An industrial joystick manufacturer was facing performance issues with a high performance model. The joystick design was required to operate in extreme temperatures and hostile environments, the sub zero temperature performance was of particular concern and there was a galling issue between zinc surfaces. The manufacturer was also under pressure to increase warranty durations for their joystick range and therefore increased functional life of the devices was demanded.
The joystick had performance issues at sub zero temperatures and there was a galling issue between the zinc surfaces.
This particular joystick is a ‘spring loaded’ return to centre design that is used for industrial/high performance tasks including cranes, excavators, access platforms, tractors and harvesters. There are variants manufactured some with the addition of an enclosure and rubber boot giving some models an IP rating of IP66; water ingress was not highlighted as a major concern.
The chosen lubricant needed to prevent wear on the metal (Zn) surfaces, improve overall joystick performance and the tactile feel of the device for the operator and must meet functional life testing of 7 million cycles. Competitor greases that were tested stiffened at sub zero temperatures which affected ‘return to centre’ times on some joystick variants.
- A heavy viscosity synthetic grease with damping characteristics to improve the tactile feel of the joystick and also suitable for metal on metal lubrication (no excessive contact forces).
- A Polyalphaolefin (PAO) based grease with a silica thickener had necessary temperature stability.
- The organic/solid Molybdenum Disulfide (MoS2) additive was selected as this is typically spherical in form and would help maintain low breakaway forces and prevent wear.
- The chosen damping grease should not exhibit excessive oil separation.
Applying The Grease
A production application method for the Nyogel 774H-MS was devised to apply the grease to the ball of the joystick during assembly. Normal production quality procedures ensured that the grease was well distributed around the ball area prior to packaging and dispatch.
It should be noted that there are lower viscosity base oil variants of the Nyogel 774H-MS that can operate down to -45°C should market demands required even lower temperature use in the future, although there would a slight compromise with operator tactile feel.
The Nyogel 774H-MS greatly improved overall performance of the joystick. Functional life testing up to 7 million cycles was passed, there was no galling/wear issue, the tactile feel of the joystick was improved and the sub zero performance issue was overcome.
The Nyogel 774H-MS grease was applied to a number of joystick variants as the performance and pedigree of the lubricant was accepted by the engineering design team.
Nyogel 774H-MS use in the joystick overcame the wear issue, improved tactile feel, sub zero temperature performance and passed the required functional life testing.
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