In this work, we propose a different approach in which the moulding tool itself is generated by a moulding process, i.e., the tool is generated by metal casting from a replication template. Metal casting is a long-established technology, but it has proven difficult for high-resolution casts, as the choice of potential materials for replication template with sand casting is the most common method for the use above 1000 °C. If finer surface details are required, high temperature silicone16 is often the material of choice. Although structures in the micrometre range17 and surface roughness in the sub-micrometre range18 can be achieved, this process requires low-melting metals16,19 or special alloys20, as the silicone will degrade at high temperatures. The need to use low melting alloys thereby limits the mechanical stability of the moulding tool significantly. We reasoned that it should be possible to directly cast relevant tooling materials, such as cobalt-chromium, if a technology for manufacturing high-temperature resistive and high-resolution template structures is available. In this paper, such templates are made directly from fused silica glass using so-called Glassomer nanocomposites which we previously described21. These nanocomposites are converted into fused silica components by thermal debinding and sintering, resulting in high-temperature stable pure fused silica templates. The nanocomposites can be processed by stereolithography, 2-photon polymerisation, lithography, injection moulding or casting21,22,23,24. We have previously demonstrated, that a wide variety of techniques can be used to structure these nanocomposites at high resolution yielding optical surfaces via inexpensive, fast and flexible processes.

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As you say, there is a wide range of mold types we produce. The mold industry was Japan's strong area. The recent (2023) ratio of mold production output is as follows, China ranked first with 47%, the U.S. second with 15.3%, and Japan third with 14.4%. Competition will further intensify in the future. Chinese manufacturers are on a remarkable offensive and are expanding their market share in Japan. Traditionally, they have had the advantage of low cost and quick delivery, but recently quality has also improved. To become a mold manufacturer that can survive in the global environment, we must take on the challenge of manufacturing high value-added molds. There are three major global trends. The three are "guaranteed accuracy," "high-end," and "fine/precision." In order to meet these challenges, it is essential to specialize and to be familiar with the environment, processing equipment, and resins. We believe that the essential condition for a mold maker to survive is to take advantage of our strength in 5 integrated production of molds and molding to take on the challenges of these new fields.

We believe in the importance of people-to-people relationships, even in different countries. Respecting each other's values, culture, and business practices, and continuing to do so, leads to a strong relationship of trust. We believe that without a relationship of trust, they will not understand what we are seeking. Our partner factory in China mainly produces tag pins and tag fasteners, which are our main products. We sell our products to customers in Japan and overseas, and have established a firm position as a high-quality product. In order to continue to assure quality, we must meet these requirements, which include highly difficult 6 Domestic molds and molding, and rigorous inspections. In addition to technical guidance, we established a quality assurance system early on. Furthermore, we have made it a rule to have issues and problems reported and discussed immediately. Recently, we have also been working on online communication.

In many interviews with other key players in the industry, they emphasized how participating in open innovation finding local partners overseas, and combining their expertise was crucial to unlocking the international market.

Nature Communications thanks Guido Tosello and the other, anonymous, reviewers for their contribution to the peer review of this work.

Kelly, A. L., Mulvaney-Johnson, L., Beechey, R. & Coates, P. D. The effect of copper alloy mold tooling on the performance of the injection molding process. Polym. Eng. Sci. 51, 1837–1847 (2011).

Chung, S., Park, S., Lee, I., Jeong, H. & Cho, D. Replication techniques for a metal microcomponent having real 3D shape by microcasting process. Microsyst. Technol. 11, 424–428 (2005).

The Worldfolio provides business, industrial and financial news about global economies, with a focus on understanding them from within.

I see there are only few advantages in this current macro-environment However, due to geopolitical risks and the weak yen, some major Japanese manufacturers are returning to their manufacturing bases in Japan, so-called 1 "reshoring", which are for projects that do not involve large capital investments. This trend of returning to Japan is an opportunity for small and medium-sized suppliers to increase new transactions and orders. We are also focusing on this trend and conducting sales activities to acquire new customers.

In this work we demonstrate that using these fused silica templates, metal moulds of high quality can be obtained featuring structures in the single-µm range and surface roughness values of 8 nm (Rq) without post-treatment. The production time for a metallic mould inserts with this process requires less than 36 h allowing fast tool replacement as well as frequent design iterations (for further information see supplementary section). The fabricated moulding tools can be used in conventional high-throughput injection moulding process without limitations. As this process workflow effectively generates a moulding tool by a replication process, multiple fused silica replications can be generated from the same master structure thus rendering the common concerns in tool calculation (per-tool manufacturing cost, wear, yield-per-tool, etc.).

a Schematic representation of the manufacturing process of a metal insert and its use in injection moulding. b Close-up of the injection mould which was used as an insert (scale bar: 10 mm). The inset shows a magnification of the dot matrix structure (scale bar: 500 µm). c Close-up of an injection-moulded polymethylmethacrylate (PMMA) component replicated from the metal insert (scale bar: 10 mm). The inset shows a magnification of the structure (scale bar: 500 µm). d White-light interferometry image of the 2000th PMMA component produced from the mould (IM-Part 2000) e Comparison of the cross-section measured using WLI of the first polymer replicated PMMA component (IM-Part 1, red) and the of the 2000th component (IM-Part 2000, blue) created using the metal insert (black).

As mentioned before, Sanyo Seisakusho produces molds for different products with various resin types and processing technologies such as your tie-binding band and super engineering plastic used in the automobile industry. -With such a wide range of molds made, which one would you reckon to have the most growth potential from a business perspective?

This "integrated production process" is our strength. It not only reduces adjustment costs, but also enables us to handle high-performance, high-value-added resins. This integrated production process is also the reason for our extensive expertise in super engineering plastics (SEP). This interaction enables us to serve a wider range of customers and contributes to improved sales and profitability.

