Imagine you need to decorate a cake. Easy! You fill a container with a sticky liquid, and squeeze it out into the pattern you want. Now imagine that instead of having 3 minutes to decorate the cake, you've got 0.03 seconds. And the icing is actually molten hot. And you have to put the icing on the inside of the cake, without looking. And you've got to decorate ten cakes at the same time. And the cake is on fire. And if you make a small mistake, the bakery explodes. And if the cake doesn't taste as you planned, you need to buy a new kitchen.
Welcome to the world of plastic injection moulding.
For every single piece of plastic produced, lurking in the corner of some factory there's a mould, or 'tool' that gave birth to it. Simply put, a mould is a block of steel with the negative shape of the plastic part you want to make, into which plastic is injected under huge pressure and temperatures. Inside each block of steel, there's a labyrinth of gates and channels, needles and bolts. And although the actual cutting of steel is performed by an automated machine, the design of the mould and its intricacies are built by hand. Half a degree of angle, or an extra millimetre of length in a channel can make the difference between a mould that works and a mould that fails.
In other words, the men and women who make tooling are simply wizards. And, anyone that tells you that tooling is cheap or easy is lying or ill-informed.
The tools fit into their host injection machine. Bags of plastic pellets, 25 kg at a time, are poured into a container that preheats the raw plastic into a plastic soup. The machine then slams the mould closed, injects the molten plastic via needles into the mould under huge pressure, holding everything in place as the plastic cools, before ripping the metal apart and ejecting the freshly built piece.
Like so many 'simple' processes, there are so, so many things that can go wrong.
The moulds must be pre-heated to high temperatures to ensure the plastic doesn't cool before the mould is filled. Too hot, the piece won't have enough time to cool, and will fail. Too cold, the plastic won't fill the mould. If a shot sticks and you inject on top of another injection, catastrophic failure.
If your mould doesn't close perfectly, at best, your part is junk. At worst, catastrophic failure.
If the gate or channel isn't perfectly shaped, at best, it will have inconsistencies and will probably break. At worst.. catastrophic failure.
Winner's tip: if you're inspecting a moulding factory, look at the ceiling. A poor factory will have its ceiling covered in plastic from every time a mould failed catastrophically.
Even for the most 'simple' plastic piece, creating the perfect tool takes months and costs a small fortune. When everything is finally ready, you set up the machine. Setup takes at least a day. The machine needs to be prepped and cleaned. All plastic from the previous jobs needs to be meticulously removed. Then, the machine needs to be pre-heated. The first shots, at least 20, but often 100, will be junk. Finally, you cross your fingers and hope that the part that comes out is perfect.
If it's not (and it's rare that it is), you need to modify the mould. This involves disassembling everything, pulling the mould to pieces, cleaning it, and then machining the changes.
Want to make a part a bit bigger? That involves removing metal from the mould: you'll probably end up making a custom part that will be used in an EDM machine to etch away at the mould to make the change. This costs time and money.
Want to make a part a bit smaller? That involves adding metal to the mould, which is impossible. So, either an entire section is cut out and replaced (this costs time and money), or the entire mould has to be scrapped and replaced (this also costs time and money).
In our experience, plastic injection moulding is one of the trickiest processes to nail; many, many crowdfunded projects fail at this step.
Simply put: experience and investment.
Team Pocket have been working with the same injection moulding factory for 15 years. On a daily basis, the factory makes precision parts for the aerospace and automobile industry. Its engineers are wizards.
We firmly believe it's unacceptable to risk our backer's trust and money, if we're not prepared to make investment ourselves. All the moulds and tooling are already made, tweaked, tested, and perfected.
PocketSprite required three moulds:
We made five mould iterations to ensure the case and the gameplay are perfect. We scrapped a mould and started over because we found that the select button didn't feel as good as it should. We retooled the A/B buttons by 0.02 mm, because we wanted to add a soft-touch finish to the case to ensure a quality finish.
All in all, we spent over four months and $15,000 USD to perfect the case, buttons and screen, so that we can reciprocate your trust invested in us with an amazing product, delivered on time.
This week should see us achieving the goal of $100,000 USD in backing funds.
Sincerely, thank you. As China comes back from its New Year's holiday, our assembly factory is already cranking up to have the early bird packages assembled and dispatched.
We'll keep you up to date!
PS: If you're interested in learning in closer detail about injection moulding without bad bakery analogies, http://www.custompartnet.com/wu/InjectionMolding provides a great resource.