Help please with fibreglass & thermoplastic moulding.

[MikeG.]

The reason I have posted nothing in wood for months now is that I am making something in steel & MDF which is a half-scale mock-up for a product I hope to develop commercially.

The final version will be aluminium and thermoplastic, and so I want to know a little more about the process of moulding largish shapes in plastic. I'm particularly interested in the design of the moulds, what they are made from, and any limitations on the shapes they can make. But I am also going to make a full size prototype out of fibreglass to test the thing in the field. Has anyone any experience they can pass on of making stuff out of fibreglass?

Just to give you a clue about sizes......the part will be about 1500 square and 225 deep, and will be essentially a shallow 4-sided squarish tray.

Any advice would be most welcome.

Thanks.

Mike

 

[Oryxdesign]

I think you've got me interested like this before Mike, is it a shower tray? I've got some experience with fibreglass what do you need to know?

 

[Chris Knight]

Mike,
I am sure someone who knows more will be along soon. However FWIW, it sounds as though vacuum forming with a material like ABS is what you will need. Things like quantities will determine the mould material - aluminium for large runs whilst wood, expoxy, grp etc. could be used for smaller runs.

You will need draft angles of around 3-5 degrees to get the parts out of the mould.

 

[MikeG.]

Goodness, you guys were quick!

No, its not a shower tray........its a more commercial variation on this:

This is the second rooftent I have made........I spent 6 months driving the length of Africa using the first one about 14 years ago.

What do I want to know about fibreglass? Well, I've never used it at all, so a from-first-principals description of the materials and processes would be ideal!!! Short of that, some tips and some links would be great.....

As for the moulding plastics (what is ABS?)..........does that mean that it might be possible for me to make my own moulds?

Mike

 

[Chris Knight]

Mike,

ABS is described here http://en.wikipedia.org/wiki/Acrylonitr ... ne_styrene

I worked at a car company that used it for all sorts of stuff like airboxes etc. We also did GRP (fibreglass) in great quantities. GRP is simple in concept and depending on the size/shape easy enough to do. You can make moulds with it (for GRP products too) and finished articles - eg car bodies. It is easily coloured by using a coloured gelcoat.

There will be a ton of stuff on the web for general background. You can also buy small GRP repair kits from auto stores. I suggest you get one and have a play with it to get a feel for the process.

 

[jasonB]

Mike, I get my fibreglass from these people, have a look at the project Info section on how to make moulds and lay up the GF.

Jason

 

[Oryxdesign]

I use these guyshttp://www.cfsnet.co.uk./

 

[MikeG.]

Thanks guys for all the fibreglass stuff.....it doesn't sound too complicated (although I haven't yet worked out whether I make this thing inside a female mould, or outside a male mould. I'll keep reading......
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I'd love to hear some more on the thermoplastics.....

Cheers

Mike

 

[Oryxdesign]

Have a look at thishttp://www.peterheadacademy.aberdee...ics Properties & Processes/Vacuum Forming.pdf

 

[MikeG.]

Thanks OD, but all I got was a 404 error message......

 

[Oryxdesign]

Not sure why the link still works for me.

 

[wizer]

Thanks OD, but all I got was a 404 error message......

Have a go at thisMike

 

[MikeG.]

Not sure why the link still works for me.

I've worked out why. It's because I am an silly person!

I hadn't spotted that it was a PDF, which with Firefox seems to need to be opened by "saving as" rather than double clicking.....sorted now, and looks just the job.

Many thanks!!

Mike

 

[MikeG.]

I would just like to publicly record my thanks to Roy (Digit) who has sent me 7 private messages on the subject of thermoplastic moulding, despite not being well. These have been enormously helpful.

Many thanks Roy....hugely appreciated.

Cheers Mike

 

[Digit]

Roy.

 

[MooreToolsPlease]

Rather than start a new thread, could anyoen advise me on how fibreglass is bought?
I've had a look at the links provided within this thread, and it seems that its bought in kilos, in 300, 450, 600 thicknesses, usually 100cm wide.
Can anyoen tell me how long a roll is in these thicknesses?
I'm in the process of making a water filter for my spraying, and need to make a trough 3.6 metres long and about 450mm wide and 300mm deep.
ANy clues?

thanks

 

[Digit]

Hundreds of metres if you are a commercial user.
Try these...

http://www.ecfibreglasssupplies.co.uk/s ... 3_102.html

Roy.

 

[agbagb]

Mike,
To chose internal or external mould for fibre glass, you need to choose inside or outside to look smooth. It's a good choice for prototypes as you can easly add bits, reinforce and modify. Last thing I made was tube for a telescope, very much a working prototype with extra bits of steel moulded in where needed to give stiffness.

Mooretoolsplease,
I haven't got details of a recent supplier but in the past I've used mats of various thicknesses and fibre sizes around 1200 wide and as long as needed. You can also get woven glass fibre sheets and tapes.

Andy