It is over the news since 20th October '09 that "The FDA is warning food manufacturers about false claims on food labels that may mislead consumers". Food manufacturers are touting their products for healthy or smart choices using all kinds of colorful logos, symbols to attract consumers.
Even though the primary purpose of these labels is to communicate health related information. Many food companies are using it as a marketing tool.
Labels like American Heart Association's heart shaped logo, Smart Choices check mark and many others appear on the front of food packages that contain large amount of sugar, salt and other ingredients that may be unhealthy.
Busy consumers shop for groceries by looking at the signs and symbols that indicate the food is healthy. Many consumers may not read the ingredients on the package before deciding to purchase the product. As rightly said "the devil is in the details", ingredients, nutritional information from the label would give the consumers better idea about the quality of food inside the package. It pays to take the time to read the label information.
FDA has warned consumers to read food labels before buying food products.
So the next time you go grocery shopping, plan to spend some extra time in the food aisles to look at those labels on food packages before buying them!
Thursday, October 22, 2009
Tuesday, October 6, 2009
Can Cp be used for unilateral tolerances?
When I go through the topic of capability indices for unilateral tolerances in my training class or consulting sessions, I usually get surprised looks from quality practitioners searching for Cp values. The common reaction is where is the Cp index? How come it doesn’t show on the chart or on my capability report?
For unilateral tolerance, Cp does not apply.
Why?
Because, by definition Cp is estimates process capability for a centered process. For unilateral tolerances the target may not be at the center of the specification limits.
The formula for calculating Cp is USL - LSL / 6σ
For unilateral tolerances, we have either the upper or lower specification limit.
That is why Cp cannot be calculated.
So what capability indices can be used for unilateral tolerances?
Cpk, Cpkm can be used. For details on these indices, please download our white paper on capability indices.
Cpk is Cpu for upper specified unilateral tolerance and it is Cpl for lower specified.
How do you track capability of your processes?
For unilateral tolerance, Cp does not apply.
Why?
Because, by definition Cp is estimates process capability for a centered process. For unilateral tolerances the target may not be at the center of the specification limits.
The formula for calculating Cp is USL - LSL / 6σ
For unilateral tolerances, we have either the upper or lower specification limit.
That is why Cp cannot be calculated.
So what capability indices can be used for unilateral tolerances?
Cpk, Cpkm can be used. For details on these indices, please download our white paper on capability indices.
Cpk is Cpu for upper specified unilateral tolerance and it is Cpl for lower specified.
How do you track capability of your processes?
Friday, August 14, 2009
Does sample size affect Cpk?
This was a question from one of my training class participants.
I found the question interesting and answered using the formula of Cpk.
Cpk = Minimum of [USL - Overall Average]/3sigma or [Overall Average - LSL]/3sigma
For Xbar-R chart,
Sigma = Rbar/d2
d2 increases as sample size increases.
So for the same Rbar, sigma reduces as sample size increases.
Cpk increases as sigma reduces.
That means for the same overall process average and range, Cpk will change as sample size changes. In fact as sample size increases, Cpk will be larger.
Example
Outside diameter of a pipe has specifications of 9 and 11. Design target is 10
For a dataset, let's say that...
Overall average = 9.3 and Rbar = 0.5
We will now calculate Sigma and Cpk for two different sample sizes - 5 and 7
For sample size 5, d2 = 2.326
sigma = 0.5/2.326 = 0.215
Cpk = Min [ 10 - 9.3] / 3 x 0.215 or [9.3 - 9] / 3 x 0.215
Cpk = Min of 1.09 or 0.465
Cpk = 0.465
For sample size 7, d2 = 2.704
sigma = 0.5/2.704 = 0.185
Cpk = Min [ 10 - 9.3] / 3 x 0.185 or [ 9.3 - 9] / 3 x 0.185
Cpk = Min of 1.26 or 0.54
Cpk = 0.54
For the same data set, sigma and Cpk change based on the sample size selected. As sample size increases, sigma reduces and Cpk increases.
If a smart quality engineer wants to trick the system and project good process capability, he/she can simply do that by increasing the sample size.
What is the sample size you use? Have you tried finding process capability with different sample size?
Drop us a line at info@sybeq.com and tell us about your process and capability calculations. We would love to hear from you.
I found the question interesting and answered using the formula of Cpk.
Cpk = Minimum of [USL - Overall Average]/3sigma or [Overall Average - LSL]/3sigma
For Xbar-R chart,
Sigma = Rbar/d2
d2 increases as sample size increases.
So for the same Rbar, sigma reduces as sample size increases.
Cpk increases as sigma reduces.
That means for the same overall process average and range, Cpk will change as sample size changes. In fact as sample size increases, Cpk will be larger.
Example
Outside diameter of a pipe has specifications of 9 and 11. Design target is 10
For a dataset, let's say that...
Overall average = 9.3 and Rbar = 0.5
We will now calculate Sigma and Cpk for two different sample sizes - 5 and 7
For sample size 5, d2 = 2.326
sigma = 0.5/2.326 = 0.215
Cpk = Min [ 10 - 9.3] / 3 x 0.215 or [9.3 - 9] / 3 x 0.215
Cpk = Min of 1.09 or 0.465
Cpk = 0.465
For sample size 7, d2 = 2.704
sigma = 0.5/2.704 = 0.185
Cpk = Min [ 10 - 9.3] / 3 x 0.185 or [ 9.3 - 9] / 3 x 0.185
Cpk = Min of 1.26 or 0.54
Cpk = 0.54
For the same data set, sigma and Cpk change based on the sample size selected. As sample size increases, sigma reduces and Cpk increases.
