MIT Media Lab Shenzhen, 2013-01-22, AUK Connectors
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Written by Akiba
Monday, 28 January 2013
2013-01-22 AUK Connectors
For the final factory tour, we visited AUK Connectors. Bunnie wanted to
show us a connector factory because connectors are the pinnacle of
plastic injection molding technology. Making connectors is orders of
magnitude harder than making things like injection molded enclosures
because the tolerances are so tight. Any type of flashing occurring due
to tool wear will drastically affect the connector and hence somebody's
design. A good connector manufacturer needs to constantly check and test
their tooling to make sure it's always within spec.
Before I saw the AUK manufacturing operation, I did not realize that
connector manufacturing was so difficult. The tour started off in their
sample room with them showing us the various connectors they make and
also showing us a short PPT intro of their company. One of the things
that caught my attention was that one area they focus on is customized
connectors. Of course I started asking a lot of questions about it. I
was curious what it took to make a custom connector. The tooling fee
varies but it is in the area of around $30k for a custom connector. In
my opinion, it's worth it after seeing what they have to go through with
the tooling. The per connector charge also varies depending on the
composition and complexity of the connector, but in general, it sounds
like the NRE for the custom connector is the big hurdle.
In a normal plastic injection molding setup, the tooling would be pulled for testing approximately every 10,000 shots. This would probably be every few days for a line that was operating constantly. For a connector injection molding setup, the tooling is checked multiple times per day to make sure it stays within the proper tolerance. If any connector is found to be faulty, they throw away the whole batch. Most connectors contain some type of metal contact molded into the connector. The plastic is then injection molded around the metal contacts. Any tool wear would show up as flashing around the metal contacts and could prevent contact being made to the connector. This constitutes a serious quality issue which is why whole batches would be thrown out if any faults are found.
Also, the connectors are constantly getting smaller. The micro USB connectors have a tiny metal contact insert with only a few fractions of a millimeter between them. Plastic needs to be injection molded around the metal contacts to create the tiny insert, after which, it gets assembled into a metal shell. The space between the contacts is unbelievably small. If you don't believe me, look inside any micro USB connector (most Android phones use micro USB) and check out the contact inside the connector to see how tight the spacing is.
Because of this, a lot of time is also spent on machine vision and optical inspection of connectors and contacts to make sure no quality issues don't come up. When a faulty connector is found, the tooling gets pulled and is sent to the measurement room. There, technicians measure each of the tooling inserts to see which inserts are bad. If the insert is salvageable, they'll try to have one of the metalworkers fix it. Otherwise, the tooling is tossed and they make another insert.
AUK also had a very impressive automation department that creates automated assembly jigs for various connectors. It makes sense since the cost of connectors has essentially sunk to near zero for commodity types. Automated assembly is probably the only way to survive in the connector business. Their automated assembly setup was extremely intricate and garnered a lot of oohs and aahs from the other designers. The sounds that were made felt almost musical in their rhythmic step-wise march from plastic shells to completed connector. Their automation skills are so good that many famous Japanese connector companies that originated many of the connectors AUK makes purchase automated assembly equipment from them.
The final part of the tour was to check out their testing room which I always like. They had a lot of custom and very specific equipment here. At one station, they would pull samples from different batches and do insertion testing on the connectors. The insertion testing could last months depending on the parts and the testing is all automated. A device would insert and remove a card into a connector in an infinite loop and check for electrical failures. They also had an environmental test chamber, tensile strength tester, and an impressive looking X-Ray spectrometer for ROHS testing.
I definitely have a new respect for connector manufacturers after seeing the AUK operation. The amount of work they put into achieving such high tolerances was very impressive. I can also see that it's not a good idea to have a connector injection molded at a normal injection molding manufacturer since they're a completely different ball game. I'll be remembering that if I ever need a custom connector made.