Manufacturing simulation model requirements checklist

Good initial planning is often the key to success for a project, this is particularly true when considering a modeling assignment. Project planning and management techniques are equally applicable to aid the modeling process as they are for any other activity, ensuring that well defined objectives are set and that project timescales met. However, when looking specifically at the modeling phase of the simulation project the use of a simple set of guidelines can assist the whole process. Although not intended to be exhaustive, this fact sheet endeavors to cover the main areas which should be considered when collecting data for the project. Individual models would not necessarily be expected to include all of these items.

The Layout

The layout of the facility is often required in order to produce an accurate and meaningful representation of the facility. Many modeling applications require accurate measurements of the facility, particularly when modeling line automation and the movement of materials. Once incorporated into the model, the layout will allow the user to communicate with other interested parties how the process with operate.

Processing Equipment

The model will need to understand which equipment is used within the facility and how it processes its products. Information in this area should include whether the equipment processes products individually, in batches or according to some other constraint.

Material Handling Equipment

An important factor in many processes is how the raw materials, WIP and finished products are transported around the system. It is all too easy to design or revise a system without fully investigating the limitations imposed by the material handling system.

The key items for consideration should include;

Conveyors, the lengths, product capacities, and layout will be required.
Forklift trucks, AGV’s, pick up and drop off points, capacities
Cranes pickup and drop off points, capacities

Storage Equipment

The storage of raw materials and finished goods is also an important factor. The key items should include:

Warehouse racking, number of bays, storage capacity
ASRS, storage constraints and capacities

Cycle times

The operation times for all the equipment within the system, together with any variability or ranges for items such as manual operations. This data may also be product dependent. For any material handling equipment load and unload times should also be investigated.

Set-ups

The reasons for equipment set-ups, their frequency and durations need to be identified. These may include change-over’s based on product type changes, or resetting based on some other constraint such as number of operations completed for example.

Buffering and Palletisation

The positions, capacities and control logic for any storage buffers or portable storage such as pallets and stillages should be identified. In many projects the model is frequently used to determine these and various alternative buffer configurations may need to be incorporated.

Resources

The types of labour which are included within the system together with their responsibilities will need highlighting. Not all of the labour used to run the facility will need to be included, for instance operators who are tied to single operations are not normally considered within a simulation.

Shift Patterns

The shift patterns operated by each labour type and section of the facility need to be identified. These should include breaks and show which operations are allowed to continue through which types of break.

Logic/Routing

The way in which products and materials flow through the system needs to be understood, together with the priorities and routing options which may exist. Complex decision rules may form part of the process and will need to be considered as they may need to be modeled in some places.

Products

It is important to identify the key products being produced by the system, important information which may also need to be considered includes the objects size, weight and product type identifiers, as these are often used when determining where products are routed and stored.

Arrivals Profiles

The way in which products and sub-assemblies enter the system needs to be considered. This may be by means of a schedule, or may be by means of some triggering mechanism to fit in with a JIT approach. Each of these can be easily accommodated, but the precise rules need to be investigated.

Breakdowns

Breakdowns are usually a key feature of a simulation model, it is important that the basis of the information is as accurate as possible. The two key pieces of information concern the frequency and duration of breakdowns. This usually is in the form of observations over a period of time and should include the following:-

The time over which the observations were made
The number of breakdowns which occurred during this time
The duration’s of the breakdowns, grouped into the number occurring in a series of time intervals. For example these may be less than 10 minutes, 10-20 minutes, 20-40 minutes etc.
The actual output achieved in this time period If possible, the time between breakdowns split down the same way as the breakdown duration information.

For a facility which has not been built actual data is clearly not available. Data for existing machinery may be thought appropriate, or manufacturer’s data may be used as a basis. Where only limited data is available the use of a statistical curve fitting package is essential in order to properly represent the behaviour of the process.

For more information contact Saker Solutions at info@sakersolutions.com or call 01789 762255