This how-to walks through designing a new system using the SeedTactic: Planning software. We will investigate project goals, compare automation versus labor, develop a flexibility plan focused on lean manufacturing, and analyze the cost per piece. The guide Throughput and Cost of a new FMS has a high-level overview of the steps we will be going through. This walkthrough and the SeedTactic: Planning software as a whole have been designed to be usable without special training, so any engineer should be able to design a new system.
Create a Project
Go to the account page.
Use the trial project
- Open the trial project by clicking on the trial project in the list of projects (the trial project only shows up if you have not yet purchased a project).
The trial project is limited to two parts and three workcenters. The trial project can be upgraded to a complete project at any time by creating a new project and selecting the option to copy the trial project data into the new project.
Create a new (paid) project
Click on the "Create new project" button at the top of the account page, or go directly to the create project page.
Create a new team by entering a team name in the box and clicking "Create Team". Teams are the unit of billing and access.
Next, enter a new project name. If you have an existing trial project, you can copy the trial data into the new project by selecting the checkbox. Click "Next" after entering the name.
Finally, enter your payment information and click subscribe.
(Optional) View your plan and bill
Return to the account page
At the bottom of the card for the team, click "Plan and Billing". This will open a new page with the billing information for the team.
Under "Current Plan", you click on the plan card to expand it to see details on upcoming payment and buttons to cancel or change your plan.
Under "Past Invoices", click on the date to open the newly paid invoice.
(Optional) Add other users to your team
By adding other users to your team, they will be able to collaborate and view or edit projects.
Return to the account page.
At the bottom of the card for the team, click "View/Edit Members". This will open a new page to edit the team.
In the card at the top labeled "New Member", enter a user's email address and then select their access. Click on the "Invite to Team" button to add them to the team. When the user logs in with this email address (case sensitive), they will see all the projects for the team on their account page.
All the team members are listed below the "New Member" card. For members besides yourself, you can alter their access or remove them from the team.
Stage 1: Project Goals
Open the project by clicking on it from the account page. The left sidebar shows the current connection to the cloud and provides navigation between the stages. By default, the project opens in "Stage 1: Project Goals".
Horizon For Project Study Card. Start by selecting a planning horizon. We suggest you study an entire year. Smaller horizons can be dangerous if you have seasonal part demand and are more sensitive to variations in predicted demand.
Production Demand Card. Type a part name into the "Enter a new part name" textbox and press enter. Next, put in the total projected demand for this part for the horizon you selected (e.g. one year). If you are not sure of the total demand, you can always guess and come back later to refine it or see how variations in demand will effect the resulting design. Continue entering parts until you have the total demand for the system.
To produce a part, it goes through a sequence of workcenters and dwells at each workcenter for some amount of time. A part can even return to a workcenter more than once. In our experience, labor and machining should be separated into separate workcenters for easier study.
Production Sequence. Enter the sequence of steps used to produce parts. For example, for a typical machine tool production, create a production sequence as follows:
- Click on the plus sign under "Parts flow through the following sequence".
- Click on "Step 1" to expand the step.
- In the "Workcenter" textbox, enter "LoadUnload". Click on "LoadUnload (create new)" to create a new workcenter to represent the task of loading and unloading the part into the machine.
- In the "Labor Required" textbox, select "Entire Operation" because an operator must be present for the entire time the part dwells at the "LoadUnload" workcenter.
- Click on the "Step 1" header to collapse the step.
- Click on the plus sign under the "Step 1" card to add a new step.
- Click on the "Step 2" header to open the card.
- In the "Workcenter" textbox, enter "Machining" and click on "Machining (create new)" to create a new workcenter to represent the task of machining the part. Leave the "Labor Required" box as "No Labor Required" to signal that the operator does not need to be present while the part dwells at the machine.
- Click on the "Step 2" header to collapse the step.
- Click on the plus sign to add a new step, and click on the "Step 3" to expand the card.
- Click on the workcenter textbox and then select "LoadUnload" from the dropdown. Notice that the "Labor Required" field is filled in automatically, because the part is returning to the existing workcenter.
- After the above steps, you should have three steps: a load workcenter, a machine workcenter, and a return to the load workcenter.
