To assure a certain metal-to-metal contact and a solid grip of the cold rolling mills, the viscosity of cold rolling oil should be as low as possible. However low viscosity oils usually come with low flashpoints and undesired VOC emissions. That is not the case for the new generation of Q8 Bach RSD cold rolling oils with increased safety profile.
Most cold rolling mills need low viscosity neat cold rolling oil for best metal surface quality. The cold rolling oil is needed for lubrication in the roll bite and for cooling of the metal strip.
Why cold rolling mills require low viscosity cold rolling oils
The cooling efficiency of the cold rolling oil increases with reduced viscosity. And at higher speed, a low viscosity cold rolling oil is required to prevent a hydrodynamic film from being built up. Higher viscosities may result in a hydrodynamic film at high rolling speed. Lubrication in the hydrodynamic region means that there is no metal-metal contact and therefore reduced friction and grip. In order to process a metal strip through the roll bite and reduce roughness of the surface, metal-metal contact is required.
This means that the viscosity of cold rolling oil should be as low as possible within the design limits. For cold rolling mills that also use the cold rolling oil to lubricate the bearings, a certain minimum viscosity is demanded (e.g. kinematic viscosity of 7.6 mm2/s at 40 C).
The safety issues of low viscosity oils
Obviously, low viscosity oils have also low flashpoints. As temperatures in some cold rolling mills can possibly approach flashpoints of standard cold rolling oils, new developments have been undertaken. These investigations to increase flashpoints can often be aligned with reduced VOC emissions. In both flashpoint and VOC, the smaller (organic) molecules play an important role. Furthermore, it is not only about reducing VOC emissions for the environment, but it also improves the air quality for the people working closely at the mill.
Q8 Bach RSD cold rolling oils with increased safety profile
Already more than six years ago, Q8Oils introduced the Q8 Bach RSB product range with reduced VOC emission and higher flashpoints to accommodate more stringent local regulations on emissions and safety. Recently, Q8Oils research departments in Italy and Netherlands jointly developed the next generation cold rolling oils with increased safety profile.
This new range Q8 Bach RSD is based on the latest technology of high purity synthesized base oils resulting in a high flash point and advanced safety profile. It contains additives especially developed for the manufacturing of metal strip to ensure a high quality surface finish.