טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentStav Ori
SubjectSimultaneous Shot-Peening of Hard and Soft Particles for
Friction Reduction in Reciprocal Sliding
DepartmentDepartment of Mechanical Engineering
Supervisors Dr. Haytam Kasem
Professor Emeritus Izhak Etsion
Full Thesis textFull thesis text - English Version


Abstract

Friction between mechanical components experiencing relative motion is responsible for about 20% of the total world energy consumption. By making use of the latest tribological technologies, friction can potentially be reduced by 40% in the long term. Lubrication is the basic technique for friction reduction, and it is generally divided into three lubrication regimes characterized by the thickness of the lubricant film: boundary, mixed and full-film lubrication (thinnest to thickest lubricant layer). Direct contact between surface asperities occurs at the first two.  Reciprocal motion is an example of relative motion in which a transition through the different regimes of lubrication occurs.

The present research is focused on the reduction of friction for boundary and mixed lubrication regimes in reciprocal sliding. The effect of Simultaneous Shot-Peening (SSP) of hard and soft particles on friction reduction between mechanical components experiencing reciprocal motion was experimentally investigated.
Reciprocal test rig lubricated with a fully formulated oil was tested under severe conditions of high temperature and various speeds and loads. Thus, providing results which are relevant to a wide range of mechanisms, such as piston ring and cylinder liner in internal combustion engines (ICE), plunger pumps (oil drilling), hydraulic press etc. and making a step towards proving the feasibility of SSP surface treatment for applicative uses.

The relationship between Stribeck number and lubrication regimes to friction reduction was investigated as function of crank rotation angle. As well as the relationship between roughness, hardness and chemical composition to friction reduction.
A novel micro-shot peening (MSP) device for Simultaneous Shot-Peening (SSP) is described, along with a reciprocal test rig. In addition, the mechanisms which provide high durability to the SSP is discussed. Total of 25 combinations of normal load and sliding speed were tested. Comparison between a treated SSP specimen and a Reference specimen shows an average friction reduction of up to 33% with local maximum friction reduction of up to 65%.