Plastic injection moulding?

[nadroj]

Anyone here do this?
I'm interested to find out what's involved to make some custom items - core bobbins as in a transformer. These are hollow, so could be tricky?

Jordan

[Graziano]

What kind of bobbins? for a ferrite tranny or a conventional E-I unit?.

[nadroj]

Laminated steel cores. Actually for permanent magnet alternators, but look to be the same as E-I transformer type.
I've just ordered some bigger ones, thinking to cut them down to size, but proper ones would be better.
The core size I want is 18 x 11mm.

Jordan

[Master Splinter]

Last time I looked at the price of doing an injection moulding setup...well, the finished parts were cheap (not even a cent each) but the setup costs were huge ($20k plus).

[nadroj]

I know there are some hobbyist injection moulders, and have seen designs for some bog simple, manually-operated machines. The most difficult part I think would be making the steel moulds, luckily right up our alley.
Or, maybe 3D printing?

Jordan

[kwijibo99]

Hercus used to make an injection moulding machine, there was one at Hiedelburg tafe which I don't think ever got used.
It wasn't that big, looked kind of like a drill press but was bolted to the wall.
I remember using one in secondary school to make file handles.
I vaguely remember seeing a Hercus one on ebay a while ago which sold for bugger all because I don't think people knew what it was.
Cheers,
Greg.

[Michael G]

There are Gingery plans for making up an injection moulding device using a drill press for the injection pressure. Only small parts but may be big enough.

Amazon.com: Build a Plastic Injection Molding Attachment for a Drill Press (9781878087317): Vincent R. Gingery: Books

Michael

[Graziano]

Laminated steel cores. Actually for permanent magnet alternators, but look to be the same as E-I transformer type.
I've just ordered some bigger ones, thinking to cut them down to size, but proper ones would be better.
The core size I want is 18 x 11mm.

Jordan


I took a look at a Neosid catalogue http://www.elnamagnetics.com/wp-content/uploads/catalogs/MMG/catalog.pdf
They have E42/20 bobbins on page 41 (59-120-66) that are 11.7 x 19.4mm x 19.6 tall core size. If it's the right size, you could remove any air gap between the bobbin and your core steel with a few strips of lamination and then glue in place to prevent vibration. You need to minimise any air gap in the core with transformer steel as much as possible.