unit- II processplanning activities.pptx

Definition and Importance
Process planning is the systematic determination of methods by which a product is to be manufactured economically and competitively. It involves selecting appropriate resources, including machinery, tools, and labor, as well as determining the sequence of operations required to convert raw materials into finished products. The primary goal is to achieve optimal efficiency, quality, and cost-effectiveness in the production process.

Steps in Process Planning
Analyzing Product Design and Specifications:

Understanding the design requirements, tolerances, material specifications, and functional aspects of the product.
Identifying critical features that influence the manufacturing process.
Selecting Materials:

Choosing materials that meet the design specifications and are cost-effective.
Considering material availability, machinability, and performance characteristics.
Choosing Manufacturing Processes:

Evaluating different manufacturing processes such as casting, forging, machining, welding, and additive manufacturing.
Selecting processes that align with product requirements, production volume, and cost constraints.
Determining Operation Sequence:

Establishing the sequence of operations to ensure efficient workflow and minimal handling.
Considering factors like setup times, tool changes, and part orientation.
Selecting Equipment and Tools:

Identifying appropriate machinery and tools required for each operation.
Ensuring equipment availability and compatibility with the selected processes.
Designing Jigs and Fixtures:

Creating custom jigs and fixtures to hold and support workpieces during manufacturing.
Enhancing precision, repeatability, and safety.
Estimating Production Time:

Calculating the time required for each operation, including setup and machining times.
Using time studies and standard data to ensure accuracy.
Defining Quality Control Measures:

Implementing inspection and testing procedures to ensure product quality.
Establishing tolerances, sampling plans, and acceptance criteria.
Documenting the Process Plan:

Creating detailed process plans that include operation sheets, tooling lists, and quality control checklists.
Ensuring documentation is clear, accurate, and accessible to all relevant personnel.
Tools and Techniques in Process Planning
Computer-Aided Process Planning (CAPP):

Using software tools to automate and optimize process planning.
Integrating with CAD/CAM systems for seamless data transfer and collaboration.
Simulation and Modeling:

Utilizing simulation tools to model manufacturing processes and predict outcomes.
Identifying potential issues and optimizing processes before physical implementation.
Lean Manufacturing Principles:

Applying lean techniques to eliminate waste, reduce cycle times, and improve efficiency.
Focusing on continuous improvement and value-added activities.
Value Stream Mapping (VSM):

Creating visual representations of material and information flow.
Identifying bottleneck

1. ME8793 PROCESS PLANNING AND COST ESTIMATION UNIT II PROCESS PLANNING ACTIVITIES

2.  The process planning involves the various activities such as drawing interpretation, material evaluation and process selection, selection of machines and tooling, setting process parameters, selection of work holding devices, selection of quality assurance and inspection methods, cost estimating and documenting the details using route sheets.

3. Cutting speed Feed rate and Depth of cut.

4.  The cutting speed also known as surface cutting speed or surface speed , can be defined as the relative speed between the tool and the work piece. It is the speed at which the metal is removed by the cutting tool from the work piece. In case of lathe machine cutting speed is the peripheral speed of the work past the cutting tool. It is expressed in meter/min. or mm/min. Cutting speed (V) = π DN/60 × 1000 mm/min

5. Nature of the Cut Work Material Cutting Tool Material Cutting Fluid Application Purpose of Machining Kind of Machining Operation Capacity of the Machine Tool Condition of the Machine Tool

6. Cutting Speeds for different combinations of operation and material

7. Feed is the distance through which the advances into the work piece during one revolution of the work piece of the cutter. It is the relative motion of tool in one revolution of work piece. It is expressed in mm/rev.

8. Work material (type, strength, hardness etc.) Capacity of the machine tool (power, rigidity etc.) Cutting tool (material, geometry and configuration) Cutting fluid application Surface finish desired Type of operation Nature of cut

9. Depth of cut is the thickness of the layer of metal removed in one cut or pass, measured in a direction perpendicular to the machined surface. It is the total amount of metal removed per pass of the cutting tool. It is expressed in mm. It can vary and depending upon the type of tool and work material. Mathematically, it is half of difference of diameters. Depth of cut (t) = D-d/2 mm D- Outer diameter, d- Inner diameter.

10. Depth of cut for Turning and Boring 6 mm for roughing and 0.4 mm for finishing . Depth of cut for Milling Half of the cutter diameter. Depth of cut for Drilling Half the feed rate of the tool and minimum considered to be 0.3mm. Depth of cut for Shaping and Planing The range of 1-4 mm. Depth of cut for Grinding The values for feeds selected in mm/pass.

11. The process planner has to identify the need for a work holding device or a jig or a fixture for the selected operation. The process planner will communicate the identified requirements of the work holding device to a specialised tool engineer for the detailed design and drawings that are needed for manufacturing it.

12. The main purpose of any work holding device is to position and hold a work piece in a precise location while the manufacturing operation is being performed. Types of work holding devices are:

13. A jig may be defined as a work holding device which locates and holds the work piece for a specific operation. It is also provided with tool guiding elements. Jigs are usually lighter in construction and direct the tool to the correct position on the work piece. Jigs are usually fitted with hardened steel bushings for guiding or other cutting tools. a jig is a type of tool used to control the location and/or motion of another tool.

14. A jig's primary purpose is to provide repeatability, accuracy, and interchangeability in the manufacturing of products. A device that does both functions (holding the work and guiding a tool) is called a jig. An example of a jig is when a key is duplicated, the original is used as a jig so the new key can have the same path as the old one.

15. It is a work holding device that holds, supports and locates the work piece for a specific operation but does not guide the cutting tool. It provides only a reference surface or a device. What makes a fixture unique is that each one is built to fit a particular part or shape. The main purpose of a fixture is to locate and in some cases hold a work piece during either a machining operation or some other industrial process.

