Posts Tagged OvenRIDER
Diverse Needs, Diverse Solutions – We’ve got an App for That!
Posted by Paul Austen in M.O.L.E. MAP, MegaRIDER, OvenCHECKER, OvenRIDER, Reflow Profiling, Thermal Profiling on March 29th, 2010
How many different MOLE profilers and Test Pallets does it take to monitor a reflow solder machine? It depends on who you are and why you are monitoring it? We just want to make sure there are as many tools as there are reasons for running a thermal profile. Here are a few good reasons:
1. “I’m from the Metrology lab and it’s time for the annual calibration of your reflow oven.” We’ve got an app for that. After you’ve finished with the oven’s calibration procedure, you can run the MegaRIDER-20 with a Process Test Pallet to see if the machine is uniform across the conveyor width and has the same heating capacity as it did the last calibration or maintenance.
2. “I’m the Manufacturing Engineer and our QC Department wants me to show that this oven is in control.” We’ve got an app for that. You probably need more information than the once a year Metrology profile can provide. So weekly you can an OvenRIDER and see that every zone in the oven is performing the same using X-Bar R charts to prove it.
3. “I’m on the New Product introduction team and I need a good recipe to solder a new board without killing the parts.” We’ve got an app for that. The Super M.O.L.E.® Gold thermal profiler will let you connect T/Cs to the board to see exactly what’s going on, thermally, on the areas where you and the designer have the most concern. Use the Prediction tools in the new MAP software to lock in the perfect recipe.
4. “I’m a Line Technician and I have to know my reflow oven is ready to run product without all the wires and circuit board stuff.” We’ve got an app for that. OvenCHECKER is one pallet loaded with the most powerful profiler on the market today. It takes no more time to run than the first production board and it lets you know if the reflow oven is ready or not. No downloading, no comparing numbers on a chart, just Go, or No-Go.
GR&R as it applies to ECD products – OvenCHECKER™, OvenRIDER®, WaveRIDER® and MEGARIDER®
Posted by Paul Austen in G R&R, M.O.L.E. MAP on November 6th, 2009
Gage Repeatability and Reproducibility (GR&R) studies are designed to show the amount of variation certain portions of the measurement system contribute to the total variation in measurement, often expressed in percent. There are many ways and products available to help you calculate these numbers, which range from a piece of graph paper to full blown software packages costing 1000s of dollars.
So let’s take a look at the values produced by a typical G R&R study and then see how they could fit with the data produced by the OvenRIDER® or OvenCHECKER™ software:
Appraiser Variation (AV%) – This is the percent of the total variation which we humans introduce because the measurement method may vary due to physical or subjective interpretation issues. Things like value interpolation between two tick marks on a ruler or how hard they squeeze a caliper around a part. This is the “Reproducibility” part of a measurement. The lower the measurement variation caused by the appraiser, the better its reproducibility and so almost anyone can do it and get the same or very close answer. If it is more than 30%, then there is too much variation from one person’s measurements to another’s. You will want to make sure they are following the procedure and not taking some shortcut.
Equipment Variation (EV%) – This is the percent of the total variation which is caused by the measurement equipment or tools used to make the measurement, like a ruler for length or thermometer for temperature. This is the “Repeatability” part of a measurement. The lower the variation caused by the equipment, the better its repeatability. Again, more than 30% means a good portion of the variation lies with the measurement tools.
Reproducibility and Repeatability (R&R%) – This is the combination of the AV and EV and is the percent of the total variation due to the tools and the people used to measure the parts. The measurement system, people and tools should produce a percent of less the 10% to know you have a good measurement system. Between 10% and 30% and you should work to improve the component(s) contributing the majority of the variation.
Part Variation (PV%) – This is the percent of the total variation which is caused by the parts being measured. This is where most of the variation should be found no matter how small the variation. After all, the part variation is what you are trying to measure, no matter how small. So expect to see this number in the 90% range, which means your parts are what is varying.
Total Variation (TV) – The TV is typically not given in percent and is a “standard deviation” like number where one can expect 99.73% of all the measurements to fall between +/-3 times the TV.
