Doğuş Cendek 030060101 8th week

Adhesion (in turning) (31.03 11.36) Mechanical adhesion is that portion of total adhesion provided by physical entrapment of portions (larger than molecul size) of one phase of joint in another.Specific adhesion includes formation between any two surface of bonds based on primary valence force,secondary valence forces or combination of the two. (Instutation of Mechanical Engineers,Adhesion,p. 33) Figure 1: Ferguson's Paradox (modern design) Ferguson's Paradox (31.03 11.52) It would appear from our memoranda as also from other references,that it was during the year 1750 that Ferguson invented and celebrated machine called 'The Mechanical Paradox'.In several of his works he mentions that he made it 'On a vary particular occasion' but without informing us of anything regarding this 'particular occasion'.But it is now certain that be made this curious machine for the purpose of silencing of London watchmaker who did not believe in the doctrine of Trinity as will be shown by a vary interesting letter ,written by Ferguson a few months before his death to a clericel friend of his in the north of Scotland a copy of which the reader will find at the conclusion of description of the Paradox. (Ferguson J.,Life of James Ferguson,p.139) Figure 2: Ferguson's Paradox (The First Design) Flank Wear (31.03 12.31) The contact condition on the tool flank surface is of interest due to its impact on modeling of tool flank wear and the integrity of the machine surface.The way to look the problem is to understand physical processes taking place at the tool workpiece interface which is known as flank contact area.The contact processes on the tool flank are determined by the normal and the frictional forces acting at the tool/workpiece interface.The flank wear of the cutting tool increases with increasing averange normal stress acting along the flank face and the number of hard ceramic particles contacting the cutting tool and decreasing with increasing tool hardess. (Kannan S.,Machining of Metal Matrixe Composite:Forces,Tool Wear and Attainable Surface Quality,p. 102) Ratchet Mechanism (31.03 12.47) It consist of wheel calles Ratchet with saw-shaped teeth which engage with an arm called a pawl. The arm is pivoted and can move back and forth to engage the wheel.The shape of teeth are such that rotation can occur in only one direction. (Onwubolu G.C.,Mechatronics:Principles and Applications,p. 380)

Figure 3: Ratchet Mechanism