1 introduccion procesos de manufactura

PROCESOS DE MANUFACTURA

Prof. M.A. Béjar

PROCESOS DE MANUFACTURA DEFINICION

CLASIFICACION


Prof. M.A. Béjar

MACHINING PROCESSES SINGLE POINT MACHINING �TURNING �BORING �FACING �FORMING � SHAPING, PLANNING MULTIPOINT MACHINING � DRILLING � MILLING � SAWING, FILING � BROACHING, THREAD CUTTING GRINDING � SURFACE GRINDING � CYLINDRICAL GRINDING � CENTERLESS GRINDING � INTERNAL GRINDING � FORM GRINDING ABRASIVE WIRE CUTTING HONING LAPPING ULTRASONIC MACHINING BUFFING, POLISHING TUMBLING GRIT BLASTING CHEMICAL MACHINING � ENGRAVING � CHEMICAL MILLING � CHEMICAL BLANKING ELECTROCHEMICAL MACHINING ELECTRICAL DISCHARGE MACHINING LASER MACHINING ELECTRON BEAM MACHINING PLASMA-ARC CUTTING FLAME CUTTING WATER JET CUTTING

DEFORMATION PROCESSES OPEN- DIE FORGING IMPRESSION-DIE FORGING CLOSED-DIE FORGING � PRECISION OR FLASHLESS FORGING � COINING � HEADING, PIERCING, HUBBING, COGGING, FULLERING, EDGING, ROLL FORGING, SKEW ROLLING ROLLING � FLAT, RING, THREAD, GEAR, PIERCING EXTRUSION � DIRECT, INDIRECT HYDROSTATIC, IMPACT, BACKWARD DRAWING � ROD & WIRE, FLAT STRIP, TUBES SWAGING SHEARING BENDING � PRESS- BRAKE FORMING, ROLL FORMING, TUBE FORMING BEADING, FLANGING, HEMMING, SEAMING STRECH FORMING BULGING DEEP DRAWING PRESS FORMING RUBBER FORMING SPINNING EXPLOSIVE FORMING ELECTROHYDRAULIC FORMING MAGNETIC- PULSE FORMING SUPERPLASTIC FORMING


Prof. M.A. Béjar

METAL CASTING AND POWDER PROCESSES CASTING CASTING OF INGOTS CONTINUOUS CASTING SAND CASTING SHELL MOLDING SLURRY MOLDING INVESTMENT CASTING (LOW- WAX PROCESS) EVAPORATIVE CASTING DIE CASTING (GRAVITY- FEED, PRESSURIZED�) CENTRIFUGAL CASTING SQUEEZE CASTING RHEOCASTING CRYSTAL GROWING � CRYSTAL- PULLING � ZONE MELTING Electro forming Plasma Spraying POWDER METALLURGY PRESSING ISOSTATIC PRESSING SINTERING

JOINING PROCESSES MECHANICAL JOINING � BOLTS, SCREWS, RIVETS SOLID- STATE WELDING � DIFFUSION, FORGING, FRICTION, DEFORMATION LIQUID STATE WELDING � RESISTANCE WELDING � ARC WELDING � THERMAL WELDING HIGH- ENERGY BEAM WELDING � ELECTRONIC BEAM, LASER LIQUID- SOLID STATE BONDING �BRAZING �SOLDERING ADHESIVE BONDING � PLASTICS AND COMPOSITES JOINING (MECHANICAL, HEATING, SOLVENTS, ULTRASONICS�) Mfg process, �..


Prof. M.A. Béjar

MACHINING PROCESSES

Honing Superfinishing

Lapping Ultrasonic Machining Buffing


Prof. M.A. Béjar

Typical Material Removal Rate


Prof. M.A. Béjar

Tolerances A tolerance is exactly as the word implies. It is the amount of deviation that can be tolerated in the SIZE and GEOMETRY of a component or assembly. Size Tolerances To have any chance of manufacturing components, the dimensions specified on drawings, need to show the acceptable upper and lower limits of size. Within reason, these limits should be as generous as possible in order to keep down manufacturing costs. Obviously there are times when it is necessary to quote very tight limits in order to provide a particular fit. For instance, it may be necessary for two components which fit together, to be assembled with a transition fit. On the other hand the components may need to be pressed together. Clearly the limits on the size of the components, will dictate the kind of fit obtainable. The draughtsperson producing the drawing cannot leave any dimension without a size tolerance. Most dimensions can be covered by an overall drawing tolerance, but areas where particular fits are necessary, need to be identified and given appropriate tolerances. As a guide, the table below gives tolerances which can be achieved by various manufacturing processes. Interchangeability is one of the major reasons for using tolerances. It is impossible to guarantee that production components will fit, without using comprehensive tolerancing on interfaces. It is necessary to be able to produce components in batches, at any time, in different locations and still be able to guarantee the fit. You imagine going to buy a spare part for your car or motor cycle and finding that it wont fit because the size is incorrect. The manufacturer must be able to rely on the tolerance specified on the drawing, in order to be able to produce fully interchangeable components, with the correct interfacing condition. On the other hand, one off or prototype components and assemblies do not necessarily need comprehensive tolerancing. It is often sufficient to allow one component to be machined to fairly relaxed tolerances whilst specifying the mating component to be machined to a specific fit, quoting only the clearance or interference required. Process Tolerance

Machining - close tolerance ± 0.1mm Machining � general ± 0.25mm Sheet metal work (small components) ± 0.5mm Sheet metal work (large components) ± 1mm Hole centres and drilling ± 0.25mm Sand casting ± 3mm Flame cutting ± 3mm Plasma cutting ± 1mm


Prof. M.A. Béjar

Geometrical Tolerances It is sometimes necessary to specify that the faces of a component are flat, parallel, perpendicular to others etc. This is done on drawings by quoting a geometrical tolerance. For instance, the cylinder head on an internal combustion engine does need to be flat, where it interfaces with the crankcase (which of course also needs to be flat). It does not need to have very accurate size tolerances - normal machining tolerances will suffice, but size tolerances will not guarantee flatness. In the case of the cylinder head, it is a fairly rough casting, so there is no datum surface to relate to and there is no point in creating one. The cylinder head does not have to be parallel to anything, or perpendicular to a face, within close limits. However a flatness band has to be created, within which the surface must remain, otherwise the result could be a distorted and leaking cylinder head. Cylindrical components may also need geometrical tolerances. Again using the internal combustion engine as an example, the crankshaft will almost certainly need geometrical tolerances.


Prof. M.A. Béjar

There are several bearing surfaces which need to be concentric with one another. The only way to guarantee concentricity is to use one surface as a datum and use geometric tolerances, to ensure that the other surfaces do not deviate outside of the limits specified.

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Prof. M.A. Béjar


Prof. M.A. Béjar

Rugosidad Superficial


Prof. M.A. Béjar

DEFORMATION PROCESSES


Prof. M.A. Béjar

Heading Piercing

Hubbing Cogging

Fullering Edging Roll-forging


Prof. M.A. Béjar

Skew-rolling

Beading

Flanging


Prof. M.A. Béjar

METAL CASTING AND POWDER PROCESSES


Prof. M.A. Béjar

JOINING PROCESSES


Prof. M.A. Béjar

Costs and Production Times


Prof. M.A. Béjar

1 introduccion procesos de manufactura

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