The Stress-Relieving Process in CQI-9, 3rd Edition (Key Points)

Date: September 30, 2013Audience: SMI Technical Conference Location: Green Valley Ranch Resort

Presenter: Daniel F Pierre IIIPresidentJN Machinery Corp

Changes to note

The rest of the changes do not really pertain to the stress relieving process.

2)Easier to read Process Tables

3) No AMS2750D references

4) Flexibility to determine frequency of SAT and Instrument Calibration

7) Unifies tolerances in °C and °F.

This Presentation’s Focus:

3.1 Thermocouples3.2 Instrumentation3.3 SAT System Accuracy Test3.4 TUS Temperature Uniformity SurveyProcess Table EInternal Testing Pitfalls

3.1 Thermocouples

3.1.1.2 Do not splice extension wire or modify the electrical path between the thermocouple and temperature controller.

Thermocouple Wire

Thermo Coupling

ThermocoupleTemperature Controller

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All sections in 3.1 will initially covered by the OEM of your oven--if you tell them the oven must comply to CQI-9 at the time of sale.

However, be aware of a few sections when you perform maintenance or replacement of thermocouples:

Thermocouple CertsSAT - As per ISO17025TUS - As per ISO17025

…and my test equipment’s certs

3.1.1 “every 2 years”. Refers to degradation/oxidation of metal wires. After 2 years, too much damage to the wires.

3.1 Thermocouples (continued)

3.1.2.4 ISO/IEC17025 for external calibration. In earlier versions of CQI-9, OEMs had the ability to perform calibrations on their own equipment. Now, OEMs will have to have ISO/IEC17025

3.1.2.5 When replacing thermocouples, need a “calibrated” one, your thermocouple supplier can provide the calibration cert. Note: they cost more than standard thermocouples.

3.1.3 Need to keep records of first use of thermocouple. If no record at time of calibration—especially if performing calibration every 6 months—the calibrator may be required to replace the thermocouple or perhaps NOT be able to perform calibration.

3.1.1~3.1.5 tables: So many references to how often to change thermocouples:

3.1.5 180 uses—assuming you use 23 days/month—7~8 months.

3.1.2 Reference for Calibrators. i.e for the TEST thermocouples.

This is accuracy of a thermocouple,NOT an Oven.

This is the TESTThermocouple, not the oven’sthermocouple.

Non-Expendable ThermocouplesExpendable Thermocouples

3.2 Instrumentation

3.2.1.4 For digital recording, no more than 2 minutes between readings.

Data Recorded Every 2 Seconds Data Recorded Every 2 Minutes

Most sections are obvious and easy to understand. External calibrators will cover these.Notable sections if you will internally calibrate your work: (must follow ISO 17025)

3.2.1.3 Calibration frequencies: covered in detail after several more slides.

3.2 Instrumentation

Can existing ovens be converted to do digital data collection? Yes, but at a cost….

Data logging technology is evolving so fast, that what is presented today could be obsolete or considered “old school” in 3~6 months………

5) If not hard wiring, 2-wire socket/plug on control panel. ……………………………. ($$)

1) Upgrade to Temperature Controllers with Communications Capability. ($$$ $$)

2) Software to set parameters and collect data. ($0 to $$$, but 1 time only)

3) 2-wire cable between oven and dedicated computer (which has to be ON). ( $0 to $$)Or: Wireless System, but…………………………………………………………………………..($$$$)

4) Data converter at computer……………………………………………………………………. ($)

6) Physical modification to oven shell and heat chamber…………………………..…… ( $0 to $$$$! )

3.2.6 Write-once, read only electronic records. Keep Original Log files locked up. Copy the data to create a chart. Altering a log file IS detectable. i.e. does NOT have to be a “pen-on-paper” strip/chart recorder.

3.2 Instrumentation

3.2.4.2 Changing a temperature controller, leadwire, holder, or thermocouple requires a new calibration. (i.e. change at time of calibration if you can…..)

Sample Paperwork you will receive and file

J Machinery NOven ID _______________ Cal Date ______________ Cal Due ______________

1081 Rock Road Ln.East Dundee, IL 60118Tel: 24-699-9161 Initials _____________

Company Name & Logo

JN Machinery1081 Rock Road LaneEast Dundee, IL 60118

3.2 Instrumentation (“calibration”) and 3.3 SAT System Accuracy Test

Quarterly Control Instrument Calibration ( Single Point or Multi Point )

Quarterly SAT using

Probe Method A or BMonthly SAT using

Comparative Methodor

+

Quarterly SAT usingProbe Method A only

Semi-annual Control InstrumentCalibration ( Multi Point Only )

+

Unfortunately, it is not just a matter of choosing whichever method has the least amount of paperwork.

The path to the least amount of paperwork could mean higher initial costs.

+ Annual TUS

+ Annual TUS

System Accuracy TestTypically referred to as “oven calibration”, but SAT is the more accurate term.

“Oven Calibration” has the connotation that the calibrating organization will “do something internally” to the temperature controller to bring the system back into proper calibrated state.

Thermocouple Wire

Thermo Couple Holder

ThermocoupleTemperature Controller

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The SAT is used to confirm whether an oven remains in an accurate range.

ProbeMethod “A”Instruments

Instruments to be managed and stored according to ISO17025

Temperature Controllers can have what is called “Voltage Leaks”. There is a small amount of electricity that travels along these wires. Cheap temp Controllers generally have more leakage (40~85V)! Quality controllers will have 0.3~8V. Critical applications can require <0.1V leakage, and these cost several hundreds of dollars.

