Time The Operation

Before we start timing the operation there are a number of checks that should be made: -

• Is the operation being performed SAFELY?  IF NOT, STOP JOB AND REPORT IMMEDIATELY.
• Is the SUPERVISOR / TEAM LEADER aware that you are about to conduct a study?
• Are the correct MATERIAL and PARTS being used?
• Are the correct TOOLS and FIXTURES being used in the correct manner?
• Are the MACHINE SETTINGS correct?
• Is the operation PROCESS CAPABLE and meeting inspection requirements?
• Is the LIGHTING, HEATING and VENTILATION acceptable?
• Is the person using the ESTABLISHED METHOD correctly?
• Is the STOCK-HANDLING correct?
• Are any HOLDING DEVICES operating correctly?
• Is the MACHINE operating correctly?

DESCRIBE THE OPERATION

Operations are normally made up of a number of elements, each of which can be identified and timed. Ensure you stand in a position where you can see all parts of the operation and view the operation until you are familiar with it, and then start the element description.  An easy way to describe what is happening is to use the ACT BREAKDOWN technique. This technique is often used for short-cycle, high volume operations and describes a person’s action while performing the operation.

There are three acts: -  GET (G)  - PLACE (P)  - DISPOSE  (D)      plus  WAIT - DRIFT - HOLD

See below an example of this type of description of an operation where a gasket is being added to an assembly that has been taken from a track. When the gasket is fitted the assembly is returned to the track.

Question: - why bother to describe the action of each hand when all we needed to record was “fit gasket to assembly”?
Answer: - We could have done just that but by recording in the manner outlined we give ourselves a better understanding of what is happening and what we can do to improve the operation.  For example at the start of the operation the Left Hand is waiting while the right hand gets the assembly from the track – could the Left Hand get the gasket while the Right Hand gets the assembly from the track?  Would it be better for the Left Hand to get the assembly and the Right Hand to get and place the gasket to the assembly? – it would if you are right handed – gasket would be easier to fit.  Could you fit the gasket while the assembly is still on the track?- maybe – lets try it.  A further refinement to the Act Breakdown description is recording the approximate distances that the hands move when getting parts.  If you want to see the difference that distance makes to time get some parts (suggest Lego bricks) and place them close to you.  Pick up a part in each hand and place them together and dispose.  Time the operation.  Then repeat the operation but this time place the parts 1 metre away from you and time the result.  

TIME A SINGLE ELEMENT OPERATION

Timing the elements is usually done using a decimal minute stopwatch as the following work standard calculations are more easily completed if the original data is in decimal format. However most of us are used to using watches that measure time in hours, minutes and seconds, so we will use an “ordinary” stopwatch that can clearly show minutes and seconds.

The method of timing is either: -   Snap-back or Continuous timing.
Snap-back, as the word suggests is re-setting the watch after taking every reading.   This method is no longer favoured as time can be lost during snap-back.

Continuous timing allows the watch to continue running while readings are recorded and the individual times are calculated later. 

TIME A MULTI-ELEMENT OPERATION 

Element 1            Assemble Gasket to Main Assembly
Element 2            Assemble Cover to Main Assembly
Element 3            Pressure Test Main Assembly

If you have identified a number of elements in the cycle then it is necessary to layout the recording and calculation differently. Ensure that each element has a definite start and finish that is easily recognized. (you can often use sounds created in process to confirm element completion) 

Note that if you are recording a number of elements then the calculation is not horizontal: -  

Start stopwatch running and at the completion of element 1 of the 1^st cycle 15 seconds has elapsed.  Stopwatch continues to run and by the end of the 3^rd element 45 seconds has elapsed, at which time we have assembled the gasket and cover and pressure tested the assembly.  We then return to the top of 2^nd cycle and continue. By the time 60 seconds has elapsed we have assembled a gasket to the second assembly.  The difference in time between finishing the testing of the first assembly, at 45 seconds, and the time at finishing the assembly of the gasket of the second assembly, at 60 seconds, is of course the time taken to assemble the second gasket, 15 seconds. We then continue move down through the elements of the 2^nd cycle until it is time to move up and across to the 3^rd cycle etc.

Question: Why bother to split up the cycle into a number of elements; why not time the total cycle?
Answer: Once again we could have done just that but at a later stage we might want to split this job up and share some of these tasks with another person.  That decision will need to be taken later when we will be looking at balancing the flow of work through the system.

Once the element times have been calculated it is necessary to calculate the average of each set of individual readings for each element.  

The frequency is the number of units processed in each element and is usually recorded in the form of 1:1 or 1:2 or 1:120 etc.

The layout of the recording and subsequent calculations could therefore be as summarized as follows -                                  

Element 4 would generally be classified as an “Operational Allowance”.  In addition to these types of allowances you could also encounter “Shift Allowances”, which can also contribute to the total average cycle time.  However the purpose of this section is to give us a grasp of timing operations, not setting labour standards, which would involve these other factors.

Question: What if one person is faster at the job than someone else, surely we will get wrong times.
Answer: Yes this is not such an exact science as we make it out to be.  Professional work-study practitioners are usually specially trained in rating an operation, that is to say they view each element and apply their judgement of its speed and effectiveness.  They are able to rate the actual against an “acceptable base standard” and then recalculate the time accordingly.  If a person were working faster than the standard rate the calculated time would be increased to represent the “standard work rate”.  Conversely if a person were working below the “norm” the time would be down-rated.  Without this expensive and time consuming training you could time several people and take an average or simply rely upon your own judgement and only time people that are neither exceptionally fast or slow.