Root Cause Analysis

Root Cause Analysis 1 Root Cause Analysis • Root Cause Analysis is a method that is used to address a problem or non-conformance, in order to get to the “root cause” of the problem. It is used so we can correct or eliminate the cause, and prevent the problem from recurring. • Traditional applications of Root Cause Analysis – Resolution of customer complaints and returns. – Disposition of non-conforming material (Scrap and Repair) via the Material Review process. – Corrective action plans resulting from internal and customer audits. 2 Objective • Through this training course, you will: – Understand the meaning of “Root Cause” – Know the steps used to identify the root cause of problems. 3 What is Root Cause? • Root Cause is the fundamental breakdown or failure of a process which, when resolved, prevents a recurrence of the problem. Or, in other words • For a particular product problem, Root Cause is the factor that, when you fix it, the problem goes away and doesn’t come back. • Root Cause Analysis is a systematic approach to get to the true root causes of our process problems. 4 Philosophy of Root Cause Analysis • Each problem is an opportunity (“golden nugget”) because it can tell a story about why and how it occurred. • It is critical that everyone take a personal and active role in improving quality. • The “true” problem must be understood before action is taken. – Problems are often masked for a variety of reasons • To do this well, we must be – Both focused and open-minded – Both patient and quick – Above all, we must be relentless 5 We Perform Root Cause Analysis to Prevent Turnbacks and Customer Escapes from Recurring Defects found at: Own Next Process Process Step Step Later Process Step Before Reaching Customer Found By Customer $1 Very Minor $100 Rework $1,000 Significant Rework $10,000 Warranty Cost Cost: Impact: $10 Minor Delay Reschedule Delay in of Work Delivery Additional Inspection Admin. Cost Reputation Loss of Market Share 6 Symptom Approach vs. Root Cause • If we do a poor job of identifying the root causes of our problems, we will waste time and resources putting bandaids on the symptoms of the problem. Symptom Approach Root Cause • “Errors are often a result of worker carelessness.” • “Errors are the result of defects in the system. People are only part of the process.” • “We need to find out why this is happening, and implement mistakeproofs so it won’t happen again.” • “This is critical. We need to fix it for good, or it will come back and burn us.” • “We need to train and motivate workers to be more careful.” • “We don’t have the time or resources to really get to the bottom of this problem.” 7 How do we do Root Cause Analysis? • Said simply, Root Cause Analysis is asking why the problem occurred, and then continuing to ask why that happened until we reach the fundamental process element that failed. Why??? • The following example illustrates the basics of Root Cause Analysis. 8 Fishbone Diagram - A Useful Tool • Using a fishbone diagram while brainstorming possible causes helps you to focus on the various possibilities. Some useful categories: Materials People Instructions Environment Problem Machines PM Measuring/Test Equip. Design 9 Example: The Washing Machine Problem ProblemDescription Description “Machine “Machineisis22weeks weeksold old (Serial (Serial#2345017). #2345017). When When doing doingthe thefourth fourthload loadof of clothes, clothes,IIheard heardaaloud loudnoise noise and andthe themachine machinestopped! stopped! ItIt wouldn’t wouldn’tre-start.” re-start.” 10 Verify the Complaint Problem ProblemVerification Verification Service Servicetechnician technicianchecks checks washing washingmachine machineoperation operation to totest testprocedure procedure(#8496). (#8496). The Themachine machinedoes doesnot not operate. operate. ?? Y Y H W WHDetermine Determine the theCause. Cause. 11 Investigate Why Power Off? Machine Unplugged? Machine Machine Doesn’t Doesn’t Work Work Fuse Missing? Fuse Blown Fuse Blown? ?? Y Y H W WHDetermine Determine the theCause. Cause. 12 Investigate Why Electrical Overload? Motor Overheated? Fuse Fuse Blown Blown Lightning Storm? Motor Overheated Power Surge? Corrective CorrectiveAction Actionfor for Specific SpecificDeficiency: Deficiency: Replace Replacethe theFuse Fuse ? ? Y Y H W WH Determine Determine the theCause. Cause. 13 Investigate Why Cooling Fan? Fly-Wheel Loose? Motor Motor Overheated Overheated Shaft Damaged? Motor Mis-Installed? Shaft Damaged ?? Y Y H W WHDetermine Determine the theCause. Cause. 14 Investigate Why Wrong Belt? Bearing Destroyed? Shaft Shaft Damaged Damaged Mis-Handled? Mis-Installed? Bearing Destroyed Incorrect Tolerance/Fit? ? ? Y Y H W WHDetermine Determine the theCause. Cause. 