By Nikolaus Fecht
The technical and financial risks in flexible production plants are high. They can often only be reined in if the manufacturer can verify that the plant will fulfill all customer requirements using "virtual commissioning" (VIBN) before the plant has been delivered. Dr. Christian Daniel, Business Manager for Simulation Technology at ISG Industrielle Steuerungstechnik GmbH in Stuttgart says: "We test and optimize the complex functions of real controls with real field buses on virtual simulation models. Customers expect simulation systems which are constructed from reusable virtual components, like virtual twins."
Effort for commissioning reduced
The digital twin reduces the time required during VIBN for the real commissioning by up to 80 percent and is therefore increasingly being used in all engineering phases. The VIBN has proven itself in the Homag Group AG from Schopfloch: The manufacturer of machines and plants for wood processing was able to complete a highly-automated sawing center including all tests weeks before the actual commissioning. "The use of simulation technology has now far surpassed the classic use of VIBN," reports Michael Zetsche, Senior Manager Control Development Edge Processing at Homag. Simulation technology does not only secure the plant dimensioning. The digital twin also accompanies the production ramp-up and production as a Golden Reference. "In order to ensure that all plants reach their promised performance, Homag tests the performance of compound machines beforehand," reports Zetsche from his experience.
The implementation of VIBN occurs in different ways. Sometimes, a machine which is cycled in an assembly line is observed during the ramp-up phase in order to react quickly in case of risks. In a different case, the process data of a system is recorded in order to use this to optimize the system for the customers.
No delivery without a digital model
"At the start, we created the behavior and power models individually. Today, the VIBN draws the required elements including the correction factors directly from the library," explains Daniel. In order to avoid mathematic surface integrals and matrix calculations for drive modules in future, Homag brought drive manufacturers into the fold to program the virtual twins for their drives in the ISG simulation models. The differences between the real and virtual results of all drives should now be so small that real and virtual logs can no longer be distinguished from one another. In order to fulfill quality assurance requirements, Homag expects its suppliers to deliver real components with the corresponding digital model.
Simplified virtual configuration
The configuration of virtual systems will be easier in future thanks to reusable virtual components and modules, as the component manufacturers can deliver these as so-called cyber-physical systems. "This will enable virtual systems to be fully automated on this basis," Daniel is sure. The test of complex production scenarios, including all known malfunction scenarios from services, will also be able to be carried out completely automatically using computer-supported test systems.
The use of simulations in the engineering sector is also increasing. Marc Vidal, Manager for Business Development at Cadfem GmbH in Grafing near Munich, explains: "Many companies appreciate it if they can accelerate the process of bringing their products to market with the desired quality using simulation. This then increases their competitiveness." The maximum benefit would be achieved if all those involved in the development used simulations to inspect their products. Three requirements must be fulfilled for this:
- Simulation depicts many product properties from different angles within an application platform. Many companies are interested in the strength, flow and temperature properties of their products.
- The functionality of the software provides sufficient depth alongside the physical width to create secure and robust simulation results. According to Cadfem, it is important to proceed flexibly step-by-step and only go into greater detail if required.
- In an ideal case, the existing team carries out the simulation at the manufacturer and without external experts in order to reduce costs, achieve results quickly and above all, to learn more about the behavior of their own products.
Precise models for the calculation
"Companies with their own simulation groups multiply their value creation by standardizing simulation tasks. They also use known platforms in order to make the tasks accessible to many users in a simple-to-use environment," Vidal says and continues: "This not only minimizes prototype loops during the product creation process, but also calculation loops." Thanks to the use of a simulation platform during construction, an automotive engineering studio in Berlin was able to provide the calculation engineers with models displaying a far higher completion status than previously possible.
Success stories of this nature also encourage others. Companies which had previously only used simulation to a lesser extent are now deciding to use simulation as a strategic development tool. "However, they have to deal with the issues of staff resources and timescale. After a short learning curve, the goal is to cover as many simulation tasks as possible in the first step with the existing team," says Vidal.
These companies are supported by manufacturers who develop programs to simulate physical behavior completely naturally and rapidly. "This is the key to making value creation through simulation accessible to everyone," Vidal explains. "A new Technology Preview for this is available to all our customers on our homepage, completely free of charge."
Quickly inspect changes to the model
The talk is of a simulation environment with which the user can calculate flow, temperature distribution, vibration behavior or strength within seconds. "The physical behavior is calculated and visualized live," Vidal praises the application. The user can implement changes to the model in real time and assess their physical effects.
Shorten set-up times
Simulation has also proven itself in Numerical Control. Mike Weißenborn, Senior Consultant DACH at Spring Technologies GmbH from Wetzlar, explains: "In order to avoid risks during the Numerical Control (NC) simulation, the NC code is simulated and inspected for errors so that transition and swinging movements can also be taken into account. Our customers do not want to stand at the machine with their hand on the potentiometer or to start up with restricted speed, but be able to press start with a good feeling." Additionally, set-up processes can take multiple hours or days if NC simulation is not used, during which time the machines are not available to production. This is not acceptable for many companies.
