INMA Innovative Manufacturing of complex Ti sheet components 3rd period summary report FP7-2010 Project No. 266208

In the aircraft, there are high costs and long lead times associated to the production of titanium sheet metal parts such as after pylon fairings, fan blades, exhaust ducts or air collectors because of forming technologies used today (cold/hot stamping, SPF) are based on dedicated tooling. The INMA project aims to lead to cost reduction and increased flexibility when manufacturing titanium and other difficult-to-deform materials sheet metal parts by introducing the asymmetric incremental sheet forming technology (AISF) into the production chain. The AISF technology shows the potential to produce complex sheet metal parts without dedicated tooling. Thus, the development costs will be reduced and agility and flexibility will be gained during the design phase for prototyping or the production of spare parts and low volume series.

The project was launched on 1st September 2010 and was completed by 30th June 2014 and along the last year many expected achievements were confirmed. The set up and improvement of hot forming means and methods to hot form Ti 6Al-4V alloy without specific tooling was completed. The operation conditions were adapted to the temperature requirements of the alloy and parts before and after were evaluated. Two different heating approaches were implemented and assessed in terms of the obtained part quality, associated costs and energy consumption. The measurement of the residual stresses induced by the forming operation and heat applied was a result of particular interest since this aspect of the part quality has not been addressed up to date by studies on hot forming using the AISF process. The experimental development of hot forming was accompanied by FE modeling of the process. Thus, the two considered heating approaches were coupled with forming algorithms to provide numerical simulations of hot forming. It is expected that they will provide helpful understanding of the effect of process parameters on strain fields, thickness distribution or geometric accuracy.

Based on the technology basis implemented since the beginning of the project, demonstrator parts were fabricated. A strut half made of Inconel 718 was fabricated to assess the potential of the technology to fabricate realistic parts made of this alloy or other Ni-base alloys. A couple of generic shapes showing design features typical of pylon fairings were also fabricated to assess the capabilities of the technology to fabricate accurate parts made of Ti 6Al-4V by hot dieless forming. Other demonstrator parts were also produced as representative show cases of the project technological achievements.

The residual stresses of hot formed parts are much affected by the heating applied

INMA Innovative Manufacturing of complex Ti sheet components 3rd period summary report FP7-2010 Project No. 266208

Other demonstrator produced

Before After Part within ±1mm range (%) 40.00 90.40 Max positive dev (mm) 3.42 1.39 Average positive dev (mm) 1.06 0.36 Max negative dev (mm) -11.24 -3.40 Average negative dev (mm) -3.24 -0.60

The assessment of the demonstrators reported very promising results about the attainable surface quality, thickness distribution and even geometric accuracy of parts. Obviously, the technology still needs from further developments, particularly in terms of numerical simulation and tool path correction capabilities. It can be said that well founded results have been generated to be optimistic about the industrialization in a near future of an AISF-base technology for the aeronautic sector and, very likely, for other industry sectors as well.

Keywords: difficult-to-deform alloys, asymmetric incremental forming, hot forming, knowledge-based techniques, cost-efficient and green production

For more information, visit the project web site: www.inmaproject.eu

Technology demonstrator produced: strut half (left), airframe demonstrator-1 without before trimming, airframe demonstrator-2 after trimming

Geometric deviations of airframe demonstrator-2 before/after implementation of hot forming practices and tool path correction