Sanyo Seisakusho, a prominent company specializing in mold design, manufacturing, and plastic product molding, provides insights into its diverse business operations and strategies. The company's core strengths lie in its integrated production process, which seamlessly combines mold design with molding, and its expertise in super engineering plastics (SEPs). While discussing the evolving demands in the automotive sector, Sanyo Seisakusho explains how it leverages its specialization in SEPs to capitalize on the industry's shift toward lightweight and eco-friendly materials.

In order to produce master structures, the “NanoOne” printing system from UpNano GmbH (Austria) was used. The structures were printed on a glass substrate with the refractive index matched 2-photon resin “UpBrix”. The print was carried out using 10× magnification, a laser power of 50 mW, and a layer thickness of 5 µm.

NeptunLab, Laboratory of Process Technology, Department of Microsystems Engineering (IMTEK) University of Freiburg, Georges-Köhler-Allee 103, Freiburg, 79110, Germany

Pham, D. T., Dimov, S. S., Ji, C., Petkov, P. V. & Dobrev, T. Laser milling as a ‘rapid’ micromanufacturing process. Proc. Inst. Mech. Eng., Part B: J. Eng. Manuf. 218, 1–7 (2004).

Fang, F. Z., Zhang, X. D., Weckenmann, A., Zhang, G. X. & Evans, C. Manufacturing and measurement of freeform optics. CIRP Ann. 62, 823–846 (2013).

a White-light interferometry measurement of the generated metal inserts for bronze (red), brass (yellow), and cobalt-chromium (green). b Optical lens master structure which was used to characterize the overall shrinkage during the process. c Fused silica replication of the optical lens. d Resulting cast bronze metal lens (negative). e AFM-Measurement of an unstructured casted bronze insert with a surface roughness of only Rq 8.0 nm. f Comparison of Vickers hardness values of manufactured samples of bronze (error bar standard deviation n = ±4 HV), brass (error bar standard deviation n = ±5 HV for casted and n = ±11 HV for nickel plated) and cobalt-chromium (error bar standard deviation n = ±9 HV for casted and n = ±13 HV for nickel plated) in pristine form and after nickel electroplating. The error bars were determined using the standard deviation of measured data, 10 measurements were carried out in each case.

-Where would you like to expand your sales channels and how do you aim to do so? Are there any specific countries or regions you would like to cater your products to? - Where would you be interested in continuing your international expansion and/or which strategy would you use to achieve so? (New subsidiary, joint-venture, M&A, etc...)

Through seamless communication between the divisions, the manufacturing of molds and the molding process using the molds are performed consistently, enhancing the synergy effect.

Atsumi, H. et al. Microstructure and mechanical properties of high strength brass alloy with some elements. MSF 654–656, 2552–2555 (2010).

Our company hasn't been directly affected by these new demands as the parts we manufacture primarily serve as decorative components rather than core structural or engine-related parts for cars. We see the increased focus on automotive weight reduction as a great business opportunity for our company, which also specializes in SEP products.

Freiburg Center of Interactive Materials and Bioinspired Technologies (FIT), Albert Ludwig University of Freiburg, Georges-Köhler-Allee 105, Freiburg, 79110, Germany

Dobbs, H. S. & Robertson, J. L. M. Heat treatment of cast Co-Cr-Mo for orthopaedic implant use. J. Mater. Sci. 18, 391–401 (1983).

Our stable clientele in Japan enables us to operate with flexibility and stability. While general-purpose plastics are indeed produced in China, factoring in shipment costs and customs, the final sale price would surpass what we offer to our Japanese clients. Our enduring relationships within the Japanese market sustain our presence.

The roughness was measured using an AFM of type Multimode 8 (Bruker, Germany) on an area of 10 × 10 µm as well as a WLI of type NewView 9000 (Zygo, USA) on an area of 350 × 350 µm and 860 × 860 µm (see Supplementary Fig. 1 and Table 1). All surface roughness measurements were carried out three times, at different locations. The corresponding values can be found in Supplementary Table 1. The replication limit was determined by comparing the cross-sections of a structure at different stages of the process (master, fused silica, metal) using WLI. Vickers hardness was measured using a micro Vickers hardness tester of type FALCON 608 (INNOVATEST, Netherland). The applied load was 100 mN at a loading time of 20 s.

Zhang, H., Zhang, N., Han, W., Gilchrist, M. D. & Fang, F. Precision replication of microlens arrays using variotherm-assisted microinjection moulding. Precis. Eng. 67, 248–261 (2021).

The automotive industry is undergoing a significant transformation, transitioning from combustion engines to hybrid and EVs. This shift is impacting material choices and design preferences, favoring one-piece designs over multiple assemblies. There's also a focus on lightweight vehicles, reducing the use of heavy metals while increasing the adoption of new plastics and resins. How is your company addressing these evolving demands in the automotive sector, particularly concerning compact components and the development of lighter-weight materials?

