Micro 3D printing provides manufacturers with an alternative to micro injection molding and micro machining. 3D printing addresses key design and manufacturing considerations about crossover volumes and material properties. When choosing a polymer for 3D printing, you need to consider your application as well as the attributes you require for your final part.
Today, there are four major areas of applications for Micro 3D printing:
- Form and fit based prototype
- Mechanical prototype
- Functional prototype
- End-use product
Depending on your application, the attributes you need your final part to encompass vary. These include geometric fidelity, mechanical properties, chemical and thermal properties and longevity. There are a number of polymers used within manufacturing that possess these attributes and are used across a wide range of industries.
Choosing the Right Material
In addition to the medical market, there are opportunities in micro-optics, microfluidics, smart devices with micro mechanical systems (MEMS), and applications with increased levels of sensing for the Industrial Internet of Things (IIoT). Micro molded polyetheretherketone (PEEK) polymers are also replacing micro machined stainless steels to reduce waste and weight. Micro injection molders are rightly concerned about costs, but they also want assurances that 3D printed materials can replicate the properties of traditional polymers. µ3DP can address these concerns.
Key Considerations When Selecting the Right Polymer
There is a crossover production volume at which micro IM becomes more cost-effective than 3D printing. For standard parts, this volume is typically in the low thousands. For small, high-precision parts, the crossover volume is significantly greater because of the high cost of micro molds. 3D printing only becomes a viable alternative if the required resolution is achievable and if suitable materials are available.
When comparing traditional polymers to photocurable resins suitable for micro 3D printing, micro manufacturers need to examine material properties and determine the primary and secondary criteria for evaluations. If strength, a mechanical property, is most important, the metrics for comparison are flexural strength and tensile strength. With medical applications for high precision micro manufacturing, specific levels of biocompatibility may be required. There are currently photocurable resins available that can meet specific ISO 10993 standards such as ISO 10993-5 (vitro cytotoxicity) and ISO 10993-10 (skin irritation). There is also a growing list of photocurable 3DP polymers that are mapped to traditional polymers for other applications.
By choosing the right materials for µ3DP, micro manufacturers can profit from the projected growth in both medical and non-medical applications. For example, PEEK could be used for prototyping orthopedic implants or for micro-pump housings, micro gears, and lens holders. Possible applications for polysulfone (PSU) include prototyping microfluidic devices and end-use micro gears. Polycarbonate (PC) applications cover prototypes and end-use parts for both cell containers and implantable ports. Polyimide (PA) could be used for medical parts such as pupil expanders or for non-medical parts like the housings for electrostatic valves. These are just are just some of the available materials and applications that µ3DP can enable.