The present of industrial manufacturing is very much based on injection molding. The ability to gradually introduce the advantages of additive manufacturing into consolidated formative technologies is paramount in the effort to commercially implement AM in the short term. Using the THERMA DM500 resin for DWS stereolithographic AM systems, Italian 3D printing hardware, materials and service provider Shapemode was able to produce molds for low-batches of 100 ml customized medical syringes. The final product, made using a polypropylene material (PP), was successfully used for microbiota transplantations on patients suffering from serious infections.
The final product consisted of a thin-walled body in the form of a cylindrical container. Products of this type normally are obtained using a cyclic injection process, which is the most common method for polymer plastics processing today. Production costs of an average syringe are low, as multi-mass and mass production are widespread nowadays.
However, making a traditional metal mold requires investments for thousands of euro (between €5,000 and €100,000 depending on the mold’s complexity) and several weeks (between 4 and 8). As customization demands and fast product evolution rates increase, there is a growing need to reduce the time and costs required for the production of small lots, enabling both start-ups and consolidated brands to quickly obtain finished parts.
By implementing new techniques for low-batch production with 3D printed molds, Shapemode was able to more carefully plan the process and select the appropriate parameters to minimize unnecessary capital expenditures. In this case, it was important to carry out preliminary tests and comparative analyses regarding process procedures and product properties in order to minimize costs by rationally selecting a series of conditions.
Shaping the mold with THERMA DM500
During the trial phase, several production options were tested: parameters with reduced injection pressure or absence of pressure, with a reduced temperature of the injection mold. Thanks to an intimate knowledge of the process, Shapemode suggested modification, in accordance with the client, such as minor changes in the syringe geometry, in order to make it more suitable for the injection molding process. The final product met all technical requirements while still ensuring lower manufacturing costs, bio-neutrality and sterility.
Shapemode’s successful application shows that by implementing 3D printing in the mold-making process it is possible to combine some of the key benefits of additive manufacturing technologies – such as more streamlined, on-demand, custom manufacturing – with the final materials used in traditional formative processes.
THERMA DM500 is a photosensitive material developed specifically for the production of molds for injection of plastic materials, resistant to hundreds of cycles, at very high temperatures (180-220°C) and high pressure. This resin is meant to finally fill the gap between prototyping and production in terms of both costs and benefits. The ability to 3D print the molds is spawning a new generation of products that can take advantage of both advanced geometries and final materials, while shortening the time to market. THERMA DM500 makes it possible to produce dozens of molds in a just matter of hours.
The Shapemode solution
Through ongoing R&D activity, the engineers at Shapemode have fine-tuned a complete workflow that leverages the unique properties of THERMA DM500 materials combined with advanced geometric capabilities of the stereolithographic process. This process goes beyond good product designed and is based on the optimization of mold design. The use of 3D printed molds is not so different from traditional ones, but the mold designers need to take into account a number of elements identified by Shapemode.
Shapemode’s process takes into consideration 4 key steps: mold design, mold 3D printing, tooling support for part removal, and the actual injection molding phase.
The design phase includes elements to consider such as dimensional tolerance, angles and point of injection. In the next phase, the actual 3D printing of the mold, Shapemode describes how to accurately position the molds on the printing platforms to best leverage the TTT system (the vat’s movement system, developed to increase the vat’s lifetime). Shapemode also explains how to best design the supports using Nauta software and how to proceed to the UV post-processing phase.
Shapemode continues to improve its services. The recently introduced DWS XPROS SLA 3D printer offers a much larger volume (30x30x30cm), creating entire 3D printed molds or other complex mold parts that can be placed inside classic metal molds for augmented geometrical capabilities even with most traditional materials.
This case study was created in collaboration with Shapemode