The French industrial technical center for plastics and composites (IPC) has conducted research to assess the usability of molds printed with a 3D printer for low-volume injection molding. Our report documents the production steps and injection testing for molds printed with Formlabs solutions, highlighting the results obtained and best practices.
Why print injection molds with a 3D printer?
Injection molding is a cost-effective technology with a very high repeatability capability for producing large quantities of plastic parts with precise geometric or dimensional tolerances. However, the high cost of traditional steel molds makes injection molding challenging for producing smaller quantities of parts and often becomes a barrier to bringing new products to market. With 3D-printed injection molds, engineers, manufacturers, and product designers can reduce costs, shorten production times, and bring better products to market. 3D-printed injection molds are an excellent option for those looking to design functional prototypes with real-use materials, produce multiple identical prototypes before mass production, or even manufacture custom or limited-run functional parts.
Research by IPC, a leader in plastics and composites.
IPC is an industrial technical center specializing in plastic and composite innovation in France. IPC develops new approaches and tools to support all types of businesses, particularly small and medium-sized enterprises. This center works closely with key scientific stakeholders in Europe to support companies in research and development (R&D), innovation, technology, and skills transfer, without limiting the manufacturing processes used.
IPC has developed three technology transfer projects to address key challenges in the industry by supporting various companies through expertise in research and development in circular economy (DIS 30), additive manufacturing (PRINTER), Industry 4.0, and high value-added products (HYPROD 2). The IPC team assists the industrial sector or manufacturers in driving innovation by conducting studies, establishing testing methodologies, assessing feasibility, and transferring technology.
Recently, IPC conducted a research project to assess the feasibility of injection molding using molds printed with 3D printers. In this report, we summarize some of their findings, particularly those related to the use of Formlabs 3D printers.
Study details and standard shapes for comparison
IPC's research project consists of a technical study over a period of 2 years, divided into 3 phases as follows:
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Comparison of 3D printing technologies
A preliminary classification has been made from the technical data of several manufacturers. Thermal and mechanical data were assessed through Heat Deflection Temperature (HDT) and Young’s Modulus values, respectively. Standard benchmark parts were produced in 4 types for each specified technology to highlight important properties and to select the top 3 most promising materials. Resin-based 3D printing solutions were chosen as the most suitable option for injection molding due to their high resolution and smoother part surfaces.
Overall, it was found that the dimensional tolerance range of all considered 3D printing technologies was similar, ranging from ±0.02 mm to ±0.05 mm for small details and from ±0.05 mm to ±0.2 mm for larger dimensions. The standard accuracy of metal molds that have undergone machining or milling is expected to be ±0.02 mm. This level of precision is required to ensure that the parting line of the mold fits properly and to avoid the occurrence of excess plastic flashing. In this report, IPC will present 2 methods to improve the parting line of polymer molds printed with 3D printers for better suitability.
Standard shapes for testing and comparison
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Material characteristics and properties identification, design guidelines, and 3D printing guidelines
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Injection Molding Testing: IPC conducted two tests using different mold sets. In the first test, they used a "torture-test" design and injection molded nearly one hundred polypropylene parts using a mono-material mold printed with Formlabs High Temp Resin. In the second test, they used a more challenging "torture-test" design and this time injection molded thousands of polypropylene parts using a multi-material mold, where the core and inserts were printed with Formlabs Rigid 10K Resin and the mold frame was printed with PA12 material using SLS technology.
Our white paper covers sections of the study conducted using Formlabs' 3D printing solutions, particularly in the areas of design and manufacturing guidelines, injection molding conditions, and observed outcomes
Results
IPC has evaluated the usability of molds printed with 3D printers for low-volume injection molding, using cores printed with Formlabs Rigid 10K Resin and soft mold frames printed with PA12 material. They were able to inject thousands of polypropylene parts while reducing costs by approximately 80–90% compared to metal molds
The patterned surface on the final part injected with multi-material molds, which consists of molds printed with Rigid 10K Resin and assembled with metal molds
Desktop 3D printing is a powerful solution for rapidly and cost-effectively producing injection molds, requiring minimal equipment, saving CNC machine time, and reducing the burden on skilled operators so they can focus on higher-value work during the same period. These molds can seamlessly integrate with existing injection molding processes as they are easy to install, use, and maintain
Manufacturers can benefit from the speed and flexibility of in-house 3D printing to create molds and utilize them alongside the production capabilities of industrial injection molding machines to deliver parts made from common thermoplastics in quantities within just a few days
Download the full report to see a summary of the technical study, which includes guidelines for 3D printing and insights into mold assembly and production process conditions
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