Application RapidOxy: Stability of Neat Cutting Oils

Neat cutting oils are used in machining operations, e.g. grinding, turning, milling, broaching, drilling, tapping, gear cutting etc., to provide cooling and lubrication of the tools and a good surface finish of the components being machined.

Alternative to Traditional Stability Test Methods

The rapid small scale tester, RapidOxy, is a fast, safe and user friendly alternative to traditional stability test methods. The instrument measures the induction period, which can be used as an indication of the oxidation and storage stability. Compared to other oxidation and storage stability test methods, the RapidOxy procedure requires only a small sample to give exact test results in a short period of time.

Quick Preparation and Easy Handling

All it takes on preparation is to fill the sample into the PTFE dish, tighten the screw cap and close the instrument. The test chamber is automatically charged with oxygen pressure and heated until it reaches the test temperature of 140 °C in the standard program. Now the pressure is monitored until a pressure drop of 10 % from pmax is detected.

Fig. 1: Display of test progress

Antioxidants Screening

The following table shows the oxidation stability of two neat oils with and without antioxidant.

Results of Neat Oil Antioxidants Screening
Sample Anti-
Time until pressure drop of
10 % below pmax
(in min.)
Whole oil   Test 1 Test 2
Esther-based 20 cSt
(sample 1)
without 50.26 49.66
with 78.01 76.93
Esther-based 40 cSt
(sample 2)
without 48.43 47.30
with 64.73 62.00


Antioxidants extend the oxidation stability of neat oils. Therefore, the results show that products with antioxidant have a longer induction period than samples without antioxidant.

With antioxidant the shelf life of sample 2 was extended by more than 30 %, of sample 1 even by more than 50 %.

Do you have any questions?

Contact Anton Paar ProveTec directly: support.provetec[at]

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