jennarivo Posted September 17, 2011 Share Posted September 17, 2011 Hi everyone Strictly speaking this isn't a railway related question, but i can't think of a better place to ask. I am working on a project at the moment that requires a few hundred dimensionally identical small transparent plastic lens covers (approx dims 15 x 4 x 2mm) in various colours. My initial thought was to have them injection moulded, but I am struggling to find a supplier that can produce the tooling at what I consider to be a reasonable cost. Can anyone point me in the direction of a low cost injection moulding outfit or if anyone knows of any alternative manufacturing options that may be available to me? Any suggestions would be welcomed as without this component my project is completely stumped. Thanks in advance Link to post Share on other sites More sharing options...
micknich2003 Posted September 17, 2011 Share Posted September 17, 2011 In the "Model Railway News" Colin Binney described how to make and use an injection moulding machine. This was sometime in the '60's, may be worth your while following it up. Best Wishes, Mick. Link to post Share on other sites More sharing options...
Titan Posted September 17, 2011 Share Posted September 17, 2011 Coincidentally I have recently been looking at injection moulding with a view to comercial production of a range of items for OO. The most expensive part of the investment by far will be getting the moulds made. They are not cheap!!! I would have to shift 1000 packs of ten before I recovered the cost of the mould and started to make a profit!! I would expect that unless you want very high numbers injection moulding would not be cost effective, Although in your case you would probably be able to use the smallest mould, and it would not be too complex. I would still expect the mould to be a four figure sum mind! Link to post Share on other sites More sharing options...
Etched Pixels Posted September 17, 2011 Share Posted September 17, 2011 You don't get moulds made cheap unfortunately. It's a hefty lump of machine cut and/or spark abraded metal to very high precision and which can take very high pressure. Depending on the actual shape you need you might want to try talking to some of the packaging suppliers. Things like generic bottle tops perhaps ? Link to post Share on other sites More sharing options...
Guest Natalie Graham Posted September 17, 2011 Share Posted September 17, 2011 In the "Model Railway News" Colin Binney described how to make and use an injection moulding machine. This was sometime in the '60's, may be worth your while following it up. Best Wishes, Mick. Colin Binnie's article was in four parts, June to September 1968. Link to post Share on other sites More sharing options...
Guest baldrick25 Posted September 17, 2011 Share Posted September 17, 2011 For what is really a small quantity of parts , take a look at a Reprap or cupcake 3D printer - OK might take a couple of days , but depending on size , they could easily have the 3D image reworked to print 4 at the same time. It might have a lot of advantages in that the 'moulds' ( 3D files) could be tweaked to give a MK2 , MK3 etc, and show possible avenues to explore in future work ( and more brownie points), with real samples, not just sketches on the back of an envelope. Link to post Share on other sites More sharing options...
BobD Posted September 17, 2011 Share Posted September 17, 2011 Injection moulding is very expensive for small quantity runs. The cost of the tool (mould) is a high value cost, but aluminium tooling is cheaper than steel. If you can find someone willing to do it, youcan get a resin mould, suitable for the temperatures for injection moulding. How many is a few hundred, 300, 500, 900....................... Link to post Share on other sites More sharing options...
bigherb Posted September 17, 2011 Share Posted September 17, 2011 You could also look at companies using rapid prototyping machines. Link to post Share on other sites More sharing options...
hollywoodfoundry Posted September 17, 2011 Share Posted September 17, 2011 The OP needs transparent plastic lens covers in various colours, and you do not normally get to choose the colour with the materials used in rapid prototype production. Link to post Share on other sites More sharing options...
34theletterbetweenB&D Posted September 18, 2011 Share Posted September 18, 2011 ...Depending on the actual shape you need you might want to try talking to some of the packaging suppliers. Things like generic bottle tops perhaps ? Similar thought: is there anything in existence that you are aware of that matches the component you are looking for? You may have to compromise on dimension and shape for 'close enough' ; and if such a tool exists then there is the little matter of negotiating a price with the owner to allow it to be used for your multiple colour shots. Where to look? The little lenticules used for light up shoe soles, small panel indicator lights, lights fitted to large size toys, possibly fashion clothing, there was quite a vogue for translucent plastic in dresses a couple of years back, costume jewellery makers, fancy dress makers. There must be more, but those are a few to start with. Link to post Share on other sites More sharing options...
