Mistake Proofing Control Kaizen Facilitation

Objectives Review top causes of errors and the importance of mistake-proofing Learn 3 functions of a mistake-proofing measure: Shutout Control Warn Recall the steps to mistake-proofing Explore examples

Approaches Inspection / Judgment Discovers defects after they have happened A person or piece of equipment inspects/compares product or service with a standard, discovers items don’t conform and rejects them Focus on alerting defect producing process about the problem Statistical Process Control (SPC) – Process Behavior Charts Self-check of each output Successive checks of each output At The Source [Focus of Mistake-Proofing Measure] Catches errors before they cause defects Uses devices (methods) to shutout (or shut-down), control, or warn of an improper process

Inspection/ Judgment Method Exercise Read the sentence below and count the number of times the letter f appears. When you are asked to stop, note the number of f’s you have counted. Finished files are the result of much effort of many people effectively filing the materials of many other persons. Number: ____

Top 10 Causes of Errors Processing omissions: leaving out one or more process steps Processing errors: process operation not performed according to the standard Error in setting up: using wrong tooling or incorrect setting/ adjustment Missing parts: not all parts are included in assembly/ process Improper part/ item: wrong part installed in assembly

Top 10 Causes of Errors (continued …) Processing wrong work piece: wrong part machined/ processed Operations errors: incorrect revision or specification sheet Errors in equipment, maintenance or repair: Defects caused by incorrect repairs or component replacement Error in preparation of inspection equipment, fixtures or tools: Damaged inspection tooling; poorly designed fixtures or wrong tools; mis-measurement

Errors are the actions that cause defects Errors and Defects Defects Errors Errors are the actions that cause defects

When to Focus on Mistake-proofing When a process step has been identified where human error can cause mistakes or defects to occur, especially in processes that rely on the worker’s attention, skill or experience In a service process, where the customer can make an error which affects the output At a hand-off step in a process, when output or (for service processes) the customer is transferred to another worker When a minor error early in the process causes major problems later in the process When the consequences of an error are expensive or dangerous

Detection or Prevention People make errors & errors can lead to mistakes However… Mistakes can be eliminated through the use of mistake proofing devices (poka-yoke) that are used to either detect or prevent defects from occurring in the first place

Functions Basic mistake proofing functions to use against defects: Shutout / ’shutdowns’ machine, process or operation Control a process or operation Warn that a defect has occurred (or is about to…)

Determine Process Condition Following process produces defects Change process, defects go away Generally, easiest to change Incorrect Process Process hard to follow consistently Process problem, not people problem Process Not Followed

Definition A ‘poka-yoke’ or mistake proofing device eliminates defects by preventing errors. What does it mean? poka – error (foolish action); yoke – to avoid Replaces earlier version baka yoke (fool proofing) – a more negative connotation

Poka-yoke Reduces Window of Waste Potential Error – No power for laptop back at the Hotel 1) Drive to Hotel 2) Check-In Hotel 3) Plug-in Computer T i m e Mistakes happening within several ‘windows’ Consider several “Interventions” (measures) 1) Attach Car Keys on Power cord 2) Hotel Key(s) in Wallet / on Lanyard or Belt Loop 3) Extra power cord in Computer Bag (redundancy) “It is good to do it right the first time: it is even better to make it impossible to do it wrong the first time.”

Mistake-proofing Steps Step 1: Identify and Describe the defect/ red flag condition Step 2: Determine root cause (where the defect is discovered or where it is made) Step 3: Detail the sequence of events in the standard procedure Step 4: Review the steps that differ from the standard (deviations) (identify contributing conditions or potential failure modes) Step 5: Identify the mistake-proof device type required (S,C,W) Step 6: Create device(s) and test for effectiveness (incorporate into Standard Work practices)

Examples Microwave Oven (Shutout) Garage door sensor (Shutout)

Examples Fuel Gage w/ indication light Automatic MPG calculation (Warn) Automatic MPG calculation (Control)

Examples Gas Cap Eliminated Tethered Gas Cap (Control)

RR Crossing Eliminated Examples RR Crossing Eliminated RR Crossing (Warn)

No skateboarding allowed Examples No skateboarding allowed (Warn) Decorative Metal tabs (Shutout)

Examples Uniform Signage On Terminal

Examples Standardized Vessel Labor “Start-up” / Line-up Routine

Guidelines 1. Try not to spend. 2. Simpler is better. 3. Don’t make them optional. 4. Don’t confuse gages (process checks / verification) with mistake proofing. 5. Eliminate decision making.(Done only one way!)

“Red Flag” Conditions Adjustments Hand processing Unclear or no instructions Rapid repetition Undefined process High volume demand or deadline pressures Many units/mixed units Environmental conditions Multiple steps Infrequent production Ineffective or lack of standards Multiple handoffs

Review Use an inspection approach for preventing defects (mistake proofing at the source) by applying prevention methods at the point in the process where the defects originate Always validate 100% (process check / step verification) Provide for immediate feed-back for corrective action when errors or defects are detected Because humans are not infallible, use mistake-proofing measures to prevent mistake causing errors or at least to warn that a defect or error has occurred Strive for Shut-out