- 16 May 2008 -
Technical Conference Track II Highlights Surface Preparation

Track II of the SUR/FIN 2008 Technical Conference, which takes place on Monday, June 16, 2 p.m.–5 p.m. at the Indiana Convention Center, focuses on “Surface Preparation & Treatment.”

Track II programming kicks off with “An Investigation of Vibratory Media in Relationship to the Performance of Vibratory Finishing,” authored by William Nebiolo, REM Chemicals, Southington, Conn. In summary: As a technique introduced in the late 1950s, mass finishing (vibratory finishing in particular) has become a commonly employed procedure to reduce hand labor and overall cost in the refinement of metal components during pre-plating or pre-painting preparatory operations. Pursuant to this technology, a search of the recent literature associated with vibratory finishing has revealed an emphasis on procedures for the optimization of machine motion and/or the use of chemical accelerators for greatly accelerating the rate of refinement, thereby shortening vibratory processing time. This paper will generically review the common types of media and their compositions, with an understanding of how this information is related to media density, media attrition, rate of refinement, and overall expectations of part surface quality. Media size and shape will be reviewed in relationship to an understanding of the geometry of the parts to be refined, as this is a primary concern in process optimization and the minimization of media lodging. Finally, an overview of the waste treatment impact of assorted media will be presented, since solids minimization is always an area of concern, especially with ever-increasingly stringent environmental regulations.

Next up is “Sonochemical Surface Modification—A Route to Lean, Green, and Clean Manufacturing,” by Dr. Andy Cobley and Prof. Tim Mason of The Sonochemistry Centre at Coventry University, United Kingdom. In summary: Traditional surface modification techniques utilize hazardous chemistry, operate at high temperatures, and require copious rinsing. Ultrasound has long been a “bolt-on” for such processes, with little thought to optimizing its driving force—the process of acoustic cavitation. This paper demonstrates that, by understanding the factors affecting acoustic cavitation and the employment of suitable ultrasonic equipment, sonochemical surface modification can be achieved on a range of substrates in solutions as benign as water, therefore reducing process stages, rinsing, and operating temperatures. Sonochemical surface modification is, therefore, lean, green, and clean, and could potentially lead to more sustainable manufacturing.

Following on the heels of that session is “Advances in Chemically Accelerated Vibratory Surface Finishing (CAVSF),” by Juergen Fischer, Engineered Surfaces Center, University of North Dakota. In summary: It is known that with the inexpensive CAVSF process it is possible to reduce the average surface roughness of helicopter gear teeth from the conventional 16 micro-inches down to approximately 2 micro-inches. The friction and the surface stress at the mating surfaces are remarkably decreased. This results in an increase of the fatigue lifetime on the order of 300% to 400%, reduced downtime, reduced component weight in new designs, higher energy efficiency, and overall lower costs. This paper looks at different effects of the process, such as the chemical reaction and erosion during the process, which were examined separately and in combination with each other.

Alonso Lozano-Morales, Ph.D., Faraday Technology, follows up with a presentation on “Electrochemical Surface Preparation of Passive Metallic Substrates for Electroplating." In summary: The overall objective of this work is to electrolytically prepare metallic substrates of passive materials for subsequent electrodeposition. The challenge in plating on passive materials such as titanium, stainless steel, and nickel–based alloys is the tenacious oxide film that readily forms on the surface almost instantaneously when exposed to the atmosphere. Currently, this is overcome through aggressive precleaning steps that often include toxic electrolytes such as nitric and hydrofluoric acids. An alternative surface preparation technique to mitigate the need for aggressive chemicals is presented in this work. The focus of this engineering study was to develop the preliminary understanding required to successfully remove the surface oxide and plate on passive substrates, from an electrolytic benign process.

Rounding out Track II of the Technical Conference is “Surface Modification of Materials by High-Power Laser: State-of-the-Art and Prospects,” by M.Z. Huq, J. Rindt, and D.B. Mitton, Engineered Surfaces Center, University of North Dakota. In summary: The ever-increasing and often conflicting demands made on engineering materials for suitable physical, chemical, and mechanical properties have led engineers to take an increased interest in surface coating techniques for material protection. Laser treatment has shown that high-quality, low-distortion, cladded, alloyed layers or heat-treated surfaces can be generated successfully on base materials. Due to the intrinsic characteristics, lasers can be focused onto material surfaces producing a broad range of treatments from heating to melting depending on the input energy. So, phase transformation on the surface of a base metal can be carried out to increase the surface hardness or cladding/alloying to obtain new materials. In this context, a review on laser surface alloying and cladding on different base materials for corrosion and wear-resistant applications will be discussed. Directions in which work is currently being pursued will also be mentioned.

(For a complete listing of technical sessions, please visit www.sur-fin.net. Also, look out for more SUR/FIN-related announcements in next week’s newsletter.)