Tool based manufacturing (TBM) is the process of choice when it comes to cost-effective mass production. Even high-precision components such as cell phone camera lenses, Fresnel lenses or micro-diffusers1,2 with tight tolerances must be manufactured in large quantities at affordable costs. This requirement profile leaves very little choice in the manufacturing procedures and can only be realised by TBM3,4. Most prominently, injection moulding has emerged as the de facto gold standard for high-throughput manufacturing of complex-shaped components with a high standard of quality5. Among all, tools with highly polished moulding surfaces are of particular interest due to their ability to produce high-quality components of optical quality at relevant scalability and costs. However, their manufacturing is complex and expensive and remains the main bottleneck6. Today, moulding tools for TBM are mainly produced by subtractive machining such as drilling, turning, milling and polishing7,8. These procedures are time- and material-intensive and do not scale well8,9. To produce moulds with optical surfaces, ultra-precision machining is usually required, including diamond turning and polishing of surfaces well into the nanometre surface roughness range7. This limits the applicability of TBM and makes moulding tool prototyping extremely challenging. Depending on the quality, even simple moulding tools can range from thousands to tens of thousands of euros in cost9 with the actual manufacturing process easily spanning weeks, depending on its size, complexity and the required surface quality8. If micrometre or even sub-micrometre resolutions are required, electroplating is usually the method of choice. In this process, prefabricated templates shaped, e.g., via a photolithography, are copied into a hard metal substrate which can withstand the stresses of the forming process8, while providing surfaces of optical quality. The decisive disadvantages of electroplating are slow growth rates, 12 µm/h10 are not unusual for nickel coatings, and the limited freedom of design for moulding tools with significant variations in dimensions. Various attempts have been presented to enable faster and more convenient generation of moulding tools, a field commonly known as rapid tooling or direct tooling. Several techniques have been presented to structure a preform of the moulding tool via generative techniques such as, e.g., selective laser sintering (SLS)11 or laser beam machining (LBM)12. Achievable surface roughness values of these techniques are in the range of Ra 2–40 µm13,14,15, still requiring time-consuming and expensive post-processing. The generated preform moulding tool is then post-processed using classical machining techniques, therefore saving material and overall processing time. So far, rapid prototyping for TBM is considered viable only in selected applications and is generally not considered a scalable alternative to the classical manufacturing techniques for moulding tools.

Resins are constantly evolving and new resins are coming onto the market. We handle everything from general-purpose resins to high-performance resins (super-engineering plastics), and recently we have also been handling environmentally friendly materials. As research and development facilities, or as "mother plants" (which are "high-value-added factories" in charge of making prototypes of new products and key components), we are familiar with a wide variety of resins, which helps us to respond to the various requests of our customers in the mold and die business.

Morrow, W. R., Qi, H., Kim, I., Mazumder, J. & Skerlos, S. J. Environmental aspects of laser-based and conventional tool and die manufacturing. J. Clean. Prod. 15, 932–943 (2007).

Baumeister, G., Mueller, K., Ruprecht, R. & Hausselt, J. Production of metallic high aspect ratio microstructures by microcasting. Microsyst. Technol. 8, 105–108 (2002).

The production of a metal replica using our process consists of four steps: master structure fabrication, replication using the Glassomer nanocomposite, glass transformation via heat treatment of the nanocomposite and finally metal casting. Figure 1 illustrates the workflow schematically. The production of a master structure requires a free shaping method with an optical surface finish. We fabricated the master structure using 2-photon polymerisation, which is a 3D printing technology capable of printing photoresins with a resolution of down to 100 nm25,26 and a surface roughness in the single nanometre range23 (see Fig. 1a). The printed template is subsequently replicated into polydimethylsiloxane (PDMS) (see Fig. 1a). The PDMS is capable of casting features down to 500 nm27 and is transparent to light down to 280 nm. As illustrated in Fig. 1b, the liquid nanocomposite is poured on the PDMS-Replication mould and cured by UV light at a wavelength of 365 nm, resulting in the so-called “green part”. If necessary the green part can be further post processed using conventional subtractive polymer shaping technologies28. The green part is subsequently converted into transparent fully-dense fused silica glass via thermal debinding and sintering at a maximum temperature of 1300 °C as previously described28 (see Fig. 1c). The Glassomer L50 nanocomposite has a solid loading of 50 vol% which results in an isotropic linear shrinkage of 20.6% during the sintering process. For the metal casting, the fused silica replication is embedded in a phosphate-bonded embedding material (see Fig. 1d). Before casting, the melting chamber is flushed twice with nitrogen. The melting of the metal takes place under vacuum (10−1 bar) preventing the formation of oxide layers which can lead to defects in the casted metal surface. While pouring the liquid metal, a nitrogen overpressure of 3 bar is generated in the casting chamber, which ensures conformal replication from the embedded fused silica replication.

We believe that strategy and sales channels are a pair. It is important to gain a new and deeper understanding of our products. Our products, as mentioned above, are molds, molding, and tag pins/tag fasteners. We cannot proceed with business unless we clearly define "what kind of strategy we want to use to expand our sales channels," and based on these, match the needs of our customers with our strengths. This is even more true overseas. We will exhibit at SMART MANUFACTURING SUMMIT (2024.3), an event for the manufacturing industry connecting Japan and Europe, and promote research. https://sms-gi.com/ Many of the manufacturers in our industry who have expanded overseas belong to KEIRETSU. We consider it extremely risky for an independent manufacturer like our company to enter the market. In addition to careful research and targeting, it is essential to secure a basis for ensuring profitability. Since domestic demand is not expected to grow, we place importance on designing overseas sales channels. There is still an untapped market in the existing tag pin and tag fastener business. We value our contacts with overseas sewing manufacturers and buyers who come to fashion and general merchandise exhibitions held in Japan. Currently, we have been conducting business (making contact) with those customers online. In the future, we are considering visiting local markets with high potential and exhibiting at trade shows.

For the metal casting, the prepared steel cuvette with the fused silica replication master was preheated to 200 °C to increase the form filling. The setup was then installed in the casting furnace (type M20, Indutherm, Germany). After closing the casting chamber, it was flooded with nitrogen, then a vacuum was applied and the crucible with the casting material was brought to the desired melting point (bronze 1050 °C, brass 1020 °C, Co-Cr 1450 °C). When the melting point was reached, the entire casting chamber was tilted, and the melt was allowed to flow into the steel cuvette and onto the glass body. In the tilted position, a pressure of 3 bar nitrogen was generated in the chamber. The casting furnace was left in this position until the metal body cooled.

The ratio of external sales of molds, handled by the mold manufacturing division, are 81% for automotive parts manufacturers and 16% for consumer electronics manufacturers. Our independence allows us to offer a broad range of products, aiming to serve diverse industries as comprehensively as possible.

Additionally, China and Vietnam primarily focus on mass production, unlike our approach. They are less inclined toward small lot orders, whereas our specialization lies in crafting unique products tailored to our customers' specific needs.

