LIGO Document E960022-v25

LIGO Clean and Bake Methods and Procedures

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E - Engineering documents
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11 Mar 2016, 13:35
13 Apr 2012, 13:34
19 Jan 2012, 11:28
10 Dec 2011, 07:45
26 Sep 2011, 22:26
26 Aug 2011, 16:16
11 Jul 2011, 16:11
28 Jun 2011, 19:41
15 Mar 2011, 13:16
17 Feb 2010, 10:10
13 Jul 2009, 08:52
This document is used as a reference for LIGO clean and bake processes.
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Notes and Changes:
N.B.: Approval for this document version has been rescinded; See the following comments. In the interim use this document together with the following notes. [Dennis Coyne]
[Dennis Coyne] E960022-v24, Appendix 4, has vacuum baking information for viton, but it was (for some unknown reason) deleted for -v25. As indicated in -v24, castings should be baked at 182C. E960022-v25, Appendix 4, pg. 32 does not state the bake temperature for class A viton. However in Appendix 3, pg. 29 the bake temperature for class B viton is stated as 180C.
[Dennis Coyne] Appendix 5, 3rd section on "Cables (PEEK shielded Kapton cables ...)" is not correct. Two methods should be described. (1) Preferred procedure for longer and larger cable bundles (particularly with particulates embedded in the assembly): Use the aqueous parts washer to agitate and clean with soap & water and rinse with water, followed by an air bake to remove the water and finally a vacuum bake at 120C with a 48 hr hold. (2) Alternative procedure for smaller cables (particularly cables without significant particles): Ultrasonic clean in solvents, air dry and then vacuum bake at 120C with a 48 hr hold.
N.B.: This version calls out baking PEEK at 200C. This is generally far too high a temperature. The maximum allowable bake temperature for PEEK (as a material, not as a part) depends on the PEEK grade (aka type), and could also depend on the part or assembly and it's application. PEEK grades have varying glass transition temperatures. For example the grade used for Accu-Glass Product's PEEK cable ties can be baked at 250C. However for a common PEEK grade, Victrex 450GL30, the glass transition onset temperature is only 143C.
For "general" PEEK parts:
  • Ultrasonic clean in solvent -- isopropanaol or methanol for say a canonical 10 minutes
  • Air dry -- on a flow bench or in a clean room
  • Bake in vacuum at 120C for 48 hours.

[Dennis Coyne] The latest version of the LIGO cleaning document (E960022-v25) does not mention calcite. However versions -v10 through -v24 state that calcite prisms are to be cleaned per E000007, "Liquinox Cleaning Procedure for aLIGO optics", and then vacuum baked at 12C for 48 hrs. The change notes for -v25 don't mention dropping the cleaning instructions for calcite. HOWEVER, since Liqui-nox is an aqueous cleaner and calcite is dissolved in water, we should not use Liquinox to clean calcite. In addition, molecular deposition on the optical surfaces of the calcite optic can also lead to degraded optical performance. According to the "Melles Griot Cleaning Procedures" document, calcite can be cleaned by (in order of preference, depending on the level of contamination, from least to most aggressive): 1) Blowing with particulate-free, dry nitrogen or CO2 2) Drop and drag cleaning with methanol and lens tissue paper 3) Wiping with lens tissue with acetone, isopropanol and methanol. I recommend adopting the Melles Griot Cleaning Procedure for calcite polarizers and prisms, without any vacuum bake. This will be added to the next version of the LIGO cleaning document, E960022.
NOTE that this version has mysteriously dropped the processing instructions for chamber orings - see the prior revision which contains this: VE Larger diameter O-rings (ie. for VE chamber doors) Process per LIGO document: E960159-01-V Vacuum bake at 150 C for 48 hours.
-Vacuum Compatibility and Qualification will become a separate document shortly. -Clean and Bake general information may now be found in the body of E960022. Clean and bake information for specific materials and assemblies may now be found in the appropriate appendices of E960022. -Appendices 3,4 and 5 are alphabetical lists.
Rich Abbott Addendum Relating to Processing of D-sub Shorting Boards The shorting boards ( D1400282 and D1400278 ) are to be Class-B processed as follows: 1. Clean by sonication in IPA and rinsing 2. Air-bake at 85C for 24 hours
Also need a kapton only clean and bake procedure defined in this document.
In Appendix 5, under "Music Wire", there is reference to storing the wire "with the desiccant wrapping provided by the vendor". The wire should not be wrapped with Volatile Corrosion Inhibitor (VCI) paper, but rather stored in a container with dessicant.
[Dennis Coyne] Nowhere in any version of the E960022 document is silver-plated, stainless steel fasteners/hardware directly addressed. However we have always "precision" cleaned them as metal parts and baked them as Stainless Steel parts. A clarifying note should be added in the next (v26) revision. Specifically, as per the current version of the document (E960022-v25), the precision clean and bake steps are then:
  • Ultrasonic clean in Liquinox for 10 minutes. (Implicitly then rinse in DI water multiple times, but this should be made explicit).
  • Vacuum bake at 200 C for 48 hours (implicitly with a nominal 6 hr ramp up time, and a 6 hr ramp down time, in addition to the 48 hr hold time.)

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