If a smart quality engineer wants to trick the system and project good process capability, he/she can simply do that by increasing the sample size.
What is the sample size you use? Have you tried finding process capability with different sample size?
Drop us a line at info@sybeq.com and tell us about your process and capability calculations. We would love to hear from you.
Monday, July 27, 2009
Top 10 Trends in Quality
Since we are on the topic of pictures and videos, I thought it would be a good time to talk about emerging trends in quality.
Most trends including those emerging in quality are driven by technology and making use of intelligent systems to get accurate information quickly.
We live in the world where abundant data/information is available and users have little time to look at it.
The challenge is to present data in formats that are easy to understand in a short span of time.
These are the key factors driving the trends that are emerging in quality
Based on our experience in the manufacturing industry, the top 10 trends in the field of quality are:
1) Use of Real time systems in Quality is increasing
2) Quality practitioners need accurate data presented in the form of charts
3) Charts should be designed to tell them the story of their process and product quality in a few minutes
4) Practitioners need to be alerted about problems in real time
5) Quality Engineers have to generate reports for customers and management. Systems should have an easy way to create reports as and when required.
6) Managers and executives need color coded dashboards that tell them about the quality of the parts that are being produced/shipped, overall process capability, production losses, downtime etc.
7) Quality professionals analyze data for finding root causes of problems. They need to slice and dice the data many different ways. Systems should allow them to do this in every possible way
8) All information/reports/analysis should be available on the web. That way quality practitioners can access this information from anywhere in the world.
9) Tracking and correlating data about quality throughout the supply chain should be possible.
10) Information should be available not only on PCs but also on mobile devices like phones, PDAs
Most trends including those emerging in quality are driven by technology and making use of intelligent systems to get accurate information quickly.
We live in the world where abundant data/information is available and users have little time to look at it.
The challenge is to present data in formats that are easy to understand in a short span of time.
These are the key factors driving the trends that are emerging in quality
Based on our experience in the manufacturing industry, the top 10 trends in the field of quality are:
1) Use of Real time systems in Quality is increasing
2) Quality practitioners need accurate data presented in the form of charts
3) Charts should be designed to tell them the story of their process and product quality in a few minutes
4) Practitioners need to be alerted about problems in real time
5) Quality Engineers have to generate reports for customers and management. Systems should have an easy way to create reports as and when required.
6) Managers and executives need color coded dashboards that tell them about the quality of the parts that are being produced/shipped, overall process capability, production losses, downtime etc.
7) Quality professionals analyze data for finding root causes of problems. They need to slice and dice the data many different ways. Systems should allow them to do this in every possible way
8) All information/reports/analysis should be available on the web. That way quality practitioners can access this information from anywhere in the world.
9) Tracking and correlating data about quality throughout the supply chain should be possible.
10) Information should be available not only on PCs but also on mobile devices like phones, PDAs
Sunday, July 19, 2009
Wednesday, June 10, 2009
A picture is worth thousand words - Part III
Would you prefer reading through the 14 step given below or just viewing the picture of the process?
Picture showing flow of material and information at company "Funplace" that makes toys
Steps describing the flow of information and material in Funplace
1.Funplace electronically sends a 4-week order forecast to XYZ toys. The quantities
are confirmed on a weekly basis and the purchase order is placed.
2.Based on this input, XYZ Toys electronically orders the parts from their
suppliers. XYZ Toys sends a 3-week forecast and confirms the quantity every week.
3.XYZ holds at least 2 days worth of raw material inventory in the warehouse.
4.Production control manually issues finished good quantities required on a weekly
basis. This information is sent to production.
5.Based on the production volumes required each week, the production manager
prepares for manufacturing. He gets his team together and the line leader Nick
plans for production. Per the daily production volume, Nick requests the warehouse
to issue raw material to the assembly line.
6.The assembly process consists of 4 primary steps…
- Gear assembly : putting gears in the plastic body of the toy
- Audio assembly : assembling the audio system in the toy
- Testing
- Packing
7. Everyday a truck shipment of 2000 toys is sent to Funplace.
Tuesday, June 9, 2009
A picture is worth thousand words - Part II
To convey a message, it is usually recommended to use pictures or diagrams rather than plain words. Are pictures really better than words?
We are used to learning faster with pictures.
Just like small kids learn to read looking at colorful pictures, adults understand better with pictures.
In a corporation, every level uses pictures that make sense to them and communicate what they need to know to do a better job.
Managers look at dashboards giving them information about an area, a location or the overall company.
Staff look at diagrams or charts to track critical process information. People doing the job look at pictures in their work areas as aids to guide them perform a given task.
Pictures enables everyone in an organization get the information they need very quickly. People looking at these pictures only need to be responsive when the picture calls for action.
Do you use pictures for getting critical information about your process, product or service?
We are used to learning faster with pictures.
Just like small kids learn to read looking at colorful pictures, adults understand better with pictures.
In a corporation, every level uses pictures that make sense to them and communicate what they need to know to do a better job.
Managers look at dashboards giving them information about an area, a location or the overall company.
Staff look at diagrams or charts to track critical process information. People doing the job look at pictures in their work areas as aids to guide them perform a given task.
Pictures enables everyone in an organization get the information they need very quickly. People looking at these pictures only need to be responsive when the picture calls for action.
Do you use pictures for getting critical information about your process, product or service?
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