0.3 ~ 85 Volts!

Photo shows a Thermocouple Holder with a Test Probe Hole in the middle(currently, 2 thermocouples are connected here, this is a Dual Thermocouple Holder for a 1-Zone Oven and its Over-Temperature thermocouple.

A Probe with a diameter as large as ¼” can fit inside this hole.

The Test Probe is less than 50 mm from the thermocouple tips

Be aware that there is a small risk a probe can end up in the shadow of thermocouple tips

Probe Method “B”

Note: Probe Method B can be useful on larger ovens when the control panel is not easily viewable from the probing position.

Comparative Method

Not all ovens are set up to use the Comparative Method:1)Older ovens without an Over-Temperature Controller.2)Multizone Ovens will have a TC without a test instrument <50mm away and still need Probe “A” or “B” method.3)Ovens with Over-Temps, but are not next to (<50mm) the control thermocouple.4)Investment cost to permanently install a test instrument.5)When purchasing a new oven and you plan to use Comparative Method, inform your Oven maker that you want an established Delta. (Usually no cost for the Delta data, but there can be added cost for an initial calibration certificate.) 0500

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Comparative Method

3.3.4.3.4 If both devices have their respective thermocouples in the same protection tube they shall be of a different type.

J & J J & K

✗ ✓

Some Ovens will dictate which method you can use without an initial investment cost.

You may not be able to do the same method on all ovens, which is acceptable as the probe method used will be noted on the oven cert, however, Mixed Methods can not be in conflict of the CQI-9 regulations.

3.2 Instrumentation (“calibration”) and 3.3 SAT System Accuracy Test

Quarterly Control Instrument Calibration ( Single Point or Multi Point )

Quarterly SAT using

Probe Method A or BMonthly SAT using

Comparative Methodor

+

Quarterly SAT usingProbe Method A only

Semi-annual Control InstrumentCalibration ( Multi Point Only )

+

+ Annual TUS

+ Annual TUS

( Review of all test

methods )

3.4 Temperature Uniformity Surveys

Performed Annually, or after a major rebuild/modification.

Key to success in performing the TUS is to Define Your Workzone

Typically, the final 1/3 of the chamber is where “stress relief” occurs. A potential “workzone” can be defined as the final 40% of a chamber, less the final 8% (where ambient air will affect chamber temperature).

Time through oven

Workzone

Temperature Uniformity SurveysTypical data logging apparatus

Notes: •These 3 Controllers and the 3 thermocouples all have to have current calibration certificates.

•The thermocouples need records of the number of uses to remain valid for use.

•The apparatus (and thermocouples) have to be stored and monitored (temp/humidity) as per ISO/IEC17025.

Temperature Uniformity Surveys

This is the exact area out of all CQI-9 regulations that will probably cost springmakers the most money to achieve compliance. Pushing the envelope a little too far to maximize the amount of product through an oven—either too much product or too fast a belt speed—will reveal itself during TUS, and ultimately require investment into a larger oven.

Placing thermocouples right at the walls, at 1” from walls and 2” (max 50mm) from walls did not show much difference. However, missing and degraded curtains DID show worse results at the oven walls.

Recommendation: Set your instrument to approximately 1” from walls, but do not beat yourself up to measure distance to wall so precisely.

If you fail a test, consider first that perhaps your curtains need attention.However, it is possible that a failed test is an indication that your process is not optimal and you are over-loading the oven.

Not recommended. The maximum length of study is 3 x thermocouples x 60 minutes. One data file can easily handle readings every second.

3.4.3.1 TUS Data Collection

Use the normal belt speed as your regular product. Slower belts do provide better results, too fast belts will show parts in oven do not even get to the set temperature.

A good curve shows that the workzone is in control.

No more than a 30 second interval data collection.

Temperature Uniformity SurveysBatch Ovens

Experience shows that older ovens fail at front corners (or middle if french doors) when the door seal degrades.

You CAN pass a test if you declare your workzone accordingly. Make sure you place a message on the oven showing which position(s) are NOT permissible locations for placing product in oven.

Temperature Uniformity SurveysA problem with CQI-9 regulations as represented in section 3.4.3.1 is that it more closely affects annealing and normalizing and possibly could be “not applicable” for stress relieving.

On its own, the sections doesn’t sound too bad:

“TUS test thermocouples shall be traversed through the furnace at a traverse speed typically used in production (and representing all test locations as required in table………)”

I would suggest that if SMI wants to develop a “best practices” regarding CQI-9, beforehand, organize a roundtable discussion or a committee to discuss “oven capacity” and “belt speed” as it relates to the question “when does the actual stress relief occur?”

Process Table E relates to Stress Relief

Do not miss the Glossary. It is tremendously helpful!

Alarm systems (if set per acceptable limits) satisfy the sign-off requirement

Internal Testing Pitfalls

Belt speed.Manual vs Automatic data collection

Data-collecting is a bit of an art. Training and experience is necessary.

Curtains/no curtainsNOT changing damaged or well-used thermocouples (TUS)Mixing thermocouple types (J, K)

A System with “Double Negatives”

A few samples of thermocouple terminations showing thermocouple type.

Outer covering

Shield material

Wire insulation

Bare wire

T K J