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Film about Mullard valve manufacture

Discussion in 'classic' started by Mike P, Sep 6, 2019.

  1. Mike P

    Mike P pfm Member

    I found this on youtube and thought it was fascinating.

    TheDecameron and eastone like this.
  2. eastone

    eastone pfm Member

    This is incredible.
  3. Mike P

    Mike P pfm Member

    Isn't it just!
  4. Tw99

    Tw99 source last

    Thanks for posting, that was really interesting. I thought it was surprising that they made the whole thing from raw materials in the factory, even down to making their own wires. You'd need a lot of dexterity and patience to be assembling them all day long. I didn't notice too many OMG health and safety moments apart from the open bath of mercury.
  5. Vinny

    Vinny pfm Member

    This has been posted here before and is, or was, on the home page of Watford Valves.

    As mentioned, it was an extremely unusual factory in that it bought-in little more than basic raw materials. The production processes and machines are identical to those used in lamp-making, which is why the big lamp-makers, such as Philips, GE, Thorn, had such dominant positions in the market. Even Telefunken started life as a joint venture between AEG and Siemens-Halske, and Siemens were making lamps from the very earliest times.
  6. 337alant

    337alant Negatively Biased

    Wow no wonder valves are expensive
    Thanks for posting, very interesting

  7. Vinny

    Vinny pfm Member

    It is volume, not how they are made. A hell of a lot of the work and machine time, though less iron-mongery, in an ECC83, for instance, goes into a 60W GLS lamp. A 60W GLS sells/sold for what? 60p?
    It is a long while ago, so precise numbers have been forgotten, but some of the fastest GLS production was in GE in the US and that was faster than one a second, so, just one final exhaust machine producing 80-90,000 GLS lamps per day, and there were lots of those around the world.
    The machines that you see in the Mullard film were of their age but were still in use when I was making lamps for a living only 10 years ago, but for low volume, high value lamps, in the main.
  8. Chops54

    Chops54 pfm Member

    Seeing that video brought back some memories. I also worked on the crt production line in another factory with similar machinery though somewhat larger. No computers then so quite an achievement too.
  9. TheDecameron

    TheDecameron Unicorns fart glitter.

    It would be interesting to see how much contemporary manufacturing differs, if at all.
  10. Vinny

    Vinny pfm Member

    I very much doubt that current manufacture varies much at all.
    What could/would you change? To achieve any change would mean reinventing something, which would likely be very expensive and a substantial risk.

    All of the machines in the film, and the huge majority that I have worked on, worked from combinations of indexing gearboxes and cam switches. Most of the machines that I was familiar with were built pre 1970, but one or two brand-spankers came on site. One in particular, a final exhaust machine for mirror lamp capsules, had been built for a competitor who could not get it to work and a second competitor similarly failed. We couldn't get it to work either, but did discover why it would NEVER work in the form in which it was designed - on all machines, the exhaust tubes are fitted into compression heads which contain a rubber (today usually a silicone rubber) insert. The insert is "pinched" onto the glass exhaust tube by one of various methods to form a seal. The rubbers on this machine were very large and no matter how much of various pre-treatments we gave them, they always seeped less than tiny quantities of volatiles from the silicone, into the lamps, which killed the lamps.

    Today, you'd just use PLC controls, but the machines would be essentially identical. To make machines run faster, they just get bigger, so that the dwell time on the machine for each component stays about the same - to take the easiest example to imagine, think of final exhaust. To purge, outgas, exhaust and tip-off each valve/lamp just cannot be done ever faster, you have to work within the limits of what the laws of physics and chemistry allow. At the very least, pumping to a reasonably low pressure (a VERY long way from actual vacuum), through a 4" long, 1/8" bore exhaust tube takes quite some time.

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