The form shows a typical example of a GR&R with sample data one way the values can calculated. How the numbers are calculated is not too important at this point. What they mean and how one can apply them to the data captured from an OvenRIDER® or OvenCHECKER™ is the real question.
So what does it take to do a GR&R?
- Two or more Appraisers – These are the people who are going to use the measuring tools to measure the parts.
- At least 5 sample parts – These are the things the manufacturing process is designed to produce.
- At least two trials measurements – This means measuring the same value from the same part at least two times.
How do these three things map into to the data produced by the OvenRIDER® or OvenCHECKER™:
- We have two or more appraisers, no problem!
- How about at least 5 sample parts? Well, what is the “part” we are making? We have an oven, and the oven has a recipe which was characterized to melt solder without killing the parts on your boards. So, the oven is set up to make … thermal profiles, or time vs. temperature graphs of a specific shape. We assess the shape in many ways, just like we could assess a bolt made by a screw machine. On the bolt we could measure its length, diameter, thread pitch, hardness, etc. On a profile, we measure the initial ramp slope, soak time, time above liquidous, peak temperature, etc. So the profile is the sample part, and one of the profile measures is the value we want to study. Let’s say, peak temperature. Then you run the RIDER through the oven at least five times to make at least 5 sample parts (profiles). So far so good.
- Now each appraiser is to take at least two trial measurements of the same value off the sample parts. So for a given profile, instruct each appraiser to measure the same value off the part (profile) at least two times. How? The software, which takes the data out of the profiler which was recorded from the RIDER, extracts that data from the profiles automatically. No matter how many times or who you instruct to ask the software to give you the peak temperature for a given profile, it will produce the exact same value. If you wanted to do it the hard way, and have each appraiser look at the profile graph using a straightedge and pen, and interpolate the peak value from the graph, you would likely get some appraiser caused variation. But no one in their right mind would do this.
What does this mean? It means that no matter what version of GR&R you use to run the math, the AV and EV will be 0%, leaving all the variation in the parts, which does not make for a very practical GR&R study.
But wait, could you just run the RIDER through the oven again to take a second trial measurement of the SAME profile (or part)? That is NOT a second measure of the same part. That would be producing another new sample part, not a second trial measure of the same part.
This is a typical problem with over half of the measurements we are asked to take in industry these days. It can only be measured once, and then it’s gone. If you want to pull to failure test a bolt as the GR&R studied value, you can only do it once, and then the bolt is broken. You can’t put it back together to make a second or third trial measure. It is the same with a profile. It happens in time and once the profile is produced, that specific profile at that instant in time cannot be measured again. It’s gone! You can only produce another profile (or part), which is not the same as measuring the same profile value twice.
So GR&R is not really the best method of assessing a RIDER product’s variation. The real question is, what is the accuracy of the instrument (the MOLE® thermal profiler), which is stated in the specification, and the variation in the RIDER sensors?
Great care is taken to manufacture sensors to a tight tolerance and tested to show that they have consistent response time to temperature changes. That, coupled with the fact that the materials do not break down or alter properties with use, makes it reasonable to accept any variation measured by the RIDER products lies most completely with the machine producing the profiles.
References and Tables:
“DataMyte HandBook Sixth Edition – A practical guide to computerized data collection for Statistical Process Control” by DataMyte Business, Allen-Bradley Company, Inc.
Understanding Gage R&R by Rick Sloop, Quality Magazine, September 2009
Oven Verification using OvenRIDER®
Posted by Paul Austen in OvenRIDER, Reflow Oven Verification on May 6th, 2009
A good Thermal Quality Program (ThQM) demands consistent oven verification to show that the reflow oven is reproducing the same thermal environment as it has in the past. The OvenRIDER is a good way to verify oven performance. How do you make best use of these tools, both the OvenRIDER pallet and the OvenRIDER SPC (ORSPC) software?
