News

"Quality 101: An Introduction to Gage R&R"

04 de Mayo de 2012

I found this blog on Quality Magazine's website and thought it tied in somewhat with the last article posted here (see below) about accuracy and repeatability. Written by William D. Kappele and John D. Raffaldi, this article:

Identifies sources of variation in measurement
Defines part-to-part variation, repeatability and reproducibility
Shows how Gage R&R helps determine if a measurement system meets your requirements and helps identify the sources of variation within a system

Click here to view the article.

As always, if you have any questions related to this material, our support staff at Cooper Instruments is available to help. Contact them by calling (800) 344-3921 or emailing Esta dirección electrónica esta protegida contra spambots. Es necesario activar Javascript para visualizarla .

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What Is the Relationship between Accuracy and Repeatability?

12 de Abril de 2012

Load cells and other measuring devices usually have published standards for accuracy and repeatability. In the United States, the two main bodies governing these standards are the National Institute of Standards and Technology (NIST) and National Type Evaluation Program (NTEP). Let’s begin by defining these terms, because although I’ve sometimes heard them used interchangeably, they refer to different aspects of interpreting data.

Accuracy: is the degree of closeness (proximity) of measurements of a quantity to that quantity’s actual (true) value.

Repeatability: can also be called “precision” and refers to the variation in measurements taken by a single person or instrument on the same item and under the same conditions. Or, put in other terms, the degree to which repeated measurements under the same conditions show the same results. When the variation in measurements is smaller than some agreed-upon limit, the measurement is said to be “repeatable”. According to NIST repeatability is dependent on the following: use of the same measurement procedure, the same observer, the same measuring instrument, the same conditions, the same location and that the repetition occur over a short period of time.

Let’s use one of our most popular load cells, the LFS 210 1K s-beam load cell, to illustrate how individual measurements could be accurate but not repeatable or repeatable but not accurate. According to the published specifications for this unit, the accuracy should be +/- 0.05%, which would be 0.5 pounds, the linearity should be +/- 0.03%, which would be 0.3 pounds and the repeatability should be +/- 0.01%, which would be 0.1 pounds. (In these example, I have not provided individual data points, but you can assume a data set for each scenario.)

For example: let’s say this load cell was not being loaded properly (off-axis). We could repeatedly load this 1K load cell with a known weight of 500 pounds and consistently produce a reading of between 496.0 and 496.4 pounds. Then we could say that these measurements meet the published standards for repeatability, but not for accuracy, because in order to be accurate for this range, our readings would have to be between 499.5 and 500.5 pounds. So in this example, the measurements are repeatable, but not accurate.

Now let’s say that a series of measurements with a 500 pound load produced results varying from 499.0 to 500.5. Any measurements falling between 499.5 and 500.5 pounds would be considered accurate for this load cell, but because some of the data points were lower, you could not claim to meet the published standard for repeatability.

Now imagine a series of readings between 498 and 502. This data set would be neither accurate nor repeatable as defined by the published standards.
Conversely, a data set where all points fell between 499.8 and 500.0 would meet the qualifications for accuracy and repeatability.

As always, if you have any questions related to this material, our support staff at Cooper Instruments is available to help. Contact them by calling (800) 344-3921 or emailing Esta dirección electrónica esta protegida contra spambots. Es necesario activar Javascript para visualizarla .

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How to Select the Right Torque Load Cell

29 de Marzo de 2012

Torque is measured by either sensing the actual shaft deflection caused by a twisting force, or by detecting the effects of this deflection. Selecting torque measurement equipment can be difficult since different models offer their own advantages. The right supplier can help you select the best equipment for your application. You should choose a supplier with the knowledge and experience to assist before, during and after the purchase. After you’ve identified the right equipment, in order to obtain accurate measurement, you still need to install it correctly and you will need instrumentation to go with it. Here are some guidelines to help you identify the right equipment for your application.

