# Time study procedure - overview - PowerPoint PPT Presentation

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Time study procedure - overview. Perform methods analysis. Identify elements. Observe one or more operators to find observed time. Give a rating to adjust observed time and find normal time. Add allowances to normal time to find standard time.

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Time study procedure - overview

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### Time study procedure - overview

• Perform methods analysis.

• Identify elements.

• Observe one or more operators to find observed time.

• Give a rating to adjust observed time and find normal time.

• Add allowances to normal time to find standard time.

• Procedures attempt to reduce inaccuracies of going from the sample to the population and from the present world to the future world.

### Step 1: Methods analysis

• Purposes:

• Establish a safe, productive job.

• Leave a permanent record of method for future use.

• Most of effort should be in job design and productivity rather than time standards.

• Once the best method is established, break the job into elements.

• Use the following forms as needed …

### Forms

• Flow chart

• product / people flow

• motion patterns

• Process chart

• Right and left hand chart

• Multi-activity chart

• Operator / Machine chart

### In-class exercise

• Time to fill peg board – old method

• Follow the method given in the handout

• Determine the time to completely fill one board

• Repeat 5 times and calculate the average …

• Redesign workspace and work method … (5 minutes)

### Step 2: Break the job into elements

• Why …

• Makes it possible to reuse the data.

• Permits different ratings for different elements.

• Permits consistency checks.

• Improves methods descriptions.

• Makes incomplete data useful.

### Step 2: Break the job into elements

• How …

• Identify complete actions, e.g.

• Get a part

• Assemble two pieces together

• Define action endpoints (EP) or terminal points (TP)

• Easily recognizable

• Logical in context

• Example: Get part A, TP is part A at center

Assemble two parts, TP is release of assembly in bin

• Endpoint of one action is beginning of the next

• Always keep manual and machine time separate

### Operator selection

• Treat the operator with dignity and respect.

• Try to make the sample representative of the population.

• Select experienced rather than inexperienced workers.

• Select average or typical workers.

• Vary the times and days of studies.

### Timing techniques

• Stopwatch

• Use snapback mode.

• Use electronic watches.

• Avoid using continuous mode.

• Videotape

• Provides a permanent record of the method.

• Analysis can be done by person other than camera operator.

• Elements can be performance rated.

### Statistical approach – pg. 492

• Number of observations depends on:

• Accuracy desired

• Confidence desired

• Data variability

• Example: A time study is being planned. A preliminary sample of 20 times is shown to have a mean of 16 seconds and a standard deviation of 0.4 seconds. If a relative accuracy of 10% and a 95% (round to 2) confidence interval are desired, how many observations are required?

### Statistical approach – example (cont.)

• Standard deviation method:

• Alternatively, use range method (see box 25.1)

### Importance-of-decision approach

• Number of observations depends on:

• Importance of accuracy of the time standard

• Cycle time

• Activity/year

• Cost of an inaccurate standard

• See table 25.2, pg. 493

### Irregular and foreign observations

• Irregular elements: operator activity that the observer did not anticipate

• include like other elements

• determine how often per unit produced

• example: clear hopper, change blade, etc.

• Foreign elements: operator activity that is outside normal work

### Delays

• Avoidable delays will not be included in standard.

• Drinking coffee

• Chatting with coworker

• Unavoidable delays will be included in standard.

• Talking to supervisor about work

• Waiting for supplies

• Breaking a tool

### Recording technique for unusual events

• ‘M’ in time slot

• Omitted elements

• ‘-’ in time slot

• Elements out of order

• see columns 6-8, next page

• Unexpected elements

• code events (A, B, C, etc.)

• explain code elsewhere in short (1-3 word) note

Sample time study form (fig. 25.2, pg. 495)

### Rating

• Ensures that the standard is based on the method, not the operator.

• To improve rating accuracy, study an average operator.

• Studying average operators also improves worker acceptance of the standard.

### Normal pace

• Normal pace must be defined prior to observation.

• Define motivated productivity level (MPL) first.

• Acceptable productivity level is within expectancy of MPL.

• MPL is the work pace of a motivated, skilled, physically fit worker.

### Rating techniques - problems

• Micromotions change their proportions of the total task as the pace changes.

• Low-skill micromotions change less than the overall task.

• High-skill micromotions change more than the overall task.

• Levels of methods detail

Level 1:Management-controlled

Level 2:Management attempts to control

Level 3:Operator-controlled

### Rating techniques: solutions

• Pace rating: Observer estimates the pace.

• Objective rating:

• Observer rates the speed.

• Observer multiplies speed factor by difficulty factor to get pace.

• Improve accuracy

• number of observations

• skilled operator

• observer skilled at job

• Train raters

### Setting allowances

• Personal and fatigue allowances are set from tables.

• Delay allowances are set from delays actually occurring on the job.

• Delays during a time study may provide estimate for the delays to allow for the standard.