Hiram is a Quality Control Supervisor of a plant manufacturing specialty pellets. This is about his struggle with particle-size sieve testing and results analysis.
The principal quality factors of the product and process
are related to:
- Moisture of the raw material and of the finished product
- Finished material color
- Particle size distribution at the grinder output and of the finished product
Hiram’s responsibilities include testing each variable and comparing the results to the standards for each of five different products, which are produced in batches. Stan, the production Superintendent, expects Hiram to report any anomalies within one half hour of batch completion, to facilitate addressing problems before delivering pellets to customers.
The plant normally produces 15 batches a day. Sieve tests require a nine-sieve stack for grinder output and a six-sieve stack for process output.
Those familiar with pulling out distribution results form sieve tests will know the procedure well:
- - Measure and weigh a sample, record the weight
- - Load it and start the shaker
- - Wait 5 to 10 minutes.
- - Remove the stack and brush out the residue in each sieve on a balance
- - Record the weight.
- - Take each weight and divide by the total recorded weight.
If the procedure is performed correctly, the weights retained will equal 100%.
Weight collection and result calculation take between 10 and 15 minutes. Preparing and reporting these sieve results takes four to five hours a day.
Remember that Hiram needs to get the results to Stan within one half hour.
Like all of us, Hiram is under constant pressure to control his costs. Including all QC Tests, he 
needs about 12 man-hours a day. The process is at the same time exacting, tedious and boring. He has one full-time person and must borrow an employee from another department for the remainder.
The borrowed person is changed frequently, which necessitates training both his full-timer as well as a new part-timer as needed. To minimize errors, Hiram must provide close supervision.
If one of his people is on vacation or sick, Hiram often must fill in personally.
The whole sieve analysis process was a pain. We can almost feel sorry for Hiram.
Is there more to the story?
Click here to see.
Still trying to figure it out,
Art
We are back with Hiram, the QC Supervisor in a specialty pellet plant.
We pick up the story after the QC department was hit hard by the flu season.
Not only was his main sieve tester out for an extended period, but the borrowed part-timer was also afflicted. He thus had to rely on temps, which made training a continuous process as well as exponentially increasing the level of required supervision. Hiram also found that he was increasingly performing the testing himself, taxing his abilities to perform his normal responsibilities.
Hiram began to wonder if there was a better way to accomplish his particle size sieve analysis.
Hiram then turned to Google.
He found some alternatives, including fully automatic systems, in which the sample is thrown in followed by a printed result. Considering the cost-control constraints mentioned in Chapter I, such a method was too expensive.
He did find a reasonable approach that eased weight collection and result calculation. The 
meticulous residual sample weighing and removal from each sieve continued to be a part of the system. Still this was a considerable improvement from the previous method, requiring less training and supervision.
Hiram was glad that he had made the change. Business was growing, so extra batches were added each week resulting in the need for overtime. The extra tests were manageable as was the additional supervision. At least the calculations were consistent and reliable.
Now a new challenge for Hiram came roaring in. Business was so good that a new shift was needed. At least 2 ½ new people will require training and supervision.
Even if he convinces his trained full-timer to work this new night shift, he has to train a another set of people for the first shift with its attendant supervision issues.
Hiram figures he will be at the plant most nights to monitor the second-shift staff. Remember Stan still needs accurate results within ½ hour of each batch being completed.
What to do?
Go to Google again!!!
What did Hiram find this time?
Click here to find out.
I wonder what's next.
Art
As you may remember Hiram is the Quality Control supervisor of a specialty pellet manufacturer. His problem is to find a way to get his sieve-testing results done with two shifts and a limited budget.
When we last visited Hiram, he was Googling for solutions regarding
monitoring his second shift people. He does not have the budget to hire a second shift supervisor, but still needs to get accurate results to production within a half hour of batch completion.
Amongst the Google results is a Sieve Analyzer link. Not knowing what that was, he clicks on the site of a company claiming to allay all his concerns.
After performing a one-time set up, according to the company, none of Hiram’s steps would be needed except loading the shaker and pouring in the sample -- which did not even require weighing.
The Sieve
Analyzer company further claimed that, for a six-sieve stack, a complete analysis could be done within a minute of the shaker stopping.
Hiram was incredulous. That would require only part of his one full-time tester’s time. “Not possible,” he thought.
The web page offered a live online demo that Stan, the controller and his main tester could watch together, then ask questions and see answers demonstrated.
Hiram signed up for a demo, got the key players together and scheduled a time. In about an hour, they saw how it worked on an actual stack of test sieves, discussed questions and ended up signing on for an in-plant trial.
The sieve analyzer work so well that Hiram never sent it back.
