Assignment 3

Process Improvement & Control Analysis

(A Quantitative Computational Solution: Control Charts for Variables & Attributes)

Author:            

Margarita Rodriguez

Department:                                                                                                                 

Industrial & Manufacturing Engineering

Professor:

Paul G. Ranky, PhD, PMP

Course:                                                                                                                                          

IE 673 -Total Quality Management-Live

Email:  mr244@njit.edu

eLearning Pack ID:

IE 673-Spring-2009-80-79

Table of Contents

 

 Objective. PAGEREF _Toc226523730 \h 2

Project Description. PAGEREF _Toc226523731 \h 2

Methodology. PAGEREF _Toc226523732 \h 3

Statistical Process Control PAGEREF _Toc226523733 \h 3

Collaborating Companies. PAGEREF _Toc226523734 \h 3

History of Control Charts. PAGEREF _Toc226523735 \h 4

How to calculate the control limits. PAGEREF _Toc226523736 \h 5

How to calculate the control limits. PAGEREF _Toc226523737 \h 5

Control charts for variables. PAGEREF _Toc226523738 \h 6

Control Charts for Attributes. PAGEREF _Toc226523739 \h 9

P-Chart PAGEREF _Toc226523740 \h 9

U Chart PAGEREF _Toc226523741 \h 10

References. PAGEREF _Toc226523742 \h 10

Templates & Tools Used. PAGEREF _Toc226523743 \h 10

Objective

 

The purpose of this project is developing and delivering clean renewable energy to homes and business in collaboration with Cattron, Stanley Vidmar, Bolaball and I.D. Systems, INC.  Bio-Green Alternative Energy Solutions is intended to replace fuel sources without the undesired consequences of the fuels Our company’s mission is bringing innovative ways to cover the need to overcome the shortage in energy by developing secure energy solutions that are sustainable and are technologically and financially viable.

Our experience in industry gives us a deep insight into the technical, policy, economic, and regulatory challenges being faced by our energy clients. We help clients view energy issues in a broader context, and to manage energy strategically to ensure that their clean energy and energy reduction solutions grow with the organization.

                                

Project Description

 

For many years mankind has been looking for an alternative source of electrical power.  Presently, high oil prices make the investment for this new alternative viable.  This is needed to solve the continuing pollution resulting from burning fossil fuels and from nuclear waste. 

 

Methodology

In order to monitor and control the wind percentage in turbines and reduce its power consumption Bio-Green Alternative Energy implements controls to achieve maximum performance in manufacture and installation of superior quality wind turbines by using control charts for variables and attributes. These charts are one of the most useful tools when studying variation. They offer a method that determines whether a process is stable or unstable which enables the user to modify when unstable or control the process if already stable. This can be accomplished by sampling of a particular process, analyzing the results; assign a cause and taking any needed actions.

The turbines are designed for maximum durability in sustained high wind environments with multi-voltage controller is included and excess power is diverted through a resistor network that can also be used for area heating.

 

Statistical Process Control

(SPC) is an effective method of monitoring a process through the use of control charts. Control charts enable the use of objective criteria for distinguishing background variation from events of significance based on statistical techniques. Much of its power lies in the ability to monitor both process center and its variation about that center. By collecting data from samples at various points within the process, variations in the process that may affect the quality of the end product or service can be detected and corrected, thus reducing waste as well as the likelihood that problems will be passed on to the customer. With its emphasis on early detection and prevention of problems, SPC has a distinct advantage over quality methods, such as inspection, that apply resources on detecting and correcting problems at the end product or service one.

In addition to reducing waste, SPC can lead to a reduction in the time required to produce the product or service from end to end. This is partially due to a diminished likelihood that the final product will have to be reworked, but it may also result from using SPC data to identify bottlenecks, wait times, and other sources of delays within the process. Process cycle time reductions coupled with improvements in yield have made SPC a valuable tool from both a cost reduction and a customer satisfaction standpoint two.

Collaborating Companies

1. Stanley Vidmar Tough Storage Solutions:

 

2. Bolaball INC:

http://www.bolaballinc.com/Images/logo3.gif

3.  Cattron Group International:   

  

4. ID Systems INC:

 

History of Control Charts

 

Control charts for variable were developed by Dr. Walter A. Shewhart while working for Bell Telephone labs in 1920’s.  These Variable Control Charts is a statistical tool to determine if a process is in control that deal with items that can be measured, such as height, weight, speed, and volume. The reasons for using control charts, is because it improves productivity, make defect visible, determines what process adjustments need to be made, and determines if process is in or out control. To calculate the major lines in a control chart, we can:

bullet

Take the average value by taking the average of the sample data,

bullet

UCL: Multiply the standard deviation by three, and then add the value to the average value

bullet

LCL: Multiply the standard deviation by three and then subtract that value from the average value.

