THERMAL STRAP SPECIFICATIONS
In order to simplify the process of generating your thermal strap specification, whether you are ordering our copper or graphite thermal straps, we'd like to provide our customers with the following helpful hints:
TAI requirements and Helpful Hints When Generating your Thermal Strap Spec:
General Rule 1: be careful what you put into the Specification. If it’s included, then it must be proven, which takes time and money. If you include a requirement but do not have the budget to pay for the test, it’s best to omit the requirement. In many cases, TAI can provide heritage data which may be enough to satisfy any concerns on your side, so please discuss this with our Program Manager, Design Engineer, and Director of Business Development, and we are happy to help!
General Rule 2: be specific and realistic. When it arrives at your receiving dock, it won’t be you who inspects and accepts it. It will be an incoming inspector who was not privy to our meetings and conversations. The inspector will not know that this-or-that provision in the spec or PO wasn’t meant to apply.
1. Does TAI have to be an approved vendor before the finished flight units can be accepted? If so, this activity must be planned for during the proposal phase. Otherwise it becomes an emergency later and will involve out-of-scope work and expense. Our products and processes have been qualified and approved by customers across the globe, from JAXA, to ESA, NASA, Airbus, Lockheed Martin, Honeywell, and many others.
2. Involve your Quality Control department when writing the Specification, Statement of Work and Purchase Order. Make sure all plans and documents satisfy your own Quality Control system. Errors here result in cost and schedule overruns while the documents and requirements get fixed.
Have your Quality Control department mark up the Specification document for First Article Inspection, or have them approve the FAI markup. This way your QC department can specify what is required for acceptance.
Is a Source Inspection by a customer representative required for all delivered parts? If so, then do not schedule staggered delivery unless you are willing to send a representative weekly/bi-weekly/monthly. What does TAI have to supply for the Source Inspection? Include a sample Source Inspection checklist.
3. Be specific about what is expected from TAI. List everything required for acceptance of the thermal strap units in the Specification. Do not rely on a reference document alone to specify a requirement, even if this is a flow-down requirement for you.
Unacceptable: “Refer to applicable sections of Company Supplier Manual or Quality Control Manual for quality requirements.”
Acceptable: List all requirements called for in the Supplier/Quality Manual, such that if all requirements on the list are met, the delivered units will be acceptable. IT’s best you not force TAI to interpret a Supplier Manual or Quality Manual for requirements. This will take time and can potentially result in errors due to differences in interpretation.
Unacceptable: “Mark finished units per MIL-STD-130.”
Acceptable: “Tag finished units with PN / rev, SN, part name, and DOM as shown in Figure X. Refer to MIL-STD-130 for additional details if needed.” This way the requirement has been spelled out and the MIL-STD-130 flow-down requirement has been satisfied, but in a non-binding reference form.
Unacceptable: “Chromate treat the aluminum end fittings per MIL-DTL-5541.”
Acceptable: “Chromate treat the aluminum end fittings per MIL-DTL-5541 rev F, Class 1, Type 3.”
4. Make the Specification as simple as possible. Do not spread the requirements across multiple sections; list the requirements in one place.
5. Any reference documents must be provided to TAI during the proposal effort.
SAE-AMS--QQ-A-200/8 - Aluminum Rod and Bar, Extruded, 6061-T6
Is it really required to procure aluminum material that conforms to this spec? If so, then it has to be certified material and TAI will have to procure material certs that state this. This will usually take extra time and cost. If it’s not required, then omit this reference document.
6. Are there any special processes that require a customer-qualified vendor? If so, specify which process and supply a list of qualified vendors. If shipping and lead time is involved, this must be accounted for in the delivery schedule. This must be specified during the proposal process.
7. Does TAI have to write specific Work Instructions for assembly or test of these units? If so, must they be approved before use? If so, who approves them? How long should the approval process take? What assembly information and inspection data must be included in the Work Instruction?
8. Do not include standard requirements on the Purchase Order that do not apply to the program. Review Purchase Order requirements and eliminate the ones that do not apply.
Unacceptable: “All printed circuit boards must be manufactured and tested per MIL-STD-xxx.”
Acceptable: Eliminate this line from the PO. TAI is not delivering circuit boards. This standard PO requirement does not apply and may cause confusion and delay during FAI, Source Inspection, or incoming inspection.
10.What acceptance criteria are there for delivered units? What testing must be accomplished on your end before accepting the delivered units? What is the time frame for the acceptance testing?
11.Make the Interface Control Drawing (ICD) as simple as possible. Include only relevant dimensions, which will usually only be bolt patterns, keep-out zones, and relative dimensions between thermal strap end fittings. Make sure the dimensions to be inspected are clearly spelled out on the drawing and that they actually can be inspected. Do not include surface treatments, torque specs, thermal performance, etc. on the drawing. These requirements are already in the spec, and will force a revision to the drawing whenever a change is made.
...That's a lot to take in! But there is more to discuss. In next week's blog, we release Part II of our series "Help Hints When Generating Your Thermal Strap Specification for TAI," and cover: SCOPE and BACKGROUND, APPLICABLE DOCUMENTS, ORDER OF PRECEDENCE, QUALITY ASSURANCE PROVISIONS, THERMAL STRAP REQUIREMENTS, DELIVERY, AND DESIGN OF THERMAL STRAPS