Now only one person per shift is needed, eliminating most of the training. When a temp is needed, training only takes minutes. Hiram can monitor the test results form home, thus removing any need to personally supervise the test sieve results process.
He can 
now detect anomalies from his living room and only has to go to the plant at night if there is a problem.
Thus, Stan can expand production without a QC hassle and Hiram can train new temps in minutes if necessitated by the likes of a flu epidemic.
Hiram has successfully eliminated his particle size distribution test problems.
I thought you might find Hiram’s story interesting. Please share it with colleagues who might find it appropriate.
Sometimes I understand,
Art
P.S. There is a video of The Sieve Analyzer
P.P.S. Fill-in your email and subscribe to or rants, infoblogs and tall tails.
Image credit: imageegami / 123RF Stock Photo
I am regularly startled by little things that trigger new understanding about our slice of the instrument World. This time it is about surface tension.
As you know, if you’re involved with the phenomenon of surface tension, the most common unit of measure is the dyne/centimeter. This represents the force needed to overcome the energy that keeps the surface of a liquid from flying into the air.
The tensiometer is an accepted device for making surface tension measurements. These range from simple mechanical instruments to complex automatic electronic tensiometers. Since we manufacture and distribute tensiometers, we are regularly asked questions about the phenomenon of surface tension, how to measure it in different liquids, range of readings to expect for a material, how the instrument works and other questions about these analyzes.
Historically, tensiometers have had scales in the range of 0 to 100 dynes/centimeter. Over many years of working with tensiometer users, I never speculated about the reasons for or appropriateness of this measurement range.
Recently we’ve been asked, several times;”How do you measure surface tension above 100 dynes/centimeter?” These inquiries provoked us to investigate the reasons behind the question. Our inquires soon lead us to examine another proposition; “Why would you want to measure more than 100 dynes/centimeter?”
In our research about high levels of surface tension, we found to our surprise that water, ranging from 72 at room temperature to just above 75 at near boiling, had the highest surface tension of all but one other material. The exception is Mercury which has a surface tension of about 500 dynes/centimeter at room temperature. The other exceptions are 
molten metals but at very high temperatures.
Our findings clearly show that what may look like an arbitrary scale on simple mechanical and as well as on complex automatic tensiometers, represents appropriate ranges for an overwhelming majority of materials,
Thus, with water at the top in the 70’s and the low end at less than one, the answer is that this range is more than enough to meet the needs of industry for a wide span of surface tension measurement.
As an aside, we did not find an application that required a surface tension measurement of Mercury.
Click on the button to check out manual and automatic tensiometers.
Hope this is helpful. Please share it.
Wonder what will astound me next.
Art
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I am very excited about a new update to the CSC Digital Moisture Balance. To give you a perspective of why I’m excited about this Moisture Content Analyzer update, I thought you my be interested in the story of the transition from a classic mechanical moisture analyzer to the current highly robust and durable electronic instrument of today.
Over almost five decades, the Company’s classic CENCO Moisture Balance
enjoyed a reputation of being indestructible. However, the CENCO is limited by its mechanical architecture. In the late 1980’s loss-on-drying moisture analysis designs, based on emerging electronics, permitted features such as automatic shut off, digital readouts and direct printing of results. These were not possible on the CENCO.
In those early days, electronic loss-on-drying moisture analyzers were known for being skittish and really only viable for use in laboratory environments. We saw the need for a rugged electronic instrument to measure moisture content in the plant.
In 1990 CSC Scientific introduced the Digital Moisture Balance to fill this need for a durable electronic loss-on-drying moisture content analyzer that could withstand the rigors of a production floor environment.
Armed with customers experience over the next five years, we developed several up-grades leading to the selection of a special type of balance for the engine of the Digital Moisture Balance. This new engine proved to significantly improve its toughness.As electronic component developments improved reliability, reduced size and added capability, we incorporated these into the Digital. These developments made it possible to add features and capabilities requested by our customers.
About the only thing we have not changed is the shape and brown color, which some admirers have termed “ugly”.
Near the end of 2011, we discovered a new balance. This unique balance of analytical quality that is hard to break. The balance, when exhibited at trade shows, created a sensational buzz. The demonstrations included the crashing of a heavy weight onto the balance pan. After a brief pause a small sample was place on the balance pan and the result was right at tolerance ( +/-.001 grams for the model we selected).
It reminds me of the heavy weight boxer who gets knock to the canvas then jumps up to KO his opponent.
Of course our interest was high. We jumped to our design boards and incorporated this heavyweight into The Digital Moisture Balance. This new (still brown and ugly)
moisture content analyzer has been shipping since January 2013.
We have a video of the crunching demonstration. Click the button to take a look.
