Injection mold design

We have been working with press molds (for the rubber parts) for a few months, but now our first injection mold is being prepared. This is also our first experience ever with injection mold design.

Finally we have understood the reasons behind the very high tooling costs. The mold is very big and heavy (it's made of steel), and a crane must be used to move it around. The part below is just a portion of the mold.









Here's how the parts are positioned. You can see the receiver, remote control and the DL2K-LINK.



The receiver's holes are undercuts. A sliding mechanism must be used to produce these holes. Many more moving pistons must be precisely oriented in order to push the plastic out of the mold from the bottom when the plastic has solidified.



The mold is really not a static piece of metal but a robotic system including many big steel moving parts. Most of which are completely custom.



Hand positioned parts (inserts) for our problematic third hole for the arousal inducer (not enough space there for a sliding part)



Then... because we've asked Jason to overmold the brass inserts to allow you to open and close the receiver an unlimited number of times, these must be positioned manually (not shown), and material flow must be planned so that inserts are not displaced.

Another two views of the undercuts:





This is the whole bottom part of the injection mold.





The mold includes a cooling system (shown in blue).







Our mold's construction plans are already being passed back and forth between engineers who're studying them like a bank's floorplan.







The drawings are getting a bit messy with all this oil but the finished parts will be perfectly smooth and squeaky clean. It will be a big improvement from the machined parts you've seen so far!!

That's it. This is the result of two years of work and effort, and we're so excited to see it all coming to life before our eyes. We're also relieved to see that we're really getting our tooling money's worth! The mold wasn't just a piece of steel with some holes into which plastic is poured like molasses, as we previously naively thought as we cursed injection molding factories for their "insane" fees. No wonder tooling fees are high... they're building us a little steel robot here with lots of moving parts, precisely designed with fluid dynamics, cooling and who knows what else in mind - and it's so heavy they need a crane just to move it around! :)

Is this cool or what?

Comments

By sub-eli at 2010-07-02 14:42:53 Reply

Way cool. Definitely moving into reality. You ought to be able to get a set of parts every few seconds with that.

By Henry at 2010-07-02 20:45:46 Reply

What a scary user interface on those screens -- the Space Shuttle must be easier to operate!



BTW thought you guys had left China.

By dreamloverlabs at 2010-07-02 21:22:17 Reply

That's Unigraphics a CAD package by Siemens. Still here in Guangdong and now the temperature is over 35 degrees with 99% humidity, absolutely unbearable. Trying to plan an escape for a couple weeks while the mold is being produced but it's very very tempting to just stay here and take pictures and movies of the mold being CNCd, spark finished, polished...

By Henry at 2010-07-04 07:28:41 Reply

Other screenshots of Unigraphics don't seem quite so intimidating, may be it's the Chinese hieroglyphics that make it worse.



I didn't realise injection moulding was so complex. But presumably once the mould is ready it's easy to scale from 1000 to 1,000,000 units. Actually, the thought of that many units in use around the world is a little unsettling!



Good luck in the hot factory in that heat. Perhaps you can find one of these on ebay :-D

http://www.hightechscience.org/portable_cooling_unit.htm

By fgordon at 2010-07-13 17:42:23 Reply

Wow, 10 days with no update! I hope you guys are OK...

By dreamloverlabs at 2010-07-13 17:44:14 Reply

Just waiting for the mold to be completed...

By Frank Hilbert at 2010-07-15 22:19:58 Reply

Thanks for blogging about this, because I had no idea what was involved with injection molding, and it really is interesting. Not just this mold either -- I am enjoying reading the whole engineering story. The design part would have been cool too, but the manufacturing saga is enjoyable to follow on its own. It's the kind of thing that helps one appreciate that engineering is a creative discipline too, like painting or architecture.