Sanyo Manufacturing can trace its roots back to 1956 and you have since grown to become a specialized manufacturer of molding and forming of different materials such as plastic, ceramic, metal, and super engineering injection moldings. - Could you highlight some key milestones in your history and how your business model evolved over time?

Yes, I partially agree with this sentiment. We do not deny the interest of various countries in Japan's manufacturing industry due to the international situation. Certainly, Japan is politically stable, the revision of laws and legal interpretations are legitimate, and since we are not under dispute with other countries, our country's geopolitical and country risks are low. In this respect, our reliability is high. Since Japan possesses advanced technology, there is a possibility that it can replace China. On the other hand, while there is a labour shortage worldwide, the shortage of human resources in Japan is becoming an even more serious problem. Even when we receive inquiries, only companies with highly automated production systems are able to respond. The recent weakened yen has been an advantage for Japan's export industry. However, we do not see it as a great opportunity. This is because exchange rates fluctuate. Changes in the international situation, especially in the U.S. domestic situation, may cause a major change in the U.S. interest rate policy. It is quite possible that the yen will appreciate even in the short term. Negative factors such as the rising cost of raw materials due to the weak yen cannot be ignored.

In the next 15 years, one in three people in Japan are expected to be over the age of 60. This could lead to a labor shortage, as well as a shrinking domestic market. - For Sanyo Seisakusho in particular, what are some of the challenges that this demographic shift has caused, and how are you reacting to those challenges?

Freiburg Materials Research Center (FMF), Albert Ludwig University of Freiburg, Stefan-Meier-Straße 21, Freiburg, 79104, Germany

We maintain the quality of our molds and mass-produced products in accordance with ISO-based quality standards and based on know-how that has been handed down for 65 years. In addition, we have documented our own design standards, and we also systematically manage the problems that have occurred in the past by compiling them. Moreover, we ensure that work is not assigned to a single person, the work does not belong to a specific person and maintains the same quality. (Supplement) - Recent Trends and Our Definition of Quality The commitment to MONOZUKURI is one of the outstanding aspects of Japanese manufacturing, and this commitment is based on the perfectionist mindset of the Japanese people. We have been uncompromisingly and thoroughly improving the quality of our products, bringing to market products that we believe are 100% perfect. In the past, those were the usual goals of companies at all levels. In the global world, however, the trend has shifted to how quickly products can be brought to market and how cost-effectively they can be produced. Also product life cycles are becoming shorter, and customer quality requirements are declining, with the trend not to demand 100% quality except for some very advanced equipment and products requiring safety for parts and people. Under such circumstances, our products are not designed to be of the highest quality, but rather to be of a level that will not cause any problems in use. The demand for the highest quality and perfection increases the cost of production, which is reflected in the price to the customer.

Launhardt, M. et al. Detecting surface roughness on SLS parts with various measuring techniques. Polym. Test. 53, 217–226 (2016).

In order to assess the injection moulding compatibility of the casted metal inserts, we prepared bronze metal inserts with a dot matrix structure. The metal inserts were produced using the outlined process, followed by injection moulding in a commercial injection moulding system (Arburg Allrounder 370 S 500–100) as shown schematically in Fig. 3a. Figure 3b shows the assembled mould, used for injection moulding with polymethyl methacrylate (PMMA) (see Fig. 3c). To analyze the durability of the metal insert, more than 2000 PMMA components were produced and measured using WLI. Figure 3d shows the cross-section of the manufactured and used metal insert (black graph), the first manufactured polymer replica (red graph) and the 2000th polymer replica (blue graph). The cross-section shows no notable change after 2000 replication cycles (for further information see supplementary section).

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Kluck, S., Hambitzer, L., Luitz, M. et al. Replicative manufacturing of metal moulds for low surface roughness polymer replication. Nat Commun 13, 5048 (2022). https://doi.org/10.1038/s41467-022-32767-2

Piotter, V., Hanemann, T., Ruprecht, R. & Haußelt, J. Injection molding and related techniques for fabrication of microstructures. Microsyst. Technol. 3, 129–133 (1997).

The theoretical shrinkage Ys is calculated by Eq. (1) which depends on the solid loading Φ, the final density ρf, and the theoretical density ρt of the produced part. The actual shrinkage was determined by measuring the parts in the green state, in sintered state and after metal replication using the digital microscope model VHX 6000 from Keyence (Japan).

The shortage of human resources is an urgent issue that requires structural reform in all industries. In March of this year, we reformed our website and strengthened our recruiting (personnel recruitment) site. We also visit 2 universities and vocational schools to introduce our company and actively engage in recruiting activities. We will promote the company's appeal, including the fact that it offers a healthy and comfortable work environment, to increase employment opportunities. We do not believe that simply stepping up recruiting efforts will solve the labour shortage issue. Among existing human resources, we will promote multi-skilled workers and increase opportunities for female employees. Furthermore, as a manpower-saving measure, Japan needs to further strengthen DX and automation, which are lagging far behind developed countries. As for the promotion of DX, Japan is lagging behind, but there is room for growth. The situation is similar in our company. We will aggressively promote those measures to address the labour shortage. As for the shrinkage of the domestic market, we do not feel such a great sense of urgency because our competitors in both the mold and injection molding divisions are being eliminated as the market shrinks.

Kotz, F. et al. Two‐photon polymerization of nanocomposites for the fabrication of transparent fused silica glass microstructures. Adv. Mater. 33, 2006341 (2021).

Khaing, M. W., Fuh, J. Y. H. & Lu, L. Direct metal laser sintering for rapid tooling: processing and characterisation of EOS parts. J. Mater. Process. Technol. 113, 269–272 (2001).

Japanese manufacturing is at an exciting time. The past three years have seen large supply- chain disruptions due to COVID and the US-China decoupling, and as a result, corporate groups are looking to diversify suppliers for reliability. Known for their reliability and advanced technology, Japanese firms are in an interesting position. Due to a weakened Yen, observers argue that this is a unique opportunity.

