This new technique comprises of single-piece production of nozzle i.e. convergent, and divergent parts without the involvement of welding these parts separately to bolster the strength of the nozzle and increasing the efficacy of the nozzle.

1. Design and Preparation of Aluminium
Nozzle using Metal Spinning Process
FINAL PRESENTATION
Project Work- MTIR 17
Group 10
Presented by
Astbhuja (112116014)
Bibhav Singh (112116015)
Nitesh Kumar Sharma (112116041)
Guide
Dr. D. Nagarajan
Assistant Prof.
Dept. of MME

2. Presentation Overview
• Introduction
• Objective of the project
• Literature review
• Experimental work and designing
• Results and discussion
• Scope of the future work
• References

3. Introduction
• Rocket Nozzle is the one of the most important components of the rocket.
• It is responsible to used to expand and accelerate the combustion gases thus
generating the thrust required to propel the rocket.
• Rocket nozzle works in a hostile environment of high temperature, high pressure,
outer space thus it must be able to withstand high temperature, high pressure,
caustic chemical gases and the outer space environment.
• There are numerous techniques available to fabricate the rocket nozzle such as
individual pipes that made up the cooling channels are autoclaved and brazed
together, machining the whole nozzle, 3-D printing technology and metal forming
processes using CNC lathe.
• Most of the techniques employ the use of welding process to fabricate the nozzle
thus the strength of the nozzle is poor.
• Metal spinning technique without welding process is employed in this project to
fabricate the convergent-divergent nozzle.

4. Rocket Nozzle
● A rocket engine nozzle is a propelling nozzle (usually
of the de Laval type) used in a rocket engine to
expand and accelerate the combustion gases produced
by burning propellants so that the exhaust gases exit
the nozzle at hypersonic velocities.
● Generally, a convergent-divergent nozzle (de Laval) is
employed for the rocket nozzle.
● Convergent-Divergent parts are joined at the portion
called throat using welding process.
● To avoid welding of parts, nozzle can be prepared by
the spinning technique using convergent-divergent
mandrel and suitable tools. Thus, fabricated nozzle
has better mechanical property and no welding
defects available.

5. Nozzle Design (Converging - Diverging Nozzle)
● Fixed convergent section followed by a fixed divergent section for the design of the nozzle.
● Hot exhaust leaves the combustion chamber and converges down to the minimum area, or throat,
of the nozzle.
● Downstream of the throat, the geometry diverges and the flow is isentropically (adiabatically and
reversibly) expanded to a supersonic Mach number that depends on the area ratio of the exit to
the throat.
● The expansion of a supersonic flow causes the static pressure and temperature to decrease from
the throat to the exit, so the amount of the expansion also determines the exit pressure and
temperature.
● The exit temperature determines the exit speed of sound, which determines the exit velocity. The
exit velocity, pressure, and mass flow through the nozzle determines the amount of thrust
produced by the nozzle.

6. Metal Spinning Process
● Metal spinning, also known as spin forming or
spinning or metal turning most commonly, is a
metalworking process by which a sheet of
metal (blank) is rotated at high speed and
formed into an axially symmetric part.
● Spinning can be performed by hand or by a
CNC lathe.
● It is a type of increment sheet metal forming
where sheet is deformed into final shape by a
series of small incremental deformations.
● Thus, in this way the overall stress generated
in the final product is less and even complex
shape like CD nozzle can be fabricated.

7. Objective of the project
• Designing of tool and mandrel for the process
• Microstructure, microhardness and tensile strength and residual stress of
workpiece before spinning
• Conventional metal spinning of Al 6061-T6 sheet to form convergent-divergent
nozzle
• Analysis of the microstructure, microhardness, tensile strength and residual stress
of the nozzle.

