The Toyota Way Fieldbook phần 4 docx

Your initial impression is of the waste! If we ask the question regarding the job depicted in the figure we might get the answers: “It is a mess,” and “Look at the long distance between operations,” or “The operator has to crisscross his work pattern.” These are observations of the waste. Once the waste is understood we can ask: “Is there a better method?” As you progress through the improvement cycle your use of the Standardized Work Chart will change. The initial effort to achieve standardization and elimi- nate waste within a si ngle operation shifts to creating operations that are aligned and balanced with other operations in the flow. This alignment is achieved by designing jobs that are aligned to a common pace known as takt time (explained below). 4 6 Page of Job Name Group 1 1 2 2 2 3 3 Safety Standard In-Process Stock Quality Check 23 2 3 3 1 1 5 1 Work Elements 1Pick up bracket A 8 Total Standardized Work Sheet Walk Time Part Name: Part #: Work Time SIP Stock: Takt Time: 76 Sec T/L: G/L: # 1 6 1 1 5 1 3 33 2 Load in fixture 3Pick up bracket B 4 Load in fixture 5Pick up side support 6 Load in fixture 7Pick up stiffener 8 Load in fixture 9Pick up brace 10 Load in fixture 11 Start Robot cycle Fixture 1 2 A Bracket Side Support B Bracket Stiffener Brace 9 10 11 5 7 3 8 Figure 6-5. Standardized Work Sheet Chapter 6. Establish Standardized Processes and Procedures 127 THE TOYOTA WAY FIELDBOOK128 Standardized Work Combination Table As the name implies, this table (also called the Standardized Work Combination Sheet) is used for analyzing jobs that have combined work. The intent is to show the relationship in terms of time of two or more activities that occur simultaneously. It is used primarily for operations that have a combination of manual operations and automatic equipment, but it can also be used for operations where two or more operators work together on the same product at the same time. For example, a good application for this tool would be if an operator loads a robotic welding station and pushes the start button, and the robot welds while the operator unloads and loads another station. We have seen many people attempt to use the Standardized Work Comb ination Table for all jobs, but using it to analyze a single operator who does not utilize automatic equipment is a waste of time and effort. You will not learn anything from this analysis except how to fill out the form. Figure 6-5, above, depicts an operation with an automatic cycle robot. The shortcoming of using a simple Standardized Work Sheet analysis in this case is that it does not show what happens after the robot cycle is started. There will TIP Focus on the Work, Not the Operator One advantage of documenting the work flow and showing it to operators is that it removes the “fault” for a poor method from the operator. If you see waste and point it out to operators, they will likely explain why it is necessary (defending the method, which they own). If you diagram the work and show operators the diagram, they are likely to respond, “Look at the poor work pattern. We should change that!” TIP The Operator Is Your Most Important Resource The Toyota Way philosophy is that the operator, not the machine, is the most important asset. The machine serves the person, not the other way around. Toyota believes that it is disrespectful to the individual to waste his or her value by waiting for a machine to complete its cycle. The Standardized Work Combination Table is used to gain an understanding of the man/machine relationship and to effectively utilize the human asset. likely be the waste of waiting by the operator. The operator may perform mis- cellaneous tasks to “keep busy,” such as getting the next parts ready or “organ- izing” the work area (we observed one operator neatly restacking every part in the bin, which looked nice but was of no value). It is not clear what the cycle time of the robot is. The Standardized Work Combination Table (Figure 6-6) is useful for this situation. Figure 6-6 shows the same job depicted on a Standardized Work Combination Table. Read it by following the work elements one by one from left to right, and you can see where in the cycle the operator walks to perform the next work element. In this example the operator picks up Bracket A in one second, walks to the mach ine in two seconds, loads Bracket A in six seconds, walks to get the next part in two seconds, and so on. By Step 11 all of the parts are loaded into the robotic welder, and you see by the dotted line that the machine cycles for 23 seconds. Date: Group: Manual Auto Walk 12 22 33 43 51 61 72 82 9 1 6 1 5 1 3 1 8 13 10 5 11 1 3 123 12 13 14 15 Totals 33 21 23 Time Elements Process Name Part Name Part# # Work Elements Standardized Work Combination Table Takt Time 76 Operation Time (Seconds) 10 20 30 40 50 60 70 Pick up Bracket A Load in fixture Pick up Bracket B Load in fixture Pick up Side Support Load in fixture Pick up Stiffener Load in fixture Pick up Brace Load in fixture Start Robot cycle Manual Automatic Walking Wait Time Figure 6-6. Standardized Work Combination Table with one robot Chapter 6. Establish Standardized Processes and Procedures 129 THE TOYOTA WAY FIELDBOOK130 This is a fairly simple job in terms of the operator-machine interface. More complex jobs may have an operator who moves within a cell and operates three or four machines. Like the Standardized Work Chart, the