Understand your Application
First, you must determine that you want to measure torque. Applications for torque sensors include determining the amount of power an engine, motor, turbine, or other rotating device generates or consumes. In the industrial world, you may encounter quality control specifications that require companies to measure torque during manufacturing, especially when fasteners are applied.

Next, you’ll need to determine if you are going to measure reaction or rotary torque. A rotary torque sensor is used when you need the transducer itself to rotate, whereas reaction torque transducers are used to measure torque loads where the sensor doesn't have to rotate, as they will only rotate as much as the shaft will deflect (if you turn them too much, they will overload or break). Another component in understanding your application will be your testing environment. Will the sensor be exposed to extreme temperature, corrosive liquids, intense vibration, etc.? Other considerations that may influence your final decision are size, cost, availability and special requirements.

Define your Capacity Requirements
As with load cells, you’ll want to choose a capacity over the expected maximum operating torque, so as not to accidentally overload the sensor. Don’t forget to factor in all extraneous torque and over hung loads before deciding on the capacity you’ll need. While a torque transducer is capable of measuring torque accurately with some radial load, as the radial load increases to the point where an appreciable moment load is applied to the shaft, the resulting deflection will cause output error. You also need to determine if you’ll be using the sensor for testing clockwise, counterclockwise or both.

Define your Needs
Consider how you’ll be mounting your sensor (for example: flange to flange, square drive, shaft to shaft, etc). If your application requires a rotary sensor, you need to define the RPM requirement for your sensor also. You want to make sure that you mount the sensor in such a way that it "sees" only rotational loading, if possible and not radial loading from whatever is attached. However, one must be cognizant of how support bearings, if employed, can cause errors through drag force caused by bearings and seals. This is also the point at which you’ll want to consider size, connectors, accuracy and cost. What kind of output will you need – mV/V, VDC, mA? Finally, determine if you need a built-in encoder to measure speed and angular deflection
or position.

Select Instrumentation (if necessary)
If you need an instrument for your application, select it at the same time you select the pressure sensor. This will help ensure the compatibility of the entire system. Don’t forget to purchase system calibration with your order. This integrates your sensor and instrument as one system.

These are suggestions to help point you in the right direction when selecting your torque sensor. Of course, our knowledgeable sales staff is also available to help you select the best equipment for your application.

As always, if you have any questions related to this material, our support staff at Cooper Instruments is available to help. Contact them by calling (800) 344-3921 or emailing Esta dirección electrónica esta protegida contra spambots. Es necesario activar Javascript para visualizarla .

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Whitepaper: Does New "Stuff" Need to Be Calibrated?

22 de Marzo de 2012

In this white paper found on Quality Magazine’s website, Hill Cox, president of the American Measuring Tool Manufacturers Association, discusses:

The importance calibrating “new stuff” (his technical term for new, unused gages)
Why you shouldn’t assume that your new gage meets the specifications that it should
What he feels is the only way to ensure that your items are good on the way in – calibration

Click here to view the white paper.

Of course at Cooper Instruments, we understand these problems and work hard to ensure that every product we sell is delivered in working order and within stated specification. We are also capable of providing calibration checks on any manufacturer’s load cell system.

Although we do our best to ensure that our customers do not encounter the problems referenced in Cox’s white paper, he does make a valid point in his last sentence: the only way to confirm your gage is good is to check it yourself. Cooper Instruments has a solution for this too – the FCM Force Calibration Machine. This precision instrument serves as an in-house quick check system for customers who need their force measurement devices quickly verified between calibration cycles. For more on how the FCM can benefit your business, read this white paper, written by Cooper Instruments design engineer Mike Price.

As always, if you have any questions related to this material, our support staff at Cooper Instruments is available to help. Contact them by calling (800) 344-3921 or emailing Esta dirección electrónica esta protegida contra spambots. Es necesario activar Javascript para visualizarla .

We’d love to hear your feedback regarding this or any other article we’ve posted. To leave feedback, ‘Like’ us on Facebook and then post your feedback on our wall.