8. Literature Review
● F. Rajabi et al. conducted experiments to study the effect of rolling parameters (strain
rate and temperature) on the microstructural evolutions and mechanical properties of 6061
aluminium alloy. The results indicate that the predominant restoration process during
rolling at 250 ℃ is dynamic recovery, and the driving force is not high enough to trigger
dynamic recrystallization. Optical micrographs of the initial microstructure and the related
XRD pattern from the performed experiments confirm Mg2Si, Al8Fe2Si and Al2CuMg
precipitates.
● Luca Boccaletto et al. proposed new concept of the nozzle in this. It is based on a
classical bell-shaped nozzle, which is a well-known and worldwide- flight-proven concept,
slightly modified by the addition of a small aerospike, which is implemented near the exit
plane of the main nozzle. The model used for the test activities is an aluminium nozzle,
manufactured in three separated parts which are bolted together before performing the final
machining of the inner contour, to guarantee a smooth and continuous profile. Each test
has been performed in blow-down conditions, using high pressure bottles filled with
compressed air and setting the initial stagnation pressure level of the main nozzle by
means of a manual pressure regulator

9. Experimental work done before COVID-19
❖ Mandrel Design
❖ Material Selection
❖ Microstructural Analysis
❖ Microhardness Test
❖ Tensile Test Sample designing for wire cutting

10. Convergent nozzle Mandrel Design

11. Convergent-Divergent Nozzle Mandrel Design

12. Material Selection
Aluminium 6061-T6 - 2mm thick sheet
➢ Major Alloying Elements:
Mg (0.8-1.2)%
Si (0.4-0.8)%
Cr (0.04-0.35)%
Cu (0.15-0.4)%
➢ Al 6061-T6 is precipitation hardened alloy. T6
represents the heat treatment- solutionized and
artificially aged.
➢ Highly resistant to corrosion, stress, and cracking.
➢ Features good formability and weldability.
➢ Great strength-to-weight ratio.
➢ Tensile Strength: 310 MPa | 45000 psi
➢ Yield Strength: 276 MPa | 40000 psi
➢ Modulus of Elasticity: 68.9 GPa | 10000 ksi
➢ Elongation: 17 %

13. Microstructural analysis
● Samples were prepared according to the standard metallographic procedures
and etched.
● Generally, for Al 6061-T6 various etchants are available like Keller’s
reagent (2 ml HF+ 3 ml HCl (conc) + 20 ml HNO3(Con) + 175 ml H2O)
and Poulton’s reagent (12ml HCl (conc) + 6ml HNO3 + 1ml HF (48%) +
1ml - H2O).
● Poulton’s reagent was the most effective etchant for the microstructural
analysis.
● Microstructures of the samples were observed in the different regions of the
sample in both Rolling as well as Transverse Directions using Olympus
BX41M- LED Metallurgical Microscope

14. Continued…
Microstructures at (a) 200X (b)500X in the Rolling Direction (RD)

15. Continued…
Microstructures at (a) 200X (b)500X in the Transverse Direction (TD)

16. Microhardness Analysis
● Samples were prepared according to the metallographic procedure and polished
properly to avoid pits and scratches.
● Microhardness was measured using Shimadzu Vickers’s microhardness testing
machine.
● Loading force varied from 1 kgf and 2 kgf for the dwelling time of 10 seconds.
● The indenter shape was square based diamond pyramidal.
S. NO Rolling Direction (HV) Transverse Direction (HV)
1 107 104
2 108 104
3 108 107
Average Hardness 107.7 105
Hardness Values at 3 different location (Load= 1kgf)

17. Continued…
S. NO Rolling Direction (HV) Transverse Direction (HV)
1 112 110
2 109 109
3 113 110
Average Hardness 111.33 109.7
Hardness Values at 3 different location (Load= 2 kgf)
Indentation observed using Optical Microscope a)200X b)500X at 2kgf

18. Tensile Strength Test CAD Design
Sample were cut in three
different directions :
1) Rolling Direction
2) 90 Degree to Rolling
Direction
3) 45 Degree to Rolling
Direction
The tensile test affects the
variations among the
individual planes and the
lattice strain and the specific
grain population orientations.
Dimension of the Al-sheet for tensile test specimens
preparation
Length = 250 mm , Width = 130 mm
Total Specimen = 9