Standardized Work Combination Table converts the work into a visual format so the work/walk/wait time relationships can clearly be seen (the waiting time on this job should be the first improvement target!). The waiting time occurs after the operator starts the robot cycle. This time should be utilized for additional value-adding activ ity. Figure 6-7, below, shows the same job with the addition of a secondary task by adding loading and unloading of a second automatic operation. Notice that the operation time “wraps around,” meaning the machine operates beyond the takt time relative to the start time of the operation. The important thing to note is that the second robot completes its cycle before the operator is ready to return to reload it (the robots have an automatic unload feature, which is common in Figure 6-7. Standardized Work Combination Table with two robots Date: Group: Manual Auto Walk 12 22 33 43 51 61 72 82 93 10 11 23 12 13 2 14 45 15 1 6 1 5 1 3 1 8 1 53 1 2 1 2 10 12 Totals 46 68 29 Load Fixture Start Robot 2 cycle Pick up Brace Load in fixture Start Robot cycle Pick up battery tray and Bracket Pick up Side Support Load in fixture Pick up Stiffener Load in fixture Pick up Bracket A Load in fixture Pick up Bracket B Load in fixture Operation Time (Seconds) 10 20 30 40 50 60 70 Standardized Work Combination Table Takt Time 76 Time Elements Process Name Part Name Part # # Work Elements Manual Automatic Walking Toyota). In Toyota’s view, it is acceptable to allow a machine to wait for the operator, but it is not acceptable to allow the operator to wait for the machine. Remember, the operator comes first. Production Capacity Sheet The Production Capacity Sheet (not shown here) indicates the capacity of machinery in the process. You must consider the cycle time of the equipment, that is, how long it takes to process each piece, but also factor in planned downtime during tool changes and changeover times. It is most applicable to machining operations that involve tooling wear and tool changes, but applies to operations such as injection molding and stamping, where changeover times must be consid- ered. It is a useful tool for identifying bottleneck operations. The document used is very similar to capacity planning processes used by most manufacturing engineers to specify equipment for purchase. The primary purpose is to determine if the machinery has capacity for the production requirement. Calculati ons are based on the available run time, the cycle time per piece, and time lost due to tool changes or other changeover requirements. Some Challenges of Developing Standardized Work Aside from an attempt to develop standardized work based on the myths mentioned earlier, other challenges include attempts to standardize an entire “job,” versus task elements of the job, and attempting to standardize a task that has variation built in. Much of the work we see in companies today includes a variety of tasks that are performed by a single individual. For example, an employee may have a task to build a certain product. In addition he or she will also retrieve the materials necessary and deliver the finished goods to the next operation. The task of building the product is fairly consistent and easy enough to document, but what about the other tasks? They occur randomly, or once every so many cycles. How would you weave these two distinctly different tasks together into one Standardized Work Sheet? The answer is that generally you don’t. The work elements needed to build the product constitute the primary task (and the value-adding operation), and it should be standardized creating the most efficient, repeatable method. Within Toyota, operators do not typically retrieve their own materials nor transport finished product because these activities take away from the value-adding activities. The transportation of materials would be standardized for the person responsible for them, such as a material handler. Chapter 6. Establish Standardized Processes and Procedures 131 THE TOYOTA WAY FIELDBOOK 132 In Chapters 4 and 5 we discussed the need to isolate variation so that standardization may be achieved. The following case example illustrates the challenge of standardizing a task with built-in variation. In these cases, before the task can be standardized the variation must be separated or isolated from the remaining portion, which can then be standardized. Case Example: One Job, Three Different Tasks The “job” in this case example is to operate two automatic screw machines, which cut and machine long bars of steel into discrete metal parts. The operator’s work includes three distinctly different tasks. The variation inherent in the three tasks makes the job nearly impossible to standardize. The first task is to perform in-station quality checks and serve the machine (removing metal chips and moving finished product). The operator is required to perform a specific number of part inspections each hour. The inspections are repeatable in nature, and the task is repeated within a one-hour time frame (a standard cycle time). The second task involves loading raw material as needed. This task is also repeatable in nature, but the cycle time varies, based on the part being produced and the cycle time of each part produced. The time variation is between one and two hours. The third task is to set up and change tooling when worn and between product changes. This portion of the job is not repeatable within