【正文】 machining errors. 6σrepresents the machining accuracy reachable in a certain machining condition for a kind of process operation.Generally speaking, for the process chosen of a sequence, the tolerance of the sequence T and the standard difference σ obey 6σ≤T. For some reason, σ and μ is unknown. Fortunately, we can use the total mean value of the sample , and the standard difference SUsage of the distribution graph1) Assess the feature of the machining error2) Determine the sequential ability and the level number The sequential ability the undulation of the machining error under steady machining conditions. If the sizes obey the normal distribution, the range of the sizes should fall into 6σ. So the sequential ability is 6σ. The level number of the sequential ability represents the degree of satisfaction to the machining accuracy, in terms of Cp Cp=T/ (6σ)3) Estimate the waste rate or the qualification rate.CHAPTER FOUR INTEGRITY OF MACHINED SURFACES1 Concept of the machined surface integrity and it’s influence on the ponent functions2 Processing factors influencing the surface roughness and the improvement3 Processing factors influencing the physical and mechanical properties of the surface layer of the ponent and the improvement4 Brief introduction to the vibration in machiningSection 1 Concept of the machined surface integrity and it’s influence on the ponent functionsA Geometric form errors a) Surface roughness(粗糙度)：irregularities with very high frequencyb) Waviness（波度）： irregularities with high frequencyc) Lay/vein direction（紋理方向）：the direction of the marks left by the cutting tool during the forming operations9 / 10d) Scars（傷痕）：rarely presented defects on the surface, such as sand pits, air hole, and cracks etc. B The physical, chemical, and mechanical properties of the surface layera) Strain hardening, with the degree and depth of the hardeningb) Metallographic position Changes may occur of the metallographic position due to the cutting heat. c) Residual stress within the surface layerSection 2 Processing factors influencing the surface roughness and the improvementSection 3 Processing factors influencing the physical and mechanical properties of the surface layer of the ponent and the improvementA Strain hardeningThe strain hardening occurs whenever there is any form of plastic deformation, such as warp and aberrance of the crystal lattice , and slippage between the crystal grains, as well as the elongation of the crystal grains. In this procedure the surface layer gains energy and bees hard. So we call it a strengthening procedure. However it is in the state of instability, and it will relieve if there is a chance, say absorbing (taking in) heat (weakening).B Change of the metallographic positionC Residual stressWith factors of plastic deformation (residually pressive stress) and heat (residually tensile stress)residual stresses arising in I turning (speed, rake angle, feed ) 。 II grinding( ap, v, f, work material, last sequence)Section 4 Brief introduction to the vibration in machiningForced vibration(強(qiáng)迫振動(dòng)), selfexcited vibration (quiver)（自激振動(dòng)）, and free vibration（自由振動(dòng)）CHAPTER FIVE DESIGN OF THE ASSEMBLING PROCESSESSection 1 Introduction to assemblyA basic concept: any machine consists of ponents（零件）, set of ponents（套件）, assembly（組件）, and posite parts(部件). And the relatively independent parts to be assembled into the machine easily and conveniently is called assembling cell or unit.ponents（零件） : unit with the whole materialset of ponents（套件）:smallest assembling unit with a datum ponent and several auxiliary ponentssub assembly（組件）:with a datum ponent and several sets of ponents and several auxiliary ponentsposite parts/assemblies (部件):with a datum ponent and several assemblies ,sets of ponents and auxiliary ponentsOverall assembly(總裝): a procedure in which a ll the ponents, sets of ponents, subassemblies and assemblies are fitted into the datum ponent, forming the final product, the machine.B assembling schematic（裝配工藝系統(tǒng)圖）:The draft that indicates the relationship among the ponents and posite parts and the assembling flow. Names, numbers and quantities are presented on the assembling schematic with panes (方格)Assembling accuracy including relative position accuracy(相互位置精度), relative moving accuracy（相對(duì)運(yùn)動(dòng)精度）, and fit/mating accuracy（配合精度）10 / 10CHAPTER SIX: ADVANCE AND DEVELOPMENT OF MANUFACTURING TECHNOLOGY1 Automation of mechanical manufacturing system and puter aided manufacturing (CAM/FMS/CIMs)2 Precise and ultraprecise manufacturing technology3 Nonconventional machining technology4 Other recently developed machining technolog