(19) Motion Study Time Study
Arrangement of workplace #1
definite and fixed locations for all tools/materials should be provided to eliminate or reduce therbligs search/select
Westinghouse calculation example
do it
What is therbligs?
gilbreth backwards
principles of motion economy #3
gravity feed bins and drop delivery should be used to reduce reach and move times; ejectors should remove finished parts automatically
pupose of methods-time measurement (MTM
predict task time (overcome a limitation of time study
position vs. preposition
preposition = position right before final position for placement
principle of motion economy #5
proper illiumination, ventilation, temp should be provided
difference between reach and move
reach = empty hand move = with load in hand
What is the 7th principle of motion economy?
research must be done; up to us
principles of motion economy #5
rhythm i essential to smooth and automatic performance of operation
principles of motion economy #2
tools/materials should be located within normal working area
Engineers' work in motion study methods
1. analyze motion elements in a job 2. apply the principles 3. optimize the work method
6 principles of motion economy
1. both hands should begin and complete motions at same time 2. motions of arms should be symmetric around center of body 3. continuous movements are preferred to sharp ones 4. move as few parts of the body as possible 5. momentum should be used to assist worker 6. feet are not capable of operating pedals in standing position
steps of Methods-time measurement (MTM)
1. decompose into elemental motions 2. use pre-determined timing data of elemental motions to estimate total task time
Procedure of Time Study
1. effectively communicate with managment
4 ways to develop the most efficient work method
1. eliminate unnecessary motions 2. simplify necessary motions 3. facilitate/speed-up effective motions 4. adopt most favorable motion sequence
Why do time study
1. establish fair day's work 2. production planning 3. labor planning 4. comparison of machine and method effectiveness 5. health/safety
Researchers' work in motion study methods (2)
1. establish motion elements (Therbligs) 2. develop principles of motion economy
4 principles in design of tools/equipment
1. parts should be held in position by fixture 2. tools and materials should be prepositioned 3. tools should be designed to give best possible mech. advantage and use strongest muscle gropu 4. two or more tools should be combined whenever possible
List 7 therbligs
1. search 2. select 3. grasp 4. reach 5. move 6. hold 7 release
Westinghouse performance rating system criteria
1. skill 2. effort 3. conditions 4. consistency
Two principles of motion study
1. therbligs 2. motion economy
4 time study requirements
1. trained time study person 2. timer 3. trained worker 4. video camera/motion pic
How many therbligs are there?
17
Time Study
A method for determining standard time required by an average, fully-quallified, and well-trained operator working at normal pace to complete a tast
Unavoidable delay
Beyond the control of an operator; may require redesigning the process or machines
Founders of Motion Study
Frank and Lilian Gilbreth
Found in US of Time Study
Frederik W Taylor (Taylorism) Scientific Management
Motion Study
The study of the body motions employed in performing a job to develop the most efficient work method
Motion Elements (another name)
Therbligs
Production Line in the service sector
i.e. hostpial wait times
Avoidable delay
idle time that operator is SOLELY responsible
principles of motion economy #4
materials and tools should be located to permit best sequence of motions
allowance factor
usually 10-35%