15 Investigate Why Bearing Loads? Bad Bearings? Bearing Bearing Destroyed Destroyed Wrong Bearings? Seal Omitted? Corrective CorrectiveAction Actionfor for Specific SpecificDeficiency: Deficiency: Cause of Failure: Seal Omitted Loss of Lube Replace Replacethe theMotor Motor ? ? Y Y H W WHWas Seal Was Seal Omitted?? Omitted?? 16 Root Cause of our Example? Parts Shortage Inadequate Work Instructions? Seal Seal Omitted Omitted Fell Out? Operator Error? Missed Operation? Root Root Cause Cause -Inadequate Inadequate Work Work Instructions Instructions But..... is it? Inadequate Appropriate 17 Root Cause of our Example? Parts Shortage Inadequate Work Instructions? Seal Seal Omitted Omitted Fell Out? Operator Error? Missed Operation? Root Root Cause Cause -Inadequate Inadequate Work Work Instructions Instructions Appropriate But..... Inadequate is it? Can the design be changed to eliminate the need for a seal? Can the design be changed to make it impossible to omit the seal? Can a fixture be made to make it impossible to omit the seal? 18 Tools Used in Root Cause Analysis Y X BRAINSTORMING START PARETO CHART FISHBONE DIAGRAM SCATTER DIAGRAM VALUE LSL USL UCL X N ? LCL TIME Y RUN CHART CONTROL CHARTS HISTOGRAM 8 6 + 4 2 7 5 STOP FACTOR A FLOWCHART TREE DIAGRAM - + FACTOR C 3 1 - FACTOR B - + DESIGN OF EXPERIMENTS 19 Brainstorming WHAT IS IT? Brainstorming is a process in which a group quickly generates as many ideas as it can on a particular problem and/or subject. WHY IS IT USEFUL? Brainstorming is useful because it can help a group of people ut ilize its collective brainpower to generate many ideas in a short period of time. It stimulates creativity and promotes involvement and participation. WHEN IS IT USED? To help clarify mutual expectations and devise ground rules rela ted to a team’s way of operating. HOW IS IT DONE? •Identify a topic, problem or issue and make sure there is mutual understanding of the task and objective. Write the topic on a flip chart. •Each person presents one idea going in sequence (Round Robin). If a person doesn’t have an idea, pass and move on to the next person. •All ideas are recorded on a flipchart. •There is no evaluation or discussion during the session. •Focus is on quantity of ideas, not the quality. •When all ideas are exhausted, take a break. When you come back, people may have more ideas to add to the list. •Keep the idea generation separate from the evaluation or analysis of ideas. BRAINSTORMING GUIDELINES: •Generate as many ideas as possible. •Encourage free-wheeling. •No criticism is allowed, either positive or negative. •Equal opportunity to participate. •Record all ideas. •Let the ideas incubate. During analysis ideas should be evaluated, further analyzed and refined prior to taking further action. 20 Fishbone Diagram WHAT IS IT? The Fishbone Diagram (also known as the Cause & Effect Diagram) is a technique to graphically identify and organize many possible causes of a problem (effect). WHY IS IT USEFUL? Fishbone Diagrams help identify the most likely ROOT CAUSES of a problem. They can also help teach a team to reach a common understanding of the problem. This tool can help focus problem solving and reduce subjective decision making. WHEN IS IT USED? When the need exists to display and explore many possible causes of a specific problem or condition. This diagram allows the team to systematically analyze cause & effect relationships. It can also help with the identification of ROOT CAUSES. WHAT DOES IT LOOK LIKE? BOWLING PROCESS INPUTS PEOPLE METHODS ATTITUDE MEASUREMENT CURVE OR STRAIGHT BALL USE WRIST BAND? LENGTH OF ARMSWING ALCOHOL INTAKE AMOUNT OF BALL LIFT HOW MANY ON TEAM? - PACE EVERYONE SHOW UP? USE OF ALLEY ARROWS SCOREKEEPER - MANUAL OR AUTO # OF STEPS ON APPROACH AMOUNT OF PRACTICE USE RAG TO WIPE OFF BALL TYPE OF WRIST BAND PROBLEM: ACHIEVE HIGHER BOWLING SCORES TEMPERATURE AUTO PINSETTER SHOES USED BALL WEIGHT LANE OIL BALL CLEANER MACHINES BALL MATERIAL RAG CLEAN MATERIALS NOISE FROM OTHER BOWLERS TIME OF YEAR HUMIDITY ENVIRONMENT 21 Fishbone Diagram (cont.) HOW IS IT DONE? •Name the effect; determine the specific problem to be analyzed. Draw the diagram with a process arrow to the effect and draw a box around it. •Decide what the major categories of the causes are (i.e., people, machines, measurement, materials, methods, environment, policies, etc.). •Label categories important to your situation. Make it work for you. •Brainstorm all possible causes and label each cause under the appropriate category. •Post the diagram where others can add causes to it (i.e., experts, affected people, process owners, etc..). •Analyze causes and eliminate trivial and/or frivolous ideas. •Rank causes and circle the most likely ones for further consideration and study. •Investigate the circled causes. Use other techniques to gather data and prioritize findings. GUIDELINES •Try not to go beyond the span of control of the group. •Promote participation by everyone concerned. •Keep chart up to date so it can be used throughout the improveme nt cycle. 