plastics supplier

[chrislandy]

I'm looking for advice on which type of plastic to use for a project, I need a supplier and potentially some sheet cutting into various shapes... it's a one off project but quite large. There doesn't seem to be any local suppliers near Tewkesbury or if there are, i haven't found them yet!

[Hairy Santa]

Kings Plastics in Bristol, I think they are still around

[benchmark51]

I have used these several times now,very helpful chap.
Not Tewksbury I know, but if your in the area worth a look

City signs,
36 Midland Rd, St. Philips, Bristol, Avon, BS2 0JY

    Tel:  0117 930 0667

[Iancider]

Chris - I have done a lot of work with plastics over the years but don't know your application.  If you want Glass clear use Polycarbonate (Makrolon or  Lexan), Acrylic is cheaper but yellows and brittles with exposure to UV.  If it is opaque sheet the best general purpose material is ABS - tough and relatively cheap.  If you want really tough opaque then use type 6 or 66 Nylon (normally Creamy)If you want tough, flexible and non-stick then use Polypropylene.  PVC is good for indoor model-making and the like and can be bought in different degrees of hardness.  Always seek UV resistant materials for outdoor use.  There are also many composite opaque materials that effectively replace steel and aluminium.  Local supplier - see below - should be several industrial suppliers near Tewksbury due to the aircraft industries.  Most plastics can be cut with a fine jigsaw - use a fine metal blade or a special downstroke cutting laminate blade (teeth face down not up).  Don't let the blade get too hot so a few drips of water can help avoid melting the cut edge.  Blades need to be really sharp and do not force progress.  Thicker sheets are easier to work than thin sheets.

LINK: http://buildingplasticsuk.co.uk/Gloucestershire/Tewkesbury/sheet-plastic.php

Good luck
Ian

[chrislandy]

I need a plastic that is flexible, 6mm or 8mm thk probably and that can be subjected to 90+deg C (typical temp it will be subjected to is 80degC ) in an oven. I was thinking along the lines of PFTE, HMWPE or HDPE ? Also need a small supply of ABS rod, 25/30 dia solid rod.

The main sheet material needs to be non bondable to epoxy and polyurathane resins ideally, I was going to use a release agent anyway but would prefer something that won't create the bond in the first place to make cleaning easer.

I can make the CAD file in DWG or DXF for the linework.

This is only an experiment/research project so trying to keep costs to a minimum

[Iancider]

There is a problem with you combination 6-8mm thick, and oven at 90 degrees with a flexible material.  All such materials will have a softening point/band where the material completely relaxes before melting - 90 degrees is well short of that with all of those materials but at around 90degrees the stress will come out and the materials will buckle quite badly from the unrelieved moulding stresses (flow-patterns during moulding).  If you cool from this point, the shape will set with the buckle.  At the softening point - lets say in the range 220 to 280C for the top and bottom of the materials suggested the whole thing will relax completely to floppy but not melted so the buckle will ease out.  Cycling can be used to ease out stresses like tempering metal but the edges tend to move.  This is true for all of the flexible materials.   

Hard resins however do not buckle and the king in that area is the now rare Acetyl resin. It is a pretty inert hard material and wont buckle at 90C but dont overcook it because it does produce noxious acidic fumes at near it melting point.  HDPE is good if it is well supported  - it will exapnd significantly and does not buckle too much but think tupperware in a hot oven here - it is not inert!  Polypropylene, LDPE and PTFE are all good non stick surfaces but must be supported well to stop distortion in modest heat - e.g. secure to the inside of a box say.  Finally I think you may need a good old fashioned rigid composite like Paxolin - cloth filled resin with a polished surface.  Use release wax, or silicone relase agents to stop sticking.  This and ABS rod are very commonly stocked by almost any industrial plastic stockist.  ABS rod is used a lot in turning so it is easily sourced.  Paxolin is an industry standard for decades.  Just note that paxolin can be a little smelly when heated but otherwise it is inert.  Paxolin is used in F1 cars as skid bases to protect the underside when the car bottoms.

If you are casting, you could have any shape made in a Vacuum form. You will pay a modest about for tooling it but mutiple moulds are then cheap.  The mould would itself then be set in something completely inert like a block of plaster (fibre filled casting plaster would be excellent) and that itself could be in a wooden case to make it easy to handle and avoid damaging the plaster.  Agin use a suitable mould relase and don't rely on the plastic itself.

And one more thought - casting silicone rubber - e.g candle mouling material.  completely floppy so it has to be supported but nothing sticks to silicone if you add a little slicone oil to the surface.  Just make sure you have a draft angle of 1 or 2 degrees to enable release from a hard case or like a candle mould roll it inside out to release the contents.  Silicone Rubbers are safe up to 500degrees C and dont ever buckle under heat.

Regards
Ian

[Sprint 7]

Blimey mate, I thought you were writing your last will and testament for a minute. Amari plastics have always been pretty good in the past when I have been involved in any plastic work.

[chrislandy]

I think we may be talking different levels of flexibility, i need something that can be forced to conform in a mould by vacuum to provide the sides of the mould but can also be used as a pattern on the cutting table.

Max arc radius would be circa 2.5m but variable over 1.5m, I am tending towards 6mm thickness for the finishes part flexibility so 6mm sides would be spot on for the moment!

