QA during Stave Core Assembly Stephanie Qing Yang (Oxford) 25 th Sept 2014 WP4 f2f meeting at RAL

QA / QC issues: Quality Control is the process that ensure quality during production. This should address the following issues: Dimensional accuracy;  Thickness check at various stages of production;  Every stage check of sub-assembly mass allow cross reference to finished dimension  Check critical tooling dimensions periodically to ensure tooling dimensions are consistent and not deviate during production / handling or glue built-up etc Bonding quality;  glue samples (i.e. take glue sample for testing every time of mixing glue during stave production);  Control of glue usage – not ultimate control of glue thickness, but indicates the correct amount being used;  Need a test procedure for detecting delamination both during and post production– e.g. use of finger printing technique (need to develop) Flatness control  This could be influenced by ambient temperature changes, machine tool weariness, internal stress in material,  Operator dependent errors such as Debris / particles in the glue, evenness in glue application and etc. A procedure is needed to minimise such error ;

QA / QC issues Quality assurance is a set of procedures that allows the monitoring of quality. This should address the following points: QC procedures – a set of procedures to ensure the above are implemented during production Manufacturing Records – check box on procedures, traceable records on production parameters; Procedures for Document version / Change / Repair Control; Machine tool weariness – affect on product dimensional tolerance Acceptance procedures – any test required to ensure products meets the required specifications; As build dimensions – a record of final dimensional check etc

Example of QC / QA Visual inspection the surface quality of co-cured face sheet, to see if there is any wrinkles, glue bleeds, delamination.. etc Record its mass Measure the length & thickness (By Georg)

QA: Weigh sheet; Visual inspection that sheet is placed in position correctly (By Georg)

At this stage, the exactly glue thickness is not controlled as the glue is brushed to the masked area. QA procedures needed to address this (By Georg)

The tooling controls the glue thickness. The current design requires 0 thickness glue layer, the glue will flows into the void region of the foam blocks (By Georg)

8 QA: Check the bonding quality between foam blocks and face sheet, by visual inspection, any other method? Do we need to find out how much glue are soaked into the foam? The amount of the glue used for this process can be obtained by weighing the subassembly before and after – but is this accurate enough? (By Georg)

QA issues: Check the cooling pipe is bond to the foam blocks (test method needed) Graham’s previous analysis showed a 30 mm length of pipe that is not glued would only give about a 0.7 deg-C rise in temperature. Need to make a test sample with missing glue joints along the pipe and then thermally image it, to see if this can be detected. Any thing else that need to test at this stage? (By Georg)

QA: Check cleanliness of glue areas, tooling and C-channel (By Georg)

11 QA: Check the glue bonding quality between the C channel and face sheet (by visual inspection) Check the placement position of C channels (use ruler … ) Check the glue thickness between C channel face and face sheet (this is controlled by the tooling, do we need to check it still? if so, it should be easy to measure.) Gluing C-channel (By Georg)

QA: Before machining, check the glue bonding quality between the honeycomb and lower face sheet. -- visual inspection. any other method? After machining, measure the core height (if it is necessary), using the depth gauge or other method…. Check the damage, and any sign of delamination caused by machining, i.e. the bonding between the honeycomb, foam blocks and C channels to the face sheet, to see if there is any sign of delamination caused by machining.. E.g. some small pieces of honeycomb have been snapped off during the machining (By Georg)

QA: check for gluing quality - Need a test procedure for detecting delamination both during and post production– e.g. use of finger printing technique (need to develop this) (By Georg)

Glue top face sheet Glue bath depth 0.5mm, with 1mm oversized Marking area for BN loaded glue if different glue for the cooling block area is required. Pin to locate the stave partial assembly 14

Final trimming The 10mm sacrificial rim of the face sheets along the longer edges will be trimmed off (milling) and de-burred after the stave core assembly. QA: – Trimming must reference to fiducial line – check the sign of delamination due to this process and any damage may caused. – Keep track of the weight (?)

Glue locking points NOTE: During the gluing of the locking points, the 10mm over-size region along the longer edges will be removed first, but at the both ends will remain for positioning the stave on the jig during the gluing and will be removed afterwards. 16 QA: Measure the locking point positions, straightness, and its parallelism wrt stave

QA after stave core assembly Weight: -- Take measurements at each stage of assembly Flatness scan – CMM survey. what is the required flatness for module mounting? 3- point bend test (just for development model or production models?): – to determine the bending stiffness of the structure. – Finger printing (frequency check) should be conducted after 3-point test to check for sign of delamination. Delamination – thermal image camera, pressure test or finger printing (if developed) to detect the sign of delamination. Thermal performance test – Cool the stave to -30 deg C, and then scan stave with thermal image camera. Thermal shock (for development model only)