen to the mold if the foam was a bit small in width than the panel.

#10

Glad to see you trying to do this yourself but your flange is all wrong.

You want your flange to flare out away from the part at least 45 degrees.

I cant see how youll make a flange work like youve got it.

As far as shrinkage, you can mix various stuff into resin to control it but I still cant see how you would be able to measure .005 on a car body panel and have it make a difference.

If your mold is built correctly you wont have much problem with that.

#11

I was showing an example of a cardboard flange and reasons why I dont like to use them.

What material can i use to flange this part? How can i attach the flange to this part?

Should i use some aluminum sheet metal instead? I have all the sheet metal tools to roll, break and shear.

ALSO: I found some inexpensive Polystrene 3 lb foam. Do u think that would be a good way to build a flange?
I was thinking i could use an entire piece of foam placed on the inside of the panel that way i can lay the entire assembly (my panel with attached foam) onto a piece of sheet metal and start laying the material onto this plug.

What are my options? Why do i NEED a 45degree angle for the flange?

#12

I dont like foam board for flanging unless Im working with a really flat part as it is.

You dont need to have any angle but most of us build our flanges at 45 to 90 for ease of working with the mold and infusing.

Youll see that making a straight flange like you had in cardboard would kill you trying to remove the part.

Id use aluminum flashing and epoxy to make the flange.

#13

I am just trying to fill the empty space. I am going to lay everything down on a peice of sheet metal and that will be my flange.

I’ am trying to think of a way to fill the dead space before the flange.

Look my first pictures and yuo will see the dead space i am referring to.