The project is a wakeboard/kiteboar, hand layup carbon/epoxy foam sandwich construction with possible vac infusion once the first couple have been made.

after the first couple I'll hopefully be looking for a protective surface layer, I've spotted Durasurf for the bottom but is rare as hens teeth in the UK so an alternative? but also need something for the top, would only need to be 0.3ish mm thick, if that, just to provide scratch and UV protection although I have used a spay on surface coat before which may do the job. it would need bond well to epoxy resin and take the heat during the cure period, 8hrs @ 80deg with controlled ramp up and down.

Would polypropylene be inert to polyurathane for casting sections?

[benchmark51]

Yeah,but wouldn't that cause a conflict between the flux capacitor and the foo foo valve?

[Iancider]

PVC is or polystyrene is the normal choice for vac-forming but 6mm is way thick.  Both are very sensitive to solvents and would not like an encouter with PU. Thick materials are thermoformed until completely soft and laid into a mould by gravity alone or use a slight vacuum.  This is not amateur work and is not reliably performed in a DIY situation.  It sounds like you will need it professionally made.  To anwer the second part, polypropolene isn't I believe reactive to Polyureathane. 

Never ever connect the flux capacitor to the FooFoo valve - that would just be nuts! You'll knock your snurglefurge way out of geolock!

   

[chrislandy]

I'm not intending to vacuum or thermo form, I just need it to make the sides of the mould but it must be conformable to the other part of the mould... the process I am using is hand layup composites with vacuum and elevated temperature cure.

This is pretty much what I need to use the plastic for:

www.youtube.com/embed/yadNgaDwyBY

I'm not replicating this but intend to use the mould edge and marking method as the video, the whole lot then gets put in a vacuum bag and cooked.

www.youtube.com/embed/slCG7QO7lvg

I'm going to make mine on the a forming table which has the curvature previously mentioned

[Sprint 7]

I apologise for commenting in a flippant manner, but I didn't realise that the post was of such a serious nature.

[Moleman]

I think it was ok Pete. I think we all took it as a joke. 

[Iancider]

Okay Chris now I can see the project and I understand.  The side guides of templates could be a variety of materials but he oven curing is the critical part.  Most durable would be Nylon 6 and it looks like he is using HDPE.  HDPE and PPE will both have a good waxy surface to prevent resin bonding but both soften early in the oven.  Nylon 6 will go up from 220 degrees C softening point to circa 260 degrees and you can prevent resin bonding to it with mould relase wax or a spray of silicone for each use.  The latter is best when an oven is used because the wax will melt and cause contamination.  The core of the board looks like a dense foamed Polyethylene.  Loved that guy's tooling - impressive.

So any Industrial plastics supplier could do this for you and they generally provide a CNC service is you want it precisely machined. 

[Iancider]

Sprint - what are you apologising for - I thought it was brilliant! 

[chrislandy]

Thanks Ian, as always a fountain of knowledge

I've got a line on the core I'm using and I've modified the carbon layup to suit my application as the loads on a wakeboard are far higher than a kiteboard. I'm used to using TR 104 hi temp release wax so planning to keep using that if possible. I've got the resin and half the worlds supply of carbon leftover from a previous project. I need to use the resin up as it's close to its shelf-life now.

The plan is once the first few prototypes are made that I'll make some tooling similar to the video's as it seem much simpler than chasing with a router for everthing like most other board builders do. Once I've got the shapes correct and hopefully got some buyers I'll get everything CNC'd anyway to take out as much tollerance as possible and setup a small manufacturing plant

I do like a bit of light hearted banter on my posts as they can get a little technical / dry sometimes, so carry on!!

The oven I built, using a CAL 9400 process controller it can control the temperature ramp rate and hold at 80degC +/-1 for as long as I need it to, it's a little small for bonnets and full hard tops but fits pretty much everything else in:

[chrislandy]

As a bit of a follow on and update from before, the first prototype is now demoulded and ready for finishing

It's a wakeboard BTW

It's still not quite finished but getting there,

Spec's: (not that they mean much to non wakeboarders!)
1420 x 445 at midpoint, 300 tips
Approx 3kg (6.6lb) but the next one WILL be lighter (aiming for 2.5kg (5.5lb) or lighter)
10mm concave at midpoint, flat tips
late 3 stage hybrid rocker
wrapped rails at the moment but next board will have PU or ABS rails
Full Carbon Fibre & foam construction using UD, Bi-axial & twill weaves
Foam is 6mm (1/4in) Corecell M80 from Gurit, propper marine foam with decent mechancial properties

This is the foam all measured & cut out with indert positions


Layed up and in the vacuum bag, the next board will have a heated cure in the oven. (The resin I use likes a higher temperature cure cycle)


Demouled and first trim but shows the amount of rocker


Edge to edge concave, should edge well but expect it to be quite unforgiving.


Rocker profile, the camera has skewed the angles a bit as it looks a little squashed


The basic board, first trim done but needs a bit of work to get a decent finish


The concave is quite high so I'm going to have to lay up some extra over the heal/toe of the bindings to ensure it's flat.

Thats it so far once I've done some more work on it and taken it out for a ride, I'll post up the results

[Hairy Santa]

Impressive

[chrislandy]

Got it out on the water on Wednesday (not me riding it by the way!)



And he must have been confident on the board as he tried a Scarecrow... and landed it!

[Moleman]

Nice one. Good to see it worked out really well. 

[Iancider]

Really impressive,

What's next - superstretch bungee rope?!

Ian