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FEATURE ADDITIVE MANUFACTURING/3D PRINTING


expanding the hoRizons FoR heaLthcaRe designeRs


Elizabeth Norwood, senior chemist at MicroCare, LLC, examines why Additive Manufacturing is gaining momentum in the medical device industry


A


dditive Manufacturing (AM) is gaining momentum in the medical device industry as it allows manufacturers to expand their


design horizons and streamline production. As the process becomes faster, more stable and more affordable, it is a viable alternative to other more traditional machining methods like milling, cutting or turning. The most common use for


AM within the medical device manufacturing industry is building simple manufacturing support items like jigs and fixtures. But it is also used for small-volume runs of very complex biomedical devices such as dental implants, hearing aids, personalised orthotics and prosthetic limbs for individual patients. AM also appeals to device makers


when security is a concern. Since 3D printing is typically done in- house, device designs are not publicly shared with outside service providers like mould or die makers. This helps protect patents, trademarks and intellectual property.


how metaL am woRks There are many types of metal 3D printing methods used today. However, many designers choose binder jetting (BDJ) for their parts. It is typically less expensive, faster and easier-to- use than other AM methods. Binder jetting builds a part out of a feedstock made of fine metal powders and binders. It places alternating layers of metal powder and binders in thin horizontally progressive deposits, until the parts reach their final shape. The powdered metals can include medical-


grade stainless steel, titanium and other alloys to produce high-performance precision parts that meet both FDA regulations and customers’ exacting standards. Binders are typically made of wax, stearic


acid or polymers, such as polyethylene or polypropylene. The binders hold the powdered metals together to build ‘green’ parts using


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the AM layering process. The binders help form the metal powder into a


specific shape. However, the binders are only temporary. The green parts must be debound before they can be sintered. During debinding, some of the binders are selectively removed to form interconnected open pores within the parts with only enough binder staying behind to maintain the parts’ structural integrity. Successful parts debinding is a fine balance of selectively removing the right amount of binder as quickly as possible without damaging the fragile parts. The parts are then


thermally sintered at near melting temperature. This burns off any remaining binders and bonds the metal powder to its solid mass state, typically 96-


99.8% density. The parts are then post-processed using standard finishing techniques.


deBinding FoR success Parts debinding is typically done using one of four different methods. Thermal, catalytic, aqueous or solvent debinding. All have their pros and cons, but solvent debinding inside a vapour degreaser is growing in popularity because it provides both operational efficiencies and environmental advantages. Depending on the parts’ material and the


binders used, the binders are removed from the parts by either immersing them in the boiling debinding fluid, by holding it inside the vapour, or a combination of both. The low-boiling debinding fluid melts the wax binder and creates porosity within the green parts to allow the fluid to evaporate quickly before sintering.


modeRn deBinding FLuids – BetteR FoR the enviRonment


Modern debinding fluids used inside the 5 DESIGN SOLUTIONS NOVEMBER 2022 Metal powders for AM


vapour degreaser are recycled and reused for hundreds of hours before they need refreshing or replacement. The vapour degreaser concentrates the binders and other contaminants, minimising the amount, frequency and cost of your hazardous waste disposal.


Reduced eneRgy consumption Solvent debinding happens at a very low- boiling temperature that still melts the wax binders but does not damage the non-soluble fragile parts. The low boiling temperature reduces energy consumption and cost, and helps reduce your environmental footprint.


contaminant and BioBuRden-FRee deBinding


Solvent-based debinding fluids are hostile to bioburden and pyrogens. They do not contain water, which helps maintain a bacteria and virus-free environment, making it easier to validate when used in a cleanroom setting


consistent, Fast deBinding with LittLe monitoRing


The vapour degreaser debinding process, once established and tested, is simple, predictable, and repeatable. The debinding fluid remains consistent and stable and does not require daily monitoring or testing. Solvent debinding is a well-engineered process where the debinding outcomes remain consistent, making it easier to qualify and validate for medical device manufacturing.


woRk with a deBinding expeRt Debinding fluid is an important tool for successful AM manufacturing. Fabricators looking for help choosing the right debinding fluid or method should consult with a company that specialises in medical device parts debinding. They can recommend which debinding methods and fluids will work best.


Microcare www.microcare.com


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