  

UCL, LCL (Upper and Lower Control Limit)

How to calculate the control limits

 

X-bar Chart:

 

 1. Lower Control Limit:

 Mean – 3*sigma

 n(1/2)

2. Center Line:

Process mean

 

3. Upper Control Limit:

Mean + 3*sigma

    n(1/2)

 

How to calculate the control limits

R chart:

Lower Control Limit:

R-Bar – 3*d3*sigma

Center Line:

R-Bar

Upper Control Limit:

R-Bar + 3*d3*sigma

 

Control charts for variables

Here is how we can interpret the data. First, the study always starts with the R-chart (bottom right hand corner of the excel document). If the R-chart shows a process in control, then the X bar chart can be analyzed, but not before. There are typically two conditions to check the status.

Condition 1 - There are out of control upper and lower limits. If they are not exceeded, then the process is in control (so far), we then check the next condition.

Condition 2 - No points are out of limits. Two sub-conditions have to be checked:

1. If there are seven consecutive points above or below the central line.

2. If there are seven consecutive points increasing or decreasing it detects non-random patterns and shows that the process is out of control.

If none of these rules applies to the chart, then the process is still in statistical control.

As part of our Eco-friendly approached, our recycle process will use microcontrollers and sensors in order to select waste plastic material less than five pounds and more than five pounds. With this process can select the amount of head that can be added in the melting process.

R-Chart1

As we can see, in the R chart, there are more than seven consecutive points above the central line; we can call this process out-of- control. Since the first condition was met, we can observe the X-bar Chart

X-Bar -Chart

As we observed, the x-Bar is in control.

After review the R-Chart, we can see that from 2 to 9 sample number, there is more than five consecutive points above the central line, it means that there is a problem to detect raw material over or less five pounds, we concluded that the process is out of control. After we analyzed back, we investigated the process during this period and we were able to determine the most important reasons why the process was out-of-control;

1- The scale that was measuring the weight of the raw material was out scale, it means that it was off by 3 pounds. It was producing that the scale were taking more than 2 pound raw material as a five pounds.

2-Tthe scale was not place on the right position. It was off by a ¾ inches.

3-Some of sensors were cover with dust so they didn’t detect the raw material when it was coming on the coverable belt. The sensors could not tell the scale that a piece of material was coming and it could not provide a valid weight.

4- Some of the micro controllers were misaligned. The controllers did not prevent the process to continue sorting wrong weight plastic material.

After correct all the problems, this is a new R-chart that we get a new “in-control process”

R-Chart 2

Control Charts for Attributes

Attributes are a very important quality check as it verifies if a particular aspect of a product is defective. If the attribute being measured is over the certain limit (UCL) for a majority of the samples, then the process is out of control. The attributes need to remain between the UCL and LCL to be acceptable or in control.

The attribute being measured is defective buttons in the ADA (Advanced Digital Assistant).

1. 100 Samples are selected at random from a batch. 2. Test is performed for 20 batches. 3. The number of units with defects is recorded.

Analysis Summary Attributes Control Chart – We tested twelve samples of 100 units. Judging from the p-chart data and u-chart data, nothing is out of control. The average failure is 3 out of 100, which is a 97% pass rating It indicates that the process was under control.

However, If any point was out of control, we would have to investigate why this is so. Once we can assign a reason to that point, we will identify the source of the variability and correct the situation and repeat the sampling process to bring the process in control.

 

P-Chart

U Chart

References

bullet

Total Quality Management (e-book), CIMware USA, Inc. & CIMware Ltd. UK

bullet

Research Supplements provided by Prof. Paul G. Ranky

bullet

Unique TQM e-Learning Pack, prepared by Prof. Paul G. Ranky

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CIMware USA website, http://cimwareukandusa.com

 

Templates & Tools Used

 Control Chart Templates, by Prof. Ranky

Microsoft Excel 2003

Actual spreadsheet files for control charts for variables:

bullet

 ContChartVar_Testrun.xls

bullet

 ContChartVar_Analysis.xls

These are the template file used with my own data:

bullet

pChartConstantSize_testrun.xls | template: pChartConstantSize_templ.xls

bullet

pChartVartSize_testrun.xls  | template: pChartVartSize_templ.xls

bullet

cChart_testrun.xls | template: cChart_templ.xls

bullet     uChart_testrun.xls  | template: uChart_templ.xls

 

 

 

 

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