Industrie 4.0 as a practical solution
An intelligent, connected and automated manufacturing solution is in demand. Companies must therefore store knowledge in digital form as know-how for the whole company. The NC simulation of the development and manufacturing processes provide the foundations to connect the virtual and real worlds. "The customer expects continuous and connected Industrie 4.0 production processes, but as practical solutions," Weißenborn reports. This specifically refers to the use of NC simulations in practice:
- up to 70 percent time saved when setting up
- unattended night shifts
- shorter processing runs of the NC program due to error checks and the optimization of tool paths
- quick, simple and automatic adjustments when entering changes thanks to a continuous and bidirectional data structure
- inspection of all tools and their data before the simulation step thanks to the fully-integrated, bidirectional tool management
- real-time access to documentation of all data and immediate implementation of all changes
- complete emission of complex interfaces and their maintenance due to the continuous process chain
- target-actual comparison of the geometry deviations
- control of the complete process with the help of an interactive 3D film
Paperless, automated production
This already sounds like science fiction and the question is now where exactly the simulation journey will take us. "For our customers in mechanical and plant engineering, the goal is a paperless and automated production with intelligent and continuous processes," emphasizes Weißenborn. According to Weißenborn, this includes continuously available tool geometries and data which flows directly into the system and can be integrated into the machine simulation.
Managing locations and suppliers
However, Weißenborn not only views the NC simulations as important challenges, but also the recording, returning and managing of all relevant data above and beyond company borders. "Another important point is managing locations and supplier networks while simultaneously protecting knowledge. And we have already implemented this step in a cryptic format which was developed specifically for this," says Weißenborn.
Abel GmbH, a pump manufacturer from Büchen, is also a user of simulation technology. Friedrich Wiechmann, the Head of Design and Development, primarily sees the benefit of the simulation in that the customers only pay for what they want or what they have ordered. The simulations aid in avoiding unnecessary ballast. Abel uses them in particular for strength analyses and for material savings to reduce costs.
Uniform standards desired
Simulations are also in high demand during the project engineering stage. "Ever more customers are requesting 3D components during the project phase which are then entered into the virtual environment to describe the assembly space and to complete the stock lists," tells Wiechmann from experience. The available assembly space is a significant topic for maintenance, contribution and accessibility. However, Wiechmann would like to see uniform standards for the interfaces, but these are yet to be developed by the software providers.
Wiechmann assumes that the simulations will require increasingly larger spaces in future. They may not be able to make the real test runs completely redundant, but they may be able to reduce them significantly. "It must be taken into account that these tools need to be easier to use as not every medium-sized company can afford a simulation engineer," Wiechmann adds.
Ensuring constructive solutions
Customers of Siemens Industry Software GmbH in Frankfurt am Main who are from the mechanical and plant engineering industry mainly use the simulation in structure analysis and multibody simulations. Eckardt Niederauer, responsible for Product Lifecycle Management in the Digital Factory Division, explains: "Individual customers have started simulating flows and heat transfer." However, the focus remains on ensuring constructive solutions. The simulation helps with innovation and the creation of new, constructive solutions.
"The solution must also be open for all common CAD formats and the geometry processing must be simple, associative and intuitive to use," explains Niederauer. The company attached importance to exactly this facet when developing the architecture of the 3D solution. This openness requires that the program also supports as many typical calculation programs, so-called Solvers, as possible, including those from other manufacturers. The customer can then decide which Solver to use depending on the application case, as is possible when using the Siemens 3D program.
A current trend is the so-called Simulation Driven Design. "Simulation apps check the designs directly in the CAD environment," explains Niederauer. "The developer receives immediate feedback on whether their constructive solution improves the product or not. This accelerates the development as waiting times for simulation results are omitted and the developers learn to fit their design to the purpose," says Niederauer, praising the new trend.
Krones AG in Neutraubling, a leading manufacturer of packaging and filling systems, was able to reduce the time for the complete simulation by 75 percent thanks to the simulation app. The company from Neutraubling was therefore able to inform its customers much quicker whether a new design of a mineral water bottle could be used in the filling plant or not.
However, the possibilities afforded by the simulation are by no means exhausted. "We must continue to increase the capacities and the capabilities of the simulation," Niederauer says. The future requires faster simulation processes that are suitable for sporadic and inexperienced users. Automated simulation projects are also supposedly on their way.
Number of tests per simulation decreasing
"All in all, the number of physical tests will not decrease," emphasizes Niederauer. However, the number of tests per simulation will decrease. In order to master the product variety, as well as the product complexity, it is absolutely imperative that more simulations are run. The test at the end of the product development cycle only confirms that all preliminary simulations have provided the correct information. According to Niederauer, the best example is that of crash tests for vehicles: "If everything goes to plan, then there should only be one crash test prior to production approval. The path up to this point, however, is paved by simulations."
Meinolf Gröpper, VDMA Software and Digitalization.