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RFID
RFID's prominent usage is in supply chain. According to JAKS, even at this preliminary stage, the promises of RFID in supply chain are staggering. Inventory reduction through transparent real-time visibility, reduced man-hours through automated item tracking, increased warehouse accuracy, fewer shipment errors and control over items with temperature sensitivity are some of the benefits of using RFID.
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Six Sigma |
Six-Sigma is a data-driven quality measure that strives for a near perfection of any process. It is important to understand Six-Sigma as a tool, as too many incomplete definitions have made it look like a complicated fad. According to Thomas Pyzdek, acknowledged six sigma consultant and author, six sigma can be summarized as, Six Sigma focuses on improving quality (i.e., reduce waste) by helping organizations produce products and services better, faster and cheaper. Six-Sigma focuses on defect prevention, cycle time reduction, and cost savings. Unlike mindless cost-cutting programs which reduce value and quality, Six Sigma identifies and eliminates costs which provide no value to customers, waste costs
To understand the concept of Six-Sigma one must understand the concept of normal curve.
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Normal Distribution Curve |
The normal distribution curve is a symmetrical Bell shaped graph representing the distribution of a data set. The bell-shaped curve results when a normal distribution is represented graphically by plotting the distribution f ( x ) against x . The curve is symmetrical about the mean value. |
| Normal curve features |
Normal distributions are symmetric around their mean.
The distribution has two parameters, mean (µ, mu) and standard deviation (s, sigma).
The mean, median, and mode of a normal distribution are equal.
68% of the area (data points) lies within one standard deviation (+/-1 sigma) of the mean.
95% of the area (data points) lies within two standard deviation (+/-2 sigma) of the mean.
99.7% of the area (data points) lies within three standard deviation (+/-3 sigma) of the mean |
| Values of Area under Normal Curve |
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Before Six-Sigma methodology came in vogue, 3 sigma tolerance levels (for any process) used to be the benchmark for quality measurements. But Motorola engineers argued that a process can shift 1.5 sigma in regular course, as shown in the figure on the right. Now, to keep the data points within earlier permissible area, with mean shifting by 1.5 sigma, the sigma level has to be half. Thus, to accommodate 1.5 sigma shift, they proposed that the tolerance has to be +/- 6 sigma. In six sigma methodology 99.9996599% (or more) of process data lies within +/- six sigma from the mean, thus having only 3.4 defects per million opportunities (DPMO). Now, 99.9996599% value is actually for 4.5 sigma level in Normal curve, but keeping in view the 1.5 sigma process shift, the process sigma level is actually six. |
| In Six-Sigma process, 99.9996599% data will be within +/- 6 sigma levels, which is a total of 12 sigma under the curve. To have a six sigma process, 12 standard deviations should be able to fit in the permissible spread (customer specification limits). Let's look at few terms:
LSL = lower specification limit
USL = Upper specification limit
Permissible Spread under the curve = USL - LSL
In Six-Sigma, we can conclude:
12*standard deviation (sigma value) = Permissible spread under the curve
Here's a practical example:
The customer wants cloth of thickness 1mm +/- 0.001 mm, so the customer wants between 0.999 mm to 1.001 mm thickness.
LSL = 0.999 mm, USL = 1.001 mm
Permissible spread = USL LSL = 0.002
Since, 12*standard deviation (sigma value) = Permissible spread under the curve
So standard deviation (sigma value) = (0.002)/12 = 0.000167 for a six sigma process
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| For any business process six sigma methodology offers following benefits : |
1. Fewer defects
2. High customer focus Voice of customer(VOC) 3. Lower costs GE, Motorola has saved billions of dollars
4. High Employee focus Voice of employee(VOE)
5. Data driven better decision making
6. Effective management vision
7. Multiply benefits by integration with ERP etc |
| Six-Sigma has following methodologies : |
1 . DMAIC : Define, Measure, Analyze, Improve and Control
2. DMADV : Define, Measure, Analyze, Design and Verify
3 . DFSS : Design for six sigma by IDOV- Identify, design, optimize and validate
4. BPMS : Business process management systems, nine step process |
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