several hours, and the frequency of this event is highly variable. The tasks range from fairly repeatable and consistent to very variable and inconsistent. When blended into one job, it is not possible to determine a repeatable pattern that can be standardized. To complicate matters, each operator is responsible for two machines. If one machine is in setup and the other needs material, the machine in setup will wait. If both machines are in setup simultaneously, one machine will wait for attention. In many cases this lost time exceeded several days. If both machines were operating normally, the first task was not enough to fully occupy the operators’ time and they had considerable waiting time. This scenario created waiting time for both the operator and the machine. To isolate variation, the work tasks were reassigned. The first task was assigned to one person who was now responsible for servicing 10 machines and performing the quality checks. The loading of material was assigned to one operator who was responsible for 10 machines, and the setup responsibility was assigned to two people for all 10 machines. This reassignment “freed up” an operator, and the team leader role was created to provide additional support to the line. The reassignment also provided additional advantages, such as two people working simultaneously on setup activities, thus reducing the overall setup times. This reduction facilitated the reduction of batch sizes, increased the run frequency, and reduced the overall inventory. The team leader position ensured that each position would be filled every day and the output would be consistent. Andon signals were added to the machines to notify the material feeder before the machine ran out. The andon also included notification of impending setup and tool changes. These signals allowed the operators to prepare for upcom- ing tasks, verifying the readiness of tools and material before the actual need. These changes increased the overall output of the operation by 30 percent. TRAP Is Standardized Work an ISO-Controlled Operator Instruction? Many companies today have pursued ISO certification. As organizations struggle with defining ISO requirements, this question will undoubtedly be raised when we begin to use standardized work: “Is standardized work a controlled document per the ISO requirement?” While we are not ISO experts, we have seen the result as companies struggle with the paperwork nightmare often associated with ISO. Many companies opt to refrain from posting any documents out of fear of getting “dinged” on an ISO audit or because every change to the process will require a laborious effort to update the paperwork. One company we observed removes all standardized work documents prior to an ISO audit and replaces them afterward (to appease the lean auditors). Whether standardized work is in fact a controlled document per ISO requirements depends upon interpretation. Remember that standardized work is used as an analysis tool and establishes a baseline for continuous improvement. It is not an operator instruction, and it is not provided to the operator as a training tool (see myths, above). Management uses it to audit and verify the general steps of the job, and as such, it should be up to date. If you do make standardized work a controlled document, create a simple system that allows it to be “a living document” and makes it easy to change (e.g., one level approval process). Chapter 6. Establish Standardized Processes and Procedures 133 THE TOYOTA WAY FIELDBOOK134 Auditing the Standardized Work As mentioned, it’s a common myth that standardized work is posted so the operator can refer to it while doing the job. At Toyota operations, standardized work faces out toward the aisle, where the operator cannot easily see it. It is for the benefit of the team leader and group leader who are responsible for auditing the standard work. Isn’t auditing a coercive type of management practice that reinforces the view of standardized work as the framework of a rigid bureaucracy? In an adversarial environment, auditing anything is the basis for conflict and tension. But in an environment where the focus is on eli minating waste to better serve the customer, auditing standard work is a way to maintain stability of the process. It is a coop- erative venture between management and the worker. Operators often deviate from the standardized work because of a problem (creating a “work around”). Management audits uncover the root problems and ensure that they are corrected quickly and standardized work is re-established. TIP Allow Time for Adjustment to the New Method A change in the work method (standardized work) will require an adjustment period. The body becomes “habituated” and will tend to return to the familiar pattern. For example, if you change from a standard-shift car to an automatic shift, you will reach for the shift lever unconsciously (and it will not be there!). It is necessary to provide continued support as the operator adjusts to the new method. Two things trigger an audit at Toyota. First, a problem: What caused a defect? What is causing an operator to repeatedly get behind? Often, observing the operator through several cycles compared to the standard work will reveal the source of the problem. Second, it may simply be time for the audit. Toyota has a standard work auditing schedule, much as they have a schedule for preven- tive maintenance. You don’t need