Cooper Instruments to Attend Farnborough Airshow

14 de Marzo de 2012

According to their website, the

Farnborough International Airshow (FIA) is the largest truly global event of its kind. A platform for some 1,400 exhibitors from the aerospace, defence, space and security sectors to showcase and demonstrate aircraft, equipment and technologies, the show is specifically designed to facilitate tailor-made and unrivalled opportunities to meet, negotiate and announce business transactions.

Taking place every other year, Farnborough International Airshow 2010 was attended by over 120,000 trade visitors with exhibiting companies announcing order figures of US$47bn during the show.

The next Farnborough International Airshow will take place from 9-15 July 2012.

Because of our long-standing relationship with several companies in the each of the industries above (aerospace, defense, etc.), this seemed like the perfect event for us to attend. The equipment we offer at Cooper Instruments can be critical for these industries in researching and developing new technologies.

As referenced in a previous blog, we’re attending this trade show as part of our partnership with the VALET (Virginia Leaders in Export Trade) program. VALET will have a booth that showcases several Virginia-based companies looking to grow their export business. Cooper Instruments & Systems will be one of these companies found at the VALET booth.

We’re excited and looking forward to this opportunity to meet face-to-face with customers both old and new. If you’re attending the show and would like more information about where to find us, please contact us as we look forward to seeing you.

As always, if you have any questions related to this material, our support staff at Cooper Instruments is available to help. Contact them by calling (800) 344-3921 or emailing Esta dirección electrónica esta protegida contra spambots. Es necesario activar Javascript para visualizarla .

We’d love to hear your feedback regarding this or any other article we’ve posted. To leave feedback, ‘Like’ us on Facebook and then post your feedback on our wall.

Cooper Instruments' Participation in VALET Program

01 de Marzo de 2012

In 2011, Cooper Instruments & Systems partnered with the Virginia Economic Development Partnership and began participation in their VALET program to increase our presence in international markets. While we have always exported to international customers, we saw this as an opportunity to learn new and more effective ways of generating international contacts and improving our export process.

VALET stands for the Virginia Leaders in Export Trade program, which, as of January 1, 2012 has had 107 companies “graduate” the program with another 50 companies currently participating. Because of our participation in the VALET program, we were able to redesign our website last year making it more comprehensive and user-friendly and also adding Spanish translation to large portions of the site. VALET has also provided us with semi-annual networking and educational events, where we’ve gained a better understanding of marketing strategies including social media, as well as learned about topics like the dos and don’ts of hiring international distributors and sales representatives.

We feel one of the biggest advantages we’ve been able to offer our customers as a result of our participation in this program is that we can now offer terms (Net 30 payments) to qualified international customers, instead of requiring payments in advance. We’ve also learned about more effective shipping methods and gained a better understanding of trade barriers and the laws and regulations concerning the export of goods. In addition, we are partnering with VEDP to attend the Farnborough International Airshow in England this summer (look for more on this in a future article).

Since our participation in the VALET program began, we’re proud to say we’ve seen a 25% increase in our international sales. We hope to see this trend continue as we work toward our goal of becoming a bigger international presence in the force and pressure measurement market.

As always, if you have any questions related to this material, our support staff at Cooper Instruments is available to help. Contact them by calling (800) 344-3921 or emailing Esta dirección electrónica esta protegida contra spambots. Es necesario activar Javascript para visualizarla .

We’d love to hear your feedback regarding this or any other article we’ve posted. To leave feedback, ‘Like’ us on Facebook and then post your feedback on our wall.

Newsletter Archives

News Categories

"Quality 101: An Introduction to Gage R&R"

What Is the Relationship between Accuracy and Repeatability?

How to Select the Right Torque Load Cell

Whitepaper: Does New "Stuff" Need to Be Calibrated?

Cooper Instruments to Attend Farnborough Airshow

Cooper Instruments' Participation in VALET Program