Plastic injection moulding

[trent_julie]

Hello,
I am developing a device that measures 130mm x 50mm x 50mm. I have had success using my 3d printer to make prototypes that have been successful. My printer isn't any good for production rates so I am looking to invest in a mould. I know from hear-say that they can be expensive. What I am wondering is if anyone has any specific experience in making moulds or has a good point of contact. I hope to use ABS plastic or equivalent.
Cheers,

Trent

[MikeyB]

What you are looking for is usually referred to as a 'die', not a mould. Moulds are for pourable castings, whereas injection moulding uses high pressure as well as heat, to force the molten plastic into the cavities of the die.

My knowledge FWIW is more than 30 years out of date now, but in those days steel die-making was amazingly expensive - starting at tens of thousands of dollars and often running into hundreds of thousands (or more), for very complex, multi-item dies. I have seen lower cost, short-run dies made from cast aluminium, but those were only for disposable items where precision quality was not a requirement.

ABS is an engineering plastic and one of the more difficult materials in use for injection moulding, requiring pre-drying and precise temperature control. I think you will need a high-precision steel die if it is to be your chosen material.

An injection moulding company will be able to give a better idea of current costs and requirements, as well as the range of materials available that would suit your purpose.

[gary]

Hi Trent,

If you are building anything electronic, don't even start to think about the expense of
designing enclosures and ejection molding before you have CE, FCC and C-Tick
compliance or at least pre-compliance. That means a gauntlet of tests by a NATA
accredited lab such as EMC Technologies here in Sydney. Be warned, it is
extremely expensive but without the compliance folder backed-up
by an accredited lab, you can't legally sell in just about the whole western world.

The reason for dong that first is that if you require additional shielding but have
already designed and tooled a plastic enclosure, you will be blowing a lot of money
if it can't be retro-fitted.

Designing the cores and cavity for injection molding requires lots of expertise and
years of experience. Forget anything you know about 3D printing being carried
across. Draft angles, ejector pins, movable cores, shrinkage and a mind boggling
array of complex technologies, techniques and hard-won skills come into play.

Consider the task of the humble industrial designer. Many people see
industrial design as being the outer appearance of a product. But the
complex, subtle intricacy of how it is to be successfully, reliably and consistently
injection molded is where the real skill and experience is required. A good industrial
designer is thinking ahead as to how the tool maker will make the tools and how
the injection equipment used will operate. Sometimes there are moving parts
in the process. When you talk to an industrial designer, they can point out the
subtlest of details they have incorporated into some inner part of an enclosure
that the general public will never see but can make a world of difference as to
whether the enclosure is going to fit together or otherwise be too structurally
weak at a certain point. Where most of us are thinking in terms of some static
object, these guys are thinking in terms of plastic flowing into the tools and
how it is cooling and so on. They see the fabrication of an enclosure as a
dynamic process, almost like it is a living thing.

So there is the expense of the industrial designer, the expense of the tool maker,
the expense of the tools (sometimes half a ton of steel can be involved in the
tool for a plastic enclosure you can hold in one hand) and the cost of the molding
itself. Prices have come down over the years but are still not for the feint hearted.

Getting back to the industrial design process for one moment. Consider the humble
lunch box. About as easy a shape as one can imagine. The box itself typically has
a natural draft angle. But consider that sealable lid for one moment. It is often
features like that, which we take for granted when we peel off the lid
and eat a fresh sandwich, that an industrial designer and a tool maker know how to do.
For the rest of us, we would eventually figure out how to do it too, but only after
dozens of iterations and millions of dollars.

[GeoffW1]

Hi,

R E Davison at Lindsay St Rockdale

Roblan at Catherine St Leichhardt

Bell Dies at Beaconsfield St Revesby

These have been in business for years and years, and are top-line. I agree with Gary though, brace yourself for the cost of it.

Yes, there are several types of short-run low-cost die around for prototyping and approvals trials.

Good luck.

[jjjnettie]

I suggest going to an injection moulding factory, and asking them who they suggest you use.
I used to work in the industry many years ago, our factory held the moulds to various products for companies such as Rover Mowers, Baileys Ladders and Qantas (serviette rings, plastic cuttlery)
There are good mould makers and ordinary ones. An ordinary mould means more work post production, trimming and filing back bits of sprew. So you get what you pay for.

Gary bought up some very good points in his reply too.

[trent_julie]

Thanks everyone!
The bulk of information provided here is a testament to the both the quantity and sheer diversity of knowledge available at the drop of a hat.

Mikey,
Thanks for the tips. I will avoid ABS for any production version. Price is a factor, I just hope that it isn't going to be a ruling factor.