22 PEOPLE MACHINES MEASUREMENT Questions to Ask When Performing RCA PROBLEM • PEOPLE – – – – – – – – – – Was the document properly interpreted? Was the information properly disseminated? Did the recipient understand the information? Was the proper training to perform the task administered to the person? Was too much judgment required to perform the task? Were guidelines for judgment available? Did the environment influence the actions of the individual? Are there distractions in the workplace? Is fatigue a mitigating factor? How much experience does the individual have in performing this task? MATERIAL METHODS ENVIRONMENT • MACHINES – – – – – – – – – Was the correct tool used? Is the equipment affected by the environment? Is the equipment being properly maintained (i.e., daily/weekly/monthly preventative maintenance schedule) Was the machine properly programmed? Is the tooling/fixturing adequate for the job? Does the machine have an adequate guard? Was the tooling used within its capabilities and limitations? Are all controls including emergency stop button clearly labeled and/or color coded or size differentiated? Is the machine the right application for the given job? 23 PEOPLE MACHINES MEASUREMENT Questions to Ask When Performing RCA PROBLEM u MEASUREMENT – – – – – u METHODS ENVIRONMENT Does the gage have a valid calibration date? Was the proper gage used to measure the part, process, chemical, compound, etc.? Was a gage capability study ever performed? – Do measurements vary significantly from operator to operator? – Do operators have a tough time using the prescribed gage? – Is the gage fixturing adequate? Does the gage have proper measurement resolution? Did the environment influence the measurements taken? MATERIAL – – – – – – – u MATERIAL Is a Material Safety Data Sheet (MSDS) readily available? Was the material properly tested? Was the material substituted? Is the supplier’s process defined and controlled? Were quality requirements adequate for part function? Was the material contaminated? Was the material handled properly (stored, dispensed, used & disposed)? ENVIRONMENT – – – Is the process affected by temperature changes over the course of a day? Is the process affected by humidity, vibration, noise, lighting, etc.? Does the process run in a controlled environment? 24 PEOPLE MACHINES MEASUREMENT Questions to Ask When Performing RCA PROBLEM u METHODS – – – – – – – – – – – – – – – – – – – – MATERIAL METHODS ENVIRONMENT Was the canister, barrel, etc. labeled properly? Were the workers trained properly in the procedure? Was the testing performed statistically significant? Have I tested for true root cause data? How many “if necessary” and “approximately” phrases are found in this process? Was this a process generated by an Integrated Product Development (IPD) Team? Was the IPD Team properly represented? Did the IPD Team employ Design for Environmental (DFE) principles? Has a capability study ever been performed for this process? Is the process under Statistical Process Control (SPC)? Are the work instructions clearly written? Are mistake-proofing devices/techniques employed? Are the work instructions complete? Is the tooling adequately designed and controlled? Is handling/packaging adequately specified? Was the process changed? Was the design changed? Was a process Failure Modes Effects Analysis (FMEA) ever performed? Was adequate sampling done? Are features of the process critical to safety clearly spelled out to the Operator? 25 Fishbone Diagram Exercise PEOPLE METHODS MEASUREMENT CHALLENGE: HIT CONSISTENTLY A FASTBALL BETWEEN 85-95 MPH. MACHINES MATERIALS ENVIRONMENT Q.) What are the factors that drive hitting a baseball? 26 Asking Why: sometimes Simple, sometimes Complex Root Cause Analysis sometimes requires the additional resources. Expert Lab Complex, High-Tech Equipment Component Failed Failure Analysis Lab, More Sophisticated Equipment Circuit Board Malfunctioned Sophisticated Tools or Analysis Equipment Resources Controller Failed Simple Tools Hose Disconnected 1 Person (Brainpower) Not Plugged In Complexity 27 Summary • • • Root Cause Analysis is a method to focus our efforts on the true “Root Causes” of escapes, so that we truly prevent their reoccurrence. Root Cause Analysis helps us reduce turnbacks and frustration, maintain customer satisfaction, and reduce costs significantly. Each problem is an opportunity. It contains the information needed to eliminate the problem. But to identify the root cause, we have to ask “Why?” over and over, until we reach it. 28