to wait for the machine to break down before you maintain it at Toyota. Similarly, you don’t need to wait for an operator error to audit the standard work. Auditing allows for the discovery of deviation from the standard method. We often erroneously conclude that the operator is at fault when a deviation occurs. Upon investigation, we may find that the deviation is due to a malfunc- tioning piece of equipment or a problem with the product. The reason for the audit is to find the cause of the problem and to correct it. In many Toyota operations there’s a visual system set up for auditing the standard work. Each work group may have a visual board with cards called a kamishibai board (story book). At NUMMI, group leaders check one process each day for compliance to standardized work, watching work cycles. This brings them to each job at least once per month. The cards contain questions they complete on the performance of standardized work and the accuracy of the standardized work document. Discrepancies are noted and countermeasures described on the card. There is a card slot for every process in a team. The cards are moved to a corresponding adjacent vacant slot once the check has been performed. When a problem is noted, the card is turned with the dark side facing out, indicating that something needs correction. Assistant managers check the boards each day to verify that the checks are be ing made properly. They randomly select a card from the board, obtain the standardized work and conduct a check of a process with the group leader. There are approximately 90 boards throughout the shop. Now compare this to many companies that “have” standard work. A standard work sheet is filled out and posted, perhaps by an industrial engineer. If they get really fancy, it may have photos of the work steps. It is posted so the operator can see it. No one does anything with it, but it looks good to visitors, who can say, “They look lean.” Standardized Work as a Baseline for Continuous Improvement After the initial standardization of tasks the real fun begins. We should now ask, “Where is the next level of opportunity?” This is where the answer becomes more complex. We must reconsider our primary objective—to get more value- added activity with less cost, or in other words, to make more parts with fewer resources. Before running off and making improvements, however, we should first understand what will be done with the gain. It is important to always make improvement based on need, rather than because improvement is possible. Improvement will always be possible! If you continue to reduce setup time, for example, what will you do with the addit ional time? Is it important to drive down batch si zes, to increase flex- ibility, or do you need the volume? Too often we see companies “do setup reduction” and reduce the time significantly, but there is no plan for using the freed up time, and the setup times slowly creep back to the original level. This same phenomenon applies to other “improvements.” When improvements are made, you must change the process so that sustaining the improvements is necessary for continued success. The improved level must become the new standard, and the excess removed. If there is no need to sustain, any gains will not be maintained. Chapter 6. Establish Standardized Processes and Procedures 135 THE TOYOTA WAY FIELDBOOK136 Takt Time as a Design Parameter Many people get confused about the difference between takt time and cycle time. Takt time is not a tool. It is a concept that is used to design work, and it measures the pace of customer demand. In terms of calculation, it is the available time to produce parts within a specified time interval divided by the number of parts demanded in that time interval. The number you get tells you, for instance, that a part needs to be produced every three minutes to satisfy customer demand. Seem straightforward? Yet takt time is often misunderstood. And determining it for lines that produce a variety of products with varying demands, becomes a tricky issue. Here’s an example: If the available operation time for one shift is 400 minutes, and the demand for the product is 400 per shift, the time allotted per piece (takt time) is one minute for each part. The cycle time of each operation needs to be one minute or less on average to meet the demand. If the cycle time (actual time to complete the tasks in a single job) is greater than takt, the operation will be a bottleneck and additional time will be necessary to meet the production schedule. If the cycle time is less than takt, there will be overproduction or waiting time. Amajor challenge that arises is determi ning the customer demand. In most cases (unless you are a supplier to Toyota) the demand varies significantly. How can takt time be determined when the demand varies? You must understand that takt time is a “reference point” for designing the work, and consider what the effect of an incorrect reference point will be. The first thing to recognize is that cycle times—the time necessary to complete the task—do not vary significantly if they are standardized. Using our example above, the machine cycle time is 23 seconds and the operator work and walk time is 56 seconds. The combined cycle time is 75 seconds and var ies only to the extent that the operator can load the robot faster now and then. This means that the output from this process will be fairly consistent provided there are no losses due to equipment downtime. If the demand varies significantly, what effect does this have on the operation? None. The operation cycle time will not vary more than a few seconds. If demand increases, how will the requirement be met? The operation time can be increased (e.g., using overtime if the demand does not increase too much). The utilization of takt time will not change this reality. TIP A New Standard Requires a Learning Period It is not uncommon to see a slight drop in performance as people adjust to the new method. Do not rush to “go back to the old way.” Continue observing to ensure that the method is being followed as planned and that any minor adjustments are made immediately. [...]