TOOL OBJECTIVE METHODOLOGY WHEN TO USE TYPICAL USERS
1. PDCA (Plan, Do, Check, Act) Problem-solve by trial and error Plan the work; execute; check results; take action if there is a deviation between desired and actual results. Repeat the cycle time till deviation is reduced to zero. When more powerful tools unknown Mostly lone workers
2. Data Collection and analysis . Assess Quality
. Control a Product
. Regulate a Process
. Accept/Reject Product
. Interpret observations Define specific reason for collecting data; decide on mgmt. criteria (attribute vs. variable vs. rank); assure accuracy of measuring equipment (min. 5 times greater than product requirement); randomize; stratify data collection (time, material, machine, operator, type and location of defects) analyze data using several S.P.C., D.O.O.E., tools. At All Times Universal
3. Graphs/Charts . Display trends
. Condense Data
.Explain to others Select 2 or more parameters to be displayed; determined method of display (bar, line, or circle graphs are the most common); select the most appropriate scales of the parameters for maximum visual impact. At All times Universal
4. Check sheets . Transform raw data into categories . Determine categories into which data is subdivided (e.g., types of defects, location of defects, days in the week, etc.). Enter quantities in each category. In preparation for a Histogram or Frequency Distribution Universal
Tally Sheets Groups cells in semi-pictorial fashion For tally sheets, divide variable being recorded into 10 levels or cells. Plot cells boundaries or mid-points. Make tally (with slash marks) of the number of observations in each cell.
Histograms/Frequency Distribution Translate data into a picture of the average and spread of a quality characteristics Convert tally sheet data into bar graph (Histograms) or line graphs (Frequency Distributions) showing the relationship between various values of a quality characteristic and the number of observations (or percentage of the total) in each value. For process capability studies in pre-production or production Engineers, Technicians, Line workers
5. Pareto’s Law Separate the vital few causes of a problem or effect from the trivial many. Concentrate attention on former. Identify as many causes of a problem and the contribution of each to a given effect ($, percentages, etc.) plot causes on X-axis, effects (cumulative) on Y-axis in ascending or descending order of magnitude. Prioritize action on those few causes that account for most of the effect (generally, 20% or less of causes contribute 80% or more of effect) At All times Universal- A fantastic tool for prioritization in MFG. or white collar work.
Generate as many ideas to solve a problem or improve a process, utilizing synergistic power of a group Gather a group most concerned wit the problem; define problem precisely; ask each member to write down cause of problem or improvement ideas; then, open the floor for an outpouring of ideas, rational or irrational; no criticisms allowed; record ideas; narrow down the most worthwhile ideas. Initial problem-solving
”Process” Improvement Quality Circle
Cause & Effect (Ishikawa fishbone diagram) Organize problem causes into main groups and sub-groups in order to have total visibility of all causes and determine where to start corrective action Define the problem; construct a “fishbone” diagram with the major causes (e.g., materials, machine, method and man) as the main “branches” and add detailed causes within each main cause as “twigs”. Quantify the spec. limits established for each cause where possible, the actual value measured for each cause and its effect upon the problem. If a relationship between cause and effect can be shown quantitatively draw a box around the cause. If the relationship is difficult to quantify, underline the cause is related to the effect, do not mark the cause. Prioritize the most important cause with a circle. Experiment with these in PDCA, fashion until root cause is located.
CEDAC Cause & effect Diagram with the Addition of cards Same as Cause & Effect Diagram & earlier identification of causes & better worker participation Workers, at their individual workplaces, identify causes on the spot as they occur. Cards, used to identify such causes can then be readily changed by the workers. Same as cause & Effect diagram Same as cause & Effect diagram
7. Control Charts Maintain a parameter with minimum variation after causes have been captured & reduced. Detailed in text Section Not for problem-solving
Production Engineers, technicians, line workers