INTRODUCTION TO PROCESS PLANNING

INTRODUCTION TO PROCESS PLANNING

1. PROCESS PLANNING AND COST ESTIMATION

2. U-I INTRODUCTION TO PROCESS PLANNING

3. PROCESS PLANNING DEFINITION: Set of instructions describes mfg product and its parts. Operations planning as systematic determination of engg processes and systems to mfg a product competitively and economically. Prepare work instructions for mfg and assembly of components to product in discrete mfg environments. Systematic determination of methods products to be mfg,economically and competitively. Consists of selection of mfg processes and operations,production equipment,tooling and jigs and fixtures,

4. Determination of mfg parameters,specify selection criteria for quality assurance ensure product quality. IMPORTANCE OF PROCESS PLANNING: Link between engg design and shop floor mfg,product is how mfg,production costs and profitability,indepth of knowledge, equipment capabilities, tooling availability, material processing characteristics, shop practices. PRODUCT DESIGN AND MFG CYCLE: Intermediate stage b/w designing the product and mfg. Three main functions marketing and sales,design,mfg .

5. PROCESS PLANNING: LINK B/W DESIGN AND MFG: Cross functional teams are employed to design and mfg functions,known as simultaneous or concurrent engg .

6. RESPOSIBILITIES OF PROCESS PLANNING ENGINEER: Part print analysis and symbols. Fundamentals of product design(rough stock, production rate,finish,dimensional tolerances). Machining processes(setup time,quality,type and cost of tooling). Operations sequence,inspect the equipment,production tolerances,cutting tools and cutting conditions,overall time by work measurement techniques.

7. PROCESS PLANNING ACTIVITIES: Drawing interpretation: Analyse finished part in engineering design.component drawings( features,dimensions,geometric tolerances,surface finish,material specification,part required). Material evaluation and process selection: (Function,appearance,reliability,life,environment,compatibility,productivity,cost).Evaluate the materials, ( features,dimensions,geometric tolerances transform rough state to finished state).Process evolution(rough to finished).Part evolution(final state to initial state).

8. Selection of m/ c,tooling,workholding devices: Economic considerations,production rate per unit cost,durability and dependability,lower process rejection,minimum setup times,long life of m/ c,functional versatility.best m/ c,make or buy,BEA . Selecting process parameters: Machines selected,calculating operation setup time and cycle time,tooling sequence,equipment capability,shop practice. Calculation of part processing time requires determination of sequence of processing steps on each m/c as outplanning . Part loading,unloading,m /c indexing for 1 cycle. M/c cycle time allowances added to standard cycle time.Calculate cycle time & m/c rates to find out cost.

9. Selecting quality assurance methods: Inspection criterias ( dimensional,geometric,surface finish),tools and techniques,increases costs&time . Cost estimating: Process of determining the probable cost of product before manufacture. Material,labour,overhead costs-profit. Material,mfg processes,batch size,make or buy.

10. Process planning documentation: Document clearly all the detail information. Documented as job routing or operating sheet. Production operations&associated m/c tools for component and subassembly. Route sheet information as part identification,processing,operation of m/ c,std times,setup cycle times,tooling requirements,production control information shows planning lead time operation. Reasons: part process- design,job quote,cost estimate,std cost systems,communication vehicle.

11. Communicate process knowledge: Mfg to shop floor,economy,consistent quality. Inputs and outputs of process planning: Route sheet and operation sheet as single sheet.

12. PROCESS PLANNING METHODS(APPROACHES TO PROCESS PLANNING): Manual process planning( traditional,workbook approaches). Computer aided process planning( retrieval,generative ). Manual process planning: Traditional approach: Process plan prepared manually. Examine and interpret eg,m /c process,equipment selection,opns sequence,shop practices,skill,judgement and experience,different planners. Product opns,manual tools( feed,speed,setup time,opns time),documented as routing sheet.

