Reduce the quantity of foam with a low dosage!

Reduce the quantity of foam with a low dosage!

Friday, 3 December, 2021

In the metalworking fluids sector, a reduction in friction between machinery components is sought. The phenomenon is generated by contact between moving mechanical elements and causes their wear and tear. Oil-based lubricants allow friction between parts to be reduced by avoiding direct contact. In this way, we achieve more rapid and precise movements at the same time as reducing overheating, increasing productivity and, above all, extending the service life of machinery due to a reduction in wear and tear.

However, pumping lubricants through the internal circuits of machinery generates air or foam, reducing its efficiency. A defoamer or air release additive should be included in the formulation to avoid this effect. BYK has increased its range of defoamers for oil-based lubricants with new products, which stand out due to the following properties:

Compatibility with a wide range of oil-based lubricants
High performance at a low dosage
Good stability during storage – does not precipitate or separate
No solid particles – avoids filter blockages

The efficiency of this new range of additives has been tested in trials in accordance with the ASTM D 892 test method, which allows us to determine the foaming tendency (quantity of foam upon disconnecting the stream of air) and the stability of the foam (quantity of foam after the waiting period).

The methodology used is as follows: in a cylinder in which we have added the sample, we pass a constant stream of air through our lubricant sample for 5 minutes and we measure the volume of foam generated (foaming tendency). After a 10 minute settling period, we measure the foam value again (foam stability).

This method is applied to two identical samples at different temperatures (24ºC and 93.5ºC). In addition, the sample at 93.5ºC is left to cool and the foam to collapse completely to reapply the same methodology at 24ºC. In this way, with the first sample we obtain two measurements at 24ºC and with the second sample we obtain four measurements, two at 93.5ºC and two at 24ºC.

Figure 1: Instrument used to test the efficiency of the defoamers

The recommendations for defoamers according to oil type are as follows:

BYK-LP D 24347: Silicone-based defoamer recommended for all types of oils (paraffinic, naphthenic and PAO). Its high degree of compatibility with different oils maintains high levels of transparency.

	Paraffinic oil	Naphthenic oil	PAO
Oils without additive
BYK-LP D 24347 (dosage 0.2%)
	Light turbidity. Stable during storage.	Transparent	Light turbidity. Stable during storage.
Figure 2: Impact on transparency by adding the BYK-LP D 24347* additive*

BYK-LP D 24894: Silicone-free polymeric defoamer, recommended for PAO type oils. It presents very good long term stability and does not alter the appearance of the lubricant.

BYK-LP D 24895: Polymer/silicone blend defoamer recommended for all types of oils (paraffinic, naphthenic and PAO). Its high compatibility with different oils maintains high levels of transparency.

	Paraffinic oil	Naphthenic oil	PAO
Oils without additive
BYK-LP D 24895 (dosage 0.2%)
	Transparent	Transparent	Transparent
Figure 3: Impact on transparency by adding the BYK-LP D 24895* additive*

In summary, the newly developed defoamers from BYK provide high efficiency with a low dosage. In addition, they are stable in terms of storage and sedimentation and have a high level of compatibility in different systems without altering the visual appearance of the lubricant.

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