Chapter 03 - Visualizationの最近のブログ記事

Q: We want to install an Advanced Planning and Scheduling System but cannot yet service the BOM. What kind of tools should we use for maintenance?

A: The first barrier to starting up an Advanced Planning and Scheduling System is the servicing of BOM. The larger the amount of data, the more difficult the servicing of BOM maintenance. A BOM editor is an important tool for simplifying the work of BOM maintenance. Asprova sent out questionnaires to its more than 1200 users of its Advanced Planning and Scheduling System and found out that easy BOM maintenance is what they want most.

BOM editor in tabular format

The results of the user questionnaire survey show that the greatest demand was for "the ability to input BOM in a format similar to EXCEL. Certainly, most of those who are engaged in production control are using EXCEL every day to manage BOM, orders and raw materials. It's easiest to use a tool when the entry and display are the same in ease of operation as the tools that they use every day. From the results of those user questionnaires, Asprova has put together a BOM input screen that is in the tabular format shown below.

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Data may be directly input into this table, or the data that is entered into excel may be copied and pasted. Data that is stored in a database may be directly imported. Data is just directly entered into this table. This works well when there are a large number of linear steps in production and assembly.

Graphical BOM editor

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The presence of branch and a merge gives a sense of immediately understanding the process flow. This is suited a comparatively low level of production and manufacture of items complex in assembly and of production of projects with branch and flow.

Maintaining BOM in this way moves BOM visualization forward by sharing information and data that used to be in the heads of only designated persons.

Related articles :

Visualizing the Skills of Workers (Skills Table)

Just-In-Time Products and Non-Just-In-Time Products

Parametric BOM

Multi-Site Planning

Q: We want to start maintaining BOM; what data format should we use?

A: To maintain BOM, we have to design according to the kind of format BOM is stored in. It is very difficult to design from zero any format that will be used for a long time. That is why we recommend starting from the BOM format in the Advanced Planning and Scheduling System that has achieved excellent performance results in operation in many plants and factories. It reduces the time and trouble of design. You may well have properties (data items) that are insufficient. This software can add properties for those that are deficient.

One thing we have to watch out for in BOM maintenance is making the BOM design overly complicated. It is important that BOM maintenance have continuity. If the design becomes too complicated, the first draft may be fine, but it might not be able to keep up with the maintenance

Q: How do you use the results of production scheduling to find out what the progress is of specific orders?

A: The results from production schedules are displayed in Gantt order charts. With these charts, we can see whether each order is on time for delivery, what the lead-time is, what the progress is, and the lead-time dispersion. The sales personnel in the sales department can check on the state of progress and the time for completion of each of his or her customers. Each line in the diagram below is an order. The order code is shown on the left. The left edge of the bars in the chart are the dates on which the order arrived and the right tip is on the date that the order is to be completed. The smaller, darker colored bars within the larger bars indicate each step in the process.

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Related articles :

Visualization and Forecasting the Future

Multi-Site Planning

Q: How do we find out what the results of the production schedule are, and what is the schedule for resources (equipment and personnel)?

A: The result of creating the production schedule will display the Gantt resources chart. You can see the schedule for each machine and each employee. It then outputs the work instructions for each machine. If the work is done following these instructions, the delivery date displayed in the Gantt order charts will be observed. Each line of the diagram below shows resources. At the left is the resource code. The bars in the center of the chart show the work in each process. A line is drawn between each job. The entire flow of the work connected by vertical lines is the manufacturing order.

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Related articles :

Visualizing Conditional Orders

Visualization and Forecasting the Future

Multi-Site Planning

Q: We are assigning our safety stock in article units and reducing inventories in a range so that nothing goes out of stock. Fluctuations in demand make it difficult to determine how much safety stock is reduced. Is there a method for knowing what the appropriate stock level is for each item?

A: The results of preparing a production schedule show in an inventory graph (see below). Trends in inventory shifts both past and future can be seen for each production (complete manufactures, partial manufactures and purchased goods). We can see whether there is too much, or whether we barely have enough and how much the inventory is worth in monetary terms for each item, so that we can manage the safety stock for each. One of the distinctive features of the Advanced Planning and Scheduling Systems inventory graph is that we can see/forecast what the inventory will be in the future. With it, we can check for excessive inventories, insufficient inventories and inventory value in the future.

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Related articles :

Visualization and Forecasting the Future

Multi-Site Planning

Q: Is there a method by which, once you know the number of workers you will need next month, you can make adjustments in advance through the use of part-time workers and thus decrease personnel costs? Can you know what it will be for each day?

