Digital twin in service

The term "digital twin" has existed for almost exactly two decades in connection with the advancing digitalisation in mechanical and plant engineering.

What is this term all about?

The word "twin" is derived from the numerical word "two" and originally means "that which occurs twice", "of which there is a second". A digital twin therefore means that a virtual counterpart exists for a physical product.


Experts currently assume that there will be over 75 billion things (generally components/products/systems) connected to the internet by 2025. The term Internet of Things (IoT) was coined back in 1999 to describe this comprehensive networking. The physical products that communicate via the Internet are also known as cyber-physical or cybertronic products.

The term "digital twin" is therefore extended to mean that the physical product and its virtual counterpart are linked by a continuous exchange of data via the Internet.

The aim is to be able to offer new service-orientated services (e.g. preventive repairs as part of a predictive maintenance strategy) and thus pave the way from the Internet of Things to the Internet of Services.

How are the digital twin and the product life cycle connected?

In general, the product life cycle can be structured into three main phases:

1. As-designed phase

  • The as-designed phase comprises the product development phases and concludes with the release for production.
  • Note: Today, products are usually developed as product variants within a product family; in the event of an order, they are configured on a customer-specific basis.

2. As-built phase

  • The subsequent as-built phase includes the configuration-specific production of a product version and extends to the handover of the product to the customer.
  • The result of the as-built phase is the physical product.

3.    As-maintained/in-service phase

  • Finally, the as-maintained/in-service phase accompanies the product over its remaining service life.
  • Maintenance and services can be provided by the operator, the manufacturer or other service providers in order to ensure the required availability of the physical product or system.  

How does SAP software support the above requirements?

BDF EXPERTS has been advising machine and plant manufacturers on product lifecycle management, supply chain management and service and asset management with SAP for over 20 years.

Based on its experience in the consulting business, BDF has developed a unique solution approach over the years to meet the challenges in mechanical and plant engineering. With the help of SAP Product and Process Governance by BDF (SAP PPG), which is distributed by SAP, any complex product structure can be mapped in SAP. To do this, BDF utilises SAP's integrated product and process engineering (iPPE), among other things, and builds the structure in the form of so-called iPPE nodes.

During product programme planning, a product variant structure is first created in the template library for all products of a machine or plant manufacturer, which maps the product hierarchically including all possible variants.

When an order is received, a customer-specific order structure is derived from this 150% structure as a 100% as-designed structure or, if necessary, further elaborated, which contains not only the material master and product structure data, but also all documentation data in the form of document info records in the sense of a product configuration.

In addition to supporting the as-designed and as-built phase, SAP PPG also provides functions to carry out the preliminary planning of technical objects (functional locations and equipment) and object parts lists (equipment parts lists) for the as-maintained/in-service phase from the order-specific as-designed structure.

Based on this planning data, both the service object structure, consisting of hierarchically organised functional locations and installed equipment, and the assigned spare parts lists in the form of equipment parts lists are automatically extracted at the defined time. Only the service-relevant items are transferred from the defined customer-specific product configuration to the spare parts lists and only the service-relevant documents are transferred to the service object structure via logics to be defined on a customer-specific basis.

This creates the digital twin for the as-maintained/in-service phase virtually (semi-)automatically from the customised product configuration for development and production purposes.

Which SAP product serves as the IoT Enterprise Platform?

An IoT Enterprise Platform is required so that the physical product on the operator side can communicate with its digital twin on the manufacturer side after commissioning and both the manufacturer and operator can exchange information.

To this end, SAP offers the cloud solution SAP Asset Intelligence Network (AIN). According to SAP, AIN "... provides a digital platform for collaboration in equipment definition and maintenance. It enables business partners to collaborate on a common digital twin across the entire asset lifecycle, resulting in optimised maintenance processes, improved asset performance, reduced operating costs and safer operations."

Once the manufacturer has published the service object structure including the spare parts lists and service-relevant documents on SAP AIN, the data collected during plant operation can be used by all collaboration partners to ensure the required plant availability and to optimise products and processes jointly and continuously.

The near future will be characterised on the one hand by convincing the above-mentioned process participants of the advantages of a shared collaboration platform and on the other hand by making the cloud-based platform capable of handling the large (mass) amounts of data that are common in mechanical and plant engineering.

Gerd Hartmann, Consultant – BDF EXPERTS