Jumping on this late, but better late than never...Chlorinated vs Non-Chlorinated Soluble Cutting Oils - What's the Difference? Pro's con's etc, according to mfr they are both great and have same basic description, does one work better than other, or is one just less carcinogenic than other, or......
Chlorine in the form used in metalworking fluids is usually a chlorinated paraffin or chlorinated olefin. The reason for using a chlorinated coolant would be to extend tool life when cutting iron-based metals. The chlorine will react with the iron to form a metallic soap. This formation helps prevent BUE, welding, etc. Chlorine is not used for bacterial or fungal control in metalworking fluids. In the absence of a chlorinated EP, many producers will use a sulfurized compound that behaves in a similar way. However, using a sulfurized EP in a water-based coolant gets tricky because sulfur becomes a food source for bacteria.
Chlorinated coolants work best in operations that run slow with deep cuts (relatively speaking). Shops in Europe have been faced with very high disposal costs when using chlorinated coolants, so most do without. Increasing speeds, reducing depth of cuts can help you program out of most EPs. That being said, if you can use them, they are usually a benefit and rarely a con.
Some metals and industries avoid or prohibit the use of halogens because of potential detrimental affects should the part see very high temps in use. With the exception of nuclear work and some jet engine/turbine work, chlorine is rarely a problem. Titanium often sees the use of chlorinated coolants without issue so long as the parts made do not see elevated operating temps. Chlorine is still widely used in the ortho implant industry without problem, for example. Most companies that avoid using chlorinated fluid do so for environmental/waste disposal reasons.