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The highly innovative process, proposed by CNIM and chosen by F4E, is based on a pultrusion technique that involves the manufacture of profiles of epoxy S2-glass. Each pre-compression ring (PCR) is manufactured by winding the flat pultruded profile (2 mm thick and about 2800 m long) and utilizing an adhesive tape (0.12 mm thick) between layers to freeze the geometry. After the curing cycle, the PCR is machined to reach the required geometry tolerances. Each PCR will have a diameter of approximately 5 m, a cross-section of 332 mm × 288 mm and will weigh approximately 3 tons. The PCRs will finally be proof tested at 600 MPa in hoop stress that corresponds to 1.5 time the operational hoop stress. An extensive qualification phase has been released to prove that both materials and manufacturing technology can procure PCRs according to requirements. This paper describes the manufacturing processes, the results of the qualification phase and the status of the production.

The plasma confinement of the International Tokamak Experimental Reactor (ITER) is provided by the magnetic field generated by 18 toroidal field coils. Fusion for Energy (F4E), the European Domestic Agency for ITER, is responsible for the supply of 10 TFC to ITER project. Their procurement has been divided into three main work packages: I) the production of the radial plates, structural stainless steel components housing the Nb3Sn conductors, II) the manufacture of 10 Winding Packs (WP) and III) the cold test of 10 WP plus their insertion into the Coil Cases. This article gives an update of the status of the production of the third and last work package performed under the framework of an F4E contract assigned to SIMIC SpA, an Italian company. In particular, the details of the WP thermal cycle, the insertion of the firsts TF coil in their coil cases, the closure weld, the gap filling and the machining strategy adopted to optimize the final TF coil shape optimized to minimize the field errors are presented.

The first European superconducting winding pack (WP) and the first set of coil cases [toroidal field coil cases (TFCC)] for ITER are going to be delivered in 2017. The TFCC are steel structures that provide structural integrity to the WP, contribute to neutron shielding capacity, provide support to operating forces, and offer interface connections with the rest of the ITER machine. The TFCC assembly is formed by four main parts: two sectors with U-shaped section and two closure plates, which, after being welded together, enclose the WP. Each TFCC weights about 150 t and presents a wall thickness from 60 to 120 mm. The presence of distortions when welding such thick structures is particularly problematic in these components, which require tight tolerances and include several interfaces with other parts of the machine. In order to compensate the distortions, extra material is present in the critical areas to allow postwelding machining. The amount of extra material has to be optimized to reduce machining time and therefore the cost of the manufacturing. Thus, the evaluation of the welding-caused distortions is essential in order to confirm the extra-material strategy. In this scenario, an experimental and simulation campaign has been set up to predict the deformation of the TFCC during welding. First, welding coupons were welded in representative configurations. Then, these data were used to build a preliminary finite element method (FEM) model tool, using ANSYS software, which was then benchmarked against a “blind test” coupon and three TFCC-like mock-ups of 1-m length. Finally, a full FEM model was constructed using the previous outputs and is currently under assessment to predict the deformation of the TFCC during the welding process. This paper presents the numerical and experimental activities carried out so far, being EnginSoft S.p.A. the developer of FEM models, SIMIC S.p.A. the responsible of welding processes and data acquisition, and Fusion for Energy the contractual and technical supervisor.

Electro discharge machining process (EDM) is frequently used when machining of high complex and accurate features is required. Indeed, it is specially recommended for hard materials and micro-machined features. However, due to the process nature, there is still incomprehension on process parameters influence at the final quality features, ending up by lower productivity and quality ratios. On the other hand, fashioning and re-shaping of required electrodes for each feature are time consuming phases and the number of stored electrodes is very high. Therefore, in order to increase the global EDM process productivity, quality and flexibility, standardized simple electrode shapes, capable to machine different features, must be found. This study presents the influence of the main EDM process parameters and different tool geometries on basic process performance measures. A set of designed experiments with varying parameters such as pulsed current, open voltage, pulse time and pulse pause time are carried out in H13 steel using different geometries of copper electrodes. In addition, material removal rate , surface roughness and different dimensional and geometrical micro-accuracies are analyzed through statistical methods. Results help to select appropriate EDM process parameters to machine parts depending on product requirements.