CT - Efficient Support for Development Project 'AGENT-3D-CastAutoGen'

By Gina Naujokat / June 11, 2020
The project:

As different as people are, so diverse is the range of goods on offer in today's global consumer society. In the automotive industry, there are not only various car manufacturers, but each producer maintains several brands with many models, of which in turn many different types are offered. Individual components often differ only minimally.
Many components of a vehicle, especially engine and chassis, are metal castings. The production of casting molds and the casting processes themselves are complex procedures that only pay off through series production.
Representatives from seven companies (Fraunhofer IWU, Fraunhofer IWS, BOHAI TRIMET Automotive Holding GmbH, EDAG Engineering GmbH, Oerlikon AM Europe GmbH, Audi AG and ZF Friedrichshafen AG) have started the AGENT-3D_CastAutoGen project funded by the BMBF to find out in a first step how a standard casting can be modified for different requirements by use of additive manufacturing. 
The test object for Scenario 2, led by Fraunhofer IWS, was a 25 cm long casted bracket made of the aluminum casting alloy AlSi12Cu1(Fe) which needed additional stability and connecting elements. For this purpose, a supporting geometry made of AlSi1MgMn was applied through 3D printing (Laser Metal Deposition - LMD). Computer tomography was able to provide clarifying insights.















The casted bracket with a 3D-printed support



A 12-minute scan with the YXLON FF85 CT computed tomography system provided significant findings: In contrast to the additive part of the hybrid engine bracket, which had almost no porosity, the pore volume in the contact area with the die-cast base component was increased. The porosity in the bonding zone was comparable to the porosity in the less stressed casting areas (see red marking in the picture “Virtual cross section”).
 

 

CT volumetric display
 

Virtual cross section: porosity in contact zone (green marking)
as well as in casted areas (red markings)
 

Two assumptions were made:
 
  • The casting was outgassing into the contact area, which could be reduced by a higher vacuum during the die casting process.
  • The angle of the LMD powder nozzle was not optimal for accessibility reasons.

Step 1: 
The bracket was casted at a higher vacuum. After applying the support geometry by 3D printing, a significant reduction of pores in the contact area was visible.
 

 

Step 2:
The support geometry was applied to the bracket produced under higher vacuum with an optimally aligned LMD powder nozzle. The number of pores in the contact area was reduced even further.
 


With only three 12-minute CT scans, the manufacturing process of this hybrid bracket could be developed cost-efficiently with a significant increase in quality.