Hope this little vignette has been interesting.
As usual I’m amazed and usually baffled by this moisture measuring business.
Art
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P.P.S. If you want to see the (Ugly Brown) Digital Moisture Balance simply click this Button.
The CSC Sieve Analyzer
The CSC Sieve Analyzer was designed to deliver a record of a sieve test results, eliminate operator error and significantly reduce the time to process and calculate these results.
History
Since ancient times until current days, outcomes of sieve tests have been recorded as the amount of material that is retained on each sieve used; usually expressed as the weight or percent retained. Some applications use the amount passed as an alternative.
The original process requires the emptying the material in each sieve onto a balance and recording the weight. These weights are used to calculate the retained amounts and percentages…. A tedious and error prone process.
Changes with the CSC Sieve Analyzer
With the advent of smart electronic balances and small computers some relief from this process has been achieved in the lab. Also totally automatic, comparatively high cost, systems are available.
The CSC Sieve Analyzer changes this landscape. This instrument is a
self-contained sieve analysis machine. It can be used in the lab and on the production floor. Therefore, it can serve the needs of occasional sieving as well as 24/7 production requirements.
It is this simple to use
– take a sieve off the stack place it on the Sieve Analyzer,
– press start,
– wait a second for the beep and
– get the next sieve
The Sieve Analyzer almost totally eliminates training and is as close to fool proof that we could get.
Since our first beta test units were delivered, the test evaluators would not return the units because the Sieve Analyzer out-performed their wildest expectations in saving money and time and eliminating errors, customers have found the CSC Sieve Analyzer an indispensable tool.
Test results are displayed on the graphics screen and can be printed on a local printer or sent to a computer or LIMS system.
It stores the characteristics of each sieve in a stack and calculates the total weight of the sample. This does away with the need to weigh samples before starting the shaking process.
We feel that the CSC Sieve Shaker is an important addition to the productivity and data integrity of any sieving process.
Check out this video.
I know that if you use it you will be as excited as we are about the CSC sieve Analyzer. If you would like to see how this instrument will save time and money and enhance your sieving operation join us for 15 minutes of analysis with a sieving consultant.
Please forward this to those colleagues who live with problems of sieve test analysis.
This time I’m not necessarily befuddled, just excited
Art
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As you know the Karl Fischer Method of moisture analysis has a reputation of being water specific. The method works through the use of a special Karl Fischer Reagent.
Basics of Karl Fischer
As a quick review, the material to be tested is dissolved in a solvent. The water is released and converted by the reagent. This process happens inside an enclosed airtight titration cell.
The amount of reagent needed to make full conversion is a measure of moisture. Note that the material to be tested is dissolved in the presence of the reagent.
When Basic Karl Fischer will Not Work
As with many testing methods there are complications. Some substances are difficult to dissolve and require solvents that operate on the Karl Fischer reagent to cause side reactions that distort the water content calculation. Other materials only release the water at high temperatures. In these cases the simple process of dissolving the sample in the presence of the Karl Fischer reagent won't work.
Solution to the Problem Samples
The answer to side reaction problems or high temperature exigencies is an instrument known as a Karl Fischer Oven or Evaporator.
A Karl Fischer Oven consists of a heating tube in which the temperature can be controlled between 60ºC to 300ºC. Provision is made for a carrier gas to flow through this heating tube and move the escaping water into the titration cell. When the sample is ready to be tested, it is placed into the heating tube (operating at the appropriate temperature for the sample). As the moisture is released, the vapor is transported by the gas (usually dry Nitrogen) to the titration cell where it is bubbled into the reagent. The Karl Fischer process is completed and the moisture content calculated. Some of the materials that need to be processed in an oven are plastics and salts. These Karl Fischer Oven/Evaporators are used with standard Karl Fischer Titrators. When the moisture content is low (<1%) the Coulometric technique is recommended, otherwise a Volumetric Karl Fischer titrator is used.
Video
For more information on the Karl Fischer Moisture Method click here.
We hope that this has been useful. If it has please share it with you associates.
Another case where the simple has been complicated by reality.
Art
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P.P.S. Check out the demo Video.
As I've said many times measuring Moisture Content, Surface Tension and Particle Size often confounds me.
Moisture measurements are nothing compared to the measurements needed to check out the Universe. Came across this video and thought you'd fnd it interesting and fun.
This makes understanding the instruments we deal with seem like childs play.
A Loss-on-Drying Moisture test - No Problem. Surface Tension of a strange Liquid - A Piece of Cake. Or Particle Size Distribution of an agglomorated powder - A Picnic By The Shore.
I hope you found the Video as engaging as I did.
