MICE Target l Jason Tarrant – STFC l Investigative work on T2 with plastic bearings »Stopped after >2 million cycles »Disassembly with photographic investigation.

MICE Target Jason Tarrant – STFC

Investigative work on T2 with plastic bearings» Stopped after >2 million cycles» Disassembly with photographic investigation» Microscopic investigation of bearing surfaces» Observations» Resolutions

Disassembly – To upper Bearing

MICE Target

First look

Little dust(polished flat)

A lot of dust(rough flat)

Polished flat

Rough flat

Amalgamateddust balls

DustOn shaft,On bearing,On lock ring

Survey point

Disassembly – To shaft & vacuum tube

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Coatingon shaft Deposits

on magnet In vacuum bore

Bearing regionExternal to Target

Dust to here

Disassembly – To lower Bearing

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Dust around bearing,lock ring removed

Internal face

External face

Disassembly – To bellows

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View into bellows

MICE Target Observation – Dust

» Amount– Most at upper bearing – esp. anti-rotate rough flat side– Amalgamated at bearings – scraped off

» Location– Coated internal components, has escaped externally– How does it move against gravity?

Thrown off Electrostatic attraction Vibration movement

» Attachment– Fixed – by what?

Inspection - Upper bearing

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No wear

Tram lines

Worn smooth

Inspection – Lower bearing

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No wearLongitudinal scratches

Machining marks

Worn smooth

Wear regions2 & 5 – Worn smooth1 & 3 – Little wear, m/c marks4 – Some wear, smooth + m/c marks

MICE Target Observation – Wear orientation (lower bearing)

Angle to vane

Angle to statorpower out

Angle to anti-rotation

Inspection – Anti-rotation component

MICE Target

Machiningmarks

Rough flat wear

Rough flat wear

Longitudinalscratches

Longitudinalscratches

MachinedSurface

Smooth flat wear

Smooth flat wear

MICE Target Observation – Wear on anti-rotation

» Smooth side, machine marks in centre, longitudinal scratches on outside = rotation wear

» Rough side, no machine marks, much longitudinal scratching = rotational + lateral wear

» Wear region smoother than as machined

MICE Target Reducing Dust

» Smooth bearing interfaces– Polish shaft (both flats & cylindrical

elements)– Burnish bearing faces (to size)

» Harder wearing plastic– Duratron & Celazole alternatives to

Vespel?

» Target unit like T1?

» Running less cycles Managing Dust

» Dust catcher

MICE Target Conclusions

» Plastic bearing is more tolerant to T2 running (DLC could not cope)

» Wear does occur but bulk material tolerates wear (DLC too thin to do so, 3-5um thick)

» Dust created– Fixed to unit (requires mechanical removal)– Will be reduced– Can be managed– Does not appear as ‘gritty’ as DLC