Return on Investment uses the cost model feature of MAST to justify the capital expense for any automation project. The strategy is to model the current operation in MAST and assign machine replacement cost and direct cost of labor. Project the current operation using forecast demand to establish a base cost per part if the current operation were to expand to meet forecast demand. 

Then build a MAST model of the proposed automated operation for the same product mix and forecast volume. This new model will have additional cost for automated handling and different labor configuration in the model. 

MAST cost model will project a cost per part based on automated operation. The difference between the projected cost per part using the current operation and the cost per part for the automated operation defines the annual savings available for the project. The total savings is the cost savings for each part multiplied by the annual volume for each part. 

This total savings compared to the annual capital cost required to implement the automated capacity. Divide the annual cost by the annual savings to determine the number of years required to return the capital investment. 

Please see the following document for capturing MAST Cost Model results and determining return on investment for automated capacity. 

The simulation lab provides a hands-on learning environment to become familiar with all MAST and SAIL software operation, check accuracy of all data, and debug all data sharing interfaces with ERP and other factory software. The lab is established prior to actual machine installations and is used for training and documentation of the Operation Plan. 

Benefits of the Simulation Lab 

- Hands on learning. Operators, schedulers, and managers become familiar with all software operation, screens, and menus. Confidence is achieved in software operation and become a knowledge base for the actual operation. This provides the ability to focus on the actual operation and not question software or data. 

- Customize Software. The lab provides a opportunity to become familiar with performance monitor reports. These reports can be customized prior to actual operation. 

- Test/Debug all Data Sharing Interfaces. Order import and reporting with ERP systems can be developed and fully tested prior to actual operation. Interfaces with inspection processes, part marking devices, and OEE reports can be fully developed and tested. This eliminates any delays in actual system startup and establishes all software operation as background to system start up. 

Simulation Lab Configuration

The simulation lab is a local computer network with 5 computers on the network. Following is the list of computers and function in the local network. 

- SAIL Watch Computer. This computer is running the SAIL Watch software and simulates the network server computer. 

- Machine Watch Computer. This computer is running the Machine Watch software and a simulation copy of the actual cell control software. Most cell control software provides a test version that can be used as a simulator. 

- SAIL Computer. This computer is running SAIL Software. SAIL is used to add and update part data, import orders, generate schedules, download schedules and view all performance reports. This is the primary user interface software. 

- Inspection Computer. This computer is running the SAIL Part Inspection software. This software shows parts that are signaled for inspection and close loop the inspection process. 

- Load Station Computer. This computer is running the SAIL LUL Software. This software shows the load and unload instructions for each load station. Assigned serial numbers and order number to fill are displayed and checked. Links are available to work instruction documents. 

Alternative Paths 

Another common characteristic of the MAST/SAIL project is the definition and use of paths. A path is defined as a combination of part number, pallet number, fixture, machine, and tool set. All available paths for a part number can be on-line (requiring no setup) or require a changeover to make it available. Also, on-line paths are always available anytime during the FMS operation. Changeover to provide an alternative path for a part number is allowed as long as the change over time is less than the typical process cycle time. These alternative paths are useful to offset the negative impact on production rate due to low and fixed WIP characteristics of the pallet handling system. 

The use of these alternative paths is the primary benefit to flexible manufacturing and the outcome of the MAST/SAIL project. Alternative Paths are defined using the MAST modeling software. A variety of production mixes (forecast and other) are evaluated for performance using MAST. Paths are added to the model to achieve balance and optimal machine utilization. It is recommended that at least 25% of all machine hours have an alternative path. Once these paths are defined and proven, then SAIL uses these paths when generating daily schedules. Daily schedules optimize machine use and prioritize to order due dates. SAIL then automatically transfers all data needed to the cell control software. SAIL manages the large quantity of data needed to operate alternative paths in the automated operation. 

A set of alternative paths for a part number can be designated as Exclusive. When a set of paths is designated as exclusive, the allocation algorithm will review alternative paths according to the priority set in each algorithm. When one path has been introduced for a part with exclusive path designation, then all other paths will be unavailable for the part. This will ensure that only one path is used to process an order for a part when alternative paths are available for the part. This feature is most beneficial with orders with low machine hours avoiding inspection of multiple paths. 

Types of Flexibility 

Part number. The components of a path define the specific types of flexibility utilized in FMS. Part Number flexibility allows different part numbers to share the same pallet, fixture, machine and tool set. The collection of part numbers into a part family allows the production of any family members without setup or changeover. Each part number receives a unique numerical control (NC) program and these will be automatically engaged using the CNC features. 

