Groupe des Ecoles des Mines - Research Center for Materials Forming Tools

This center focuses on the optimization of tools used in forming various kinds of materials (metals, plastics, glasses, ceramics, composites, etc.). The research programs are carried out in close connection with industrial problems whose resolution requires a multi-disciplinary approach.
Research work is oriented around four (4) scientific axes, which share a common culture and manage complementary competencies and facilities, and yet collaborate to address industrial needs :

Behavior and durability of tooling materials,
Tool surface assessment,
Tool modelling and design,
Tool solicitations measurement.

Behavior and durability of tooling materials (Acting Group Manager : Prof. G. BERNHART)

The scientific research deals with the study of the bulk behavior, tools and mold damage, and more specifically, with:
 the relations between microstructure, behavior and  life-time under thermomechanical loadings (isothermal and thermomechanical fatigue, monotonic loadings and creep) ;
 the mechanisms of damage and cracking (initiation and propagation of cracks) under the same conditions.

Research is mainly focused on following materials:
 martensitic tool steels,
 heat resistant Ni-Cr-Fe cast steels,
 cast martensitic steels and spheroidal graphite cast iron,
 heterogeneous ceramics: dense multiphase ceramic, refractory concretes.

Tool surface assessment  (Group manager: Prof. F. REZAI-ARIA)

Surface and sub-surface of metallic tools in hot or cold metal formed by solid, molten or mixed (semi-solid/semi-liquid) processes have a tremendous role on the transfers of thermal and mechanical loading (friction, wear, thermal and thermomechanical fatigue) to tools.
Surface and sub-surface are preferential areas for damage development that greatly limits the life of tools. In addition to thermomechanical solicitations, oxidation and corrosion always contribute to increased damage to tool surface

The major scientific and technical topics the team deals with are :
 Development of predictive models for coupled thermomechanical loading, coupled microscopic and macroscopic behavior and damage development, and surface life-time, and predictions for forming tools ;
 Specification and evaluation of appropriate surface treatments ;
 Evaluation of the effect of surface lubrication and coating on damage and lifetime of tools subjected to thermal and thermomechanical loading and to heat transfer.

Tools modelling and design (Group manager: Prof. F. SCHMIDT)

Two main topics are studied within this research axis:
 Development and use of numerical methods in order to estimate working conditions of tools (stresses, strains, temperatures) and their influence on microstructural changes,
 Development of methods for mechanical and thermal design of tools.

One particular area of application is the optimal design of plastics injection molds, within the framework of the application of « rapid-tooling » technologies.
Complementary studies deal with improved visco-plastic flow and thermal modelling for various processes.

Tool solicitations measurement and control (Group manager: Prof. J.J. ORTEU)

This group aims at selecting, implementing and developping sensors and measurement systems to monitor shape and temperature changes, during the forming processes (either the part or the tool changes). Special interest is given to contactless measurements using cameras (either CCD or classical infra-red ones). The concept of one sensor/several measurements is emphasized, for example for simultaneous displacements and temperatures fields determination. Application softwares are developed for easy calibration of stereovision systems (3D shape measurement) and ready to plug-in applications for laboratory or industry facilities monitoring.
Process control is also targeted: for example in plastic injection molding the relationship between process parameters, mold design and properties, and final molded part performances is a subject of investigation.

Director : Gérard BERNHART, Pr.

 Professors : 6
 Other academic faculty members: 11
 Staff : 10
 Post Docs and research engineers : 1
 Doctoral candidates : 21

 Mechanical testing laboratory (ambient and high-temperature fatigue tests, high-temperature, Charpy test, etc.) ;
 Thermal fatigue equipment ;
 Microscopy laboratory (SEM, with EDS microanalysis and EBSP micro-texture, environmental SEM with low temperature and heating plates) ;
 Philips and Siemens X-ray diffractometers ; residual stress measurement ;
 Polymer research laboratory (injection press, thermo-blowing pilot, hot forming) ;
 Vision equipment ;
 Infra-Red measurement apparatus.