MICE AFC Work Group meeting February 13, 2004 Introducing the Coat Hanger technique --- the Global reference system Wing Lau

MICE AFC Work Group meetingFebruary 13, 2004

Introducing the Coat Hanger technique --- the Global reference

system

Wing Lau

Distinguishing between a stand-alone item and an interfacing item through

drawing convention

Stand alone items are those within the scope and responsibility of the same supplier and as such it does not interface with any other equipment suppliers. As an example, the Magnet Coil is a stand alone item as its design bears no impact on either the Window or the Absorber supplier.

Where items made by one supplier and joined to those made by another supplier, they are known as interfacing items. As an example, the flange in the Large End Plate (marked in Pink) is an interface item as it interfaces with the Warm Vessel supplier.

In the drawing on the left, there are three different suppliers, each is marked with a different colour code. The parts that interface with other parts of different suppliers are marked in pink. Drawings on the Pink parts have a joined ownership of all the interfacing suppliers.

In the MICE project, the pink parts will have a different drawing convention than the rest. Any changes made on these drawings will be notified to all the related interface suppliers for comments and consent.

The Coat Hanger techniqueAn equipment which has multiple suppliers would comprise stand alone parts and interface parts as explained previously.

The design and supply of the stand alone parts are the sole responsibility of the individual suppliers, but the design and arrangement on the interface parts have the joint ownership of all those who have an interest in that interface.

The WBS project engineer is responsible for specifying the interface dimensions and space envelop. As long as the stand alone equipments are within the given space envelop, the suppliers are free to make changes to them. No approval is needed for making these changes. But any alteration to the interface parts must have the approval of the project engineer. This must be communicated via the interface drawings.

Even then, it is still not possible to catch all the changes made to the interface drawings because of the nature and the size of the project. A better system which could automatically trigger a warning to the project engineer of changes made is therefore needed.

The Coat Hanger technique is designed to offer this facility and is a good way to ensure interface compatibility

The Coat Hanger technique (continue)The conventional way of assembling the different parts together is by attaching the adjoining parts to a common interface boundary. Where there are multiple interfaces, or where one part joins onto another part and another part and so forth, it would be difficult to define the order of interface. It would also accumulate errors as parts are assembles related to each other only locally and not globally. This makes the checking of interface compatibility extremely difficult.

As an example, the tiling of a wall……….

The Coat Hanger technique (continue)

These are the supplied tiles

This tile is slightly oversized, but not noticeable without a dimensional check

This is what the drawing says how the wall should be tiled

Sequence of tiling is as shown:Black arrows first, followed by red arrows













Mismatch / foul went undetected until the job is nearly finished


The way to overcome this is to avoid having to assemble parts onto each other. In this new concept, every parts will have a reference centre which coincides with one of the globally registered centres designed to position the magnet modules relatively to the beam line and then to the experimental hall. This reference centre acts like a coat hanger


Global reference centre



Reference centre for the individual tile















Overlap / mismatch identified




The way to overcome this is to avoid having to assemble parts onto each other. In this new concept, every parts will have a reference centre which coincides with one of the globally registered centres designed to position the magnet modules relatively to the beam line and then to the experimental hall. This reference centre acts like a coat hanger

The referencing system works like a global navigation system. Through the reference centres, we can refer the position of each parts to a global coordinate. By hanging the various parts to a globally registered centre, it will automatically assemble the parts to a pre-defined position. Any interface incompatibility will be easily detected as each equipment / parts will have its unique place in the global coordinate system. No two parts should have the same coordinates.

We will insist on this centre being retained on all the stand alone and interface drawings.

This is how it works on MICE:There are different levels of reference centre, designated to have a similar “level” allocation as the WB packages.

The level 1 reference centre is the centre of the experimental hall;

The level 2 reference centres are those along the beam line centre for the positioning of each of the modules;

The level 3 reference centres are the centres of the individual modules

As an example:-

The Focus Coil module will have a level 3 reference centre. All the parts associated with the windows and the absorber will be referenced to this level 3 reference centre.

The Focus Coil modules, the Coupling Coil, the detector modules and any equipment that are aligned to the beam centre line will be referenced to the level 2 reference centre.

The beam line centres will be referenced to the level 1 reference centre etc.

These parts will have level 3 reference centre attached The level 3

reference centre on the FC module

All the AFC parts will then be hung to the level 3 reference centre at the Focus Coil

The hanging of the AFC and Coupling modules

Level 2 reference centres

Level 3 reference centres

Interface compatibility check at a glance

The Coat Hanger technique is an effective tool in keeping interface control simple and fool proof.

A software is being developed to allow mismatches and fouls to be check automatically.

I suggest we ask the package suppliers to apply the global reference centre to each and every drawing that they produce.

I will discuss with the Integration managers on the coordinates of the relevant reference centres applicable to all the parts within the AFC module.

It is hope that this can be applied to other modules across the MICE project.

Observations:

Documents

MICE AFC Work Group meeting February 13, 2004 Introducing the Coat Hanger technique --- the Global reference system Wing Lau