A: When a production schedule is prepared, one result will be the appearance of a load graph. If you have future unofficial estimates or sales forecast information, that data will be stored as manufacturing data and the making of a schedule will make the load on equipment and personnel known.

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The ability to see what the load will be in the future could, for example, allow us to derive what personnel numbers are needed next month, and we can make the first move in cutting down labor costs. By designating process bottlenecks and making efficient use of TOC (theory of constraints) bottlenecks the entire plant throughput can be increased.

Related articles :

Greater Throughput Through Bottleneck Centered Scheduling

Greater Throughput by Turning Internal Setup into External Setup

Mid-Term Scheduling

Just-In-Time Inventory Management and Custom-Made Products, MTO Products and Test Products

Visualization and Forecasting the Future

Multi-Site Planning

Q: There are many workers but there are great disparities between workers in work capability and efficiency. How can we go about managing those differences?

A: We frequently see skills tables (Toyota calls them "Tournament Records Charts") on plant bulletin boards. On the left side is the name of the worker, at the top is the work category and within the table are markers indicating whether or not the job could be done. Management becomes a lot simpler by organizing the data in a matrix like this. This data from a skill table can be immediately reflected, without modification, into a production schedule. That simplifies skill management and BOM assignment.

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Related article :Visualizing the BOM (Bill of Materials)

Q: Can the production schedule results be viewed by the managers and at the production site?

A: The production scheduling results will be on display at the site in Gantt chart form. The work site checks and confirms the production schedule through the use of the Gantt chart, and then does the work in line with what the Gantt chart says. That allows us to get rid of work instruction sheets and to make the site as paperless as possible. The results of work performance can then be directly entered into the Gantt charts. From this we will know in advance such things as planning and performance data from the previous process and what kind of raw materials we will have to have ready. The production site is also where we can do the work of getting a firm handle on what will happen in the future and make the first move.

Related article : Multi-Site Planning

Q: Producing through complex processes and using many different kinds of raw and basic materials leads to a lack of accurate calculations on when and how much we are going to need. What happens then is excessive material and insufficient product. Is there a way that we can know precisely the quantity of required material and the time for placing them into the process?

A: I would like to explain the method for calculating material requirements. The diagram below shows the work input and output for one particular process.

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One process has multiple inputs and multiple outputs. When any input item is entered into the process, the yield (percentage of good product) for that item will be multiplied and the amount of scrap taken out. That will calculate the volume for the main product. The same goes for the sub product.

With the material requirements, we calculate in the opposite direction, i.e., we derive the needed quantity for each input item from the quantity of main product. Asprova's calculations for material requirements have functions that allow calculation in either direction. That is to say we can either 1) calculate the volume of product to be produced from the quantity of materials now on hand, or 2) calculate the amount of material required from the quantity of product needed. Also because we will have cases in which the material requirement is nonlinear, and there is a curve in quantities so we will require functions for calculating that assign the optimum equations.

Calculations of this type can also be used in an MRP (Material Requirement Planning) system. However, MRP's fixed lead-time prevents precise calculations of the timing required for materials in theory of constraints scheduling. With theory of constraints scheduling Asprova calculates needed timing and material requirement quantities and trims down inventories of raw materials.

Related articles : 

Birth of the Advanced Planning and Scheduling System (APS)

Backward Scheduling for Theory of Constraints (JIT Scheduling)

Forward Scheduling for Theory of Constraints

Mid-Term Scheduling

Just-In-Time Products and Non-Just-In-Time Products

Multi-Site Planning

Q: There are several types of work done including internal setup, manufacture and external setup. We want to hold down excessive costs from wages, so what method is there to know precisely the number of personnel that will be need in the future.

A: Precisely scheduling the work that workers do will allow us to determine how many employees we will need in the future. The diagram below shows us the kind of schedule that will be.

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Case 1 assigns a worker during manufacturing time. Case 2 assigns workers only during setup. Case 6 is an external setup. Where the worker will be assigned to setup, manufacture or teardown is determined exactly by the settings in BOM and that way we know how many workers are necessary. We can also assign the number of workers and schedule the restrictions on them.

For example, if we have sales forecast and estimated order data and if we schedule that data as manufacturing data, then we can forecast the number of workers needed for each day next month. This way we can reduce personnel costs by cutting back on the amount of overtime and working on days off and adjust the number of part-time workers we needed in advance.

Related article : Visualizing the Future Load for Equipment and Personnel (Load Graph)

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