While you may not encounter them often, a number of VSMapping concepts that are common in factory settings may be useful in Office Kaizen settings from time to time.
drop Off Interval (dOI)
All of the calculations in this chapter and the next calculate cycle time on the assumption that only one person at a time does an activity. This is the situation in a majority of office processes. However, some activities, especially in back offices that process large volumes of work, are done by several to many people at the same time. When you encounter one of these instances, the concept of DOI and its relationship to cycle time will be important.
The DOI is the period between outputs from an activity. If an activity is being done by one worker, the DOI is the same as the cycle time. That is, if it takes a worker 10 minutes to review a loan package, the DOI and the cycle time are each 10 minutes. If there are five workers doing the reviews at the same time, the DOI is two minutes; on average, the work group produces five reviews every 10 minutes. The formula for the calculation of DOI in this example is:
5
10 2
DOI No. of workers performing the activity
Cycle time of one worker minutes minutes
= = =
If the number of workers in an activity changes during the day, the number of workers figure will have to be weighted in order to generate an average num-ber of workers doing the activity. All VSMs should always use cycle time—the time it takes one worker to do the process. Record the number of people who actually do the task at the same time in the data box for the activity along with the current DOI of the activity. These data may be important if staffing changes are contemplated as part of the improvements.
Kanban Board
A kanban board is a location that signals the presence of incoming work that is available to an activity and/or needs to be produced. In a factory, a kanban card may represent a large piece of equipment such as an engine waiting to be worked
on. In an office setting, where the “work” represented is not physically large, the kanban board may actually hold the work itself, rather than cards. Examples are a kanban board for insurance applications awaiting approval or a board with purchase orders awaiting a buyer’s attention. Kanban boards sometimes have kanbans for only one type of work/inventory. Others have many types and are organized into categories of urgency, effort, complexity, time required to com-plete, and so on, so that workers can deal with them in an organized manner rather than just letting things pile up while they work on whatever they happen to grab. These are called heijunka boards. Usually, the board is designed so that it can hold only a certain number of each type of work. When the number in a category exceeds the board’s capacity, no more is accepted. This is a signal to all concerned that attention must be paid to the problem right away. Figure 8.6 (page 162) presents the VSM symbol for a kanban post in the legend. The following description of a supermarket describes how a typical kanban system works.
supermarket
A supermarket is a particular kind of kanban board/location with kanbans that regulate the flow of materials between two activities. Mr. Toyoda chose the name after visiting American supermarkets, which he noted, “provide only what you need, when you need it” and what is taken is replenished, hopefully, before you need it again. Figure 8.6 presents a VSM-formatted illustration showing the operation of a supermarket. The illustrated supermarket is in the real estate closing office of a large bank. The two activities diagrammed are the preparation of generic closing packages (the package of standard forms with the bank’s boilerplate information already filled in) and the finalization of the closing package that adds the borrower’s and the property’s unique information.
As the illustration shows, about 35 mortgage loans are closed (the demand) each day. There are four categories, or “buckets,” in the supermarket of clos-ing packages: loans that will be closed in 90 plus days, in 90 days, in 60 days, and in 30 days. Each category has a column with slots (similar to those in a time-card rack but larger) with the number of slots equal to the predetermined inventory level shown below the supermarket symbol.
When a closing technician is notified of a customer requirement, he or she withdraws the appropriate form from the supermarket rack. In this case, the withdrawal kanban is simply the technician’s personal removal of the form since the supermarket is in the same room. In a bank with a poorly arranged pro-cess, the withdrawal kanban might be a phone call, an e-mail, or even an actual paper kanban sent through the interoffice mail, all of which would be very inef-ficient compared with having the two activities right next to each other. When
the administrative loan assistant observes an empty slot in one of the columns where one of the closing technicians has withdrawn one, he or she prepares a replacement. The assistant’s observation of an empty slot serves as the produc-tion kanban. As with the withdrawal kanban, the producproduc-tion kanban might be a phone call, a paper kanban, and so on, if the two activities are not adjacent.