Gary,
Thanks for your in-depth reply. Although I have not designed an electronic device this time, I have no doubt that I will draw upon this information in the near future. I hadn't considered the lunch box analogy for plastic injection, but I can easily relate to it. With the work that I have done on the prototypes on the 3d printer already, I still wouldn't call the device complete. This is after this many hours, and 10's of versions already. Cost can be a real killer of invention, but I can respect that it needs to be worth while for all members involved. And when trying to cater for the amateur astronomer market prices have to be kept to a minimum. Thanks again Gary.

Geoff,
Thanks for the POC, I might drop by there tomorrow, at least to get an idea of price rather than discontinue my efforts though fear.

JJJ,
Thanks for the reminder on quality, I guess there is a fine balance between investment capital and quality of part. All I need made essentially is a shape/object so it would be interesting to see how much of a variance in quality there could be. But, having said that, spending 10 minutes cleaning each object would not be worth my while in the long run.

All up I still think I should try to get a short run of these objects made up at least. The few people that have using them seem to be impressed, I just hope that I have captured a large enough sample of amateurs to get a feel for demand. Fingers crossed......

Trent

[gary]

Hi Trent,

Here is my 3000th post, so hopefully it says something worthwhile.

If your requirements are very simple, then guided by the injection molding factory,
you might be able to stick to just a few design rules.

* Make the walls a uniform thickness, the optimal dimension of which would be advised by the factory. Thinner is easier than thick.

* Radius all corners inside and outside to at least half of the wall thickness. This will help flow.

* They need to easily eject the part and what can help are generous draft angles.
The factory will advise, but if you can get away with somewhere between
1 to 5 degrees for the sides, it would probably keep them happy.

If you create a 3D CAD model and then make a 3D print prototype with the above in mind, you will be part of the way there.

[Poita]

What sort of volume are you talking for a production run?

[trent_julie]

Hi Gary,
Congrats on out 3000th post. I will take heed of your advice, and add it to my notebook of how to design things.

Peter,
This is my usual small quantity, I am looking at getting 50 made for the first batch. I am currently working with a manufacturer to achieve a quote. But no commitments have been made.

Trent

[Ausrock]

Trent,

I work in a small composites R&D company in Newcastle. The product(s) we've developed slot into the void between Thermosets and Thermoplastics and can be used for both rotational and injection moulding as well as open casting. As they're based around both poly and vinylester resins, they are catalysed as normal prior to going into the mould.

Small scale production is one of the great advantages as there's no need for the high costs involved with Thermoplastic moulds, etc. That said, the fact is that the end product is only as good as the mould it comes from which in turn is only as good as the "plug" used to make the mould..........I have made a number of moulds from both casting silicons and f/glass, both have their advantages but I will say no more without having more knowledge about your specific project.

Feel free to PM me if you wish to have a chat BUT I must warn you.........at the end of August we lost our factory in a fire and are in the process of re-establishing a new facility (laboratory and production).

I have attached a pic of a dashboard made from our "stuff" FYI.

Cheers.

[trent_julie]

Cheers Chris.
PM sent.

[jhmouldindustry]

hello friend


how are you ,i am danny working for www.jhmouldindustry.com



how are you ,i am danny,we are plastic injection,rapid prototype,precision parts,product design development and moulds factory in china, if you interested in our

products , feel free to contact me ,hope receiving your early reply.





sincerely



--------------------------------------------------------------------------------

best regard

jiahao mould industry limited

add:first industrial park,yulv village,gongming town,baoan district,shenzhen,china.

tel:0755-36602010
fax:0755-36602011
phone:18207554948
contact person:danny wang(sales manager)
skype:wangzhongbing2010

web: www.jhmouldindustry.com

[jhmouldindustry]

hello trent

i am mould maker from china,hope you everything goes well.

sincerely

danny wang

www.jhmouldindustry.com

[jhmouldindustry]

hello


how are you ,i am danny working for www.jhmouldindustry.com



how are you ,i am danny,we are plastic injection,rapid prototype,precision parts,product design development and moulds factory in china, if you interested in our

products , feel free to contact me ,hope receiving your early reply.





sincerely



--------------------------------------------------------------------------------

best regard

jiahao mould industry limited

add:first industrial park,yulv village,gongming town,baoan district,shenzhen,china.

tel:0755-36602010
fax:0755-36602011
phone:18207554948
contact person:danny wang(sales manager)
skype:wangzhongbing2010

web: www.jhmouldindustry.com

[trent_julie]

Hi Danny,
I have employed a manufacturer to build these parts. Thank you for your interest.

Trent

[Ausrock]

Trent,

Apologies for not getting back to you before this. Our engineer had been looking (and playing) with options based on the info you sent me, however with the pressures of developing a new product, demands of existing clients, teething problems with our new CNC, assisting me to rebuild our facility and the interuptions of the "silly season", available time has been limited. We saw a number of issues with the existing design that would have to be resolved to keep mold costs down but to date haven't come up with viable solutions that would meet your requirements........ie: minimal time for mold set up and injection, finished product out of the mold.

Regards,

Chris