A bewildered as usual,
Art
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Sieves make understanding the world around us not just possible, but also easier.
And with the advancement of sieves, not only are we able to separate dry particle, but also sift molecules from fluid as well. With molecular sieves developed by MIT, we can now strip a molecule’s individual parts gives us a better understanding of how things come together and work, such as diseases or even DNA.
These sieves use microfabrication technology, or a nanopore system, to separate proteins from fluid. The individual pores are so small and uniform that millions can fit into a chip the size of a fingernail.
Compared to gel electrophoresis, this process of sifting proteins is far more predictable and efficient, making it easier for scientist to learn more about these molecules and giving them a more accurate idea.
By using sieves in molecular studies, scientist can not only detect diseases, but make note of “biomarker” proteins associated with them, giving them the ability to detect a disease even before symptoms show.
Not just that, but with such an extensive, in-depth look into these particles, cures aren’t such a far-fetched possibility.
Thought you'd appreciate a short flight into the other things that can get done with sieving techniques, far removed for our Wire Mesh Sieve world of 20 microns and up. Check out the newest in the Cinderella world of Wire mesh.
These advanced applications of sieving concepts add new dimensions to my normal bewilderment.
We hope this was interesting.
Art
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Yes Harry, there is a Santa Clause. Or, more specifically, there really is a Holy Grail for ensuring consistent particle size analysis. And .
If you’ve been following along, you know it was proven by Pequeño and his family of 150 micron particles who tried to bust our friend Harry’s quality control by attempting to slip through the mesh in Harry’s test sieves and defeat sieve certification.
(If you missed this drama, check out previous posts in the Holy Grail series.)
Now that we have indeed confirmed that, yes, sieve calibration really is the Holy Grail that sieve testers have been looking for, let’s get to work and dive a little deeper. Let’s examine some methods of sieve calibration.
Walk like an Egyptian
Sieving has been around since the days of the Egyptians, who used a sieving system to measure and distribute grain. And although the reeds they used
as mesh got the job done, I’m sure they’d appreciat how far technology has taken the sieve calibration process. I mean, we consider it the Holy Grail for sieve performance!
And today, growing pressure for ISO 9000 certification has put a heightened interest in methods of ensuring quality sieves. There are several proven methods of sieve calibration, but let’s examine what really works and what doesn’t.
Master sieve stack
One method is using a master stack of sieves that includes each sieve size used in your process.
1. Two samples of your material would be selected.
2. One sample would be shaken through the master stack, and the results calculated.
3. The, the second sample would be shaken through your working sieves (similar to the master stack), and these results would also be calculated.
By comparing results you could check for variances between the master sack and working sieves,then replace any working sieves that are out of whack. Sound simple? Well maybe. But it’s not a magic bullet. It’s sometimes hard to get an exact match if any of the master sieves need replacing.
Master Samples
Another sieve testing process it to create master samples of all the material that are subject to a sieve test. Working sieves put on a sieve shaker and loaded with the selected sample of the master sample.
The shaker does its job—and then how much of the material is retained in the sieve is looked at and measured. The results are studied for acceptable tolerances. Then sieves are replaced that produced results outside these tolerances.
Sounds OK, but master samples are hard to maintain.
Neither of these first approaches really hits the mark and gives you an accurate reading of just which sieve is troublesome. What to do, what to do? Oh, wait. There is better way.
Sphere this. Sphere this.
Just as our friends Harry and Brad learned in the previous Pequeño saga, there is a solution to optimal sieve calibration. It’s called Calibration with Micro spheres..
Not only is it easy to do, but using these micro spheres gives a
truly objective measure of a sieves performance and condition.
Calibration mirco-spheres are created in exact sizes for the sieves that need to be calibrated. These beads can be used to accurately determine mean aperture for each sieve to be tested.
Let’s break down how it works:
1. Select a sieve to be calibrated, mount it on a receiver pan, and tare the combination.
2. Pour a vial of the appropriate micro spheres into the sieve, weight it and record the weight
3. Shake it, shake it, work it for a couple of minutes.
4. Empty the receiver.
5. Weight the sieve and empty receiver.
6. Using the difference in the weights calculate percent retained.
7. Find the percent retained on the chart and plot the mean aperture.
This approach works best, and it gives all working sieves a mean aperture number in microns, which can be a true predictor of performance.
To learn more about our calibration spheres, check out this button below.
I think you’ll see why these spheres truly are key to sieve calibration becoming the Holy Grail.
We have a viedo about Calibration vs Certification on the CSC Sieves page. Click on the Video button to get there.
Please share this with associates who might be interested.
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It as been a long journey since we met Pequeño in November 2011. I hope it has been worth the wait.
I remain a mystified ,
Art
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