RMweb Gold kipford Posted September 18, 2011 RMweb Gold Share Posted September 18, 2011 You need a standard plastic protective cover. See if these people have what you want. http://www.mossplastics.com/plastic-caps-plugs--bungs Dave Link to post Share on other sites More sharing options...
jennarivo Posted September 18, 2011 Author Share Posted September 18, 2011 Thanks for all the pointers guy's, unfortunately i am tied by the dimensions so can't really go for the next closest thing. Prob only need about 400 parts max. I do have a couple of tooling quotes that arein the 3 figure bracket (just) so perhaps this may be the best option, not really sure about the 3d printing as i'd hate to invest in something like that and not be able to work it. i'll maybe ponder for a wee while yet before i decide which bullet to bite cheers Link to post Share on other sites More sharing options...
Atso Posted September 18, 2011 Share Posted September 18, 2011 You could try using 3D printing and then having the parts cast in clear resin which can be tinted to your required colours. Most casting services ask for a minimum order of 50 parts so might be an option. Link to post Share on other sites More sharing options...
RMweb Gold kipford Posted September 18, 2011 RMweb Gold Share Posted September 18, 2011 I do have a couple of tooling quotes that arein the 3 figure bracket (just) Even for a simple mould tool that is not bad, as previously mentioned an Aluminium tool would drop the cost a bit more and would be good for at least 500 parts. Give these guys a ring they specialise in development parts and do small runs http://www.hitechltd.com/ Dave Link to post Share on other sites More sharing options...
RMweb Gold Donw Posted September 19, 2011 RMweb Gold Share Posted September 19, 2011 At one firm I worked for there was a small injection machine basically a strong tube with a heating element around it and a ram to push the plastic down ( operated by a lever. This feed through a nozzle to the moulds these were made from aluminium and clamped in place. The device was used to mould covering caps onto the ends of heating tapes. I know others have made such machines for modelling Stewart Hine and Colin Binnie are names that come to mind. Don Link to post Share on other sites More sharing options...
hollywoodfoundry Posted September 19, 2011 Share Posted September 19, 2011 The problem is not the machinery to do the moulding, it is the cost of the die you need to have made. There are some techniques to reduce this cost, but the vast majority of the cost is in human labour. Simply put, it takes many, many hours to make a good die. Once you have the die, running the parts off is dead cheap. Link to post Share on other sites More sharing options...
Marty Mc Posted September 19, 2011 Share Posted September 19, 2011 Hi Unless I am missing something here forget about injection moulding. By the sounds of it all you want is a disc with 3 dimensions. 400 is a very small batch run for a standard 2 axis CNC. Dont be surprised if a couple of places turn you away. You can purchase acrylic rod with many different colours. Dont skimp on the material and read the spec's to see if it suits your needs. Japanese grades are usually the best so find rod which had being manufactured using good quality resin. Finally find an engineering workshop that specializes in machining plastics who can also offer a polishing service. Martin Link to post Share on other sites More sharing options...
Etched Pixels Posted September 19, 2011 Share Posted September 19, 2011 Second that - some machines are cheap and old hand operated machines, particularly ones that need fittings and tubing replaced can be picked up at pretty much their scrap value. Link to post Share on other sites More sharing options...
RMweb Gold Happy Hippo Posted September 20, 2011 RMweb Gold Share Posted September 20, 2011 Sorry If I've got this wrong, but the OP wants a 15mm x 4mm x 2mm rectangle of plastic, not a disc as some posters seem to assume. Have you considered laser cut perspex instead of casting or injection moulding? Regards Richard Link to post Share on other sites More sharing options...
Guest Natalie Graham Posted September 20, 2011 Share Posted September 20, 2011 How about resin castings using coloured clear resin? That is well within the scope of the home workshop. Link to post Share on other sites More sharing options...
Marty Mc Posted September 20, 2011 Share Posted September 20, 2011 Hi I think your right Richard, it was the lens, I just assumed round. Sorry If I've got this wrong, but the OP wants a 15mm x 4mm x 2mm rectangle of plastic, not a disc as some posters seem to assume. Have you considered laser cut perspex instead of casting or injection moulding? Regards Richard Agree laser cut is a great option check their working tolerances..... or again a plastic specialist that has a good CNC router with a vac table. Cheers m Link to post Share on other sites More sharing options...
jennarivo Posted September 21, 2011 Author Share Posted September 21, 2011 sorry should have been clearer, part required is indeed rectangular. quite a few idea floating round in my head now, i do like the thought of home resin casting sounds like a much cheaper option. Must find out more cheers Link to post Share on other sites More sharing options...
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