In the above production sequence, load/unload and machining are separate workcenters. This accurately represents the system when an automatic handling system is in use. With manual handling of parts, typically parts are loaded directly into the machine so there are not separate load and machine stations. Despite this, we have found that it is better to model the load and machining as separate workcenters even for manual handling. We think of them as conceptually separate workcenters that happen to occupy the same place in reality. The reason to separate them during modeling is it allows more detailed study of labor utilization.
- Part Flow Card. Finally, enter the amount of time in minutes each part dwells at each workcenter. If you do not know the time exactly, you can estimate it for now (we usually start with 5 minutes for load and unload and our best guess for the machining). The times can be updated later once more information is available.
Sometimes, a part must pass through the production sequence multiple times (for example, it must be sent into the machine multiple times because it must be clamped in multiple ways). In SeedTactis, this is modeled using sequences. A sequence is a single pass through the stations. To produce a single part, it must visit all workcenters in the first sequence, then visit all workcenters in the second sequence, and so on.
- Sequences. Sequences can be added and removed using the sequence menu. To open the menu, click on the three vertical dots on the right of each part row.
Stage 2: Capital vs Labor
In Stage 2, we will compare several manufacturing strategies by comparing a range of possible uses of capital and labor. Overview of Stage 2.
Manufacturing Strategy Card
If you are investigating an assembly process, you can select "Assembly or Labor Limited Process" and skip to Stage 3 below.
"Is it the case that you will buy as many machines and tools as required to keep the labor busy?" If you answered yes, you have a labor-limited process and can select "Assembly or Labor Limited Process" and skip to Stage 3.
If the cost of machines is significant in the overall cost of the system, you have a machine limited process. Do not select anything in the "Manufacturing Strategy" card yet, but click "Help me Choose".
Ideal Manufacturing Cost Card
In the "Ideal Manufacturing Cost" card, first enter the costs for each workcenter. Since we are interested in comparisons, you only need to enter costs for impactful workcenters (e.g. you can leave the costs for load/unload workcenter blank). Note that these costs are per-station; later we will be investigating how many machines are needed and the costs will be multiplied by the quantity we will determine.
Next, in the "Ideal Manufacturing Cost" card, enter the labor wage rate per hour.
There are now three cards representing three different possible scenarios: manual operation of machines, an automated handling system which interfaces with all the workcenter but loading and unloading still happens manually, and an automated handling system with robot loading and unloading.
Scenario 1: manual operation of workcenters
Click on "Scenario 1: manual operation of workcenters" to expand the card.
For now, leave the entries in the "Horizon" as the default (based on your chosen horizon during the Goals stage).
Under "Labor Assignment", look at the utilization of the machines.
The utilization is calculated using Little's Law, and shows the percentage of time the workcenter must be busy in order to produce all the parts. Numbers bigger than 100% mean that it is impossible to completely produce all parts. In fact, in our experience, utilization larger than about 60% is unrealistic because the process should have some slack to account for occasional downtime, setups, tool changes, temporary material availability problems, and other issues. You can influence the utilization is several ways: you can increase the number of stations, alter the number of work days, or alter the number of hours/day.
Try tweaking the design until utilization is around 60%. Try changing the number of stations or try 7 days a week and 24 hours/day or 5 days a week and 20 hours/day. You could even go back to the "Project Goals" stage and alter the demand. Note that when changing the number of stations, you should keep the stations that correspond to a single machine in sync; for example, above we separated a machine tool into a "LoadUnload" workcenter and a "Machining" workcenter and the number of stations for each workcenter should be kept in sync.
Create a labor team by entering a team name in the "Enter new labor name" textbox and pressing enter.
You can now assign the labor team to a station by clicking on the "Labor" dropdown next to a station and selecting the team.
The utilization of the labor team is just the sum of the utilization of all stations the team is assigned to, and represents the percentage of time that an operator of the team is busy. Again, numbers bigger than 100% are impossible to implement and utilizations larger than about 80-85% are unrealistic (operators need break time and typically have other minor tasks).
Assign labor teams to all the stations which require labor, watching the utilization of the operators. You can either use multiple "teams" with a single operator per team, or have a couple of teams with a larger number of operators. Be careful to make a realistic assignment; while on paper it may be great for utilization to have a single team of 8 operators handling 17 machines, this is difficult to manage and implement in the factory.
