Relton REL01G-TCO14 TCO-14 Thread Cutting Oil Dark Extreme pressure additive

The Relton REL01G-TCO14 is TCO-14 thread cutting oil, dark, with extreme pressure additive, 1 gallon bottle, 1 each and 4 per case.

Dark is the specification and it carries a meaning that everyone in a machine shop knows and nobody writes down: dark cutting oils are sulphurised, and sulphurised oils are for ferrous metals.

The sulphur is the extreme pressure additive. Under the pressure and heat at a cutting edge it reacts with the steel surface to form a sulphide film — a sacrificial layer that prevents the chip from welding to the tool. That reaction is why dark oil outperforms plain oil in tough threading, and it is also its limitation.

Sulphur attacks copper, brass, and bronze. It stains them, it corrodes them, and on a finished part that is a defect. Aluminium is also generally better served by a different fluid. Dark sulphurised oil belongs on steel and stainless, and using it on non-ferrous work is a mistake that shows up as discolouration on the customer's part.

Light-coloured non-active oils exist for exactly that reason.

Thread cutting is the hardest thing a fluid does. A tap is in full contact, chips cannot escape, and the tool is brittle. Fluid is what keeps the tap in one piece.

The gallon size is for decanting.

Follow the SDS.

Brand

Relton

SKU

REL01GTCO14

Category

Metal Working

Weight

2 lbs

Dimensions

11.50 x 7.50 x 7.50

Price

$21.00

Availability

In stock

Rating

4.64 / 5.0