The Value of Digital Twin in Plant Layout Design

What is the digital twin? This article explains the use case for a digital twin and its application in plant layout design. The following case study model’s production efficiency of a future factory using various layout simulations to test and predict potential failures to improve production system and logistics planning.

Background

A company that operates a few factories planned to expand its business. The selected option was to build a new factory start from scratch. The CEO decided that the new factory would be much larger, more effective and more efficient compared to the existing ones, hence he did not mind allocating a lot of money on it. The company has just bought a plot of land that was ten times larger than the largest existing factory and has made it ready for the development of the new factory. Then, a business analyst was assigned to define the needs and to recommend the best solutions of the next steps. His business analysis activities are described below.

Preliminary assessment.

The business analyst conducts a preliminary assessment. He finds that there is no physical building on the land and no factory operations happen, hence there is no performance in the new factory that can be measured. This means that the business analyst cannot conduct Solution Evaluation as his first activity, instead he starts with Strategy Analysis. The business analyst visits the existing factories and found that the culture is driven by the technology used that is rather outdated. He also performs document analysis and interviews Domain and Implementation Subject Matter Experts. These preliminary assessment produces three important points.

Plant layout.
The importance of layout.¹

Good layout (and, arguably, master planning) practice plays a vital part in the ongoing commercial success of a project. It does this by making the plant safe and efficient to construct, operate, and maintain, while making effective use of the land available.

A well-thought-out layout also contributes to successful planning of the design and construction stages of a project. Good layout will not compensate for bad process design, but a bad layout can easily lead to an unsuccessful or unsafe plant. Changes to the layout during or after construction are very costly in both money and time. Getting the layout right on paper before construction starts will minimize the possibility of this.

What is layout and how can it influence performance?²

The ‘layout’ of an operation or process means how its transforming resources are positioned relative to each other, how its various tasks are allocated to these transforming resources and the general appearance of the transforming resources. Together these three decisions will dictate the pattern and nature of how transformed resources progress through the operation or process. It is an important decision because, if the layout proves wrong, it can lead to over-long or confused flow patterns, customer queues, long process times, inflexible operations, unpredictable flow, high costs and a poor response for whoever is within the operation, whether they are customers or staff. In addition, a radical re-layout can cause disruption to ongoing operations, leading to possible customer dissatisfaction and/or lost operating time. So, because the layout decision can be difficult and expensive, operations managers are reluctant to do it too often. Therefore, layout must start with a full appreciation of the objectives that the layout should be trying to achieve.

The first important point: the short-term activities should focus on the creation of an optimum plant layout.

Plant layout and material handling.
Relationship between material handling and plant layout.³

In a manufacturing system, no two other activities affect each other to the extent that plant layout and material handling do. The relationship between the two involves the data required for designing each activity, their common objectives, the effect on space, and the flow pattern. Because of this dependency, many designers stress the need to solve the two problems jointly. However, the only feasible way is to start with one problem, use its solution for solving the other, then go back and modify the first problem on the basis of the new information obtained from the second, and so on until a satisfactory design is obtained.

Simultaneous Development of Plant Layout and Material Handling.⁴
A number of researchers have suggested that development of both plant layout and the associated selection of material-handling equipment should be evaluated simultaneously. Only then can we obtain a truly optimum combination.

The second important point: plant layout and material handling are two things that are related very closely, therefore should be solved jointly. 

Digital twin.

The complexity of operations in the new plant will be much higher because the size is ten times of the largest current factory, hence the needs of using computer software to assist plant layout altogether with material handling design process becomes mandatory. This type of computer software is known as digital twin software.

Improving warehouse operations—digitally.⁵
A digital twin lets companies design, simulate, and test new warehouse operations and product movements virtually, before starting up new sites or making changes within existing sites.

A few companies are already able to design and visualize their warehouse operations virtually via “digital twin” simulations. The simulations allow companies to create virtual models of their existing facilities, and then test different scenarios—no shutdowns required.

This digital warehouse-design approach lets companies experiment with different floor plans, workflows, and other variables to assess the overall impact virtually.

It built models to test various layouts, material-handling-flow scenarios, picking methods, and targeted automation solutions.

The third important point: digital twin enables plant layout designer to simulate many design variations faster, until the optimum option is achieved.

Conclusion of preliminary assessment.

Based on his findings so far, the BA concludes the following:

• The short-term activities should focus on the creation of an optimum plant layout.
• Plant layout and material handling are two things that are related very closely, therefore should be solved jointly.
• Digital twin enables plant layout designer to simulate many design variations faster, until the optimum option is achieved.
  
  

Connecting the dots.

The business analyst wants to explore the connection of digital twin and plant layout and material handling hence he performs additional document analysis and interviews. Here are his findings.

Optimizing digital twin value.
To produce an optimum plant layout, simulation using digital twin must be performed under the light of:

• Principles of plant layout.
• Basic types of plant layout.
• Principles of material handling.
• Basic types of material handling equipment.

The details of each point are listed below.

Principles of plant layout.⁶

1. Principles of minimum movement.
2. Principles of space utilization.
3. Principles of flexibility.
4. Principles of interdependence.
5. Principles of overall integration.
6. Principles of safety.
7. Principles of smooth flow.
8. Principles of economy.
9. Principles of supervision.
10. Principles of satisfaction.

