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Formulating grease is often referred to as an art, but what sometimes gets overlooked is the work behind the art. A successful formulation requires tremendous resources, expertise and grease of the elbow variety. Like a successful artist, the grease formulator needs to have the proper tools of the trade: a broad palette of additive chemistry, a well-lit (and ventilated) studio and a wide range of tools to create and evaluate potential masterpieces. As many professional artists will attest, the creative process is a painstaking route that can involve a huge amount of effort to create a single finished piece and the toolkit can be a critical factor in both the timing and quality of the final product. Afton's Grease Team has assembled an exceptional array of instruments and techniques to help drive innovative development and to increase the formulator's understanding of the science behind the art.
Surface techniques
Understanding the interaction of the grease with the surfaces that it's intended to protect is critical to the creation of a successful finished product. The effect of performance additives on friction and wear, and their interaction with tribolayers formed under operating conditions can be studied with a variety of tools.
The PCS High Frequency Reciprocating Rig (HFRR) is useful for examining the boundary lubrication regime measuring friction, wear, and film formation of grease formulations. In these tests, a small sample of grease is placed at the interface of a ball and a disk. The ball is oscillated through a path that can range from 20 pm to 2 mm at a frequency of 10 to 200 Hz. Loads of up to ION can be applied at temperatures ranging from ambient to I50°C. Although the standard materials are ANSI 52100 steel, the ball and disk material can vary from brass to chrome to plastics to suit the application for which the grease is being developed.
The PCS Mini-Traction Machine (MTM) allows thin-film friction coefficients of greases to be measured under EHL, mixed and boundary lubrication conditions. A ball and disc in contact are driven independently to create mixed rolling/ sliding contact and...