Delay Study

In “Time the Operation” we looked at how to establish the basic time of operations in seconds per piece.  Toward the end of that section we introduced “Operational Allowances”, such as regular stocking up of local work containers, and also mentioned “Shift Allowances”.  The use of shift allowances into the final calculation of the standard recognizes that there are legitimate delays that can occur during the shift that can stop people from working on the fabrication and assembly of products.  These allowances are usually established through delay studies.

DEVELOPMENT OF A DELAY STUDY

The work standard for an operation should allow time for various additional legitimate delays encountered during the shift. Such items are called delay allowances. They have been classified and definite rules are set for their inclusion in the standard. The delay study provides the opportunity to identify the legitimate allowances and also provides additional very useful information on the general working of the operation during the shift

Before starting the study it is necessary to conduct similar checks to that made before conducting an individual study. It is always a good idea to get a feel for the types of delays that are likely to be encountered. A list of typical delays can be established and a key applied to each delay. This helps in summarizing the results at the completion of the study. Not all delays will be identified before the study commences but it will help if the majority of delays can be set up.

Typical rules to decide what allowances can be included in the standard are as follows:-  

Delay allowances should be included in the standard only if the delay is a definite requirement of the job and can be expected to occur at least once on every shift.

If the allowance is included in the standard then it cannot be charged out to expense.

• Tool Changes and Adjustments - this is allowed if the operator has to perform the task or has to wait at the work-station while the task is completed. (Shift allowance)

• Stock handling - this is repetitive tasks, for example; handling steel coils, bars or containers etc. (Operational allowance)

• Service Equipment - this could include making minor machine adjustments, and lubricating or changing coolant etc. (Shift allowance)

•  Job Preparation & Cleanup - this could include arranging work place, checking tooling and equipment, putting on protective clothing, cleaning work place, washing up (health or safety measure), counting parts produced or other clerical duties. (Shift allowance)

• Gauging & Inspection - this is periodic checking of the work produced e.g. SPC. (Operational allowance)

• Other delays     - Plant policy allowed delays.

•  Personal           - varies from plant to plant.

•  Tea Break        - example 10 minutes per 8 hour shift.

To conduct a delay study it is necessary to record the total shift and as in recording single operations it is advisable to use a continuous running stopwatch.

Once the study has been completed it is necessary to summarize the allowable delays and if they are classified as shift delays the available run time would be 480 minutes – tea break – allowable delays. This calculation assumes that the shift duration is 8 hours.

SIMPLIFIED STUDY CALCULATION

For a rough-cut estimate of the standard it is not necessary to conduct a full time study. A number of methods have been developed including PMTS (Predetermined Method-Time System), to establish an estimated standard. This system details times for many individual movements of fingers, hand, arm, body bend, body twist, and eye movements etc. However the application of such a system requires a lot of training and continual use to be a practical tool. Simple timing of the job will be adequate provided you are aware of the good application of effective worker movements and the undesirable in-effective worker movements.
Example:-

Time the operation in seconds and then apply the following calculation -

  * Assuming an up-time of 85% (this is a reasonable average but you may wish to adjust to suit your operation)
 ** Assuming an 8.00 hour shift (standard 5 day working week)

This is the base standard which does not include the time of the support people such as setters and stock-keepers.  To account for these people we need to calculate one final item.

CALCULATION OF ADO

We have seen how to establish standards for Direct Labour operations, however to establish the total standard we must consider the Applied Direct Operators, the ADO's. ADO's are those people who are directly related to supporting the production effort. The specific tasks that fall into this category are stock-keepers, setters, line inspectors and process attendants. Note, setter-operators are normally considered to be directs while supporting trades people would be included in departmental burden (overhead).

There are several methods employed to cover the ADO in the standard. One method is by direct study in the same way as direct labour is studied. This permits standards to be applied to individual jobs. Another approach is to apply Activity Sampling. While yet another simple method is as follows: -

Each department is considered as a separate unit.
The number of ADO's required to support the direct labour in the department is determined and the ratio of one to the other is established.
Example:-

Department A has 50 direct operators and requires 5 ADO's.
The ratio would therefore be 50 : 5  or  10 : 1.
(Note, the ratio could be slightly different if any ADO's have to work extra hours outside the normal 8 hour shift  e.g. clean-out equipment at end of shift  ) 

This ratio is then applied to the direct labour standard ( base standard ), so if we had a base standard of 100 hours / 1,000, the ADO standard would be 100 x 10% = 10 hours.

To confirm how this works, consider one shift of 8 hours production in dep't A.

Assume there are 50 people each working for 8 hours = 400 labour hours/shift.
Assuming a base standard for job "X" of 100 hours / 1,000 parts, the "direct" people would produce 4,000 parts at 100% efficiency.
The ADO standard, at a 10:1 ratio, would be 10 hours / 1,000 hence as 4,000 parts have been made, 40 ADO standard hours will have been generated.  i.e. 10 x (4000 ¸ 1000 )

To check that this 40 hours supports the number of ADO's in the department 40 ¸ 8 = 5 ADO's which is the number we have in the department.

Under this method if the direct labour operation achieves 90% efficiency the ADO generated standard is also down-rated to 90% hence the measurement of their effort is linked to the direct labour performance.

Final calculation of the Standard would be: -

Click here for a copy of a Delay Study Form

Once we have established a standard for each part being made in the department, it is a simple matter to measure the efficiency of our efforts.  The departmental efficiency calculation is normally based upon comparing the hours that we should have taken to make a quantity of parts (generated standard hours) against the number of hours we actually took (actual clocked hours).  For example:- 

Delay in receiving raw materials; Scrap generation caused by poor material or poor process; machine breakdown; quantities of work incorrectly recorded; production schedule insufficient to support the number of people in the department; too few people in the department to make what was required; lack of work containers; incorrect manning of constraint operations.  The list is endless.  If you are having problems in a particular department you need to:- detail the problems, the time of each delay and the number of people effected.  You can either make a note when significant delays occur, or conduct a detailed delay study or use activity sampling.  Activity sampling is a form of randomly spot checking individual operations throughout the shift to see what is happening.  The results are then collated to form an overall picture of how the department is performing and to indicate where problems exist.