Machining Micro Molds for Medical Devices
Machining the micro molds used to make medical devices and components require among the most demanding micro machining applications. A new type of machining platforms is making it possible to machine molds faster, more accurately, and more cost-effectively.
As medical devices get smaller and more sophisticated, especially implantable and minimally invasive devices, creating the molds used to shape new products is a challenge all by itself. In many cases, manufacturing a new medical device requires the production of tiny molds made of extremely hard metals. Soft plastic material is inserted into the mold to create the finished part. When dimensions are measured in millionths of inches, and the devices are life-saving or life-sustaining, accuracy in the mold making process is paramount. Accurate molds are required to make accurate parts.
Traditional macro machining equipment is not well suited for the machining of medical micro molds. They do not have the part handling capabilities, acceleration, stability and responsiveness to ensure repeatable processing at micro scales. Machining micro molds for implantable medical devices requires dramatically increased accuracy, repeatability, thermal stability and rigidity, and positional accuracy.
Key drivers for the advanced, purpose-built micro machining systems for medical micro molds include:
- Time to market: The medical device world is exceptionally competitive, and time to market is all-important. Anything that can give device manufacturers an edge in bringing new products to market will be of substantial value. Micro machining platforms optimized for small features on small parts with extreme precision make it possible to iterate samples and prototypes very quickly, with quick setup times for new designs and faster volume production.
- Quality: Perhaps the only thing more important in the world of medical device manufacturing than time to market is quality. The medical device industry is one of the most regulated manufacturing sectors in the world, and complex Class II and Class III implantable devices are the most highly regulated of all products. It isn’t just the final product that must meet regulators’ specifications; manufactures must be able to document how the entire manufacturing process delivers a product that performs as designed. Micro machining systems for medical devices must deliver exceptional, repeatable, provable results.
- Cost: In addition to reducing costs by accelerating time to market and delivering exceptional quality, other factors like tooling, consumables, and material savings can impact the cost of making medical micro molds. Micro machining systems designed specifically for high precision applications will optimize tooling, reduce consumables and reduce material waste when compared to attempting to use a macro-scale machine to produce micro-scale parts.
With these drivers at work in medical device micro mold manufacturing, how can micro-scale machining platforms deliver superior performance? Below are a few of the ways a precision-optimized micro machining system can improve time to market, quality, and production costs for medical micro molds.
- Spindle speed: High speed spindles can machine parts with minimal thermal damage as material is removed quickly, before a great deal of heat can be dispersed. Also, highs speed spindles result in slower tool wear and lower tooling costs.
- Positional accuracy: Equally important to spindle speed on machining accuracy is part handling and positional accuracy. Holding the part in the right place, with micron-level tolerances, is critical to the accuracy and quality of the mold.
- Acceleration: High acceleration is required to maintain the appropriate chip load on the cutting tool. Traditional macro machining systems use ball screws, which do not enable high peak acceleration. Because micro parts typically involve multiple corners and changes in directions, the high acceleration is required maintain the proper cutter velocity in order to achieve better surface quality, edge quality and part consistency.
- Measurement: Measurement is one way to demonstrate quality. A medical micro molding system should include integrated part characterization and validation to ensure compliance and at the same time increase cycle times and deliver higher yields with quality and consistency. This can give manufacturers the validation and documentation needed to achieve device approval.
- Material savings. The materials involved in medical micro molds can be very costly, and waste is expensive. Take for example Silicon, a common material molded to create implantable medical devices. Because silicon is nearly as thin a liquid as water, it tends to find any gap in the mold –– no matter how small. Also, Silicone is expensive—as much as $1500 per pound—so and leakage is costly. High precision micro machining can deliver molds with parting lines that reduce or eliminate leakage, which can dramatically reduce production costs while creating and testing molds.
- Thermal stability: Using a macro-scale machining system on micro molds can introduce thermal instability, as the size of the machine can result in growth and vibration that impacts machining performance. A precision-optimized platform will have the right design to minimize thermal growth, and environmental responsiveness to enable ultra high accuracy.
When it comes to machining parts that are small enough to be implanted in the human body, and to be delivered through human veins to target tissue, precision is everything. Traditional machining equipment is simply not capable of achieving the required dimensions, quality and cycle times needed to create the molds for today’s advanced implantable medical devices.
Microlution has pioneered a new breed of precision micro manufacturing solutions for the automotive, consumer electronics, medical device and semiconductor industries. Microlution’s entire product line of precision milling, drilling, cutting and turning solutions are especially designed to machine small features in small parts with extreme speed, accuracy and quality. Each Microlution platform features a small footprint, high acceleration, and exceptional thermal stability; and each platform can be configured as a standalone system for rapid prototyping and R&D, and can scale up to a fully automated micro machining work cell. Learn more at www.microlution-inc.com.