13. Workbook approach: Modified version uses developed workbook prepares route sheet.opns sequence of products the drawing interpretation is carried by workbook. Uses of manual approach: Small scale companies,flexible,low investments. Drawbacks of manual approach: Complex,time&data high,skill process,human error,skill,judgement and experience,increases paper work,productivity down,no response to mfg environment,process,tool,materials … Computer aided process planning: Computers reduces clerical works,rational,consistent and optimal plans,interface between cad and cam.

14. Benefits of capp : Process rationalization and standardization,productivity improvement,product cost reduction,eliminate human error,time reduction,reduces clerical and paper work,legibility improves,fast response to engg changes,incorporation of application programs. Retrieval or variant capp systems: Widely used in machining applications,similar parts have similar plans,new part recalls,identifies,retrieves existing plan for similar modified new parts. Benefits of retrieval capp systems: Standard plan,variety of parts,simple programming and installation,understandable,easy to learn and use. Drawbacks of retrieval capp systems: Planned components limited to previous planned. Experiences modify standard plan.

15. Generative capp systems: Computers synthesize individual process plan automatically w ith or without reference to prior plan. Decision logics and precoded algorithms,mfg using equipment,specific process plan for specific part. Inputting GT code as part design,monitoring the functions. Components: Part description,subsystem define m/c parameters&select and sequence individual operations,database,report generators. Advantages of generative capp : Consistent process plan,new components,integrating automated mfg facility provides detailed control information. Drawbacks of generative capp : Complex and very difficult

16. SELECTION OF PROCESS PLANNING SYSTEM: Numerous engg management decisions,identify,weight and compare interrelated factors. Best process plan-general environment,organisational structure,technical expertise,needs and objectives of MIS.

17. DRAWING INTERPRETATION: Prepares process plan for product,functional requirements of design,assembled with dimensions and tolerances. Information such as material,designation,coding,no of parts,weight,dimension of parts,geometric tolerances,size and accuracy. Engineering drawing: Language of engg and communication,orthographic projection(accurate mfg design,2D&3D,pictorial gives more information). Types of drawing: Detail drawings:single-part,collective. Assembly drawings:single-part,collective. Combined drawing. Detail drawings: Provide all the information required for mfg of product,( dimensions,tolerances,surface finish and material specifications).

18. Types: single part,collective single part. Single part drawings: Complete detail information single component mfg without reference sources.shape,dimension,tolerances,size and locations,heat treatment,surface finish. Collective single part drawings: One or two dimensions of component are variable,others being standard. Assembly drawings: Machines and mechanisms consist of numerous parts and a drawing shows complete product with all components in correct physical relationship. Sub-assembly drawings: Drawing gives small part of whole assembly. Types: Single part,collective

19. Single part assembly drawings: Information to build single sub-assembly or assembly. Part list,quantity,overall dimensions,weight,mtrl specifications,design data,operational details and instructions. Collective assembly drawings: Range of products similar in appearances,differ in size,mfg and assembled. Combined detail and assembly drawings: Assembly with part list and details of these parts on one drawing,small one-off reduces scheduling and printing. INFORMATION ON THE DRAWING SHEET REQUIRED FOR PROCESS PLANNING:(CRITICAL PROCESSING FACTORS): Dimensions: complete dimensions of the component design mfg. Functional: Influence operated part. Non-functional: Not influence operated part. Auxiliary: Not relate to operate and mfg part.

20. Material specifications: Parts evaluated,specified and manufactured. Special material treatments: Material properties treated. Tolerances,limits and fits: Component fit assembly,appropriate lower and upper limits. Accurate tolerance,cost high,good engg practice. Dimensional tolerances: 10±0.02 as 9.98&10.02mm. General tolerancing : Unspecified tolerances dimensions,saves time. Limits and fits for shafts and holes: Basic size is shaft or hole size,limits the specified design. Basic hole system-basic hole size adjusts shaft size to fit. Basic shaft system-basic shaft size adjusts hole size to fit.