Glassomer L50, Glassomer SL-v2, Glassomer Developer, and Glassomer Hardener was kindly provided by Glassomer (Germany). Elastosil M4601, was purchased from Wacker (Germany). The Plaster “Pro-HT Platinum” as an embedding material, the metal alloys bronze (BR10/L) and brass (Messinggranulat Hart) were purchased from Horbach Technik (Germany). The cobalt-chromium alloy for dental purposes” Wironit extrahart” was purchased from BEGO (Germany).

Sanyo manufacturing prioritizes stable mass production, drawing on vast experience from making over 12,000 molds for resin molding. You excel in mold design for diverse products, including those in home appliances, electronics, automotive, and medical sectors, and offer post-production support and mold repair services. -How does your company maintain high-quality standards during mass production while producing molds for various products with different resin types and processing technologies, such as home appliances and medical devices?

We have successfully used this process for the replication of high-temperature melting metals such as bronze (1050 °C), brass (1020 °C) and cobalt-chromium (1440 °C). All of these temperatures are below the softening point of fused silica, which is 1665 °C29. In terms of processing properties, bronze offers very good castability at moderate melting temperatures. Furthermore, bronze is relatively corrosion-resistant and has a high thermal conductivity which makes it a material of choice for variothermal injection moulding8,30. Similarly, brass has good processing properties but can also be nickel-plated without pretreatment, which results in a considerable increase in hardness31. The cobalt-chromium alloy was chosen as a casting material because of its significantly higher hardness32. All three metals could be replicated from the sintered fused silica replication and demoulded to form injection-moulding compatible metal inserts. No release agent was necessary to remove the metal replications from the fused silica mould, as the metal does not bond with the fused silica components. The fused silica moulds were used only once for the metal casting, this was to ensure that a consistent quality of the metal replications could be achieved. Using high-temperature metals is of great importance for the subsequent injection moulding process since these can withstand both, the repeated temperature changes and due to their higher mechanical strength and the stresses of the moulding process. In order to determine the minimum feature resolution for each metal type, lines-and-space structures were produced and replicated using the described method (see Fig. 2). The lines are tapered, having a width between 30 µm (bottom) and 3 µm (top) and a height of 23.5 µm in the master structure. The structures were characterized in each replication step using white light interferometry (WLI). Figure 2a shows the cross-sections of the investigated master structure (black), the fused silica replication (blue) and the respective replicated metal replications (red, yellow, green). The minimum feature resolution was determined by the minimum width of the generated metal structures, measured by WLI. As shown in Fig. 2a, the minimum feature resolution is 5.2 µm for bronze, 7.5 µm for brass and 5 µm for cobalt-chromium. The difference in size between the master structure and fused silica replication is due to shrinkage during the sintering process. The measured shrinkage from the master structure to the fused silica replication, is 20.9%. This is illustrated in Fig. 2b, c, where a lens is shown as a master structure with a diameter of 8.91 mm and as a fused silica replica with a diameter of 7.04 mm. This value is in good accordance with the calculated shrinkage of 20.6% (see supplementary material). The shrinkage from the fused silica replication to the metal insert was measured to be 2.0%, 2.3%, and 1.8% for bronze, brass, and cobalt-chromium, respectively. The overall shrinkage from the master structure to the metal insert is thus 22.60%, 22.85%, and 22.45% for bronze, brass, and cobalt-chromium, respectively. It is important to note that the solidification shrinkage of metals is a complex phenomenon33,34 that can only be predicted to a limited extent. It is therefore necessary to assess this shrinkage experimentally. Due to the mismatch of thermal expansion coefficients of fused silica and metals, there is a risk of the fused silica being enclosed by the molten metal. As commonly employed in replication processes, demoulding chamfers can be included in the design of the master structure in order to prevent this problem. To allow for high-resolution replication of polymeric components using the metal moulds, the shrinkage during the fused silica sintering process and the metal replication process needs to be compensated in the fabrication of the master structure. Depending on the manufacturing method used to fabricate the master structure, this process related shrinkage must be taken into account as well. In order to investigate the achievable surface quality, metal inserts were prepared from an unstructured fused silica surface. Without further post-treatment, a surface roughness of 2 nm (Rq) was measured using atomic force microscope (AFM) for the sintered fused silica components28. The achievable surface roughness in the casted metal inserts are measured to be only slightly higher with 8.0 nm, 9.0 nm, and 11.0 nm (Rq) on an area of 100 µm² (see Fig. 2e, Supplementary Fig. 1a–c) for bronze, brass and cobalt-chromium, respectively. A total of nine measurements was carried out at different positions and different sized areas in order to assess the surface quality across a large lateral area. Using the WLI on a larger area (350 × 350 µm2), the surface roughnesses were found to be 35 nm, 28 nm and 31 nm (Sq) for bronze, brass and cobalt-chromium, respectively. Vickers hardness was measured for all three metals to evaluate the wear resistance of the moulds during the injection moulding process4 (see Fig. 2f). Common, industrially employed moulds for plastic injection moulding of optical components are made from tooling steels with around 510–560 in Vickers hardness (HV)6,8. According to literature, values in the range of 120 HV are expected for the casted bronze35 and brass36 components. Our measurements showed a value of 151 HV for bronze and 157 HV for brass and thereby exceed the literature values slightly. For the significantly harder cobalt-chromium dental alloy, 445 HV was measured which is only slightly lower than the values expected from commercial tooling steels. As higher hardness values are desirable for injection moulding tools to extend the tool’s service life time, hardening techniques such as quenching or precipitation hardening are commonly employed which are, unfortunately, not accessible for copper-based alloys such as bronze and brass. However, an alternative is electroplating with hard nickel, a technique which achieves hardness values above 500 HV according to literature31. We thus coated casted brass metal moulds with a 70 µm layer of hard nickel, achieving a hardness value of 670 HV. Similar hardness values of 667 HV were achieved for nickel plated cobalt-chromium metal inserts. The Ni coating must be considered in the design, depending on the used plating technique and the layer thickness.

