Super plastic forming and explosive forming

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Auther Asim

Text of Super plastic forming and explosive forming

  • 1.Group MemberASIM ASHFAQ BSME-01113024

2. SUPER PLASTIC FORMINGEXPLOSIVE FORMING 3. SUPER PLASTIC FORMING 4. INTRODUCTIONSuper plastic Forming is a metalworking process for forming sheet metal. It works upon the theory of super plasticity, which means that capability that some materials have to undergo large uniform elongation prior to necking and fracture tension. Super plastic forming (SPF) of sheet metal has been used to produce very complex shapes and integrated structures that are often lighter and stronger than the assemblies they have to replace. Titanium alloys and alloys of zinc-aluminum; when heated , they can elongate to many times their original length. 5. Some other materials which shows superplasticity are:1. Titanium alloys2. Aluminum alloys3. Bismuth-tin alloys4. Zinc-aluminum alloys5. Stainless steel6. Aluminum-lithium alloys 6. CONSTRUCTION 7. PROCESS The process typically conducted at high temperature and undercontrolled strain rate, can give a ten-fold increase in elongationcompared to conventional room temperature processes.Components are formed by applying gas pressure between one ormore sheets and a die surface, causing the sheets to stretch and fillthe die cavity. Specific alloys of titanium, stainless steel, andaluminum are commercially available with the fine-grainedmicrostructure and strain rate sensitivity of flow stressthat are necessary for Super plastic deformation. SPF can produce parts that are impossible to form usingconventional techniques. During the SPF process, the material isheated to the SPF temperature within a sealed die. Inert gaspressure is then applied, at a controlled rate forcing the material totake the shape of the die pattern. Super plastic alloys can bestretched at higher temperatures by several times of their initiallength without breaking. 8. EXAMPLES Construction of fuel Tanks Muddy Guards of MotorcarsADVANTAGES The finished product has excellent precision and a finesurface finish. Products can also be made larger to eliminateassemblies or reduce weight, which is critical inaerospace applications. Lower strength required and less tooling costs. 9. LIMITATIONS The biggest disadvantage is its slow forming rate. Materials must not be superplastic at Lowertemperatures. It is usually used on lower volume products. 10. APPLICATION IN PAKISTANCompany: Super Plastic Doors & WindowsAddress: Suit #11,1st Floor, Fareed Plaza, 65 ShadmanMarket, Lahore, Punjab, Pakistan 11. EXPLOSIVE FORMING 12. DEFINITION Shaping metal parts in dies by using an explosive charge to generate forming pressure. OR The shaping or modifying of metals by means of explosions. 13. VARIOUS TECHNIQUES Explosive Forming Operations can be divided into two groups, depending on the position of the explosive charge relative to the work piece.1. Stand Off Method2. Contact Method 14. STAND OFF MATHODIn this method metal plate is placed over a die, with the intervening space evacuated by a vacuum pump, then whole assembly is placed underwater and explosive material is placed at an appropriate height above the plate. For complicated shapes, a segmented die can be used. intervene: become involved 15. CONTACT MATHODIn this method, the explosive charge is held in direct contact with the work piece while the detonation is initiated. The detonation produces interface pressures on the surface of the metal up to several million psi. 16. PROCESS The rapid change in explosive in to gas produce ashock wave. The pressure of this shock wave is sufficientto form metal sheet.The peak pressure , p , due to explosion, generated inwater, is given by expressionp = k(((w)^1/2)/R)^aWhere P is in psi. K is the constant depends on the type of explosive. W is the weight of Explosive in pounds. R is the distance of explosive from the work piece and a is the constant. 17. EXAMPLE 18. OTHER EXAMPLESRocket engine nozzle Space shuttle skin 19. ADVANTAGESo It can simulate a variety of other conventional metalforming techniques such as stamp- or press-forming andspin-forming in a single operation.o Explosive hydro-forming can efficiently form large parts up to 4 square or 10 in diameter.o It is particularly suitable for short production runs of alarge parts such as occurs in aerospace applications.o It Maintains precise tolerances and Eliminates costlywelds. 20. DISADVANTAGES1. Low tooling costs, but high labor cost.2. Suitable for low-quantity production.3. Due to shock waves and spillage of water it is not suitable to carry out indoor.4. It should be done in open air. 21. COMPARISONEXPLOSIVE FORMINGSUPERPLASTIC FORMINGIn Explosive forming an In super plastic formingexplosive charge is used punch or press is used toinstead of a punch or press. form metal sheet forming.It can be use for large size of It can be only used formetal sheets. limited die design.No preheating requiredbefore the explosive forming High production cost.Less production cost. It can be used for definiteAny product size, shape and shape, size and sheetsheet thickness is possible. thickness .

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