21. Standard tools as drills,reamers for basic hole system. Fit Tightness or looseness for application of tolerances to mating parts. Clearance fit Assemble/dissemble by hand,running and sliding assemblies,low cost to high temperature,minimum accuracy. Transition fit Press tooling,close accuracy,no interference. Interference fit Forced permanent assemblies,retain and locate. Geometrical tolerancing Permissible variation of form,attitude . Types: straightness,flatness,roundness,cylindricity,parallelism,squareness angularity,concentricity,symmetry,position .

22. Surface finish: Irregularities depth of surface in mfg processes. Form error: Longer wavelength deviations of surface to nominal surface,large scale problems,errors in m/c tool ways,guides,inaccurate alignment of w/p. Roughness: Finest irregularities of surface,production process. Waviness: Widely space deviations from norminal shape,m /c vibration. Surface texture= roughness+waviness . Surface roughness,surface textures(symbols), Surface roughness,surface textures(components) used.

23. Material selection and evaluation: Component-material processing-mfg-design. Metals and classification: Ferrous materials: Materials of iron as prime constituent,steel (0.05-2%),iron(2-4.5%). Steels: Alloys of iron and carbon,carbon steels and alloy steels. Low carbon steel 0.25%C,Medium carbon steel 0.60%C, High carbon steel-0.60%C. Alloy steels- chromium,nickel,molybdenum,vanadium,tungsten,cobalt . Low alloy steels-3 to 4%,high alloy steels-5%(alloying elements). Important alloy steels-stainless steels,tool steels,HSLA steels,maraging steels. Cast iron: Ferrous alloys of iron 2 to 4.5%C,3.5% silicon.

24. Grey cast iron-low cost,white cast iron-hard and brittle,malleable cast iron- ductile,yield and tensile strength,spheroidal graphite cast iron. Non-ferrous materials: Elements other than iron as chief constituent. Light weight,colour,ease fabrication, better resistant, electrical and thermal conductivity. Important non-ferrous materials- C,Al,lead,Ni,Mg,Ti,Tn,Zn . Polymers: Density, thermal and electrical insulation, resist to chemical,fabrication,low cost. Engineering ceramics: Grinding,deals,bearings,magnets,engines,pumps . Features-(melting temp,oxidation,corrosion,high temp). Alumina,SiC,Si 3 N 4 ,PSZ,Sialons.

25. Composites: Composed of two or more different materials, resultant materials superior to individual materials. Particle reinforced composites-Particles of one material dispersed in a matrix of second material. Fibre reinforced composites-Dispersed phase as fibre .

26. MATERIAL SELECTION PROCESS: Appropriate material for product under consideration is complex task. Translation-design requirements as constraints,objectives,free variables. Screening-constrained limits apply to subset of viable materials. Ranking-ordering material,excellence criteria,maximum or minimum. Supporting information- top- ranked,history,behavior,availability,sufficient choice. MATERIAL SELECTION METHODS: Computer aided databases,performance indices,decision matrices,expert selection,value analysis,failure analysis,cost -benefit analysis.

27. Material evaluation methods: Shape or geometry considerations: Process-mfg-product. Size,complexity,dimensional tolerance,surface finish,wear allowance,assembly,manufacturability . Material property requirements-Loading type,loading magnitude,impact loading,cyclic loading,wear resistance,permissible temp,material deformation. Physical property requirements- electrical,magnetic,thermal,weight,aesthetic . Service requirements- temperatures operating,life span,most extreme,maintanence,reliability,serviceability,recyclability . Manufacturing considerations: Components,ease mfg,quantity,components rate,minimum&maximum section thickness,quality level,inspection methods,assembly ease.

28. PROCESS SELECTION

29. Process selection shaping, joining, finishing, mfg-design, size, shape and precision,parts . Factors Material form, size and weight, economic considerations, dimensional and geometry accuracy, surface finish,batch size, production rate. Guidelines Prototype validate mfg,compare mfg to assembly costs for different processes.

