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INVESTMENT CASTINGS

INVESTMENT CASTINGS. CONTENTS-. 1.Defination 2.History 2.Brief process 3.Process video 4.An example of turbine rotor 5.Need of investment castings. 6.Comparision of investment castings and sand castings 7.Advantages 8.Disadvantages 9.Applications in India 10.Conclusions. HISTORY.

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INVESTMENT CASTINGS

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  1. INVESTMENT CASTINGS 1

  2. CONTENTS- 1.Defination 2.History 2.Brief process 3.Process video 4.An example of turbine rotor 5.Need of investment castings. 6.Comparision of investment castings and sand castings 7.Advantages 8.Disadvantages 9.Applications in India 10.Conclusions 2

  3. HISTORY • The history of lost-wax casting dates back thousands of years. • Its earliest use was for idols, ornaments and jewellery • In the 1940s, World War II increased the demand for precision net shape manufacturing and specialized alloys leading to investment casting boom. • Dr. William H. Taggart of Chicago, whose 1907 paper described his development of a technique. He also formulated a wax pattern compound of excellent properties, developed an investment material, and invented an air-pressure casting machine. 3

  4. DEFINITION • Investment Casting (Lost Wax Process) • A pattern made of wax is coated with a refractory material and then metal is poured. • "Investment" comes from a less familiar definition of "invest" "to cover completely," which refers to coating of refractory material around wax pattern • It is a precision casting process ,capable of producing castings of high accuracy and intricate detail. 4

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  6. FUTHER PROCESSES 1.Separation of individual components with high speed cutter. 2.Shot blasting 3.Grinding for gate removal and thick edges removal.May be manual or automatic. 4.Final product.

  7. Investment Casting a Turbine Rotor Kalpakjian/Howmet Corp Wax pattern of turbine rotor Cut-away of ceramic mold applied over over wax pattern Cut-away showing wax melted out of mold. (Metal then poured into mold.) Finished turbine rotor, near-net shape 7

  8. WHY INVESTMENT CASTINGS? • Design Flexibility:Investment casting produces near net shaped configurations, offering designers and engineers freedom of design in a wide range of alloys. • Wide Choice Of Alloys:Various Ferrous and Non Ferrous metals are routinely cast. • Eliminate Tooling Setup:By offering near net shaped configuration ,fixturing costs are substantially reduced or eliminated. continued

  9. COMPARISON OF SAND AND INVESTMENT CASTINGS QUALITY • Sand casting • Tolerance (0.7~2 mm) and defects are affected by shrinkage • Generally have a rough grainy surface • Investment casting • Tolerance (0.08~0.2 mm) • Good to excellent surface detail possible due to fine slurry

  10. FLEXIBILITY • Sand casting • High degree of shape complexity (limited by pattern) • Investment casting • Ceramic and wax cores allow complex internal configuration but costs increase significantly

  11. ADVANTAGES • Parts of great complexity and intricacy can be cast. • Close dimensional control and good surface finish. • Wax can usually be recovered for reuse. • Additional machining is not normally required this is a net shape process. • Weight is reduced to some extent. 11

  12. DISADVANTAGES • Many processing steps are required . • Relatively expensive process. • Not suitable for simple parts. 12

  13. APPLICATIONS IN INDIA • 390 investment casting units (12000 MT) 12-18 large size foundries grown by 30%n last 3 years 210 investment casting units exporting product • Product profile Valves & Pumps 50% Automobiles 30% Armaments 10% Industrial & Decorative Hardware 5% Electronics, Medical, Machine tools, 5% Turbine, Railway, Textile, Material Handling Equipment 13

  14. CONCLUSIONS • Investment casting may be termed as “lost-wax casting” • Investment casting is practical for prototype and low-volume production applications. In less than two weeks, prototype castings in numerous alloys are ready for testing,evaluation or use. • Although it is an expensive process,it produces quality casting. CONTINUED

  15. In many cases weight is reduced by more than 50% percent thus inputing more raw material usage and increasing the overall productivity of the unit. • Unlimited design freedom since draft angles, cores, parting lines, etc., are irrelevant.Very complicated products can be manufactured which are almost impossible by casting process,welding etc. • Patterns and molds are expendable

  16. THANK YOU 16

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