Optical lenses are considered ultra-precision instruments. Material science, advanced physics and innovative manufacturing technology are cornerstones in the lens design process. To create the best optical system in the world is a true achievement, and to remain number one year after year is even more so. When manufacturing a world class lens, there is always a design intent or criterion laid out by the design office. Because of the complex material behavior, in this case, structural relaxation of glass, the end design does not match the design intent. Expensive polishing using platinum is therefore required, and ultimately the raw shape needs to be iterated to try and minimize the amount of polishing and get the shape just right. Every iteration is extremely costly in terms of time, money and waste. In numbers, the compensation time to get the lens mold correct is between 3-4 months before going to market and making a profit.
We asked Anders Winkler, Senior Technical Specialist with SIMULIA who developed this workflow, to provide answers to some common questions.
Q. Why does this workflow need to be analyzed?
A. Manufacturing is crucial in creating world class optics. Optimized processes can deliver this quality – by using robust design according to Taguchi. The figure below is a very simple explanation of what robust design is. It is an undisputed fact that the Taguchi method minimizes the losses in practice. Minimizing losses means minimizing impact on the environment, and at the same time maximizing productivity. With modern simulation technology that practice can be virtualized for even greater productivity. Simulation brings three substantial advantages into the game: increased speed, reduced cost and the establishment of democratization as an internal company process.
Taguchi defines quality as ‘‘the loss imparted by the product to the society from the time the product is shipped.’’ Simulation can help minimize this loss by virtualizing that product lifecycle. With simulation, more scenarios can be investigated, more variables taken into account, all conducted quickly as a pre-amble to practical design application.
Q. Describe the workflow.
A. What we want to demonstrate in this workflow is a series of connected technologies, which will allow a number of stakeholders to harness all the advantages of simulation and combine them with their skill and experience to create a truly robust product. For this particular example, the workflow goes through CAD, to FEA, to Design exploration and finishes with the creation of a ”virtual manufacturing” environment. Although the workflow was developed with optical lenses as the focal point, the same principle of virtualization applies to any manufacturing operation in general. The workflow is thus a cross-industry template for investigating almost every possible aspect of the virtual factory.
Q. What are the key simulation goals? What are you trying to learn from the simulation?
A. Instead of striving for perfection using physical hardware, deploy simulation technology and use computational power to cut cost, save time and produce a robust product. Automated manufacturing simulation, DOE and robustness analysis can be set up and conducted in a single week. This setup allows for the users/stakeholders to maintain expertise and re-create the physical process in a virtual environment, ultimately gaining more time for innovation.
Q. Which SIMULIA solutions did you use?
A. From a technology point of view we used the 3DEXPERIENCE platform, CATIA, Solidworks, Abaqus and Isight to create a situation where virtualized lens design could be conducted in a numerically attractive, time-saving and cost-effective manner.
Q. What were the advantages (benefits) of using simulation?
A. As the simulations are rather extensive, it makes sense to break down how the information from the simulation can be applied to physical lens design. Many analyses were conducted during the simulation guided lens manufacturing. Regardless of the capability of the simulation, one question remains the knock-out factor: “How long does it take?” The total time for setting up, tuning and running the simulation (simulation perfection approach) is less than one week, compared to 3-4 months for the hardware perfection approach.
Having established that the simulation is indeed fast, the next big question to answer is: “What does the simulation show us?” In fact, numerous questions from different lens design stakeholders can be given clear and pragmatic answers. The table below is an example of typical questions in need of answers – answers that the simulation can provide – based on data provided by experts (the stakeholders).
Finally, let us try to define what the overall benefit is, apart from higher profits. In fact, it is all about increasing productivity.
Dr. Taguchi defines productivity as follows, “Total social productivity (GDP) is the sum of individual freedoms. Freedom includes situations where we can obtain what we want freely, that is, without restraint of individual freedom by others. To increase productivity (including selling a higher-quality product at the same price) requires technological research, and engineers designing a productive system constitute an R&D laboratory. An increase in productivity is irreversible.”
When a learning exchange takes place between different departments (stakeholders), employee morale will increase. And as a result, employees become more versatile and therefore more valuable. Another benefit is collaboration on a single topic, which results in knowledge being transferred to all stakeholders – this dissemination of knowledge and cross-departmental/skill learning is what produces maximized productivity, including:
The end result of maximized productivity is therefore the best quality.
In summary, utilizing proven robust methods in design simulation the users/stakeholders can:
Dramatically improve the lens net shape, reducing the amount of polishing needed
Reducing environmental impact.
Improve production throughput.
Reducing the manufacturing costs.
Creating and cementing a competitive advantage.
The opportunity for us is in consolidating skills by means of simulation, to begin creating an expert system where design and drafting, manufacturing, material science, process control – it can all be virtualized. Virtualizing does not only help you address your issues in manufacturing and product design, but also frees up time within each process. In the end, you can deliver a more robust product to the market, minimize recalls and innovate at a higher pace than previously thought possible.