30. Process selection methods(steps): Mfg process,difficult,complex and systematic Assumptions: Materials selected,specified . Design documents,information comprehensive. Stages: Drawing interpretation: Starting point for process selection. Material,shape,size,tolerance,roughness,process parameters. Three analysis and o/p-geometry analysis,mfg information,material evaluation and o/p. Identification of critical processing factors: Combined o/p from drawing interpretation analysed and correlated. Material-mfg-geometry. Comparison of potential mfg processes:

31. Correlate,appropriate,decision-making,economy data. ( Labour,equipment,tooling cost,batch and production rates),costing methods and comparisons. Identification of suitable processes: Part-primary-secondary-critical processing. Production equipment and tooling selection: Mfg-processes-production equipment. Factors for equipment: Size,weight,physical size,construction,power and torque, no of tools, type of tools. Equipment-tooling-operation. Factors for tooling: Availability,w / p,type,part geometry,tool material,m /c data,m /c tool characteristics,cutting tool materials,tool holding,quality,capability requirements.

32. Consumables tooling-cutting tools,workholding devices,jigs and fixtures. Factors in equipment selection: M/c-processes-mfg-decision making-performing. Factors for m/c selection: Technical factors-physical size,m /c accuracy,surface finish,cutting forces,power . Operational factors-batch size,.Capacity,availability . Technical factors: M/c tool-mfg component/product, physical size,m /c accuracy,surface finish,cutting forces,power . Physical size: M/c tool-process-product-robust. Machine accuracy: Capability-mfg- dimension&geometry -design.

33. Surface finish: Capability . Cutting forces: Feed,speed,depth of cut,opns of m/c tool. Machine power: Power =cutting forcexcutting speed. Operational factors: Availability,cost effective,master production schedule.[Important-batch size,capacity,availability ]. Batch size: EBQ calculated,potential economical m/c tool. Capacity: Production rate,acheives o/ p,mps . Availability: Proportion,performance,efficiency,reliability , Availability.

34. Machine selection methods(steps): First cut selection: Identify,specify,select mfg processes,physical size,type of machine. Power/force analysis: Specify. Capability analysis: Dimensional,geometry accuracy,surface finish,m /c short listings. Final selection: More than 1 machine.

35. Factors in tooling selection: Constraints on tool selection- Mfg practice,mfg process,m /c tool characteristics,capability,processing time, cutting tool availability. Operating requirements on tool selection-W/p material,operation,part geometry, tooling data. Tooling performance affecting factors-Cutting tool materials, cutting tool geometry, cutting fluids. Constraints on tool selection- Mfg practice,mfg process,m /c tool characteristics,capability,processing time, cutting tool availability. Manufacturing practice: Tool actually fed to workpiece . Two categories(continuous cutting,intermittent cutting). Continuous cutting-cutting tool is continuously fed to w/p. Intermittent cutting-cutting tool not continuously fed to w/p. Manufacturing process: M/c tools limit the selection of tooling.

36. M/c tool characteristics: Work holding devices,Tool structure,Power o/p, Feed and speed of m/c. Capability: Dimensional and geometric accuracy,surface finish. Machining time: Power,feed,speed,m / c,tooling . Cutting tool availability: Selecting the available tools. Tool selection operating requirements- W/p materials,operation,part geometry,tooling data. Workpiece material: Heat generation,cutting tool geometry material. Operation: Specific cutting tool.

37. Part geometry: Specific geometry feature. Tooling data: Mfg tooling data,suitable tools,specified operations. Tooling performance factors- cutting tool materials,cutting tool geometry,cutting fluids. Cutting tool materials: Tool performance,hss,carbides,cast non-ferrous alloys,ceramics . Cutting tool geometry: Tool angles,rake angles,cutting edge angles,tool nose radius. Influences w/p material and tool material. Cutting fluids usage: Cools w/ p,tool temperature,maintains hardness,avoid distortion. Friction b/w tool and w/ p,wear resistance of tool,improves tool performance.