4. Time Study The major objective of this chapter is to learn how to calculate a time standard based on stopwatch time study procedures.

Time Study A process for measuring the required time for performing a given task, by a given method, by a trained worker, working in a normal pace. Why needed? For methods improvement For determining time standards

Needs for Time Standard Developing schedules Determining wage payment plans Estimating production costs Providing a base for estimating productivity goals Appraising employee performance Evaluating alternative process, equipment Why is time study useful? Ask students to imagine a production plant setting. Use the quick change of tires as example.

Methods for Creating Time Standards Direct time study Cyclic work Non cyclic work Work sampling Synthetic data Predetermined times

Direct Time Study - Tools

Direct Time Study Methods improvement Selection of the examined workers Explanation (union, managers, workers) Collecting and recording information Task division into elements

Methodology Who to choose? Can you suggest a better method? Select an Average Worker (What is average?) Experienced operator Normal pace Consistency (well defined, understood by all) No undue strain for entire day (speed/effort) Pace that should be performed, not average of current rate Rating accuracy Worker acceptance Can you suggest a better method? Who do we choose? What do you mean by average? Experienced as opposed to novice. Normal pace as to the pace that should be performed not what is being performed. Hawthorne effects: Workers may think that they are being measure and work harder than usual. Alternatively, workers may try to confuse the analysts by working slower or inconsistently. PFD allowances: personal, fatigue, and delay

Preparation for Timing Identify the TASK/ CYCLE to be studied before time study Analyze the Complete Task Method Layout of workplace Equipment used Environmental conditions Machine speeds and feeds Inspection equipment Communications with foreman, workers Documents for process, task instructions Establish relationship Elemental analysis Break task into elements Look at the pit crew change tire video again. Ask students what they should do if they are asked to Analyze the process. Talk about to foreman, introduce you to workers/subjects, get information on written instructions, manual, and other documents that are useful. Compare written documents with reality. Forming a good impression and relationship with foreman, and workers are important to the success of time study. Remember, you are studying human, not some machine. Human have feelings, motivations, and has volitions.

Fundamental definitions What is an ELEMENT? Element is a component of job or task that are logical divisions with easily identifiable starting and end points, and are repeated on a regular basis What is a CYCLE? Cycle is the completion of the activities (elements) required to perform the job under study.

Element Analysis Every element must have an easily identifiable starting and ending point (breakpoints) No discontinuities between elements Elements times: 0.04min (short), 0.25min (reasonable) Relative frequency must be included

Timing Methods Continuous Snapback Advantage: Clock never stops, no time omitted Disadvantage: observer does not know at the job how individual elements vary Snapback Advantage: Observer can note individual variability within an element and eliminate substraction Disadvantages: difficult to coordinate eye, watch and task! Especially when operations are short

Determining Number of Cycles Time measurement Measuring time of each element The number of observation of each element depends on the significance level and required level of accuracy

Recommended number of cycles/observations

Maytag Company Approach

Rules for Performing Time Study Don’t comment to the worker during the task Stand (don’t sit) beside the worker Write every event (even though it may seems not important) Have a good position to observe Stop the study if the worker seems to be under pressure and it affects his/her work

Time Study On Cyclic Work Rating evaluation may be written once in a couple of cycles Elements times: 0.04min (short), 0.25min (reasonable) Denoting non-cyclic elements The breakpoint between elements should be clear (touch, push, etc.).

Types of Elements Manual/machine (determines the task duration) Cyclic/non cyclic Fixed time/ variable time (i.e. loading time as a function of weight) Avoidable/unavoidable unproductive elements (sometimes hard to identify)

Time Study on Non Cyclic Work Use continuous timing Divide the task into relatively large elements Write the evaluated performance rate at the end of each element Multiply the observed time with the rate and summarize the data

RATING FACTORS

Do we expect the average worker to work in normal rating ?

Rating Evaluation Methods Subjective judgment Practice by watching movies For a study with long elements, rate each separately Methods: Speed rating Westinghouse

Performance Rating Table (Westinghouse)

Criteria for Successful Speed Rating Evaluation Experience in the class of work performed Selection of an operator who gives performances between 85 and 115 Use of the average value of three or more independent studies

Elements of Allowances Personal Need Basic Fatigue Variable Fatigue Unavoidable Delays Avoidable Delays Extra Allowances Constant Allowances Special Allowances Total Allowances Allowances + Normal Time = Standard Time

Standard Data Systems Elemental times, based on previous time studies, which have been proven to be accurate and reliable. Tabulated element standards that allow the measurement of a specific job without the use of timing devices.

Construction Cost Estimating Given we have the plans for a new building, how much labor is needed and what will it be used for?

Punch Press Standard Data (40” strip) Given we have a new part to run through the punch press, what will be the standard time for the part?

Advantages Over Direct Time Study More consistent standards results Duplicate time studies on similar operations are eliminated Standards are established more rapidly Less experienced analysts can calculate standards (use the formula not develop it) Accurate labor costs and production times can be estimated before production begins

To Illustrate the development of standard data… Model Element 119 130 220 310 311 322 329 10 0.24 0.22 0.23 0.23 0.24 0.22 0.23 20 0.38 0.35 0.35 0.37 0.36 0.36 0.37 30 12.06 10.44 8.71 6.58 10.83 6.34 7.25 40 3.66 4.81 0.00 2.79 5.84 4.55 4.10 50 0.00 1.63 1.91 1.69 1.80 1.45 0.00 60 0.12 0.12 0.13 0.11 0.14 0.14 0.13

Possible Drivers Model NT 3/4/5 D1 D2 119 15.72 18.00 27.25 119 15.72 18.00 27.25 130 16.88 23.50 33.50 220 10.62 2.50 1.50 310 11.06 3.00 7.25 311 18.47 25.00 44.00 322 12.34 12.00 18.25 329 11.35 3.00 8.00

Correlation

Is there a relationship between D1 and the combined time for elements 30, 40, and 50? n X1 X2 X1^2 X2^2 X1*X2 1 15.72 18.00 247.1184 324.00 282.96 2 16.88 23.50 284.9344 552.25 396.68 3 10.62 2.50 112.7844 6.25 26.55 4 11.06 3.00 122.3236 9.00 33.18 5 18.47 25.00 341.1409 625.00 461.75 6 12.34 12.00 152.2756 144.00 148.08 7 11.35 3.00 128.8225 9.00 34.05 Sums 96.44 87.00 1389.3998 1669.50 1383.25 r = 0.977

Linear Regression Y X Y = b0 + b1X

Standard Times for Machining Operations How long will it take to drill a 1-inch hole through two inches of malleable cast iron?