Look at the "Ideal Manufacturing Cost" in the header of the card, directly under "Scenario 1: manual operation of workcenters".
The ideal manufacturing cost is the the workcenter costs combined with the labor wage rate times the number of operators. (The ideal manufacturing cost takes into account the horizon selected on the Project Goals stage to scale yearly costs to the proper time frame.) We call it the ideal manufacturing cost because it does not take into account overheads or material costs; the ideal manufacturing cost is primarily intended to compare between manufacturing strategies.
Scenario 2: automated handling
In the "Scenario 2: automated handling" card, you will perform essentially the same steps as in Scenario 1 with a few changes. You may have noticed when assigning labor that it is difficult to keep all the teams fully utilized. By using an automated handling system, the load workcenters can be separated from the machines. Not only does this make it easier to fully utilize labor, typically the machines operate at higher efficiency as well.
First, enter the cost of the automated handling system.
Next, edit the station counts, work days, and hours/day to influence the utilization of the workcenters similar to before. Note that because there will be an automated handling system between workcenters, the station quantities can vary independently.
In our experience, an improperly managed automation handling system will only achieve 60% machine utilization. But, with proper training and tools the machine utilization can reach 80-85%.
Next, enter labor teams and assign them to stations similar to before. Now, since the automated handling system likely puts all the load stations next to each other, it is easier for multiple operators to cover multiple load/unload stations.
Finally, compare the "Ideal Manufacturing Cost" between Scenario 1 and 2. These are calculated the same except they use different station and operator quantities and Scenario 2 includes the cost of the automated handling system.
Scenario 3: automated handling with robot labor
In the "Scenario 3: automated handling with robot labor" card, you will perform essentially the same steps as Scenario 1 and 2. In our experience, robotic loading can cause machine utilization to reach 90-95% with a proper operations plan so you can target 90-95% utilization. The main difference between Scenario 2 and Scenario 3 is that when computing the ideal manufacturing cost, Scenario 3 does not use the wage rate/hour.
Enter the total combined cost of the automated handling system and robot.
Edit the station counts, work days, and hours/day to influence the utilization of the workcenters similar to before.
Enter the robots and assign robots to stations, making sure each robot is not overloaded.
Compare the ideal manufacturing cost between the three scenarios, and select a scenario in the "Manufacturing Strategy" card at the top of the page. You can always come back later and change this if you want to fully examine all scenarios, but for now you must select a single strategy to investigate in detail.
Stage 3: Flexibility Plan
In Stage 3, we will develop a flexibility plan to implement lean manufacturing, reduce in-process inventory, and maintain a smooth part flow. Overview of Stage 3.
Inventory Management Card
The "Inventory Management" card is used to implement Lean Manufacturing.
Lean Manufacturing is the idea that by reducing in-process inventory, the system experiences higher efficiency, better throughput, and achieves lower cost. The tactic to eliminate batching and implement lean manufacturing is to use kanbans (also called fixtures or tombstones). A kanban is a container that holds one or a small number of parts. The initial casting is placed into the kanban and the kanban travels with the part through the entire manufacturing process. Lean Manufacturing is implemented by limiting the number of active kanbans.
Add a single kanban named "Universal" with a large count. (We will come back later and study a variety of inventory tactics, but for now we just want to have a basic working plan. If you have multiple separate part families, you could add an inventory class for each family.)
Leave the "Limit overall quantity of active kanbans" unchecked, we will come back later and study a variety of inventory tactics.
The "Labor" card repeats the information from Stage 2, so at the moment nothing needs to be done. As the flexibility plan evolves, you can use this card to make changes to the labor if necessary.
The "Stations" card contains the counts, efficiency and labor assignment. In addition, when the strategy is labor limited or manually operated machines it allows you to enter queue sizes.
Unlike in Stage 2 where we calculated the efficiency using Little's Law, in Stage 3 we will place an upper limit on the efficiency. This will allow us to force the system predictions to operate realistically, giving valuable information about which parts fail to finish if there is not enough capacity.
- For the bottleneck workcenter, update the field for "Efficiency %" to be the target utilization (typically 60-65% for manually controlled machines, 80-85% for automated handling, 90-95% for robotic loading). Only the bottleneck workcenter needs to be edited, the other workcenters such as load workcenter can be left at 100% efficiency.