... correct the issues that interrupt the process 4 After the major issues have been resolved and the process is reliable and stable, stand in the circle to study the job and identify waste a Use a Standardized Work Sheet to document the steps of the job b Draw a diagram of the work area and where each step is performed c Note the waste, and develop plans to improve the work process to reduce the waste 144 THE. .. higher than the others), and target them for waste reduction using standardized work as an analysis tool Chapter 7 Leveling: Be More Like the Tortoise Than the Hare The Leveling Paradox The Toyota Way is full of paradoxes, and one of the most counterintuitive is the leveling paradox: that slow and steady can beat fast and jerky, like the parable of the tortoise and the hare [which the older Toyota Production... 146 THE TOYOTA WAY FIELDBOOK the root cause of the problem, but merely pushed the problem backward onto other companies This will show up in a non-lean value stream and ultimately in higher costs and lower profits for someone—in this case the suppliers One might ask: “If Toyota is in fact lean wouldn’t they build exactly what the customer orders in the sequence in which they order, like Dell?” The. .. until setup times are reduced In our example, the pattern of every other day was established for the items that had roughly one-half the demand of the every day items, and the every four-day items had roughly one-fourth the demand of the daily items 1 54 THE TOYOTA WAY FIELDBOOK The first pass of leveling will remove a layer of waste associated with chasing the waves This will provide additional capacity... items on the same day The ED items are a given—they run every day The EOD and E4D may be changed to suit the needs of the process For example, the EOD items could all be produced on the same alternating days as in this example There are other potential patterns as well The objective is to achieve the best level volume across the pattern by row—leveled by individual item over a time window, and down the. .. 150 0 150 0 G (E4D) 0 240 0 0 0 240 0 0 H (E4D) 0 0 0 180 0 0 0 180 I (E4D) J (E4D) 180 0 0 0 0 140 0 0 180 0 0 0 0 140 0 0 Other 59 155 99 215 59 155 99 215 Total 1,325 1,325 1,325 1,325 1,325 1,325 1,325 1,325 Goal 1,325 1,325 1,325 1,325 1,325 1,325 1,325 1,325 ED = every day; EOD = every other day; E4D = every four days Table 7-2 Possible Leveled Production Pattern 156 THE TOYOTA WAY FIELDBOOK Day... refer to the change in demand and the amount of work that flows through the value stream Many managers spend time managing the waves—attempting to adjust the balance of resources and constantly fighting the fires that erupt as a result of the crashing waves These managers are always looking for the day when they catch the wave and get things back to “normal.” Unfortunately, like in the ocean, the next... 8:15 A.M.) in which the material handler might pick up a production kanban, deliver it to the pacesetter as the next order, and pick up what was produced based on the previous order In reality there are many ways to do this; for example, sometimes the orders are posted on a white board by the hour There are several variations on the theme, but all serve the same purpose—to show the “pitch” time increment... overload at the other This caused the entire loading process to stop, and the total line stoppage time was substantiated by the system data This issue was especially critical since the paint system was the constraint operation for the entire facility (it is the only operation in the plant through which all product passes), and the system was above maximum capacity The paint department manager and the loading... over 110 As the operators gained a deeper understanding of visual standards, they made several enhancements to the board, further clarifying the requirement and incrementally leveling the mix (detailed in the next chapter) Standardization Is a Waste Elimination Tool Developing standardized work is the first step It not only provides a standard way of doing the task, but the process of doing the analysis . Procedures 143 THE TOYOTA WAY FIELDBOOK1 44 d. Use the Standardized Work Sheet to diagram the proposed changes and show the waste elimination as a reduction of total cycle time. e. What effect did the. Procedures 133 THE TOYOTA WAY FIELDBOOK1 34 Auditing the Standardized Work As mentioned, it’s a common myth that standardized work is posted so the operator can refer to it while doing the job. At Toyota. Companies, Inc. Click here for terms of use. THE TOYOTA WAY FIELDBOOK1 46 the root cause of the problem, but merely pushed the problem backward onto other companies. This will show up in a non-lean

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