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Completely flexible and reconfigurable fixturing of complex shaped workpieces with magnetorheological fluids

Final Report Summary - MAFFIX (Completly flexible and reconfigurable fixturing of complex shaped workpieces with magnetorheological fluids)

The main objective of the MAFFIX project was the development of a completely flexible, reconfigurable and reusable work-holding system capable of locating, clamping and supporting firmly any type of component independently of its shape, material and structural stiffness while several machining operations or other manufacturing related operations are exerted on it. For achieving such objective a new type of fixture based on magnetorheological (MR) fluids was developed. It is defined as flexible and reconfigurable as it can be easily adapted to different profile's lengths and sections and it is able to fix parts without reference faces as the MR fluid adapts to the outer shape of each profile. The MR tooling has allowed reducing in one unit the number of different toolings needed to manufacture the part under study.

In recent years, the problems associated with conventional technology have invited research into novel, universal work-holding techniques. Ice clamps, fluidised beds and RFPE with melting materials are approaches to achieve such universal fixturing objective, but thermal deformations associated with temperature changes and lack of clamping force have confined them also to particular components, operations and/or materials consolidating them as flexible and reconfigurable alternatives but definitively not universal ones.

This reflection, and previous knowledge and experience with rheological materials, has lead the MAFFIX project consortium to propose the development of a new type of universal fixture based on magneto-rheological (MR) fluids, a class of smart materials which drastically, fast and reversibly change their consistency in a magnetic field.

Regarding its behaviour under real machining efforts, it can be concluded from the machining tests performed that the MR fixture is able to support the cutting forces applied. From the economical point of view, the new MR fixture means a great cost reduction in the manufacturing of the final part because of mainly two reasons:
i) the fact that one tooling less is needed to manufacture the final part; and
ii) the uploading time has been reduced from 80 min to 45 min. Currently four uploading are needed and each of them takes around 20 min whilst using the new MR fixture, three uploading are needed and one of them only takes 5 min instead of 20 min.

The project was structured into five work packages (WPs), as follows:
WP 1: End-user requirements definition
WP 2: Development of magnetorheological fluid formulations for the fixturing systems
WP 3: Fixture design and construction
WP 4: Final improvements and upscaling of the MR fluid synthesis
WP 5. Testing and validation of the MR fixture

MAFFIX is a CRAFT type project where SME partners obtain all the properties rights of the results reached. The SME proposers have two different profiles, fixture manufacturers and end-users, and the benefits that they will obtain for the project depending on their profile can be summarised as follows:

Fixture manufacturers
- According to market trends toward increasingly complex workpieces produced from reshaped or primary formed blanks and the fact that the percentage of blank material machined continues to fall, these workpieces introduce a unique set of clamping-related problems that cannot be solved with today's clamping systems.
- Increment of their annual turnover due to the sales of an innovative flexible fixture that will be reconfigurable and reusable for almost any component regardless of its shape, material and structural stiffness (including compliant thin wall and sheet like components).
- The flexibility of this fixture will offer the possibility to compete in new application fields such as aerospace, automotive sector or moulds and die manufacturing sector. Consequently the fixture manufacturers will access to new markets sectors or increase their competitiveness in sectors where they are already present.

End-users
- Radical reduction of the total cost of final pieces up to 20 %.
- Reduction of total manufacturing time and consequently of delivery time up to a 30 %.
- Increment of production rate due to decrease of time needed for clamping / unclamping the workpieces and due to the increased clamping strength and stability that is envisaged with the MR fixture and that will make possible the introduction of higher cutting forces improving the cycle times of the process.
- Higher quality of finished part than the one obtained with the fixturing systems and machining methods currently used.
- Capability of machining components currently manufactured by other alternative processes: chemical milling ('skin' type slim components with very low stiffness), rapid-prototyping (parts wholly formed by complex curved surfaces).