19. Dimension of the Specimen
Dimensions Inch mm
Overall Length 3.93 100
Gauge Length 1.25 32
Gauge Width 0.23 6
Thickness 0.07 2
Radius of fillet 0.23 6
Rectangular Tensile Test Specimen for Sheet

20. Tensile Strength of Al-6061
Uniaxial Tensile Test
❏ When a specimen is subjected to an external
tensile loading, the metal will undergo elastic
and plastic deformation. Initially, the metal will
elastically deform giving a linear relationship of
load and extension
❏ These two parameters are then used for the
calculation of the engineering stress and
engineering strain
Stress-strain relationship under uniaxial
tensile loading

21. Result and Discussion
● Rolling direction with number of passes plays an important role on microstructure
which inherently affects the hardness.
● The change of rolling direction can affect the grain refinement.
● Rolling direction microstructure shows more grain refinement and uniformity of the
precipitate (Mg2Si) in the Al-matrix than the transverse direction.
● Rolling direction has comparatively more hardness compared to the transverse
direction due to grain refinement and uniformity of the precipitate in the matrix.
● The average hardness value of rolling direction is 111.33 HV and 109.7 HV in the
transverse direction
● With the increase in loading force during microhardness test, the trend of the hardness
remains similar except that the depth of indent increases with increase in loading
force.

22. Scope of the future work
The main objective of this project was to fabricate the convergent-divergent nozzle (de Laval) from
2 mm thick sheet of Al 6061-T6 alloy using metal spinning process without involvement of welding
process to join convergent and divergent pieces separately at the throat of the nozzle.
This project was the precedent of the ISRO project where the same nozzle had to be fabricated using
metal spinning process from actual nozzle material C103 alloy (Nb 89%, Hf 10%, Ti 1%).
There a lot of work was to be done for this project which is listed below with a concise explanation
of the process-
● Mandrel design was finalized, so it was to be sent to the nearby industry to the manufacture
mandrel from a 100*150 mm solid cylindrical mild steel scrap.
● Tool designing was done, and material was already sent to the industry for the manufacture of
the desired smooth tool of mild steel.
● Tensile samples were designed and tensile test of the samples before spinning was to be done.
● For residual stress calculation (before spinning) using XRD technique, samples were prepared,
and it was to be sent for the XRD analysis.
● Convergent-divergent nozzle was to be fabricated using metal spinning technique to get a nozzle
of desired dimensions.
● Microstructural, microhardness, tensile test, and residual stress calculation of the nozzle to
compare the soundness of the nozzle fabricated.

23. References
● O. Music, J.M. Allwood, K. Kawai, A review of the mechanics of metal
spinning,
● Journal of Materials Processing Technology, Volume 210, Issue 1, 2010,
Pages 3-23, ISSN 0924-0136
● C.C. Wong et al. / International Journal of Machine Tools & Manufacture
43 (2003) 1419–1435
● Wang, Z.R., Lu, G., 1989. A suggestion on the standardization of English
technical terminology used in rotary forming. In: Proceedings of the Fourth
International Conference of Rotary Forming, October 17–21, pp. 38–41.
● Elkhabeery, M.M., Fattouh, M., Elsheikh, M.N., Hamed, O.A., 1991. On
the conventional simple spinning of cylindrical aluminum cups.
International Journal of Machine Tools & Manufacture 31 (2), 203–219
● Hayama, M., Kudo, H., Shinokura, T., 1970. Study of the pass schedule in
conventional simple spinning. Bulletin of the JSME 13 (65), 1358–1365.
● Kalpakjian, S., 1989. Manufacturing engineering and technology. McGraw-
Hill
● Dröge, K.-H., 1954. Forces and material flow in spinning. Technische
Universität Dortmund