Basic types of plant layout.⁶

• Process layout or Functional layout.
  All machines performing similar types of operations are grouped together at one location.
• Product layout or Line layout.
  All the processing equipment and machines are arranged according to the sequence of operations of the product.
• Combination layout or Hybrid layout.
  Mixed of process layout and product layout.
• Fixed position layout.
  The material or major components remain in a fixed location and tools, machinery, men and other materials are brought to this location.

Principles of material handling.⁷

1. Planning principle.
2. Standardization principle.
3. Work principle.
4. Ergonomic principle.
5. Unit load principle.
6. Space utilization principle.
7. System principle.
8. Automation principle.
9. Environmental principle.
10. Life cycle cost principle.

Basic types of material handling equipment.⁸

• Conveyors.
  Conveyors are used for moving material continuously over a fixed path. Examples are roller, belt, and chute conveyors.
• Cranes and Hoists.
  Cranes and hoists are items of overhead equipment for moving loads intermittently within a limited area. Examples are bridge cranes, jib cranes, monorail cranes, and hoists.
• Trucks.
  Hand or powered trucks move loads over varying paths. Examples are lift trucks, hand trucks, fork trucks, trailer trains, and automated guided vehicles (AGVs).

AGV.
AGV is “A driverless vehicle used to move materials efficiently in a facility”.⁹

Special attention is given to this type of vehicle because its technology is newer than the other options.

Types of AGVs that are typically found in manufacturing plants¹⁰ are as follows:

• AGV towing vehicles.
• AGV unit load vehicles.
• AGV fork trucks.
• Light-load AGVs.
• AGV assembly line vehicles.

AMR.
Today, however, AGVs are being challenged by the more sophisticated, flexible, and cost-effective technology of autonomous mobile robots (AMRs).¹¹ While AGVs and AMRs both move materials from one place to another, that is where the similarities cease. The major difference of AGVs and AMRs are in their navigation systems. To navigate, AGV needs to be guided by wires, magnetic strips, or sensors. In contrast, AMR navigates via maps that its software constructs on-site or via pre-loaded facility drawings. This capability can be compared to a car with a GPS and a pre-loaded set of maps.

For each plant layout type and material handling equipment type, he collects and analyzes its:

• Advantages and disadvantages.
• Risks and values.
• Constraints, assumptions and dependencies.
  
  

Final recommendation.

At this point, the business analyst concludes that the information collected is sufficient to support the final recommendation. He recommends the following points to the company:

1. Plant layout.
Changes to the layout during or after construction are very costly in both money and time. Getting the layout right on paper before construction starts will minimize this possibility. To reduce risk of executing improper layout, development of plant facilities can be divided into several phases combined with management review of developed layout between phases.

2. Plant layout and material handling.
In a manufacturing system, development of both plant layout and the associated selection of material-handling equipment should be evaluated simultaneously to get optimum combination.

3. Digital twin.
A digital twin lets companies design, simulate, and test new warehouse operations and product movements virtually using different scenarios without interrupting current warehouse operations, before starting up new sites or making changes within existing sites.

When running plant layout simulation using digital twin, the principles of plant layout and the principles of material handling are used to guide the effective and efficient selection of parameters and options.

4. Types of plant layout.
The recommendation is to implement hybrid plant layout, because the new factory incorporates a lot of process types and product types.

5. Types of material handling equipment.
All identified material handling equipment types can be used in the new factory, since each option serves different purposes, and the size of the factory is very large. The implementation of AGV or AMR needs special attention because its technology is newer than the others.

The business analyst sees the development of a new factory as a good start to introduce digital based technology to the company and encourages the CEO to adopt this kind of technology to enhance their competitiveness in today’s market. He ends his recommendation report with this quote:

“Good, bad or indifferent, if you are not investing in new technology, you are going to be left behind.” - Sir Philip Nigel Ross Green¹²

 

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References:

1. Sean Moran - Process Plant Layout - Second Edition – 2017, page 13.
2. Slack, Brandon-Jones, Johnston - Operations Management - 8th edition – 2016, page 217.
3. Dileep R. Sule - Manufacturing Facilities - Location, Planning and Design - 3rd edition – 2008, page 289.
4. Dileep R. Sule - Manufacturing Facilities - Location, Planning and Design - 3rd edition – 2008, page
5. https://www.mckinsey.com/business-functions/operations/our-insights/improving-warehouse-operations-digitally
6. Plant Layout, Principles of plant layout & Types of layout. https://www.youtube.com/watch?v=YR5jjIeIoTg
7. Material Handling Institute. mhi.org The Ten Principles of Material Handling.
8. Dileep R. Sule - Manufacturing Facilities - Location, Planning and Design - 3rd edition – 2008, page 280-284.
9. Material Handling Institute. mhi.org On-Line Training Program, Module 1, AGVS Product Section of MHI. What is an AGV?
10. Dileep R. Sule - Manufacturing Facilities - Location, Planning and Design - 3rd edition – 2008, page 349-350.
11. AGV vs. AMR - What's the Difference? https://www.mobile-industrial-robots.com/en/insights/get-started-with-amrs/agv-vs-amr-whats-the-difference/
12. Quotes Space. https://www.quotespace.org/quotes/Good-bad-or-indiffe/467345
    
    

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