7.1. Process Mapping

7.1.1. Background:

Processmapping has long been a tool used to assess the efficiency of a manufacturing system and its processes.  This evaluation helps the company and its employees identify value adding activities, bottlenecks, and opportunities for improvement. The graphical presentation of the process map is especially helpful in visualizing and quantifying the amount of time spent on each activity during the entire process.

7.1.2. Purpose:

The primary purpose of processmapping is to measure the Manufacturing Cycle Time (MCT) of a system.  This principle can also be applied to processes that are not related to manufacturing

7.1.3. Manufacturing Cycle Time

7.1.3.1.  Definition:

The typical amount of calendar time from when a manufacturing order is created, through the critical path, until the first, single piece of that order is delivered to the customer.

7.1.3.2. This definition of Manufacturing Cycle Time ensures the consistency of different MCT measurements for the same process and also allows the user to make comparisons with other processes in a consistent manner.

7.2. Flowcharting

7.2.1 Flowcharting is a technique is identifying each individual step that is required to complete a process.  For example, to make a cup of coffee:
        · Gather materials (coffee, filter, coffee cup, sugar, crème etc.)
        · Setup coffee machine (insert filter and coffee)
        · Place coffee pot into coffee machine
        · Turn on water valve
        · Turn on coffee machine
        · Wait 5 minutes
        · Pour from coffee pot to coffee cup
        · Add sugar and crème
        · Enjoy coffee

The purpose of flowcharting is to gather process information for the data collection phase (See Data Collection).  Flow charting will help the facilitator plan how the part tagging sheets should flow through the process.  In some cases, the part tagging sheet may not be able to follow the part through a process (e.g. heat treating).  Therefore, special arrangements will have to be made to ensure that the information is recorded correctly.  Flowcharting also helps the people involved in collecting the data understand the total picture and intent of the project.  This is especially useful to floor supervisors when they have to deal with different situations that may occur during the data collection phase.

7.3. Data Collection: Tagging

7.3.1. Tagging is the process of documenting every activity that occurs during a process to complete a final task.  The process of tagging involves attaching a part tagging sheet to a part and having the operator record all the steps that occurred to complete the part into a finished product.  For more details on tagging and data collection, please refer to the Data Collection section of the ISO documentation.  Other tagging techniques are also included on the help section of the processmapping website.

7.4. Data Entry: Tagging

7.4.1. Online Website

7.4.1.1. This is the first section where the website is involved.  Up to this point, the facilitator has been engaged in the planning and collecting of information via tagging sheets.  The part tagging sheets provide a similar framework to how the data should be entered into the processmapping website to document, calculate, and graph the MCT of a process.
7.4.1.2. The minimum information required to perform the data entry are:
        · Process Step Name
        · Start Date/Time
        · Stop Date/Time
7.4.1.3. This information can then be entered into the processmapping website and the engine will automatically save and graph the results.  For more details on how to enter data, please visit http://www.processmapping.com/Help/help.htm.  A demonstration of the engine can be accessed by using the following demo account:

URL: http://www.processmapping.com/New
Login: demo
Password: demo

7.4.1.4. One additional information the user has to supply is the classification of the process step; namely: 1) Value Adding, 2) Non-value Necessary, and 3) Non-value Unnecessary.  These steps are also identified by their respective color codes: green, yellow, and red.
7.4.1.5. Typically speaking, Value Adding activities are only directly related to processing the material.  All other activities can be categorized into the Non-value Necessary/Unnecessary group.  Non-value Necessary activities typically include setups, inspection, and packaging.  Movement of the material (unless on a conveyor) is usually classified as Non-value Unnecessary.  The time gaps between each subsequent activity is automatically accounted for within the processmapping engine.  This "gap" or queue time is the amount of time a part waits and therefore categorized as a Non-value Unnecessary step.
7.4.1.6. The online processmapping engine is also capable of documenting more complex processes (e.g. parallel processes) known as a task. The facilitator will be required to collect information regarding each parallel process and enter the information into the website.  The facilitator can then link up each process by using the task option.
7.4.1.7. While constructing a task, the user must distinguish the difference between a child or parent process.  A parent process occurs prior to the child process (parent process on the left side of the child process).  However, a child process can have more than one parent process.  In addition, a parent process can only have one child process.  In other words, the final task should have more processes on the left side than on the right side.  Details of how to construct a task can be found in the help files online.

Process Mapping Online Help

7.5.1. Process Mapping

7.5.1.1. After the information has been entered into the webpage, the user can click on the view button to see the results.  The processmapping engine presents the results in three different formats.

7.5.1.1.1. The first format is the bar graph that shows the different process steps within the process.  The engine also calculates the Manufacturing Cycle Time and displays it in the form of days, hours, and mintues.
7.5.1.1.2. The second format is the pie chart.  Based on the information that is entered, the processmapping engine calculates the percentage of time each activity takes during the entire duration of the MCT.  Typically speaking, the Value Adding percentage is quite some (under 1%).  However, one should keep in mind that this time is only used for one piece.  Since products are usually produced in batches, each piece is required to wait for the other pieces before going to the next process step.
7.5.1.1.3. The third format is the table that contains the information that was entered.

