Overcoming Slip-Stick Friction at Mercury NZ’s Aratiatia Power Station

Aratiatia Power Station, one of nine hydroelectric plants owned by Mercury NZ Ltd on the Waikato River, recently underwent essential maintenance on its intake gate wheels. These intake gates are large steel barriers that control the flow of water from the reservoirs to the turbines. When the gates close, the lower wheels bear an immense load of approximately 35,000kg due to the powerful water flow.

Typically submerged in fresh water and remaining stationary for extended periods, these gates face the challenge of slip-stick friction, which is critical to address if an emergency shutdown is required. In such instances, the wheels need to roll freely and quickly to close the gates.

To tackle this issue, Supply Services Ltd, in collaboration with Mercury NZ Ltd and ACM Composites, selected ACM Triboglide 15M+ as the ideal solution. These composite bearings are known for offering the lowest slip-stick and friction within ACM’s extensive range of composites, with a remarkable coefficient of friction as low as 0.04.

Beyond using ACM Triboglide 15M+, the stainless-steel wheel shafts were also surface treated with medium phosphorus electroless nickel which incorporated particles of hexagonal Boron Nitride (hBN). This unique plating has a hardness of approximately 48 Rockwell C and provides the characteristics of a very low coefficient of friction and low stiction (high non-stick properties).

Great care was taken during the planning phase to ensure consistent minimum running clearances were maintained, and strict quality control measures were implemented to guarantee the perfect finished product.

With the 250kg steel wheels now back in operation, they can be easily spun by hand, offering clear evidence of the significantly reduced friction and the success of the maintenance work.

Read more about our full range of ACM Composite bearing materials and their applications.

Whether you’re dealing with high-load, submerged, or static applications, ACM composite bearings offer a dependable, low-maintenance solution. Supply Services stocks a wide range of ACM materials suited for various industries, including hydroelectric power, marine, industrial, and transport.

If you need long-lasting, low-friction performance in critical environments, get in touch with Supply Services today. Our team can help you select the best bearing material for your needs and provide expert support throughout your project.