For labor-limited and manually operated machine processes, each station is simulated as having an input queue and output queue where parts either wait to be processed or wait to be transferred to the next station. If a queue is full, it will cause a backup, preventing more parts from flowing through the workcenter sequence. In our experience, it is better to limit in-process inventory via kanbans instead of maximum queue sizes, so at least initially we suggest you leave the queue sizes at some large number like 100 to effectively have an unlimited queue.
- (labor-limited and manually operated machine strategies only) Leave the queue sizes for stations at their default 100 for now.
The "Parts" card contains information about how parts flow through the system. The kanban column must be entered for the part to be produced, and typically the allowable stations for each part is tweaked to limit flexibility.
For the first part, click on the "No Kanbans" text in the Kanbans column. This will open a dialog.
The dialog lists all assigned kanbans, which contains nothing since no kanbans are assigned yet. Click the plus icon to assign a kanban and then select a kanban from the menu. This will assign the kanban to the part.
Repeat this to assign a single kanban for all parts. If a part does not have an assigned kanban, it will not be produced.
Edit the priority and parts/kanban fields if needed.
Click on the text "All Stations" in the "Stations to visit" column. This will open a dialog allowing you to assign parts to stations. For now, leave all parts assigned to all stations, we will come back and tweak this later.
Layout Card (Automated Handling Strategies Only)
For manufacturing strategies utilizing automated handling, the Layout card is used to enter details about the automated handling system.
Open the "Layout" card. It will show an abstract diagram of the automation system and stations. The diagram can be panned by clicking and dragging on the background, and zoomed using the buttons on the sidebar. At the moment, the only way to return to the default zoom and pan position is to reload the page.
Click on the thick horizontal black line. This line represents the track on which the automated cart will move. Once selected, the track turns green and details about the track appear in the sidebar. For now, leave the default settings. Click on the background to deselect the track.
In the sidebar, it will show all the stations not yet added to the diagram. Click on one of the stations.
Move the mouse over the diagram, the station should follow your mouse.
Click on the diagram to place the station below the track, with some distance between the station and the track.
Once placed, the station must be connected to the track. Dots will appear on the track showing the possible connection points. Move your mouse over a dot and click to connect the station to the track. The station has now been successfully added and connected.
The newly added station will be selected (colored green), and the properties of the station and connection appear in the sidebar. For now, leave the defaults as they are.
You can click and drag on the selected station to move it.
Click on the background of the diagram to deselect the station.
Continue adding stations in the above manor until all stations have been added and connected to the track.
Finally, once all stations have been placed, you must add a buffer to the diagram. Click on the buffer tag in the sidebar, move your mouse over the diagram, click to place the buffer on the diagram, and click on a track dot to connect the buffer to the track.
A buffer is used by the automation system to store pallets when the destination is full. In most actual automation systems, there are multiple buffer positions (one per pallet), but for diagramming we place only a single buffer.
The layout should now be valid. You can investigate the specifics of the automation settings on the reference page.
Click on a load station to select it. In the "Connection Type" setting in the right panel, select "No Queue". Repeat this for each load station.
The remaining settings can be left as their default for now.
Projected Operation, Flexibility, and Lean Manufacturing
Click on the "Projected Operation" tab near the top of the page.
Click on the "Start Forecast" button.
Examine the forecast results. The reference guide contains a description of what each forecast result measures.
Flexibility is the ability for parts to choose between several identical machines or more generally a specific path from a variety of possible paths through multiple stations. Flexibility is vitally important to make efficient use of the available machines in the face of variable daily part demand, but with more flexibility comes increasing quality challenges and traffic jams. We want to find the smallest amount of flexibility that keeps the system busy (and then add a small margin of safety). To do so, we will flip back and forth between the Flexibility Plan and the projected operations. In our experience, a good starting point is to have about 20% of the work flexible.
Switch back to the "Flexibility Plan" tab, open the "Parts" card, and click on the text "All Stations" in the "Stations to visit" column. This will open the station restriction dialog.
Set the part to go to only a single machine and close the dialog.
Go to the "Projected Operation" tab and rerun the forecast. Depending on the part quantity and times, you may or may not see a big change in the numbers. Primarily, look at the percentage of completed parts and the overall production rate for the part you changed.
