Toyota is excellent with their standard work. They use a series of worksheets to simplify the creation of these standards. These are sometimes also know as the “famous 3 slips”. The first one is a production capacity sheet to define what capacity you have available. The second one is a standard work combination table to define when the operator is doing what. The third one is a standard work layout sheet to help with the layout and arrangement of the machines. While there are many different ways of doing this, I like the Toyota approach. Since this is a larger topic, I’ve broken it into multiple blog posts. Lets start with the Production Capacity sheet.
Why Standard Work?
If there are different ways that things can be done, then some of these must be better than others. The idea of standard work helps employees perform consistently. Please note that any good work standard – or even any good working procedure – needs a lot of input from the people who actually do the work!
The naming of this method and the three sheets that I will show you in this and the next two posts is by no means used consistently across the lean community, and there are many different similar names. At Toyota this is known as Standard Work, which is also the name John Shook uses. However, this may lead to confusion with the more general standardized work or work standards (meaning there is a standard of some kind, but not necessarily this method). Kei Abe called it Man/Machine Balance, but this was not gender neutral and hence was changed to Operator/Machine Balance in the USA. Kiyoshi Suzaki calls them Work Combination Charts, which Michel Baudin shortened to Work Combo. Definitely many thanks to Michel Baudin for letting me know all those many names and their origins.
Where to Use It
The production capacity sheet helps with the calculations of the line capacity, and the standard work layout helps with the line layout. The standardized work combination table defines the working standard of the operator. Each of these address a specific issue in planning and standardization.
We need to know what the line has to do. The different process steps need to be defined or known. Ideally, we already have a line, but it would also work for a yet-to-be-built line as long as we know the process steps.
We need to know the target speed of the line. How fast should the goods be produced? Key metrics here are the cycle time and the customer takt (or line takt) (the ratio between the two is the OEE). The resulting metric here is the target cycle time. How fast should each machine be (without breakdowns, delays, and other losses) measured in seconds (or minutes, hours, etc.) per piece?
We need to know the speed of each machine, including the time needed for the operator and the time needed at which a machine can work without the operator as well as . At Toyota, this is usually measured using stopwatches (if the line already exists). Other countries where the unions disagree with stopwatches need to use different methods, usually a system of predetermined motions (e.g., MTM). The key metrics here are the manual work time and the additional machine work time. This is such important data that Toyota has a standard sheet for this purpose, the “Production Capacity Sheet”:
Production Capacity Sheet
The production capacity sheet is an overview with the basic data and some simple calculations regarding the machines in the line. I have created an Excel spreadsheet, based on the Toyota spreadsheet, which also does some simple calculations. Below is the overview of the sheet, but since it is a bit small, let me break this down into pieces:
Production Capacity Sheet Header
The header contains the usual things you find in the headers: The name of the part to be produced, the part number for the software system, a date, a responsible person, and also a plant section. An example is given below. Feel free to modify these as needed in the Excel sheet.
Production Capacity Sheet Process Times
Next we get to the actual data. We list the processes/machines that have to be done. Below is the detail from the data sheet, filled in with example data.
First add the machine names and numbers in sequence, so you know which machines you are talking about. Next add the working times, distinguishing between manual work time and machine-only work time. The spreadsheet will calculate the total time for you.
All machine times would have to be faster than the target cycle time. If a machine is slower than the target cycle time, it won’t have enough capacity to supply the customer. You need a faster machine or a second machine.
Production Capacity Sheet Change Over Times
In the next few columns comes the info on the lot size and changeover time. As you can see below, you add the lot size and the duration of the changeover into the cells. You can also change the duration of a shift in the header below process capacity (here 7 hours).
The Excel sheet will automatically calculate the maximum process capacity based on the manual and machine work times and the changeover time. This capacity is simply calculated as follows:
Production Capacity Sheet Totals
Finally, you will see a “Total” line at the bottom. Curiously enough, this is only for the total of the manual work times. But, if you think about it, this makes total sense. The total manual work must be less than the takt time, otherwise the line is too slow. Hence, this number is needed. The total for each individual process is in the “Total Time” column already, needed to check if the machines are fast enough. Having a “Total of the Total” is of little use here. Hence, even though it is easy to calculate the totals of the machine time and the total of the totals, you don’t need it, and hence you do not clutter the sheet with unneeded information.
Goodies for Download
During this short series of posts on the Toyota Standard Work approach I have used an Excel spreadsheet. For your convenience here is the spreadsheet as well as a PDF version thereof. Both documents are provided under the Creative Commons CC-BY-SA 4.0 license, meaning you can use them freely, but should give credit to me on AllAboutLean.com.
Now you have the data basis to do the standard work. I will describe the standard work combination table in the next post. Hopefully, this was not too dry for you, and I promise it will all start to make sense in the next post. Until then, stay tuned, and go out and organize your industry!