|
2013-01-08 The
first day of tours started and it was an amazing experience. I've never
been really super interested in the process of injection molding but
after seeing how things are done, I found the subject fascinating. We
started the day off taking the van to an injection molding factory. The
owner of the factory welcomed us with open arms and surprisingly allowed
us to take pictures inside the facility. Our first stop was a
meeting room where the owner brought out samples of injection molded
devices for us to examine. Coleman, an injection molding expert from AQS
(a contract manufacturer that's helping us organize the tours) and
Bunnie were explaining how the parts were made, the materials, finish,
what decisions went into making the mold, defects, and identifying the
markings from the different parts of the mold. I was impressed how much
information could be had just by looking at a plastic enclosure. They
were able to reverse engineer the design tradeoffs that the designers
had to make, some bad decisions, and were easily able to approximate the
cost of the tooling and cost per part.
After we had the discussion and an intense introduction to
plastic injection molding, we headed to the tool & die shop where
they make the tooling for the injection molding. The tooling is the
actual steel mold that you specify to the shop for the enclosure that
you want. You would normally send them your design files and an engineer
from either the injection molding shop or the contract manufacturer
would review the files. They'd make recommendations on how to modify the
design files to improve yield and make the design more robust. From
there, it'd get sent to the tool and die shop to have the design cut out
of steel. One thing they cautioned on was that they were able to cut
the steel molds on site, but the mold blocks which hold the molds are
usually custom designed and outsourced. These have a lead time and
during a busy period, could extend up to a few months. So as soon as
they design size is fixed, they recommended to pre order the mold blocks
to make sure they're reserved. Then have the mold and tooling made. The
tool and die shop was amazing. I had no idea how massive the tooling
was just to make a simple enclosure. The tooling is cut out of steel
using CNC, EDM (Electron Discharge Machining), and manual milling. Each
steel mold can weigh a ton or more and requires a lot of manual and
automated work. Depending on the finish, the molds also need to be hand
polished. To tool and die shop consists of a lot of heavy metalworking
equipment. The steel blocks are first cut on the CNC machine. The EDM
machine is used to remove steel in parts that can't be cut accurately
using a CNC machine. It uses electrical current to remove steel at a
rate of 5 microns per electrical burst. They can also use EDM machines
to slice large blocks of steel. The one we saw was around one foot tall
and six inches thick! After the tool and
die shop, we checked out the plastic injection molding area. They showed
us how the tooling fits into the injection molding machine. They then
load plastic pellets into the hopper and turn the machine on. The two
sides of the mold are closed, plastic is heated, and then it's injected
into the mold cavity. The plastic is then cooled using water cooling,
the mold halves are separated, and the worker takes out the resultant
part. Finally, the worker trims off the plastic runners and excess, adds
a protective plastic covering to the part, and then puts it inside a
box of finished parts. We then were taken to the
printing area of the factory. The printing area adds lettering and logos
to the finished plastic parts. There are two main methods they add the
lettering. The first method is to add lettering via pad printing. This
is to print on curved surfaces and consists of a round rubber pad that
picks up ink in the form of the desired lettering. The rubber pad then
gets pushed onto the surface and deposits the ink on to the target
surface. The second form of printing is silkscreening. This is basically
the same method as t-shirt silkscreening where ink is forced through
openings inside a screen.
Finally, we went to see the high spec
finish room. This is for finishes that are extremely high spec and we
had to take precautions to wear shoe covers to prevent tracking in
errant dust. The high spec room was sealed and we weren't allowed
inside, but we could see what goes on there. This room is mainly for
highly polished surfaces and special finishes that have an extremely
high tolerance. Customers would request this if they needed high spec
finishes and wanted to improve their yield. This concluded our tour of this injection
molding factory and the boss of the factory took us all out to lunch. I
didn't realize that lunch included drinking alcohol and we had many
"ganbei" (chinese for "bottoms up") glasses of beer with the boss. By
the end of lunch, I was fairly trashed and Bunnie was getting there too.
Interestingly enough, we had another factory tour immediately after. We weren't
allowed to take pictures of the second factory that day which was a
shame because it was amazing. They were also an injection molding shop
but had the capability to do a technique called IMD/IML (In Mold
Decorating/In Mold Labeling). This technique makes it possible to embed
graphics into injection molded parts. If you see designer cell phones
with graphic designs integrated into the body, its likely that an IMD or
IML technique was used to make it. This injection molding factory had
another special characteristic which is that they made monstrously
gigantic tooling and mold sets. They would crank out a car dashboard in
one shot using a steel mold that weighed nearly 100 tons. That tooling
would go into an even more gigantic injection molding machine to stamp
out the part. Everything at this shop was just on a completely different
scale in size. Bunnie fell in love with the huge CNC machine to cut out
the tooling and he kept on subconsciously rubbing the gigantic steel
mold :)
The day didn't end there though. AQS, a contract
manufacturer that was helping to organize all the tours and also a
company that Bunnie works closely with, took us all out to dinner with
their staff. It was a wonderful dinner and we talked about a lot of the
things we saw with them. They also broke out the Chinese hard liquor
(53% alcohol) and proudly proclaimed that they wanted to drink with us. I
hid from the "white liquor" since I've had a few bad experiences with
it but most of the others were game to try it out. Overall, it was a fun
evening with AQS and it was our first real dinner together as a group.
It was a wonderful chance to meet everyone and hear about what they were
working on, why they were on the trip, and just randomly ramble on in a
happy, semi drunken state :)
Trackback(0)
 |
TrackBack URI for this entry
Subscribe to this comment's feed
Show/Hide comment form