Efficiently planning internal transport, warehousing and service processes

An additional AGV, a new warehouse or a change to the order-picking process: In production logistics, transport, stock levels and resources are closely interlinked. Whether a solution can achieve the required throughput often only becomes apparent once it is in operation. Using material flow simulation, we test different scenarios in advance using a model, incorporating your order data, fluctuations and disruptions.

We support planners from production, logistics and factory planning in three areas: in-house transport, warehousing and service processes.

In-house transport

In-house transport supplies production lines with materials and moves semi-finished and finished products between departments and to dispatch. Forklift trucks, tugger trains, automated guided vehicles (AGVs) and autonomous mobile robots (AMRs) are used. The aim is to optimise the allocation of transport resources, as well as warehouse and conveyor stock levels, whilst reliably ensuring a steady supply. Simulation enables us to determine routes, achieve balanced utilisation and decoupling buffers, and compare alternatives.

Typical questions we answer using simulation:

• How many vehicles does the AGV or AMR fleet need to achieve the required throughput with short transport times?
• Which control strategy ensures rapid deployment of empty vehicles and short travel routes?
• How does the system respond to fluctuations in transport volume without causing bottlenecks at the sources or overloaded routes?
• Where are the best loading points and what loading cycles are required?
• Where do bottlenecks occur on the routes when there is mixed traffic with forklift trucks and tugger trains?

We also contribute our experience from AGV simulation to the VDI’s standardisation work. Our colleague Jörg Kemper from SimPlan Integrations GmbH is involved in the revision of VDI 2710 Part 3, ‘Applications of simulation for automated guided vehicle systems (AGVS)’. The guideline describes what input data an AGV simulation requires and what results it should deliver. Among other things, autonomous mobile robots (AMRs) and their throughput are the subject of intensive discussion.

Find out what really matters when simulating AGVs in practice in our article 6 practical tips for successfully simulating Automated Guided Vehicles (AGVs).

Storage

Purchased parts, semi-finished products and finished goods are stored. Simulation enables you to determine storage capacity, put-away and retrieval performance, and the technical design before making an investment.

Typical questions:

• Is a high-bay warehouse with stacker cranes or a shuttle solution the better choice?
• Which conveyor system variant achieves the required throughput?
• Which storage strategy suits the range of parts, for example when organising large, medium and small parts or fast- and slow-moving items?
• Which put-away and retrieval strategy leads to short lead times?

Service processes

Service processes include repackaging, order picking, consolidation, packing, and loading and unloading. The simulation shows the throughput these processes can achieve and the resources required for them. Order picking can be analysed in particular detail:

• How are parts arranged in the ‘supermarket’ to keep walking distances short?
• How can picking orders be grouped together effectively?
• What changes when more orders with fewer items and smaller quantities are received?

For warehouse and dispatch processes beyond the factory, you can find information under Distribution Logistics.

Practical example: AGV simulation at a tyre manufacturer

A tyre manufacturer wanted to assess whether an AGV could usefully supplement or partially replace its forklift trucks. An automated guided vehicle (AGV) and forklift trucks were to remain in use, so the model had to simulate mixed traffic. In close consultation with the AGV supplier, we determined the required number of vehicles, the load on the routes and potential overlaps with forklift trucks.

After a 45-day project duration, the number of vehicles, the duration of the logistics contract and the control specifications were finalised. However, the supplier was unable to implement these specifications within a cost-effective framework, and the customer decided against the AGV. The simulation thus prevented a bad investment before it materialised.

Project workflow: How a simulation project unfolds

Simulation can be used at every stage of planning, from the feasibility study through rough and detailed planning right through to implementation and commissioning. We also incorporate upstream and downstream areas such as production and assembly.

A project usually follows these steps:

1. Recording the layout, transport sources and sinks, processes and requirements
2. Creation of a modular model that can be quickly adapted to the current stage of planning
3. Development and testing of control strategies
4. Simulation of various load scenarios and disruptions
5. Evaluation of key performance indicators such as throughput, utilisation and transport times as a basis for your decision

Frequently Asked Questions

How many automated guided vehicles does my warehouse need?
There is no one-size-fits-all answer to this. The number depends on transport volumes, distances and cycle times. A simulation model realistically represents these variables and shows how many vehicles are required to achieve the desired throughput without the fleet being oversized or vehicles blocking each other.

Is there a guideline for AGV simulation?
Yes. VDI 2710 Part 3 ‘Areas of Application for Simulation of Automated Guided Vehicles (AGVs)’ describes the types of simulation used in AGV planning, the input data required for this, and the results that can be derived from it. Uniformly defined input data makes the results of different simulations comparable. The current edition dates from 2014 and is currently being revised. SimPlan is contributing to this revision.

What data is required for a production logistics simulation?
The basis consists of the layout, the transport sources and sinks, the transport volume, and the process and cycle times. For vehicles, parameters such as speed, acceleration, loading and unloading times, and minimum distances are also required. We will clarify with you at the start of the project which data is required in your specific case.

Which storage strategy suits my range of parts?
This depends on part sizes, turnover rates and storage technology. The simulation allows different strategies to be compared, such as the distribution of large, medium and small parts, or of fast- and slow-moving items. This reveals which variant achieves the required put-away and retrieval performance.

How can order picking be improved using simulation?
The simulation shows how the arrangement of parts in the ‘supermarket’ and the grouping of picking orders affect routes, throughput and resource requirements. Changes to order structures, such as more orders with smaller quantities, can also be simulated in advance.

How long does a simulation project in production logistics take?
That depends on the scope of the problem and the available data. In the AGV project described above at a tyre manufacturer, the results were available after 45 days.

Test different options before investing

Are you planning an AGV system, a new warehouse or a change to your order-picking process? We’ll map out your options in a simulation model and show you which ones achieve the required throughput.