There are five basic steps:
- Set up the Oven, Workbook and MOLE
- Model the oven
- Collect a base set of OvenRIDER runs
- Set the spec limits
- Monitor of verification
Let’s get right into it:
Set up the Oven, Workbook and MOLE
- Place a magnet at the beginning of zone one. The OvenRIDER came with at least three magnets. This is not because we think you only have three zones, but because we figure you may have more then one oven, and you only need one magnet per oven to mark the start of zone one and let the OvenRIDER measure conveyor speed for you. The software detects this magnet in the profile and uses it automatically place the start of the oven model on the profile’s time axis. It does not matter where you put this magnet as long as it is on or before the beginning of zone one. You can even put it outside of the oven so it can be removed when you are not using OvenRIDER. Just be sure you always put it back in the exact same spot.
- Set the oven’s recipe you plan to use for this OvenRIDER run. It can be the same recipe you are now using to solder boards. In fact, you may want to start an OvenRIDER collection of runs for all your different recipes. This does need to be a big one time effort for all your recipes. You can do this slowly for each recipe one at a time as you do line change over. In time you will have enough runs for each recipe to begin useful oven Verification.
- Start the OvenRIDER software and select the Workbook you wish to save these recipe runs. If this is the first time you opened the software, a sample work book will be opened. Go to the file menu and close this Workbook. Then open the file menu and start a New Workbook or open an existing Workbook you previously created. The Workbooks can help you group like OvenRIDER runs. Having a work book for each oven recipe is the best for Oven Verification. You can name Workbook the same as the recipe name to help keep it straight.�
- To make sure the MOLE is ready, connect it to the PC via the communication cable and run the Configuration Wizard in the OvenRIDER menu. This will find the MOLE and set it’s clock and other settings.
- Load the MOLE into the OvenRIDER barrier and connect the configuration plug
- Make sure the oven is up to temperature and ready to receive product. Also make sure the conveyor width is set the OvenRIDER’s width.
- Start the MOLE, close and lock the lid, and load the OvenRIDER pallet onto the oven conveyor.
- When it gets through the oven, open the barrier and stop the MOLE by pressing and HOLDING the button until the Status LED turns off by itself.
Model the oven
Oven modeling is critical. This tells the software how big each oven zone is and where each zone is on the thermal profile so it can correctly show which zone had what effect on that portion of the profile.
Above is a typical Oven RIDER thermal profile with an oven model (vertical dashed lines) in place. Each zone influenced the “shape” of the thermal profile of the OvenRIDER’s sensors as it passed through oven. The amount of influence depends on the oven recipe temperature set point for each zone, the conveyor speed and the convection rate (fan or air speed). The temperature set points and conveyor speed has a straight forward and expected effect. The convection rate is a little different. Some ovens allow this to be changed and may be measured in several ways like: velocity, pressure, percent, Hz or RPMs. In some ovens, the convection rate is not adjustable or has two or three settings like: Low, Medium, and High. In either case, convection rate changes are one of the leading causes of profile changes when neither the conveyor speed nor zone temperature set points have been altered. So understanding what part of the profile each zone influenced is critical to pin pointing where problems in the oven have occurred.
Here is the best way to model an oven, any oven:
- After the profile run, connect the MOLE to the PC via the communication cable and press the Read OvenRIDER button.
- The software will as you how much data you want to use from the previous run, if there is a previous run. This time, the first time don’t select anything by un-checking all three.
- The OvenRIDER profile will look something like the profile below. Because you installed a magnet, the start of zone 1 is in place on the profile, and that’s it. It is ready to Model the oven.
- Start the Manual Zone Definition by selecting it on the Manual Zone menu.
- Select the number of zones check boxes on the let that your oven has. Name them if you like. Leave the values it defaults for Zone Lengths and Units. We will take care of that next. Note it has the measured conveyor speed already calculated and entered in as the conveyor speed value.
- Enter the Zone Temperature Set Points in the Top column. Note the Bottom values copy from the Top values as you enter them since most oven use the same Top and Bottom values. Enter the bottom values, if different, after you enter the Top values. When done, click OK.
