Sea Technology

NOV 2018

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

Issue link:

Contents of this Issue


Page 22 of 52

22 ST | November 2018 There may be no need for disassembly or transportation, and only minimal need for masking and post-machining; all that's needed is a quick process that extends mainte- nance intervals and service life. The SIFCO Process has been adopted by naval forces of the U.S., U.K. and Japan, used on a wide range of components across the naval defense fleets. On turbine casings, for example, AeroNikl has been successfully used for interference fits, providing a met- al-to-metal seal with less risk for thermal disturbance than the previous repair method, welding. Elsewhere, copper capped with AeroNikl is used to fill pitting on seal surfaces of components such as main seawater valves and watertight hatches for missile tubes on aircraft carriers and submarines. In these cases, selec- tive plating can prevent the need either for disassembly and transportation to a machine shop (seawater valves), or for in-place machining after TIG welding (watertight hatches). What's more, through the ASTM C633-79 Standard Test Method for Adhesion or Cohesive Strength of Flame Sprayed Coatings, the SIFCO Process also established that the cohesive strength of the deposit exceeds that of the bonding cement. For example, the minimum tensile strength value established (at the point of cement fail- ure during testing) for nickel high speed is 22,803 kPa (11,200 psi) on an SAE 4130 steel base material. Addi- tional qualitative tests, as described in AMS-QQ-N-290 were also conducted in which the plated areas were subjected to high stresses and strains. These results also showed excellent adhesion. Protection in Port Remanufacturing is an alternative option to replacing or re-engineering equipment and is worth considering in the naval defense and marine industries with bigger com- ponents that can be especially costly. Sitting at the heart of the remanufacturing decision is the used part that is at the end of its service life. Accord- ing to the study "Remanufacturing Inspection Models" by a Ph.D. student at Exeter University, U.K., there are four main strategies applied in the decision-making process for remanufacturing, each of which comes down to value and type of component. It states: "If cores [end-of-ser- vice-life components] are relatively cheap, disposal is an effective way of increasing the reliability of the popula- tion as a whole. If cores are expensive they must be pro- cessed almost regardless of cost. In the case of low-value cores there is often a new alternative that can be pur- chased in its place." Remanufacturing of a component should be assessed on a case-by-case basis. Different processes, like selective plating, might be used in the re- manufacturing process than were used in manufacturing the original equipment or part. Due to the high cost of marine equipment combined with the lead time required to purchase new equipment, remanufacturing with selective plating should always re- main an option. Mechanizing, Fully Automating the Process When a ship is in port, multiple repairs may be need- ed. Depending on the application, selective plating can be mechanized or fully automated. Mechanizing the pro- cess minimizes the direct contact the operator has with the tooling and chemicals by using a computer program to control the rectifier performing all of the pre-treatment and plating steps, providing consistent control of the pro- cess. Fully automating the process removes the opera- tor—and the variability—from the entire operation. The main benefit of customized, fully automated systems is that they require minimal need for operator intervention. Various pumps, flow systems and cleaning agents work together to change, catch and circulate solu- tion; while a robotic arm holds, oscillates and changes the anodes needed throughout an entire plating opera- tion. By automating the selective plating process using a programmable logic controller, operators can review data captured through the human-machine interface to determine if the operation was completed correctly. If any errors do occur, or quality standards are not met, operators can review the data and trace the error to its source and assign the appropriate corrective action, pre- venting the errors from being repeated—effectively im- proving traceability and repeatability within the process. Additionally, automation reduces the ergonomic risk to the operator and increases the available capacity by al- lowing skilled operators to focus on the core business processes. ST Derek Vanek is the technical manager for SIFCO Applied Surface Concepts and has been with the company for about 31 years. Prior to that, he served as a machinery repairman in the United States Navy repairing worn or damaged parts, as well as machining replacement parts that were beyond repair for shipboard equipment, includ- ing propulsion systems, compressors, pumps, motors and valves. Vanek's role within SIFCO ASC includes application development and un- derstanding customer needs and specification and engineering requirements to determine the suitability of selective plat- ing for the component. For applications beyond traditional selective plating, Vanek works with the SIFCO ASC team to develop specialized processes. "Automation reduces the ergonomic risk to the operator and increases the available capacity by allowing skilled operators to focus on the core business processes."

Articles in this issue

Links on this page

Archives of this issue

view archives of Sea Technology - NOV 2018