On the "Projected Operation" tab, look in the "Inventory" card for the average number of kanbans in use.
Go to the "Inventory Management" tab and change the quantity of kanbans to 1. If you rerun the forecast, you should see a large drop in production because only a single kanban is active. Instead, try changing the number of kanbans to the average in use computed before.
Continue tweaking the flexibility plan:
- Try restricting the flexibility/allowed stations and watching the projected operation results. If you overload a machine, you should see two effects: fewer parts will complete because they are all waiting to use a single overloaded machine, and the machine utilizations will become uneven as one machine has much higher utilization than the others. If you see either of these, add back in some flexibility.
- Try various quantities for the number of kanbans. You are primarily looking to keep the station utilization high while also matching the actual part production rate to the target rate.
- Try restricting the overall number of active kanbans. By restricting the number of active kanbans, there are fewer traffic problems in the transportation system, less buffering, and an overall smoother flow.
- Try more complicated inventory strategies. If a part is assigned to multiple inventory classes, it will use exactly one kanban from the assigned inventory classes. This allows you to break the parts up into multiple inventory classes and limit kanban quantities per class. For example, if you have some parts which require a long time at the machine and some parts which have short cycle times, a single inventory class covering both will have uneven production rates. Instead, consider two inventory classes (one for long cycles and one for short cycles), allowing you to use fewer long-cycle kanbans and more short-cycle kanbans. You can even have a handful of parts assigned to both inventory classes to introduce some flexibility. This is just an example, try various combinations of inventory classes.
Stage 4: Part Cost/Piece
In Stage 4, we will compute a cost/piece for each part.
Fill in the costs in the "Workcenter and Labor Cost" card. The costs are shared with Stage 2 so may already be entered.
Run the forecast if the forecast results are outdated.
In the "Parts" card, each part is listed with its projected cost. The only editable column is the "Material Cost" column, where you can enter the cost of a single piece of material for the part.
The reference contains the details on how the costs are calculated, but briefly the station, labor, and automation costs are found by computing the total cost and dividing that cost among all the parts based on the percentage of utilization that each part consumes (so larger quantity parts or parts with larger manufacturing time receive a larger chunk of the cost).
Stage 5: Sensitivity Analysis
In Stage 5, the goal is to test the flexibility plan. For example, what if you have a part which is in high demand one week but has no demand a different week? How will the system operate? If this part was flexible, it was helping fill up the machines to keep them busy because it could choose to go to an underutilized machine. Are there enough other parts that are flexible to cover the change in demand?
Cost/piece is also sensitive to the flexibility plan. How much of the cost is due to overcapacity? How will the station efficiency impact the cost/piece? Typically, we see that costs are very sensitive to efficiency, and this is the primary justification for budgeting and preparing a detailed operations plan to manage the efficiency. In our experience, a common cause of project failure is improper accounting of the relationship between cost and efficiency; see any of the material about lean accounting for more information.
Currently, SeedTactic: Planning has no dedicated support for sensitivity analysis, but the good news is you can perform it anyway. For example, you can go to Stage 1 and update the part quantities and then flip forward to the projected operations to see how the results change. Or you can change the station efficiency and examine how the part costs change.
Stage 6: Operations
In Stage 6, we develop and budget an operations plan.
Setup and deploy a monitoring tool to catch efficiency problems early. The FMS Insight software is open source and free to download and is designed to monitor the system in execution for problems.
Develop a plan to properly manage the system to prevent traffic jams.
How will orders from the ERP system flow down to the automation system or machines themselves? The SeedTactic: OrderLink software is designed to solve exactly this problem, although other techniques such as Kanban cards or custom extensions to the ERP system work as well.
Decide on serial numbering and an inspection strategy. With flexibility, we want to make sure each possible combination of part and machine is periodically tested. Also, if a problem is found during inspection, which machine did it run on? The best solution is to scribe or attach a unique serial to each part. Parts can then be signaled for inspection by serials, past serials can be tracked to determine the last time a part-machine combination was inspected, and the serial can be used at the inspection stand to learn the history of the part being inspected. Our FMS Insight software is designed for exactly this problem: to help with serials and inspections.