Gissibl, T., Thiele, S., Herkommer, A. & Giessen, H. Two-photon direct laser writing of ultracompact multi-lens objectives. Nat. Photon 10, 554–560 (2016).

This work is part of the ZIM program and was funded by the German Ministry of Economic Affairs and Energy (BMWi), funding code ZF4052417EB9. This project has received funding from the Baden-Württemberg Foundation (grant MOSAIC). This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No. 816006). We thank the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG) for funding through the Centre for Excellence livMatS Exec 2193/1 – 390951807. The authors thank Dennis Weißer for providing structures forom nature to replicate and Kay Steffen for assistance in nickel-plating.

Baumeister, G., Ruprecht, R. & Hausselt, J. Replication of LIGA structures using microcasting. Microsyst. Technol. 10, 484–488 (2004).

Kumbhar, N. N. & Mulay, A. V. Post processing methods used to improve surface finish of products which are manufactured by additive manufacturing technologies: a review. J. Inst. Eng. India Ser. C. 99, 481–487 (2018).

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Our company was founded in 1956 and established two years later. At the time of our founding, we handled only molds, and our customers were mainly manufacturers of home appliances, audio equipment, and miscellaneous goods. Four years after its founding, the company established an injection molding plant. The reason why we started an injection molding factory was based on our belief that we must be familiar with the feelings of the injection molding manufacturers to whom we deliver the molds we produce. At the end of the 1960s, we began development of price tag pins and succeeded in mass production. In the early 1970s, we successfully developed and mass-produced tie-binding band, and in 1980 we developed and produced tag fasteners. We believe that this is the result of the company's two-division structure, the mold manufacturing division and the injection molding division, which we have operated since early on. During this time, our mold manufacturing business has expanded its customer to include home appliances, audio, general merchandise, automobiles, and medical products, and we have built up our capabilities to meet the demands of all industries. In 1986, we began manufacturing molds for super engineering plastics and molding products made of super engineering plastics for the medical industry, expanding the range of products we could handle. - The population grew during the 1970s and 1980s, and the apparel industry entered an era of mass production and mass consumption. In proportion to this, 3 demand for price tag pins and tag fasteners increased, and with a view to global expansion, we sought to collaborate with overseas companies. In 1986, the Plaza Accord led to a transition from a fixed exchange rate system to a floating exchange rate system. A visit to China and Hong Kong allowed us to assess the situation. Seeing this as an opportunity, we entered into a partnership agreement with a Hong Kong company in 1988. First, we moved forward with the overseas transfer of production lines for tie binding band, followed by the transfer of price tag pins and tag fasteners. In 1993, we established a factory in China in order to expand our global operations in earnest. After this, we will also promote export business of molded products to the U.S. and Europe. In the mold making business, the demand for molds decreased in the 1990s as consumer electronics makers began to produce their products overseas. We have started business with automobile molding manufacturers with whom we had no business at the time of our establishment. In 2002, a new molding plant was established in Japan. We have started production of injection-molded automotive parts with the aim of developing a pillar of revenue other than the products we have handled until now (price tag pins, tag fasteners, and tie-binding band). In the 2000s, in Japan, Sanyo promoted plant consolidation and organizational reforms with the aim of reducing manufacturing costs. In China, in response to rising labor costs, we established an injection molding production plant in Shandong Province in northern China, bringing our total number of production bases to two with DG in the south. - In the future, with a declining population and a sense of stagnation with no innovation, we need to intentionally strengthen our global awareness to more deeply "see Japan from the world" and "see the world from Japan. As in the past, domestic demand in Japan cannot be expected to increase. On the other hand, the market for price tag pins and tag fasteners, which developed globally at an early stage, is facing an uphill battle due to the aggressive competition and growing environmental awareness in Europe. The era of mass production is over, and people's needs are shifting from "getting things" to "experiencing things. Manufacturing should essentially be centered on "people" and should be creative. We are convinced that innovation will occur when our molds and molding technologies are matched with solutions to the problems of many people. - Tag pins and tag fasteners are the best of our mold design and injection molding technologies, we must reaffirm that these are creative products with "people" at the center. Furthermore, we believe that our mission is to develop products worldwide that exceed these existing products.

In the plastic molding and processing segment, sales of tag fasteners, tag pins, and cable ties (binders) accounted for 72% of total sales, followed by automotive parts (22%) and SEP products for special industries such as medical equipment (6%).As for tag pins and tag fasteners, fashion giants such as Uniqlo, Adidas, Hanes, and Nike are currently using our products. Our SEPs are used in medical devices as well as in the aerospace industry, where they are highly appreciated.

Ravi, B. & Srinivasan, M. N. Casting solidification analysis by modulus vector method. Int. J. Cast. Met. Res. 9, 1–7 (1996).

Cannon, A. H. & King, W. P. Casting metal microstructures from a flexible and reusable mold. J. Micromech. Microeng. 19, 095016 (2009).

Tool based manufacturing processes like injection moulding allow fast and high-quality mass-market production, but for optical polymer components the production of the necessary tools is time-consuming and expensive. In this paper a process to fabricate metal-inserts for tool based manufacturing with smooth surfaces via a casting and replication process from fused silica templates is presented. Bronze, brass and cobalt-chromium could be successfully replicated from shaped fused silica replications achieving a surface roughnesses of Rq 8 nm and microstructures in the range of 5 µm. Injection moulding was successfully performed, using a commercially available injection moulding system, with thousands of replicas generated from the same tool. In addition, three-dimensional bodies in metal could be realised with 3D-Printing of fused silica casting moulds. This work thus represents an approach to high-quality moulding tools via a scalable facile and cost-effective route surpassing the currently employed cost-, labour- and equipment-intensive machining techniques.

Gibson, I., Rosen, D. W., Stucker, B. & Khorasani, M. Additive manufacturing technologies. 65, 314, 458, 614 (Cham Switzerland: Springer, 2021).

