materials processing and design-ii · classification of manufacturing processes spectrum of...
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AUTO 541 - Prof. Dr. Sabri Alt ıntaş 1
Materials Processing and Design-II
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Interrelations of design, materials, and processing to produce a product
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Classification of manufacturing processes
Spectrum of activities which are encompassed by manufacturing
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A hierarchical classification of business and industry.
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Characteristics of production systems.
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Factors determining process selection
• Cost of manufacture and life cycle cost• Quantity of parts required• Complexity-shape, form, size• Material• Quality of part• Availability, lead time, and delivery schedule
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Factors determining process selection
An example of an Ashby process selection chart. This chart plots the information content of the part against the part size. It delineates those processes that are most applicable in various regimes.
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Prima selection matrix showing which materials and processes are usually used in practice.
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Comparison of costs with different forms of starting material.
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Cross-sectional profile of surface roughness with vertical direction magnified.
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Symbols used to specify finish characteristics. Roughness given in microinches.
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Approximate values of surface roughness and tolerance on dimensions typically obtained with different manufacturing processes.
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Influence of tolerance on processing costs (schematic).
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Factors determining process selectionFurther information for process selection:The Manufacturing Process Information Maps (PRIMA):
• Process description.• Materials: materials typically used with the process.• Process variations: common variants of the basic process.• Economic factors: cycle time, minimum production quantity, material
utilization, tooling costs, labor costs, lead times, energy costs, etc.• Typical applications: examples of parts commonly made with this
process.• Design aspects: general information on shape complexity, size range,
minimum thickness, draft angles, undercuts, and limitations on other features.
• Quality issues: describes defects to watch out for, expected range of surface finish, and process capability charts showing dimensional tolerances as a fuction of dimension.
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Process information map for tolerance capability in the sand casting process.
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Design For Assembly (DFA)
A list of DFA guidelines:1. Minimize the total number of parts2. Minimize the assembly surfaces3. Avoid separate fasteners4. Minimize assembly direction5. Maximize compliance in assembly6. Minimize handling in assembly
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Some design features that improves assembly.
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Early Estimation Of Manufacturing Cost
C = V Cmv + Pc Rc
Cmv = cost of material per unit volumeV = volume of material input to the processPc = basic processing cost for an ideal partRc = cost coefficient for the part design that takes into
account shape complexity, material workability, section thickness, surface finish, and tolerances.
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Average curves of Pc vs. N for selected manufacturing processes.
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Relative cost of material-process suitability, Cmp, a factor which is included in the Rc term.
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The shape classification system used to determine.
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The shape classification system used to determine.
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The shape classification system used to determine.
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Curves for determining Cc for shape classification A. (a factor of Rc)
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Chart used for determining the section coefficient Cs.(a factor of Rc)
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Charts used to determine Ct (top row) and Cf (bottom row).
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Design For Casting
Parts of a conventional sand casting process.
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Classification of casting processes.
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Selection of the proper casting process depends on the followingfactors;
• Complexity of the shapea. External and internal shapeb. Types of core requiredc. Minimum wall thickness• Cost of the pattern or die• Quantity of parts required• Tolerances required• Strength• Weight• Overall quality required
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Advantages and disadvantages of the common casting process
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Advantages and disadvantages of the common casting process (continued).
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Some design details to prevent shrinkage cavity.
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Design For Forging
The redistribution of the fiber structure direction during the forging of a part.
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Relation between reduction of area and orientation within the forging.
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Advantages and disadvantages of the common forging process.
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Schematic of closed-die forging. (a) Blocker die; (b) finishing die.
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Examples of desirable und undesirable location of parting line.
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Design For Sheet-metal Forming
Changes in design to minimize scrap loss in blanking.
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Keeler-Goodwin forming limit diagram.
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Design For Machining
Classification of metal-cutting
processes.
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Operations and machines for machining flat surfaces.
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Operating and machines for machining external cylindrical surfaces.
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Operating and machines for machining internal cylindrical surfaces.
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Classes of metals and machining processes, listed in decreasing order of machinability.
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Examples of design details that minimize the area of the machined surface.
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Design details for improved machining.
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Design For Welding
Classification of welding processes.
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Basic type of welded joints.
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Fillet weld in lap joint.
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Residual Stresses In Design
(a) Inhomogenous deformation in rolling of sheet ; (b) resulting distribution of longitudinal residual stress over thickness of sheet (schematic).
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Residual stress patterns found in quenched bars and due to thermal strains (schematic). (a) For metal which contracts on cooling; (b) orientation of directions; (c) for metal which expands on cooling.
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Transformation characteristics of a steel (a and c), and resulting residual stress distributions (b and d).
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Longitudinal residual stresses in a butt-welded plate.