Diluting of neat sliding head cutting oil

[turner13]

Good day folks.
I'm currently running 4 Citizen sliding head machines overnight and weekends (lights out).
I'm machining stainless grade 303.
My main problem is that the machines keep stopping at some point because of a coolant level alarm (please supply the coolant).
The reason for this is, because my neat cutting oil is so viscous, it sticks to my chip conveyor and eventually drips through into my swarf bin.
If i don't keep the chip conveyor on, the machine fills with swarf and the coolant gathers above this and the level in the tank falls again.

I'm using Duracut ST12 cutting fluid.

Has anyone had any experience in perhaps diluting this to make it less thick so it wont stick to the conveyor as much, or is this a really bad idea for tool life etc?#

Many thanks,

T13.

 

[dandrummerman21]

I have no experience with swiss, oil, lights out, or your machines, but a couple ideas.

When running lights out, can you program a dwell once in a while to allow oil to return to the tank? Yes you would be losing time, but better than a hard stop.

Can you move the level sensor lower in the tank?

Is your conveyor clean? What I mean is, have you taken it out and inspected the return passages to see if they are clogged? If partially clogged, it could obviously contribute to the problem.

Can the volume of the tank be expanded by adding a "buffer tank" that increases the volume? A simple extra tank with a hose running between bungs down low on the tank is what I'm suggesting here.

2 hour later edit: Can you program your conveyor to turn on and off at intervals? Or install a timer on it?

 

[rootsandstones]

2 hour later edit: Can you program your conveyor to turn on and off at intervals? Or install a timer on it?

On the lathes running with cutting oil I always used the interval for the conveyor to not fill the swarf bin with oil.

 

[dandrummerman21]

On the lathes running with cutting oil I always used the interval for the conveyor to not fill the swarf bin with oil.

Now that you say that, I think I might understand the issue with the OP a little better.

turner13, are you saying that you get a low coolant alarm because too much oil ends up in your swarf bin (we refer to them here as "chip hoppers" so I didn't fully understand) from being carried off by your conveyor and the oil falls off of it with the chips?


So another possible idea, inspired by the screw machines we have that run oil: Can you run a drain and return line from your swarf bin back to your tank?


Maybe your solution is a combination of a few of these ideas.

 

[FamilyTradition]

Diluting your cutting oil will most likely have an effect on tool life, the big thing with that is, how much you are willing to sacrifice. I have had to dilute thick cutting oils in the past due to coolant pumps that were not up to the task (the pump was fine with some types of oil but we were running something really thick, found the right ratio to still improve tool life, without killing the pump).

As others have said, if you can, you may want to have the conveyor run in intervals instead of constantly to give time for the oil in the chips to drain back into the tank. And check to make sure return screens and filters are not plugged with the really fine particles.

If you can do so, you could also elevate the chips bin, and put a drain in the bottom leading back to the machines. This would be preferred as gravity is free, and works even when you are not watching it.

If that's not possible, you could try a siphon between the machines tank and chips bin. As long as the pickup in the bin is at a higher elevation than the outlet in the coolant tank, the oil can naturally siphon back into the tank.

Another method similar to siphon is I think called "venturi effect". Basically what makes those pneumatic vacuums work. Have a pickup in the bottom of your swarf tank, a drain into your machine, and a connection to an air line with a check valve. With these parts in the right configuration, when air flows through the line, it will create suction that will pull oil from the bottom of your swarf bin, back into your tank. I see this often in the floor pans around machines to passively suck up all the oils that end up in the pan.

 

[guythatbrews]

IMO thinning the oil is a bad idea. I wouldn't do it.

A timer will really help with the oil dragout, and keep the chips from damming up the conveyor.

Was this a problem when the machines were new, or has it developed recently? If recently you have a chip damn somewhere. You may have part or all of the return paths out of the conveyor into the tank blocked or partially blocked. This is a pretty common problem.

First, check those return paths. They get full of fines in some setups and oil just can't get through. Next, pull the conveyor and clean all that crap out. Horrible job I know. Does your conveyor have filter boxes? They get slammed completely full of fines. Also common, your tank volume may be very reduced by fines in the tank

If you can get to the chute where the oil is returned to the tank, put a 5 gallon paint strainer on it to keep the fines from the tank. This really helps and it is very cheap and easy. Amazing how much crap it catches.

 

[FredC]

Lots of good ideas so far, not sure if this is practical or not. How about putting a spacer or shims under the outboard end of the conveyor? Raising the swarf tank and the outboard end of the conveyor a couple of inches may work with some of the other suggestions about getting the oil back in the machine

 

[FredC]

One more thought. I have no idea how viscous your Duracut ST12 is. I have seen very thick cutting oil that ran like molasses in January. The MobilMet 427 that we use flows fairly freely and works well with stainless. May not be available in the UK, but surely an equivalent is available. As mentioned by guythatbrews, I would not thin the oil in a screw machine.