The two pillars of our company are the mold design and manufacturing division and the plastic product molding and processing division. The secondary processing division exists to cover the plastic product molding division. Developing a second process machine internally, we can add second processing on the product and produce with additional value.

a Cicada wing made of a cobalt-chromium alloy (scale bar: 10 mm, magnified view scale bar: 500 µm). b Metal replication of a human fingerprint in brass (scale bar: 10 mm, magnified view scale bar: 500 µm). c Microlens array in brass with a lens diameter of 30 µm (scale bar: 10 mm, magnified view scale bar: 200 µm). d Bronze metal replication of different lines-and-space structures in the range of 5–25 µm in bronze showing interference effects (scale bar: 10 mm, magnified view scale bar: 100 µm). e Function test of a polymeric component replicated form the structure in d showing the expected diffractive far-field pattern (scale bar: 25 cm). f Replicated metal inserts with a mirror surface finish in bronze, brass and cobalt-chromium (scale bar: 10 mm). g Schematic representation of the production process of 3D-Printed Glassomer moulds for direct metal casting.  h Metal figurines in bronze, brass and cobalt-chromium, produced using a 3D-Printed Glassomer mould (scale bar: 10 mm). i Detailed view of the face of one figure, as brass metal replica (scale bar: 1000 µm). j Top view of the one figure, cobalt-chromium metal replica (scale bar: 5 mm). Original Sphinx design (Thing # 1404323) by Perry Engel from thingiverse.com (2016), adapted by author.

In order to prepare the sintered glass components for the casting process, the components were fixed in a steel cuvette using phosphate-bonded embedding material (Pro-HT Platinum, Horbach Technik, Germany). The embedding material was mixed in a ratio of 31:100 by weight (water/powder) and poured into the prepared metal cuvette before heating at 800 °C for 2 h.

Japan is known for its monozukuri capabilities; a philosophy deeply rooted in Japanese culture and industry, emphasizing the pursuit of excellence, precision, and quality in the creation of products. This commitment to "monozukuri" sets Japanese manufacturing apart and is a key factor in the success and reputation of Japanese suppliers. Your company is no exception and perhaps represents this more than most in its ability to develop molds for different kinds of injection molding used in various industries like automobiles, home appliances, and weak electricity-related industries. For Sanyo Seisakusho in particular, how do you ensure the highest quality of your products?

Thermal debinding of the cured Glassomer green parts was carried out in an ashing furnace (type AAF, Carbolite Gero, Germany) at 600 °C. The brown parts were sintered in a tube furnace (type STF16/450, Carbolite/Gero, Germany) at 1300 °C and a pressure of 5 × 10−2 mbar.

The Glassomer GmbH has patented the technology described within this paper (application/patent no. EP20195971.5) and is in the process of commercializing it. The authors declare no other competing interests.

Mayer, R. Precision injection molding: how to make polymer optics for high volume and high precision applications. Opt. Photonik 2, 46–51 (2007).

We believe that partnerships with partners that accelerate B2B business and innovation are the triggers for business chemistry, and we keep our antennae up and always on the lookout Currently, that movement is only taking place in Japan. Sanyo is located in Aichi Prefecture, JAPAN. The word Aichi means "love of knowledge". In October 2024 One of the largest startup support centers in Japan will open in a center of knowledge”Aichi. We have been participating in this activity since 2022, when it was still in the preparatory stage. We are taking various actions such as building connections, participating in open innovation events, attending pitch events, connecting with students who aspire to become entrepreneurs, and communicating the appeal of manufacturing in university classes. One of the reasons for the stagnant Japanese economy is the lack of major innovation. It is said that innovation happens on the frontier. We believe that when values intersect, a chemical reaction occurs. We are trying to create movement in Aichi/Nagoya by participating in exhibitions of different industries and holding cross-industrial exchange events hosted by our and we are doing so. different a company, Focusing not only on the domestic market but also on overseas markets demand in the tag pin/tag fastener business is not expected. This is because the population is declining, domestic production of applicable products in Japan is decreasing, and there are fewer places where they are used. On the other hand, if we look around the world, we see countries with growing populations and intensified production. The Southeast Asian market in particular is growing remarkably, and we are targeting it. We are looking for partners with local expertise in those regions.

Even from the perspective of supplying molds, what customers ultimately want is to use those molds to produce quality molded products. Soon after our company was founded, we established a molding factory. As a mold manufacturer, our objective is to acquire molding know-how. We believe that sharing know-how on resin characteristics and molding conditions will enable us to produce molds with good moldability. Specifically, we will include people with molding expertise in the preliminary mold design review meeting. Incorporate mold and molding training into the curriculum for new employees. We believe that through these activities, we have been able to produce molds that can guarantee mass production molding. Resins are constantly evolving and new resins are coming onto the market. We handle everything from general-purpose resins to high- performance resins(super-engineering plastics), and recently we have also been handling environmentally friendly materials. As research and development facilities, or as "mother plants" (which are "high-value-added factories" in charge of making prototypes of new products and key components), we are familiar with a wide variety of resins, which helps us to respond to the various requests of our customers in the mold and die business.

Sortino, M., Totis, G. & Kuljanic, E. Comparison of injection molding technologies for the production of micro-optical devices. Procedia Eng. 69, 1296–1305 (2014).

Schmitz, G. J., Grohn, M. & Bührig-Polaczek, A. Fabrication of micropatterned surfaces by improved investment casting. Adv. Eng. Mater. 9, 265–270 (2007).

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Faraji Rad, Z., Prewett, P. D. & Davies, G. J. High-resolution two-photon polymerization: the most versatile technique for the fabrication of microneedle arrays. Microsyst. Nanoeng. 7, 71 (2021).

Nair, S., Sellamuthu, R. & Saravanan, R. Effect of Nickel content on hardness and wear rate of surface modified cast aluminum bronze alloy. Mater. Today.: Proc. 5, 6617–6625 (2018).

