Resurrection of a CFEI 100 KVA Induction Furnace

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awemawson:
Today's task: make up a set of copper commoning links for the Raydyne complete with flying leads of the 70 mm CSA welding cable so that changing from one furnace body to the other is simplified, as the links on the Inverting Body are a bit of a pain to remove.

OK - need copper bar - no suitable copper bar in stock - squash some 28 mm copper pipe in the Epco 60 ton press and use that! So two six inch lengths were cut off, flattened, marked out, drilled, profiled, and cleaned up in phosphoric acid. I then prepared two short 'flying leads of the heavy welding cable with lugs on the end crimped so as to be at 90 degrees to each other to avoid a twist when in situ.

All then assembled and finished - well not quite as I'll replace the steel nuts and bolts with brass ones when they are to hand.

Meanwhile I dismantled the stainless plumbing arrangement that had previously been used and rescued most of the fittings for the 'may come in useful' box.

awemawson:
I've just re-filled the reservoir with 32 weight hydraulic oil - no idea what I'd used before - unlikely to have been a hydraulic oil as I had no hydraulic powered machines then.

Using just compressed air, a full tilt was 6 seconds, which is too fast. Putting 3 litres of 32 weight hydraulic oil in the reservoir (cylinders total swept volume = 2.8 litres) it takes about 30 seconds which is too slow - I'd like 15 seconds for a smooth controlled pour. Perhaps I can cut the oil with something to reduce the viscosity?

A bit of 'googling' suggests that the oil in a J&S 540 head with the plain bearings is either ISO 10 weight or 32 weight cut 10% with paraffin.

So what can I use to 'cut' hydraulic oil? Paraffin perhaps - suggestions welcomed !

awemawson:
As I don't have any paraffin oil, and getting it is a pain, I used Red Diesel. Google tells me that their viscosity is much the same. So I drew off 1 litre with a stomach feeding syringe (sorry next years lambs!) and replaced it with 1 litre of Red Diesel.

The result: the 30 second rise time is now down to 22 seconds and the current mixture is 1/3 Red Diesel and 2/3 32 weight hydraulic oil - so that is definite progress.

Tomorrow I'll adjust the ratio again to maybe 50:50 - or even less, as if I go too far I do still have the flow rate valves to adjust - they are fully open at the moment. Need some hydraulic oil in there for cylinder lubrication, but it's not a high stress application really.

When the aerated hydraulic oil that I drew off has settled it can go in the dumper truck, as it leaks like a sieve!

mattinker:
Hi Andrew,

If I remember correctly, your red diesel has a dissolved, wax ( it's the element that solidifies when diesel freezes) in it which is there to lubricate the injector pump when used as fuel in a diesel engine. So please, correct me if I'm wrong, in my opinion, lubrication is not a problem!

Cheers, Matthew.

PekkaNF:
I started thinking this Yesterday, but I have first hand experience on normal hydraulic olis of VG32 and VH46 viscosity. The company chooses Iso VG 32 over 95% of the thime, then VG 46 is used only when ambient temperature is significantly higher. On lower end of the ambient temperature tank heater kicks in and the hydraulic oil heats due to work it performs.

I wonder if the normal iso VG 32 oil would perform fine in the working temperature?

Most normal hydraulic oils are pretty much normal mineral oils that have some additives to prevent foaming, help filtering, disolve water (water is one of the biggest problem in modern hydraulics, you don't want it to steam on elevated temperature of cavitate at uner pressure, or rust) and usully a litte amount of EP additives to help lubrication.

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