FICCI CE Mistake proofing FICCI CE Mistake proofing

FICCI CE Mistake proofing

FICCI CE Mistake proofing is a scientific technique for improvement of operating systems including materials, machines and methods with an aim of preventing problems due to human error. The term “error” means a sporadic deviation from standard procedures resulting from loss of memory, perception or motion.

FICCI CE Examples of mistake proofing Gas pumps are equipped with hose couplings that break away and quickly shutoff the flow of gasoline.

FICCI CE Examples of mistake proofing The bathyscaph is a deep water submarine used to explore the very lowest parts of the ocean. It is electrically powered. Once at the bottom, if the batteries or electrical system fail the best outcome would be for the submarine to return to the surface. The designers made this outcome occur by holding the ballast in place with electromagnets. When power is lost, the ballast drops off automatically and sub starts it ascent.

FICCI CE Examples of mistake proofing File cabinet can pull over if too many drawers are pulled out. For some file cabinets, opening one drawer locks all the rest , reducing the chance of the file cabinet tipping.

FICCI CE Examples of mistake proofing Fuelling area of the car has three mistake proofing devices : • Filling pipe insert keeps larger, leaded fuel nozzle from being inserted • Gas cap tether does not allow the motorist to drive off with out the cap • Gas cap is fitted with ratchet to signal proper tightness and prevent over tightening.

FICCI CE Examples of mistake proofing Automobiles controls have a mistake proofing device to ensure that the key in the on position before allowing the driver to shift out of park. The keys can not be removed until the car is in park.

FICCI CE Examples of mistake proofing 3. 5 inch diskette can not be inserted unless diskette is oriented correctly. This is as far as diskette can be inserted upside-down. The beveled corner of the diskette pushes a stop in the disk drive out of the way allowing diskette to be inserted. This feature, along with the fact that the diskette is not square, prohibit incorrect orientation.

FICCI CE Examples of mistake proofing Electronic car locks can have three mistake proofing devices: • Ensures that no door is left unlocked. • Door automatically locks when car exceeds the speed of 18 mile an hour. • Lock won’t operate when door is open and engine is running.

FICCI CE Examples of mistake proofing New lawn mowers are required to have a safety bar on the handle that must be pulled back in order to start the engine. If you let go of the safety bar, the mowers blade stops in 3 seconds or less. This is an adaptation of the”dead man switch” from railroad locomotives.

FICCI CE Examples of mistake proofing Retail stores use electronic article surveillance to ensure that no one walks away without making payment.

FICCI CE Examples of mistake proofing This device continuously monitors the water level. If the level is too low, a valve opens to add water to the pool. You can see more examples on www. mistakeproofing. com

FICCI CE Defect Vs errors It is important to understand that defects and errors are not the same thing. A defect is the result of an error, or an error is the cause of defects as explained below. Cause Result Error Defect

FICCI CE Prevention of defects Cause Work Procedure Intermediate result Machine or human error Detect error Modify work procedure to prevent such errors Take corrective action Analyze for preventive action End result zero defect

FICCI CE Types of error • Error in memory of PLAN : Error of forgetting the sequence/ contents operations required or restricted in standard procedures. • Error in memory of EXECUTION : Errors of forgetting the sequence/contents of operations having been finished. • Error in PERCEPTION of type : Error of selecting the wrong object in type or quantity.

FICCI CE Types of error • Error in perception of MOVEMENT : Error of misunderstanding/misjudging the shape, position, direction or other characteristics of the objects. • Error in motion of HOLDING : Error in failing to hold objects. • Error in motion of CHANGING : Errors of failing to change the shape , position , direction , or other characteristics of object according to the standard.

FICCI CE Human error provoking situations • • Complex design Inadequate written standards Too many parts Mix up Too many steps Specifications or critical conditions Too many adjustments Frequent repetition

FICCI CE Principles of mistake proofing The principles of mistake proofing can be categorized into groups: A. Prevention of occurrence B. Minimization of effects

FICCI CE A. Prevention of occurrence Methods under this principle aim to prevent the occurrence of human errors from all stages of operations and make corrections unnecessary. This can be done through the following 3 methods: I. Elimination II. Replacement III. Facilitation

FICCI CE I. Elimination method aims to remove the system properties which generate operations/restrictions susceptible to human errors so as to make them unnecessary. Consider the error of an operator touching a high temperature pipe and getting burnt. One method of preventing this error is to make the pipe safe by covering it with insulating material. This improvement removes the property of the pipe which generates the restriction.

FICCI CE Elimination - Example Air baffles needed to be attached to cover to direct airflow over hot components. Adhesive could come loose if not properly applied. Baffle also prone to damage during assembly. Alternative design has baffle function stamped into sheet metal cover eliminating troublesome assembly step

FICCI CE Replacement substitutes a more reliable process to improve consistency. Examples: use of robotics or automation that prevents a manual assembly error, automatic dispensers or applicators to insure the correct amount of a material such as an adhesive is applied.

FICCI CE Replacement- Example Alignment of the adhesive overlay on the faceplate was critical over a series of port holes. If mis-aligned, the overlay would need to be stripped off, the surface cleaned, and a new overlay applied. The new model replaced this process by eliminating the adhesive overlay and using a more reliable silk screen process.

FICCI CE III. Facilitation The principles of elimination and replacement described above make it unnecessary for operators to perform operations or note restrictions. In contrast to these, the purpose of facilitation is to make such functions as memory, perception and motion required in operations easy for the operators by well designed work stations and thus reduce the occurrence rate of human errors.

FICCI CE Facilitation - Example Board orientation on bottom row 180° different from top row. Color coded board insertion screws and panel color-coding facilitate correct board orientation for insertion.

FICCI CE B. Minimization of effects* Methods under this principle aim to minimize the effects of human error and focus on processes where the errors develop into serious problems of quality, safety or efficiency. This can be divided into two categories : I. Detection and II. Mitigation *This principle is also known as Stop-in-time.

FICCI CE I. Detection The concept of detection is that even if a human error occurs, the deviations from standard states caused by it can be detected and corrected in the succeeding operation steps. The methods of correcting the detected deviations are classified into two types : 1. Operators are informed or find by themselves the deviations and take necessary corrective action. 2. The deviations are automatically corrected without operators

FICCI CE Detection There are two methods of informing the operator. The first method is to bring errors to the operator’s notice by visual or audible alarms, and the second method is by making the successive operations impossible.

FICCI CE Detection - Example A conveyor carries the product under a pivoting flag. A correctly assembled product passes under the flag. An incorrectly assembled product tips the flag, and a sensor detects the flag movement.

FICCI CE II. Mitigation The mitigation method aims to make operations redundant or incorporate shock absorbing/protecting materials so as to mitigate the effects of human errors in their development process. Example : Consider the error of burning out the motor of a production machine by forgetting to switch off the power supply. The mitigation countermeasure is to install a fuse which cuts off the power supply when the temperature reaches certain point.