sealing against white coolant fluid

Hi everyone.

I have a question,can anyone tell me what the chemical formula is for the emulsified white cutting compund used on lathes and or mills. My reason for asking this is I need to find a sealant that i can use that is resistant to ths solution. I am presuming silicon or boss white is no use here as these are intended for plumbng? Have an idea it might be from chronos  MG1 or MG5 or Alusol but this has no chemical info on it .

Martin

Edited By Martin Newbold on 20/12/2017 19:48:36

Edited By Martin Newbold on 20/12/2017 19:56:17

Hi Martin I have always found silicone sealer works well in most conditions just make sure that you degrease well before use but if you need to split the joint regularly spray one side with a release agent.

David

HI David , thanks for the reply .

I am unsure about silicon as it does say on it it does not support chemical environments, an really not sure whats in this white stuff other than an emulsion i found a wiki thread but t didnt help. I unly really want to do this once as want to ensure the plate my lathe sits on does not leak between it and the angle iron it sits in that i have around it ttps://en.wikipedia.org/wiki/Cutting_fluid  it suggests it has a ph of 4 which is corrosive. I also understand there is bio addatives to prevent mould growing in the liquid and corrosion inhibitors as well as the addatives for cutting and cooling.

Martin

Edited By Martin Newbold on 20/12/2017 20:08:55

O₂ + N₂H₄ → 2 H₂O + N₂ Is the corrosion inhibitor

The biocides can be C02 or metals such as copper and its alloys (brasses, bronzes, cupronickel, copper-nickel-zinc, and others

This is all i can seem to find but the PH4 seems the biggest problem does anyone know of a sealant that is capable of working in chmical enviroments with a ph4 or above?

Martin

Has anyone any experiance of this Bondseal **LINK**

Hi Martin,

Good news, you've misread the pH4 part of the Wikipedia article. It refers to a test that you don't need, not to the acidity of cutting fluid in use.

The emulsion is a mix of water and a soluble oil possibly with additives to discourage mould. It should be close to being chemically neutral and not difficult to use or seal at all. I think any silcone sealant for bathroom or kitchen use would be fine.

Dave

I also found this https://www.ramgaskets.com/chemical-compatibility-and-resistance

The coolant is mostly an emulsion of oil in water. If it has a pH of 4 then someone's been pouring acid into it and the emulsion will probably have broken down (along with the machine tool it was used in). Normal pH would be about 8, eg. slightly alkaline, but not much.

N2H4 is hydrazine, which is alkaline, not acidic.

Silicone rubber will work very well as a sealant. For a non-permanent sealant, Dow-Corning Molykote 111 silicone grease will work. It's useful for keeping coolant out from under surface grinder magnetic chucks and milling machine vices.

I have been a service engineer working on many machines from surface and cylindrical grinders to CNC mills and lathes I have never had a problem with most coolants and silicone sealer and as Mark said the silicone grease under clamped down items like a magnetic chuck works very well.

David

Lets put this in simple terms.

Coolant is basically a mixture of oil in water. Approx 5-20% oil and the rest is water.

The oil is called "soluble" but does not actually dissolve in water, per se. It forms an emulsion which is stable (the oil and water do not separate).

An analogy is olive oil and water mixed as a salad dressing. Normally the oil separates as an upper layer quite quickl

y (Other examples might be the way engine oil becomes milky if water leaks into the sump, or hydraulic oil becomes contaminated with water).  E

nter an 'additive' which causes the mixture to not separate after shaking. Now you can make salad cream with the oil, water and additive. Clearly not the same ratios of oil to water for cutting fluid coolant, but the same principle.

For coolant, the oil is chosen for the properties required - like cutting oil. Other additives prevent microbe growth which would otherwise send the oil rancid (like old cooking oil).

The emulsifying agent is a compound that is soluble in both oil and water to some extent.  We describe the two parts of the compound (responsible for the activity) as either hydrophilic (water loving) and hydrophobic (water hating!). In simple terms, the additive molecule combines loosely with water at one end and oil at the other, thus not allowing the two components to separate.

Lecithin is a common emulsifying agent used in cooking, but eggs also have this property.

I hope that simplifies coolant for cutting duties - the oil prevents the machine from rusting and provides some assistance for cutting, while the water is basically a coolant. Of course, there is a wide range of suitable products on the market and all can have different claims for their particular recip

e.

Edited By not done it yet on 20/12/2017 21:40:17

this is a brilliant resourse : **LINK** http://mykin.com/rubber-chemical-resistance-chart

It shows all types of rubber and silicons and how they fair under differant chemicals . I am considering buying a sheet and cutting out middle to make a proper gasket

Edited By Martin Newbold on 20/12/2017 21:35:36

Hi David,

Having read all this data it seems you are correct Flourosilicone seems pretty good at most types of sealing solutions for a chemical barrier too. Thanks for putting me on the right path

Martin

Have found some nitride sheet and going to cut a gasket out of it

Martin