Work Measurement

WORK MEASUREMENT

• Application of a set of techniques intended to establish amount of work to be done by an operator in a given time under specified conditions at the defined level of performance. • This helps in identifying correct manpower and machine requirement. • This helps in fixing number of machines to be operated by each worker. • Helps in proper planning of delivery schedules. • Helps in estimating production cost. • Helps in cost control and reduction in labour cost and idle costs. • Helps in improvement of method by identifying deviations from standard. • Helps to fix incentives. • Identifying sub-standard workers, their progress and training needs.

TECHNIQUES OF WORK MEASUREMENT • TIME STUDY - Suitable for short cycle repetitive jobs • PRODUCTION STUDY • WORK SAMPLING - long cycle jobs, heterogeneous operations / team work jobs. • ANALYTICAL ESTIMATING - short cycle non repetitive. • SYNTHETIC DATA - Short cycle repetitive jobs • PRE-DETERMINED MOTION AND TIME STUDY (PMTS)

• MTM - manual operations

TIME STUDY

• Establish time for a worker to carry out a specific job under specified conditions at the defined level of performance. Time study steps • Select the task to be timed - bottleneck jobs, repetitive jobs, Labourious jobs, jobs with longer cycle time, sections having higher over-time. • Standardise the method using method study. • Select the operator having necessary physical attributes, possesses required intelligence and education, has acquired necessary skill and knowledge to carry out the work to satisfactory standard of safety, quantity and quality. • Record details including Item name , part number, machine , speed, material , operator and supervisor. • Record type of material, shape of job, tolerances. • Environment & Working Conditions surrounding the job • Break the task into parts / or elements.

TIME STUDY

• Measure the duration of each element and assess the pace of performance to obtain rating which is a ratio of observed time and the normal time. • Time taken for the job may vary due to variation in material, tool conditions, tool locations and workmen performance hence enough cycles should be timed and average is determined. • Convert the observed time into normal time using performance rating. • Assess relaxation and other allowances for: – Personal needs ( Relaxation Allowance ) – Stoppage of alternate machine ( multiple machines attended by same operator ) ( Interference allowance ) – Unavoidable delays and interruptions.( contingency allowance ) – opportunity to workers to increase the earnings (Policy allowance )

• Calculate Standard Time

WORK SAMPLING • Statistically competent number of instantaneous observations are taken, over a period of time, of a group of machines, processes or workers. Each observation records what is seen to happen and percentage of observations recorded for a particular activity or delay is a measure of percentage of time absorbed by the occurrence. • Large number of observations are made as to state of each member of the group working or idle. The data is amplified for the reasons for being idle. • Used for cost reduction and cost control, Assessment of allowances for output standards, fixation of output standards, Testing the accuracy of the output standards. • Compared to time study, the observer need not be extensively trained. • More than one task can be studied simultaneously • The workers would have less objection as the study is not specifically measuring the skill timing of each job.

STEPS FOR WORK SAMPLING STUDY • Decide on the objective of the study • Explain the purpose to the supervisors and the workers. • Fix up work and delay elements: – Machine under set up – Machine working – Want of tools ( idle time for replacement, non availability, sharing, repairing ) – Want of work ( No work, Hold up for inspection, machine waiting for previous activity to get over, Machine set up for job not yet received, Movement of material. – Want of Inspection ( waiting for the result ) – Want of transport – Want of instructions

STEPS FOR WORK SAMPLING STUDY – Away from work place ( personal needs, official work, collection of pay/incentives, Union / society activities ) – Interference ( machine maintenance, cleaning, simultaneous stoppage, testing of jobs, tools , material ) – Manufacturing difficulties ( defects, supervisor not available ) – Absenteeism – Machine break down – Power failure – Early close and late start • Decide on the duration of study based on number of observers, accuracy desired, frequency of occurrence of the activity, cyclical work patterns • Fix the desired accuracy (2-5 %) and confidence level ( 95 % )

STEPS FOR WORK SAMPLING STUDY • Make a preliminary estimate of percentage occurrence ( Activity percentage - p ) of the activity or delay to be measured based on past experience or pilot study.

p = observations of idle activity / Number of observations. • Design the study : – Number of observations - N = C ( 1 - p ) / A p – C = Confidence level , A = limits of accuracy – Total number of rounds - R = N / m (number of subjects) – Rounds per day - r = R / S ( Number of study days ) – Computation of average time between the rounds

T = Total time available per shift / r – Fixation of time require to make ( complete ) a round - Tr depends on distance, number of stations to be covered

STEPS FOR WORK SAMPLING STUDY – Comparison of T and Tr. T should be at least 2-3 times Tr – Preparation of the schedule for the rounds ensuring randomisation – Design of observation data sheet to facilitate easy recording and understanding – Make observations ensuring that all the members are clearly visible, Observe what is happening and not what has happened or what will happen. – Summarise results in the form of each activity number ( code ) description , number of observations and %ge of observations. – Prepare report with conclusions / recommendations

SETTING PERFORMANCE STANDARDS • The observations are made at random interval whether the subject is working or idle and reasons for delays and interruptions are noted. • Production activity ( working ) is split into machine working and hand working. • Operator’s performance rating is recorded for hand working. • Individual ratings are averaged to get rating index • Production quantity is noted. • Overall time per unit ( To ) is calculated by dividing production time ( study time ) by production quantity. • Effective time per unit ( Te ) = To X Np ( Production activity ) / N ( Total number of observations )

• Np = Nm ( machine observations ) + Nh ( hand Observations)

SETTING PERFORMANCE STANDARDS • Breakdown of effective time

• Te = Tm( machine ) + Th ( Hand ) • Tm = Te X Nm / ( Nm + Nh ) • Th = Te X Nh / ( Nm + Nh ) • Normal time per piece = ( Th X R ) / 100 + Tm • Standard time per piece = Normal time per piece + allowance.

WORK SAMPLING Vs TIME STUDY • Work sampling is more economical as Time study engineer not require at the site for long time and more than one operator can be studied at a time. • Team work activities can be studied by work sampling. • Less trained personnel can also conduct work sampling study. • Work sampling study can be stopped at any time. • It gives unbiased results since workmen are not under close observation.

WORK SAMPLING Vs TIME STUDY • Work sampling is not economical for short cycle jobs and for single workman. • Work sampling does not permit finer breakdown of activities and delays. • Work sampling does not record method being used by operator. • Workmen may change their normal pattern of working on seeing the observer making the study fruitless. • Insufficient observations and lack of randomisation may produce inaccurate results. • It does not normally account for the speed of working of the workman.