| During many first time Value Stream Mapping | | | | in any standard. Things like phone calls, interruptions, or |
| exercises, we have noticed some common mistakes. | | | | reprioritization of work.4. Double counting of time. It |
| Many times when the mistake is made, it is not | | | | takes a while to understand what to put into an |
| recognized and the Value Stream Mapping tool is | | | | information box and what is a processing step. For |
| called into question. It's like trying to use excel as a | | | | example Changeovers. We know that they go into the |
| word processor, it kind of works but you just don't | | | | information box because all the books say so. |
| quite get the results you were expecting. So here are | | | | Sometimes however people still ask why that time |
| some of our observations.1. You start to follow the | | | | doesn't get recorded on the lead time line. How about |
| people doing the work. We all start out understanding | | | | travel time? I have to travel for 15 minutes between |
| that we are doing Value Stream Mapping on a product | | | | processing steps so I should have a box on my Value |
| or service however at some point, the person doing | | | | Stream Map representing travel time. Should it be |
| the job leaves the product and does something else. | | | | counted as processing time? What do we include in |
| Rather than staying with the product we start to | | | | processing boxes?The key here is to separate the |
| follow the person. It may even seem like we should | | | | things that cause inventory to build up, from the actual |
| follow the person as the task they are doing is related | | | | work to complete the part or service. Long |
| to the product we are following.For example in a | | | | changeover times cause inventory to build up, long |
| dentist's office, the product we will follow is the patient. | | | | distances to travel cause inventory to build up. |
| The patient comes in, they register, they sit down and | | | | Therefore these items are causes to be eliminated. |
| they wait. They get called into the office and the | | | | They are responsible for the inventory we see in the |
| dentist performs the work, they leave. The nurse | | | | company. We will account for them in our lead time |
| takes their folder and does some work to it, she then | | | | calculation when we count the inventory.Understand |
| works on the computer to update the file and finally, | | | | the causes of inventory build up versus the actual |
| she puts the file away.In this case we have stopped | | | | steps to completing a product or service for the |
| following the patient and we have started to observe | | | | customer.Shared Resources5. Ignoring shared |
| the work being performed by the nurse.2. Trying to do | | | | resources. In most companies there are resources |
| a final Value Stream Map without the product or | | | | that are shared. These resources are required to |
| service actually being performed. We all know that it is | | | | support more than one product family. They may be |
| sometimes difficult when you are training people to do | | | | people, assembly lines, equipment, instruments etc. An |
| Value Stream Mapping to always 'see' the product | | | | example would be a laboratory receiving area. They |
| move through the entire process. It is sometimes | | | | receive the samples for many labs and distribute them. |
| necessary to leave the client with homework to | | | | If we forget this during our Value Stream Mapping |
| actually observe the process and fill in all the | | | | process we would get the wrong results.Let's choose |
| boxes.There are cases however where companies | | | | a simple example. A receiving area receives samples |
| think that there is not enough time to get a complete | | | | for 2 labs. Each lab receives 80 samples a day. |
| Value Stream Map, the process is too long or won't be | | | | Therefore they receive 160 samples and over an 8 |
| running for another month and they need to present to | | | | hour period must supply each lab, 10 samples each. |
| management a savings plan by the end of the week. | | | | Therefore, they need 20 samples an hour and this |
| They frequently think that they can go to their | | | | requires 2 people. During the Value Stream Mapping, |
| engineered standards and fill in the information boxes | | | | we mistakenly only account for the one product |
| and then predict their savings.In this case the person | | | | families' work. We believe that they need to supply |
| has forgotten some of the basis of Lean. First without | | | | only 10 samples per hour and we only require one |
| observing the inventory, they don't have a Value | | | | person for 8 hours. This is a simple example and we |
| Stream Map, they have a Process Map. Second | | | | would probably catch it. However, lets say you have |
| without observing how the time standards were | | | | hundreds of products and many product families you |
| arrived at, how will you determine waste opportunities. | | | | may miss this error.Remember to identify the shared |
| Third the person doing the work may have many | | | | resources. If you don't you will incorrectly calculate |
| distractions - for example it may take me an hour to | | | | important numbers like the Takt time and cycle times.6. |
| change the brakes on a car but every time I start, I | | | | Mixing product families. Sometime when Value Stream |
| have to do 3 oil changes. We need to observe the | | | | Maps start to get really complex with many branching |
| work and more importantly what's happening to our | | | | streams going in and out of the main Value Stream, it |
| product when the work isn't being done.Office Value | | | | is because the people doing the Value Stream |
| Stream MappingA close relative of point number 2 is | | | | Mapping didn't do a good job of defining the product |
| doing Value Stream Mapping in the office. With so | | | | families before starting the Value Stream Mapping. |
| much information on the computer today, many | | | | This problem is generally aggravated by one or both |
| companies have all the information on their processes | | | | problems identified earlier - either not identifying a |
| and value streams on their computers. If you want to | | | | shared resource or following a person and not the |
| know how many people are in an area we can get it, | | | | product. By not doing a good job with the product |
| how much inventory between processing steps and | | | | families we can get distracted and follow the wrong |
| what the processing times are are all kept in real time. | | | | processing path.Let's say we are following a product |
| Layouts of the plant floor are kept and actual | | | | family that only goes through a lathe machine and is |
| distances traveled can be calculated right from the | | | | then shipped. The lathe may also be used in a product |
| drawing. For many companies it really is possible to put | | | | family that goes to a welding and, then to an assembly |
| an entire Value Stream Map together in an office and | | | | area and onto a de-burring area etc. If we haven't |
| for it to be technically correct.Although the Value | | | | properly identified the family we may start to follow |
| Stream Map may be technically correct we are | | | | the Value Stream Map through assembly and |
| missing the opportunity to observe what is happening. | | | | de-burring when we should have gone from the lathe |
| For example a company knew from their standard | | | | straight to the shipping area.Make sure you know your |
| that a pallet of material could be wrapped in 2 minutes | | | | product families before you start Value Stream |
| and 30 seconds. They had to be forced out to the | | | | Mapping.These are not the only mistakes you can |
| floor to actually observe the operation and to prove | | | | make during your initial Value Stream Mapping |
| they were right that they went out there. What they | | | | sessions; however they are common to many |
| observed was the pallet took closer to 25 minutes to | | | | companies when they start to learn about Value |
| complete because the operator had to answer 4 | | | | Stream Mapping. Avoiding these mistakes will help you |
| phone calls. They didn't realize that this was part of the | | | | to use the Enterprise Value Stream Mapping (R) tool |
| job of the operator.If you don't observe, you will never | | | | better. Like anything else the more you practice the |
| figure out why your lead-time is so long. Much of what | | | | better you will get. |
| takes place in day-to-day operations is never recorded | | | | |