7.5.1.2. From the above information, the facilitator may choose to do the following analysis:
        · Determine why process takes this long
        · Determine reasons for "gaps" or wait time between each process step
        · Determine coordination issues between parts in assembly
        · Determine reasons for each process step
        · Evaluate options to reduce Non-value Unnecessary activities
        · Measure MCT again after process improvements
        · Value Added Ratio (Value Adding Time / Total Time)
        · Total time to days / shifts
        · Total number of people/department involved (value or non-value)
        · Distance traveled/Area covered (material handling)

7.5.1.3. Some potential problems with long MCT and high percentage of Non-value time include:
        · Long wait/queue time
        · Long time for any type individual step (why does it take such a long time for processing)
        · Long set up times
        · Large lot sizes (more than what is immediately required)
        · WIP build up
        · Long cycle time (compared to other industries)
        · Large finish goods area
        · High material handling traffic
        · Long distance traveled

7.5.2. Frequently Asked Questions:

1. Why do you use calendar time as a basis for measurement?  Doesn't that include weekends which are not available to the company and make the "red" look larger?

Answer: Although weekends are typically not available for work and parts may have to "wait", the bottom line is the customer still has to wait for that period also.  In addition, when it comes to comparing different processes from different companies, using an absolute time frame (calendar time), is more consistent than measuring a relative time frame.  Since different companies may run at different shift during different times of the year, it becomes impossible to track what times are "available" and what times are not.  This is especially true if a company runs a skeleton crew on an off shift.  Therefore, using a calendar time approach will account for a more complete picture of the duration of time a part is required in the factory before it is delivered to the customer.

2. What is a critical path?

Answer: The critical path is defined as the longest path that a part has to travel to complete a task.

3. Why do you insist on a one piece flow/measurement for measuring MCT?

Answer: In order to be consistent, it is best to track the time each piece takes to pass through the system.  Although parts may travel as a lot, each piece is still required to wait for the rest of the parts before moving.  In addition, this also makes it easier to track the time if parts are in a transfer line (where a part can go through several steps without waiting for the next part to be processed).  This method also allows the facilitator to account for any splitting or combination of part batches.  Since we are not tracking a lot of parts, it does not matter whether a batch is divided or not.  One can make a copy of the original part tagging sheet and attach it to different batches if the batch is split somewhere during the entire process.

4. Why does MCT not stop when the manufacturing order is finished?

Answer: In some cases, ignoring the time a finished product sits in finished-goods inventory and transit time may give the company a distorted picture of how products are flowing through the supply chain.  It is just as important for the company to know how fast the product flows through the factory floor as well as how long it takes to get to the customer.  For example, some international suppliers may have transit times that are substantially longer than their own internal MCT.

5. How do I get a password protected account?

Answer: To get a password protected, please email process@gunfire.com

6. The time required to make only one piece is less than a minute.

Answer: The minimum time interval for entering the time information on the webpage is one minute.  Anything process step less than a minute should be rounded to the nearest minute.  Although this may not be accurate, our experience has been that the machine cycle time is usually not where the opportunities lie.  Most of the time, a part is simply sitting in a container waiting to be processed or moved to the next station.

7.5.3. Inventory Graphs

7.5.3.1. Background:

As part of the Build-to-Demand (BTD) initiative, John Deere will be providing the supplier as well as Supply Management a tool to gauge the necessary inventory levels at the supplier based on the information that is gathered at the supplier (MCT and Relative Capacity).

7.5.3.2. Purpose:

The purpose of this webpage is to provide the supplier and John Deere Supply Management a tool to gauge the level of inventory each supplier needs to support the cyclical production schedule John Deere is proposing for the BTD initiative.

7.5.3.3. Theory:

The inventory engine is based on a stochastic model that accounts for the delay in production time and John Deere's flexible ordering policy (2 weeks firm; +/- 20% up to 4 weeks).  The inventory engine will give the minimum amount of inventory and level of production required for each month to meet the demand schedule.

7.5.3.4. Procedure

7.5.3.4.1. Data Input
The inventory engine is located at the URL http://www.buildtodemand.com/

The inventory engine will require 15 data points to complete its computations.

· Demand data for each month of the year (12)    [percent of annual demand]
· Manufacturing Cycle Time (1)                           [month(s)]
· Relative Capacity (1)                                          [percent of annual demand]
· Estimated Annaul Usage (1)      [units]

The demand data can be obtained from John Deere's Master Schedule and the MCT and Relative Capacity will be determined through processmapping and capacity calculations (See Relative Capacity Calculation).

According to the data collection that is established for the BTD project, all the parts fall into four different categories 1) High Volume; High Complexity, 2) High Volume; Low Complexity, 3) Low Volume; High Complexity, 4) Low Volume; Low Complexity.  Each category will have a corresponding Manufacturing Cycle Time and Relative Capacity.

7.5.3.5. Results and Output

After entering the above data into the webpage, the inventory engine will automatically calculate and plot the inventory level and production level that is required for that product. 

7.5.3.6 Inventory Graph

The output of the inventory engine will be in two formats.  The first format is a graph depicting the monthly demand, production level, and inventory level.  The second format is the actual numbers that are used to plot the graph.

The production graph represents the recommended production level of a part in order to meet the necessary inventory levels which are required to meet the peak demand.  The basic premise of the inventory engine is to build up the least amount of inventory during the "off season" to compensate for the inventory consumption during the "peak season".  If the factory has enough capacity, no inventory buildup is required.  However, if the factory is already highly utilized, some inventory buildup may be required to accommodate the spike in production during the "peak season".

7.5.3.7 Cost of Inventory

In some cases, carrying inventory may be very expensive for the supplier in terms of production but also storage space.  The supplier may not be able to store the recommended inventory due to the size of the part.  Therefore, the Supply Management have to work with the supplier to detemine the appropriate amount of inventory the supplier should carry.

BTD Methodology
Pre Study | Study Prep | Roll Out | Part Selection | Data Collection | Utilization | Analysis
Build to Demand Homepage | Process Mapping Homepage | Online Process Mapping

Last Modified on: 14-Dec-2001

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