This system makes it easy to ensure that the closing technicians always have what they need and that there is never too many packages of any one kind prepared in advance of need. As an indication of what a VSM can show, a closer examination of the data box for “Finalize closing package” indicates a problem. Since the cycle time to finalize a package is 60 minutes, the DOI for the activity is 15 minutes with four technicians working. However, the takt time (TT) for the process is the 450 minutes of work time per day divided by 35 packages, which equals 13 minutes (rounded up). This means that, on aver-age, the technicians will be falling behind by two minutes times 35 packages or 70 minutes each day. Of course, if this were a typical office process, there wouldn’t be a supermarket already in place, and the problems that might moti-vate the VSMapping exercise would be the failure to keep up with closing, too many of one type of package and not enough of another, and so on.
First In, First Out (FIFO) Lane
A FIFO lane is a type of self-regulating kanban system that presents work to an activity. The work is done by the receiving activity in the order of “first
Figure 8.6 Illustration of a supermarket kanban system.
Demand = 35/day
in, first out.” A FIFO lane is typically used instead of a supermarket when there are a great many variations and/or the inventory is very expensive, per-ishable, or breakable. A FIFO lane is a great way to minimize inventory if it can keep up with demand. Figure 8.7 presents a FIFO in the place of the supermarket that was presented in Figure 8.6. The use of four different letters beneath the “FIFO” label shows the number of different item types that are in the FIFO lane; in this case, four. The listing below the FIFO box is informa-tion for the VSM reviewers. The FIFO is actually a better soluinforma-tion because the generic closing packages can be prepared very quickly; there is no need to build up a lot of packages in front of the closing technicians unless the closing administrative assistant is going to be absent for more than an hour or two, which could be the case as he or she has other duties.
reMeMBer . . .
Keep in mind that the VSM is an idealized, highly structured depiction of a process. It strives to take all of the times into account as though it were all
“first in, first out” in every activity and inventory box. This is not always the
Figure 8.7 An example of a FIFO lane.
= FIFO lane symbol
way it works in reality; some applications could sit on a desk for days in the processing center, while others might be handled immediately, such as work for a VIP client. However, without the formalized structure of a VSM, it would be hard to analyze any process in terms of cycle times and lead times. The key insight is to realize that a VSM is a distorted “but as close as we can come” lin-ear depiction of reality. As long as the same distortion assumptions are applied reliably and in both the current and future VSMs, any inaccuracies should be minor if the VSM is constructed by knowledgeable employees.
N
ow that Chapter 8 has presented the mechanics of value stream map-ping (VSMapmap-ping), this chapter presents the approach for doing the work that is required to collect data and build the current state VSM (CS-VSM). The general logistics of a VSM, kaizen, and/or lean event are dis-cussed in Chapter 11. This chapter concentrates mainly on distinct issues as they pertain to VSM construction.1. PrePare FOr The vsMaPPIng evenT
The secret of any process improvement effort is similar to that required for successful brain surgery: preparation, preparation, and then more preparation.
Prior to the CS-VSM effort, you must have a team, a team leader, a champion, and a charter that has been approved by the Executive Steering Committee (ESC). Chapter 6 provided a general overview of the ESC structure and the pro-cedures by which it operates. Office Kaizen 1 (OK1) provides more detail for those who are completely new to the process or who require more detail. If you have not formed an ESC, it is critical to get approval (or at least acquiescence) for the planned VSMapping effort from all management personnel whose areas will be impacted by the event. This includes all departments in which you will be collecting data and all of the supervisors of all team members you’ll be using for the event. Before you start, develop a charter with either the ESC or a suffi-ciently influential group of executives or senior management. If you don’t have their buy-in at the start, you run the risk of having team members kidnapped for “critical” tasks during the event or encountering resistance to pursuing the improvement opportunities you’ll be identifying.
While the next preparation item may seem obvious, my observations indi-cate that, to many people, it is not. Make sure you have ample work space reserved for the duration of the VSMapping event. There’s nothing like the