16. Jigs Fixtures It is a work holding device that holds, supports and locates the work piece and guides the cutting tool for a specific operation. It is a work holding device that holds, supports and locates the work piece for a specific operation but does not guide the cutting tool. Jigs are not clamped to the drill press table unless large diameters to be drilled and there is a necessity to move the jig to bring one each bush directly under the drill. Fixtures should be securely clamped to the table of the machine upon which the work is done. The jigs are special tools particularly in drilling, reaming, tapping and boring operation. Fixtures are specific tools used particularly in milling machine, shapers and slotting machine. Gauge blocks are not necessary. Gauge blocks may be provided for effective handling. Lighter in construction. Heavier in construction.

17. Clamping Elements Locating Elements Tool guiding and Setting Elements Tool setting Elements.

18. Location Clamping Loading Stability and Rigidity Clearance for Chips Foot Proof Design Provision for Tool Guides Provision for Indexing Weight Safety Coolant Supply Economy

19. Component Capacity of the machine Production requirements Location Loading and Unloading arrangements Clamping arrangements Clearance between Jig and Component Ejectors Base and Body construction Tool guiding and cutter setting Rigidity and vibration Safety Cost and Materials

20.  Types of Jigs: Here are some simple drill jigs : Template jig Plate jig Diameter jig Channel jig Ring jig Box jig Leaf jig Angle plate jig Indexing jig Trunion jig

21.  Types of Fixtures: These are some Fixtures available : Plate fixture Angle plate fixture Vise-jaw fixture Indexing fixture Multistation fixture Profile fixture

22. The next activity of process planner is to specify the quality assurance methods/inspection criteria for all the critical processing factors such as dimensional and geometric tolerances and surface finish specifications that are identified during the drawing interpretation. Quality assurance ( QA ) is a way of preventing mistakes and defects in manufactured products and avoiding problems when delivering products or services to customers.

23. Identification of inspection locations Identification of the most appropriate inspection and testing methods Determination of the frequency of inspection and testing Evaluation of inspection and test data. Identification of corrective action.

24. Quality Defined: Quality is fitness for use. Quality is conformance to requirements. Definition of TQM: Total Quality Management (TQM) is the management approach of an organisation, centered on quality based on the participation of all its members and aiming at long-term success through customer satisfaction, and benefits to all members of the organisation and to society.

25. Detection strategy and Prevention strategy.

26.  Statistical Quality Control (SQC) is about employing inspection methodologies derived from statistical sampling theory to ensure conformance to requirements.

27.  A control chart is a graph that displays data taken over time and the variations of this data.

28. Process capability compares the output of an in-control process to the specification limits by using capability indices. Process capability may be defined as the “minimum spread of a specific measurement variation which will include 99.7% of the measurements from given process.” In other words, Process Capability = 6σ

29. Objectives of Inspection To sort out the conforming and non- conforming product. To initiate means to determine variations during manufacture. To provide means to discover inefficiency during manufacture.

30. 100% Inspection: 100% or cent percent inspection is quite common when the number of parts to be inspected is relatively small. Sampling Inspection: The use of sampling inspection is made when it is not practical or too costly to inspect each piece.

31.  Measurement: The different types of quality characteristics that are to be measured are: Dimensions/Size, Physical properties, Functionality, and Appearance.

32. Accuracy Linearity Magnification Repeatability Resolution Sensitivity Stability (or drift)

33. The process planner should have the fundamental knowledge on cost estimating, cost accounting, various types of costs, components of costs and calculation of manufacturing of a product. The knowledge of costing will help the process planner and the management to take the following decisions: Type of material to be used for a product. Volume of product to be manufactured. Make or Buy decisions. Design of a product.

34.  D e f in i t i o n : Break-even analysis, also known as cost- volume-profit analysis , is the study of inter- relationships among a firm’s sales, costs and operating profit at various levels of output. It is a simple method of presenting to management the effect of changes in volume on profit. It is concerned with finding the point at which revenues and costs are exactly equal. This point is known as break-even point .

35. To help in deciding profitable level of output, below which losses will occur.. To compute costs and revenues for all possible volumes of output to fix budgeted sales. To take decision regarding make or buy. To take plant expansion decisions. To take equipment requirement decisions. To indicate margin of safety. To fix the price of an article to give the desired property. To compare a number of facility locations.

36. The break-even point may be defined as the level of sales at which total revenues and total costs are equal. It is a point at which the profit is zero. The break - even point (BEP) in economics, business—and specifically cost accounting—is the point at which total cost and total revenue are equal, i.e. " even ". There is no net loss or gain, and one has " broken even ", though opportunity costs have been paid and capital has received the risk-adjusted, expected return.

37. I. Break-even point in terms of physical units : Let, FC = Fixed cost, VC = Variable cost per unit, TVC = Total variable cost, TC = Total cost TR = Total revenue i.e. total income, Q = Sales volume and SP TC = Selling price per unit. = FC + (VC X Q)

38. TR = SP X Q At Break-Even Point(BEP), Total Cost= Total revenue TC = TR FC + (VC X Q) = SP X Q Or QBEP = FC/(SP-VC)

39. II . Break-even point in terms of Sales Value : This method is suitable for a multi-product firm. Break-even sales (BEP in rupees) FC / 1 – (VC/SP)

40.  The difference between selling price and variable cost per unit is known as Contribution or contribution margin . C = SP – VC Contribution margin divided by selling price is known as contribution ratio . Contribution ratio = (Selling price-Variable cost)/ Selling price.

41.  Margin of safety represents the strength of the business. It enables a business to know what is the exact amount it has gained or lost and whether they are over or below the break-even point. Margin of safety = (current output - breakeven output) Margin of safety% = (current output - breakeven output)/current output × 100