Pallet. Another type of flexibility in FMS is pallet flexibility which allows multiple pallets to process the same part number using identical fixtures, the same set of machines, and the same tool sets. The differences of each pallet are adjusted using pallet offsets to provide for alternative paths. A fixture is the part-specific tooling attached to the pallet which positions the part-specific orientation for each operation. Fixture flexibility is the ability to interchange fixtures to fit multiple pallets. Fixture offsets can be used to adjust for the differences between where the fixture is placed on the pallet, moving the fixtures from one pallet to another would be considered a changeover event. 

Machine. Machine flexibility is the most obvious type of flexibility in an FMS. Most FMS contain multiple machines that have identical characteristics. Because of the similarities of the machines, it is assumed any machine can process any part. This is true in theory but in practice it involves tool sets, NC programs, and pallet offset. Each alternative machine defines a new path that must be qualified and use the same NC program with adjustments limited to offsets. The biggest misconception of FMS is that any machine can process any part. In reality, machine flexibility in an FMS is one of the least utilized types of flexibility. The reason for this limited usage is the amount of data and planning that is required to support multiple FMS paths. Pallets and fixtures have subtle differences when located at one machine to the next. These differences are often adjusted within the NC program thus making a special program for each path. This special set of data requires special scheduling and tracking that eliminates on-line flexibility. Pallet to machine adjustments can only be accounted for using pallet offsets. In order to quality multiple paths using pallet offset alone requires extensive planning and coordinated data management. 

Tool sets. The next type of flexibility in an FMS is the tool sets. All machines have a finite tool capacity. For multiple paths, machines must have the same set of tools. However, as new parts are added, tools are added to specific machines. Eventually, tool positions fill up and prohibit multiple paths because they do not fit tools sets on multiple machines. Tool set constraints are recognized as one of the limits to on-line flexibility and a variety of solutions have been tested and implemented. Today most of these solutions are as complicated as the FMS itself has limited applications. 

Schedule. The last type of flexibility in an FMS is schedule flexibility. Schedule flexibility is implemented through the specific sequence parts are processed through the system and selection of exclusive or alternative paths. Exclusive path algorithm is used to select a specific path for a schedule from alternative proven paths. The path that is selected as exclusive is determined at the time of schedule generation and considers pallet availability, order due date, and machine balance loads. Schedule flexibility reduces the flexibility during run time by limiting pallet and machine selections but benefits with fewer paths to monitor for inspection signals. Schedule flexibility works best when parts have alternative paths and orders have somewhat equal machine load requirements. 

Degree of Automation 

Traditionally, automation and FMS have been synonymous, but they need not be. Automation in an FMS exists for the sole purpose to manage on-line paths. Consider the situation of four identical machines located near one another in a factory. A variety of parts can be processed on these four machines but moving one part to another machine requires the transportation of the fixture between machines. The actual transportation is not the issue; when to move the fixture and to which machine to move it to are the issues. The control system in the automation provides these management decisions. It is the timing of these decisions that manage the alternative paths which become the flexibility in the system. 

Operations Plan Outline This document is developed at the beginning of the project and establishes a consensus for how the machine system will operate. The completion of this document involves all stake holders of the project and usually requires 4-6 weeks to complete. 

- A. Configuration 

1. Parts

2. Machines

3. Pallets

4. Part Programming

5. Paths

6. Prove Out Procedure

- B. Labor Assignments 

1. Load Unload Operator

2. Machine / Tooling Operator

- C. Part Tracking and Quality Plan 

1. Marking Parts 

2. Inspect Paths

3. Inspection Triggers

-D. Daily Scheduling and Order Tracking 

1. Import Work Orders 

2. Demand Matrix - 

3. SAIL Scheduling and Allocation Procedure

4. Download Routing Instructions

5. Report Production Counts, Actual Hours

- E. Work Instructions 

1. Load Station Instructions

2. Close Loop Inspection

3. Order Reporting

- F. Performance Monitor 

1. Daily Production Counts

2. Machine Cycle Monitor

3. Pallet Cycle Monitor

4. OEE

5. Work Order Fulfillment

- G. Tool Management 

1. Tool List and Tool Time for Parts

2. Tool Demand and Redundant Tools

3. Tool Chain Organization

4. Tool Use Forecast and Tool Life