The Lost Art of Activity Sampling

Activity Sampling and more over Time Study Techniques seem to be a lost art within Manufacturing nowadays. I was taught everything comes down to time, and we need to look at the most efficient way we use that time in everything we do.

Activity Sampling for me, is one of those essential tools that you keep in your back pocket, a fantastic technique that enables to economically study a lengthy activity or a group of activities producing statistically accurate data.

 

What is Activity Sampling?

Over a period of time a group of machines, processes or people can be observed at regular intervals to record what activities are being undertaken. Each observation records what’s happening at that particular time, this then builds to measure a percentage of time that activity occurs thought-out the hour, day, etc.

This technique is particularly useful to estimate the proportion of Value-Added Time to Non Value-Added time that occurs within your business processes. Example observations could be machine breakdowns, moving material, change-overs, waiting, Operating, filling in paperwork, etc. These examples are more aligned to the manufacturing operations point of view, but it is as equally as important in back-office processes and even looking at your own internal time-wasting activities to raise personal productivity.

 

An Example Activity Sampling in Action

In this example three people/processes are being activity sampled regarding ‘packing’, the activity was completed over a 2 hour period with observations every 2 minutes. The results are shown in the images below.

 

 

The above images illustrate the allocated percentages of each activity, we can now start to analyse to see what improvements can be made to work smarter (NOT HARDER), this can go hand in hand with spaghetti diagram to illustrate material and person movement, more detailed time Study work and process mapping.

You ‘ll notice that Packing Process 2 has no computer time in the two hours, as we analyse and ask around the variation, Process Packing 2 batches all of their paperwork up first and then processes it in one hit. Activity sampling would have picked this out even if we had of observed it, as the observation percentage compared to the other two processes would have been higher.

 

Benefits

  • It gives unbiased result.
  • lts study may be interrupted at any time without affecting the results.
  • It can be conducted by anyone with limited training.
  • Team work can be studied by activity sampling.
  • It is economical and less time consuming than time study.

How Good is Your Factory? Are there Opportunities?

When you walk your factory floors there are nine items to get an accurate first impression of how lean you are.

1. Work Stations?
Are they clean, organised, free from unnecessary material and equipment?
Are tools organized, identified and easy to find?
(Are 5S’s in place? Visual labeling? Is the factory well lit? Is equipment clean? Supervision and support personnel on shop floor? Metal on metal contact? Safety hazards? Debris on the floors? Check out the bathroom cleanliness.)

2. How many Monuments do you see?
Monuments are massive machines anchored to the deck, not easily moved to which material has to be delivered to, can cause issues with the flow of product (lack of flexibility)
Are they still in use? Not to be confused with age, often older machines are purpose built and give us flexibility in cellular manufacturing. Can machinery, material locations, drop offs be easily rearranged?

3.Work in Process?
Are there piles and piles of Work in Process (WIP)? Has some of it grown roots, celebrated its 1st, 2nd even 3rd birthdays? Does it have any paperwork? Do you have HOT items?
In the ideal factory you should only have the WIP you are working on and its classed as Standard in Process Stock (SIPS) in my eyes as it is controlled.

4. Can everyone see if they are on Target or Behind Schedule?
Hour by hour monitoring, or close to real time as you can get. Can you see the Abnormal from Normal? Use Red and Green to distinguish. Is abnormal recorded for root cause corrective action?

5. What other Metrics do your teams have?
What charts, graphs, objectives, are posted in the area? Are they a Standard Document? (revision controlled, time and date stamped)
Are the Metrics up to date, reviewed, actioned? Again are they on Target? Can you see the Abnormal from Normal easily?

6. Are Materials delivered to or stacked at the Point of Use?
If a worker loses a component (screw, nut, rivet) do they have to go to the stockroom? Ask yourself how are items replenished? Does the replenishment depend on a crane or forklift?

7. Does the Product Flow?
Through a cell, moving line or in large batches or lots? Are associates close together, can they talk to one another, see one another’s WIP, do they help each other out if something goes wrong?

8. Look at the Testing and Inspection?
Where is the Product inspected and tested? Do the associates do most of the inspections or does the product move to another area? Do you have large numbers of inspectors? What is your inspection backlog? Are your defects recorded, reviewed actioned? Are they reducing?

9. Ask! Talk! Communicate! Question!
The biggest and most important. Show dignity and respect at all times, question and challenge, talk to the people on the front line and ask why? Understand? Use your senses.
This list is not definitive and its definitely not just for manufacturing, you apply to all functions, businesses, sectors, industries. Now Go Look See!

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