Technology developed as part of the project funded by Aeronautical Development Agency (ADA), Ministry of Defence, Government of India

Improved buy-to-fly ratio from 18.4:1 to 4:1 thereby saving raw material, reducing the manufacturing cycle and cost

This technology can be extended to large size structural components of Tejas Aircraft

The University of Hyderabad (UoH) has developed Multistage Closed Die Forging Technology for the Production of Aircraft Main Base Plate Undercarriage Fitting Component. The project with Prof. K A Padmanabhan, University Chair Professor at the School of Engineering Sciences and Technology, as the Principal Investigator was given by the Aeronautical Development Agency (ADA) for producing Aircraft Main Base Plate Undercarriage Fitting Component, used in the construction of airframe of high-performance (supersonic) aircraft, through a multi-stage closed die forging process. The project was completed in partnership with MIDHANI, Ministry of Defence.

The key driving forces in the manufacture of components for the aircraft industry are weight reduction, application-specific performance improvement and affordability. The most important factor is the strength to weight ratio and performance reliability. Apart from these primary factors, wider process windows (accommodating easier manufacture), improved structural reliability and suitability for periodic inspections for structural health monitoring are also desirable.

Presently main base plate undercarriage-fitting components are machined out of a slab feedstock. Al alloy raw material stock of weight 221 kg is machined into a finished component of weight 12 kg with a buy to fly ratio of 18.4:1. That process also results in inferior mechanical properties due to the absence of continuous grain flow and considerable material wastage. Through a newly developed close die-forging process technology, the finished component can be realized from a billet stock of 50 kg, resulting in a buy-to-fly ratio of about 4:1, says Prof. Padmanabhan.


Prof. K A Padmanabhan

Prof. Padmanabhan has further stated that the component manufactured by multi-stage closed die forging process technology has also met the following objectives:

a. Uniform mechanical properties, clearly above the AMS (American Materials Standard) specified values, for the given thickness – The results fall within a narrow band with the longitudinal tensile strength marginally higher than in the other two orthogonal directions.
b. Improved buy-to-fly ratio from 18.4:1 to 4:1: The feasibility of the process to produce such an intricate shape proves that the method can be adopted / adapted for mass production with reproducible quality.
c. Shorter manufacturing cycle: When mass-produced, the cycle time will be much less than that needed for machining the component from a plate / slab.
d. Forged components exhibit superior properties compared with machined components and this is expected to lead to vastly improved long term and reliable performance.
e. Structural integrity achieved in closed-die forging extends the design limits of the forged parts.

The process of manufacture has already been provisionally cleared by the Regional Centre for Military Airworthiness and now three production batches will have to be successfully formed at MIDHANI for final induction of this technology as a manufacturing route, adds Prof. Padmanabhan.

Prof. Padmanabhan became the FIRST INDIAN to receive the ‘FORSCHUNGSPREIS’ of the Alexander von Humboldt Foundation, a career award of the highest category of the above organization. In 1997 the University of Cambridge, U.K. conferred on him the highest academic award of Doctor of Science (Sc.D.) which he received in person in 1998. He is the SIXTH INDIAN and the FIRST Indian Engineer to receive this rare distinction.