To demonstrate the applicability of the replicative metal moulding technique, various structures from nature and technology with a size from several cm to structures of a few µm were replicated (see Fig. 4 a–e). These were moulded in PDMS directly from existing objects, no master structure produced by 2-photon polymerisation was used. Bionic structures like the wing of a cicada or a human fingerprint could be directly replicated using the metal casting process (see Fig. 4a, b). Feature sizes in the range of several tens of micrometres were replicated successfully into cobalt-chromium and brass. Further we show the successful replication of refractive and diffractive microoptical elements. Figure 4c shows a microoptical lens array with lens diameters of 30 µm in brass. The sample in Fig. 4c shows a surface defect resulting from a contaminated fused silica surface. Defects of this nature can be avoided by working under clean room conditions. Figure 4d shows diffractive line-and-space structures with line widths between 5 and 25 µm in bronze. Figure 4e shows the mirror surface finish replicated from an unstructured fused silica part without post treatment after casting in bronze, brass and cobalt-chromium using the described process. A further modification of the process also allows the direct production of a 3D-Mould, from the polymer nanocomposite as schematically depicted in Fig. 4f. This allowed the direct production of moulds in the nanocomposite polymer for metal casting without the use of a master structure via 3D-Printing. After sintering, the printed mould can directly be filled with liquid metal, resulting in a metal part like shown in Fig. 4g in bronze, brass and cobalt-chromium. The lines created by the 3D-Printing process can be seen in the metal, as shown again in Fig. 4i, j.

Sanyo Seisakusho not only has operations domestically but also through your production plants in China (1993) and subsidiaries in Hong Kong (1996)?

a The master (positive) structure is fabricated using 2-photon-polymerisation before being copied into polydimethylsiloxane (PDMS) via casting (negative) (scale bar: 5 mm, magnified view scale bar: 500 µm). b Fused silica part (positive) fabrication, by casting silica nanocomposite onto the created PDMS-Replication mould and curing it using UV-Light (scale bar: 5 mm, magnified view scale bar: 500 µm). c After debinding and sintering, a fully-dense and transparent fused silica replication structure is obtained (positive) (scale bar: 4 mm, magnified view scale bar: 400 µm). d Casting of metals against the sintered fused silica replication structure using bronze metal (negative) (scale bar: 4 mm, magnified view scale bar: 400 µm).

Williams, S. S. et al. High-resolution PFPE-based molding techniques for nanofabrication of high-pattern density, sub-20 nm features: a fundamental materials approach. Nano Lett. 10, 1421–1428 (2010).

Piotter, V., Holstein, N., Plewa, K., Ruprecht, R. & Hausselt, J. Replication of micro components by different variants of injection molding. Microsyst. Technol. 10, 547–551 (2004).

Paul, C. & Sellamuthu, R. The effect of Sn content on the properties of surface refined Cu-Sn bronze alloys. Procedia Eng. 97, 1341–1347 (2014).

Polycarbonate components comprise a mass market with significant competition from Chinese manufacturers and other countries like Vietnam. How does your company maintain competitiveness in an industry where pricing plays a crucial role?

In order to produce casting moulds directly in the polymer nanocomposite, the resin printer Prusa SL1S Speed of PRUSA (Czech Republic) was used to print. The material (Glassomer L50-SL-v2 according to the manufacturer’s specifications) for printing was kindly provided by Glassomer (Germany). The structures were directly printed onto the printing platform. The Printer was used with a wavelength of 405 nm, an exposure time of 20 s and a layer thickness of 50 µm. The printed components were developed using Glassomer developer.

F.K. and B.E.R. conceived the idea. S.K. designed and conducted the experiments. S.K. processed and analysed the materials. L.H. and M.L. performed 2PP. M.M. performed roughness measurments at the AFM. M.S. performed 3D-Printing of glass casting moulds. A.B. Performed injection moulding with the manufactured moulds. M.Mi. and C.G. conducted the hardness measurements. All authors contributed to writing the manuscript.

To become a mold manufacturer that can survive in the global environment, we must take on the challenge of manufacturing high-value-added molds. There are three major global trends. The three are "guaranteed accuracy," "high-end," and "fine/precision." In order to meet these challenges, it is essential to specialize and to be familiar with the environment, processing equipment, and resins. We believe that the essential condition for a mold maker to survive is to take advantage of our strength in the integrated production of molds and molding to take on the challenges of these new fields.

PDMS was mixed for 1 min in a ratio of 9:1 by weight (A:B component). Entrapped air bubbles were removed using vacuum in combination with a desiccator. The master structure was fixed in a Petri dish and then moulded using PDMS in the oven at 60 °C for one hour to cure the PDMS-Replication. The cured PDMS-Replication was peeled from the master structure. Glassomer L50 was mixed with Glassomer Hardener according to the manufacturer’s specifications. Glassomer L50 was then poured onto the PDMS mould and cured by illumination at a wavelength of 320–405 nm for 2 min. After curing, the nanocomposite could be removed from the PDMS mould.

In this paper, we demonstrated a replicative manufacturing process allowing rapid and cost-efficient production of metal inserts for polymer replication with low surface roughness, using a replication technique. We have shown that high-temperature metals like bronze, brass, and cobalt-chromium can be successfully shaped with a feature size down to 5 µm and single nanometre surface roughness. The inserts were successfully used in industrially-established polymer injection moulding instruments generating thousands of components. This process thus enables the flexible and cost-efficient production of metal inserts with low surface roughness by a replication process for tool based manufacturing like injection moulding or hot-embossing, bypassing the common problems of classical tool manufacturing such as high per-mould costs and processing times commonly associated with the high costs of classical moulding tools.

Vass, C., Smausz, T. & Hopp, B. Wet etching of fused silica: a multiplex study. J. Phys. D: Appl. Phys. 37, 2449–2454 (2004).