Building layers without compromising gear strength, durability and specification
Gears used in large applications are expensive to replace if damaged or worn.
With brush plating, a frequently used plating material for repairs is nickel. Other materials such as cobalt are also popular, while certain alloys like nickel tungsten alloys or nickel cobalt alloys can provide their own unique properties. With proper selection of deposition parameters, the grain structure of the nickel can be influenced to yield the desired properties such as hardness and corrosion resistance, thus enabling it to withstand the day-to-day operation that gears are subjected to.
For gears the most common repairs are shafts, bearing journals, and bores. In the right circumstances, localized damage to teeth may also be considered. For gears that will see corrosive environment, the bores and outside machined surfaces that cannot be painted are also plated when new to provide corrosion resistance.
On Site Selective Plating Brings Down Costs
Another consideration that engineers face with repairing gears is how the maintenance can be achieved while incurring the least cost. These can start rising through directly associated expenses like the shipping the gear to a job shop, disassembly and reassembly of the gear, and the repair itself. Then there are indirect costs to factor in, such as disruption, downtime and loss of productivity.
Often, the gears that are too large to simply replace are also too large to easily disassemble and too impractical and costly to ship to off-site job shops for repair. Downtime is also prolonged, due to the need to take the gear and machinery apart, and wait for it to be repaired, sent back and re-assembled.
Brush plating overcomes these obstacles. In many cases, technicians can assess the damage to the gears and make the repairs on-site.
This was the case for the pinion gear repair on the dragline excavator. Of the repair, Dave Niederhelman, Chief Metallurgist, Horsburgh & Scott Co. said: “SIFCO ASC is a well-established partner of Horsburgh & Scott and their ability to work on-site is highly attractive. Over the years they have helped us to find the most efficient ways to repair and maintain our customers’ equipment and this has added up to thousands of dollars, hours of downtime, and manpower time saved.
“In this application the SIFCO Process® has extended the working life of the gear and improved the failure rate due to the nature of the nickel coating on the journal. The cost of manufacturing and material to replace the gear would have been extortionate in comparison, as well as causing weeks of downtime.”