How thick should the mold be and does it need flange area reinforcements?

[Jonathan Muller]

Hello! I want a question! I want to make a mold and let's say I want to make 1000 pieces off the mold with a thickness of 4mm! How thick should the mold be and does it need plywood reinforcements in the flange area?

 

[gonzo]

Is this a mold for fiberglass? 1000 pieces is probably not realistic.

 

[Jonathan Muller]

Is this a mold for fiberglass? 1000 pieces is probably not realistic.

yes!It is for fiberglass!

 

[gonzo]

It depends on the size of the part and the shape. Also, the expected quality has an impact in the mold design and construction.

 

[Jonathan Muller]

It depends on the size of the part and the shape. Also, the expected quality has an impact in the mold design and construction.

Small and medium parts with a good draft angle and the majority of them will be with round shape!

 

[wet feet]

I agree with gonzo,1000 pieces is quite ambitious and for a novice to tell us that it is possible while asking for advice on the topic of mould construction is a bit unusual.If you have a real need for 1000 pieces you need to take care about storing the plug because you are likely to need it again long before 1000 items have been made.

 

[Jonathan Muller]

Thanks for your answer!I'm really a novice in building moulds so thats the reason why I'm asking!So let me reformulate!How can I build a strong reniforced mould for making as much as posible parts out from it??

 

[rxcomposite]

We are lucky to pull out 35 pcs on a mold made of poly before repairs (to the mold) start to become necessary. It is the cyclic heat of part curing that damages it plus the tapping of mallet to release deep drawn parts. However, we have used a good quality, high temperature tooling mold resin that lasted up to 350 parts (simple low curvature panels) before it showed signs of fatigue.

The flange are for alignment purposes only and a means to initiate part release. 3 to 4" will do. It should also stiffen the mold when external mold stiffeners/frames are added in.

Thickness? Manual says it should not be thicker than the part to be made/ I make mine 20% thicker or enough to make it stiff.

 

[wet feet]

I always discourage the use of mallets to achieve a release-but sometimes it is necessary.Since the part in question is described as small you could probably get away with a laminate of 1st ply 300gsm then 3 plies of 600gsm.Don't overlook that you will need it to be stable while being laminated and you may need to add support framing to hold it steady.This needn't be bonded too securely and for parts that were seeing low prepreg temperatures I have used a good bead of RTV mastic/glue to allow a little movement.

I would endorse the suggestion that a few dozen parts will lead to signs of deterioration and will add the comment that for huge numbers,it is quite common to take a heavy laminate from the first mould and to laminate it in several stages so that when released it can become the master plug for a second generation of tooling.There was one such stored in a cave beneath a Swiss mountain,and it may still be there for all I know.

 

[Jonathan Muller]

We are lucky to pull out 35 pcs on a mold made of poly before repairs (to the mold) start to become necessary. It is the cyclic heat of part curing that damages it plus the tapping of mallet to release deep drawn parts. However, we have used a good quality, high temperature tooling mold resin that lasted up to 350 parts (simple low curvature panels) before it showed signs of fatigue.

The flange are for alignment purposes only and a means to initiate part release. 3 to 4" will do. It should also stiffen the mold when external mold stiffeners/frames are added in.

Thickness? Manual says it should not be thicker than the part to be made/ I make mine 20% thicker or enough to make it stiff.

Thanks a lot for your answer!!What type of high temperature tooling resin are you using!Can you show me the product link?Thanks

 

[rxcomposite]

Thanks a lot for your answer!!What type of high temperature tooling resin are you using!Can you show me the product link?Thanks

It is rated at 250 degree C, forgot the brand as it is a long time ago. We are also using it for oven cured prepreg.

 

[rxcomposite]

I always discourage the use of mallets to achieve a release-but sometimes it is necessary.

Yup. Use it as a last resort. Wood or rubber mallet only. Tap in several places, not in one spot.

 

[ondarvr]

Use AOC MoldTru for the resin, VE tooling gel can be difficult to use, but if done correctly lasts longer. I'd make a mold or two with easier to use products, maybe just general purpose resin because it's cheaper and you'll probably mess up the first time or two. Plus after you make the first mold you'll probably want to make changes for the next one.

 

[Jonathan Muller]

Hello! Thanks for your answer!!I made this test with 3 molds and I got better at it!And now is time to build the real ones and I try to find out how can I build them (how many layers, how thick, what resin etc) for lasting longer and for demoulding many parts from it!I'm liveing in Europe and I'm not sure I can find this type of resin AOC MoldTru!I'm trying to use UNI Mould System from Easy Composite I don't know if will work for demoulding 100 pcs out of it??

 

[comfisherman]

How big of a part are we talking? Can think of some billet molds that have to be near that number.