- You will now see all of your zone boundaries located in the default locations, but not in the right locations. Note the small boxes at the top of each boundary. This is a handle for you to grab and move the boundaries to the right locations. The right locations are in that little dip that happens between zones you can see in the Ambient sensors, the Red, Blue, and Green profile lines (Channels 1, 2, and 3). So start moving the zone boundaries into place. Remember, don’t move the start of the first zone, this was set for you by the software when it detected of the magnet.
- Your profile and oven model should look like mine below. This is the “thermal” Model of your oven. It’s already saved with this profile, but let’s save it for future use with other recipes used in this same oven.
- Go to the Manual Zones menu and select Setup Zones.
- This will re-open the Oven Zone Setup dialog box. Hit the save button and name your oven model. I recommend using the Oven or line name. This model can be used for other OvenRIDER profile runs using the same model of oven, but with different oven recipes later on. Use the Load button to recall this oven model on future runs.
Collect a base set of OvenRIDER runs
You now have a good oven model and your first run at this recipe. You need to collect at least three runs at this same recipe before enough data is collected to meaningful, statistically. This can be all at once, but this take a big chunk of time from production, and most don’t have that kind of time. I recommend you take an OvenRIDER run at the beginning of each day or shift, while you are running the same recipe, for several days. You will have 3 or more runs in less then a week.
If you don’t run the same recipe for more then a day, you can set an “Oven RIDER Recipe” near the recipe setting you use most often. Start the day with that recipe, take the run, and then move to the “real” recipe you plan to use that day.
If you want to do three or more Oven RIDER runs all at once, just be sure to cool the MOLE and the Pallet to room temperature between runs. Do NOT short cut this critical cooling process. This will save the MOLE from possible over heating and assure the pallet temperatures are consistent run to run. 20 minutes on a nice fan will be enough in most situations.
Once you have several runs, you Spreadsheet will look something like this:
Make use of the user columns, the Green ones. This is where your can name the column anything you like. At least make a column for Recipe, and maybe the Machine or line name. I also have a Part Number column to identify the part or assembly soldered using this recipe.
Set the spec limits
With a good set of OvenRIDER runs collected under the same oven recipe, at least three, but five or even 10 is better, you can now set limits on the average of these runs. Do the following:
- Select the Spreadsheet tab and filter out or “hide” the runs that are NOT part of the base OvenRIDER runs. If you named each base run like I did in the example, this is easy. Select the filter dropdown arrow in row 4 of the column where you named the base runs, n my case column E, and select the name that you used to name the base runs. I used “Base Runs,” for simplicity. This hides (temporally) all the other runs. If you don’t have any other runs yet, then you don’t need to do this. The statistical data at the bottom of each column is now calculated only from those runs still visible.
- Now select the Admin tab and click the drop down arrows in the LSL and USL columns. Select the -10% and + 10%. This will set as upper and lower spec limits +/- 10% of the Average values for your base line runs showing on the Spreadsheet tab for ALL the values OvenRIDER measures. These will be good starting values to see how your oven is doing.
- Optional – You may want to select +/- 5% later on after you have a few more runs, if you wish to run tighter specs. Or, you may want to change the conveyor speed spec limits to a little tighter because you know you machine can do better then 5% or 10%. Finally you may want to remove some of the specs because you are not concerned with those measured values. To start with, it will not hurt to keep all the values.
Monitor of verification
Now each time you run the OvenRIDER at this recipe, you can see in a flash if the ALL of the measured values are within the specs you set. Simply select the OvenRIDERData tab and give the values a look.
If any of them are Red (above spec) or Blue (below spec), then there may be a problem in this portion of the oven. The values of most concern are the Average Temperatures and Process Delta per zone. If these begin to fall out of spec, then you know there may be a problem in that zones ability to heat.
All black, as in this run, the oven is ready to roll.
Any parameter out of spec should be examined to see if it’s a concern or not.
If you wish to get deeper in the SPC control you can create. Xbar-R Charts for any of these values as well. Simply drag and drop any measured value in the column to the left into one of the SPCA, B, C… boxes. Check the box to add that SPC group of charts to the tabs pages below.
Select the tab to see the X-bar R charts. Here are many production runs of the oven ruder captured of time.
These chart use all the typical SPC rules to determine process control.
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