Q&A: Materials Choice for Skinny-Walled Micro-Molded Medical Gadgets

Polymer materials choice for thin-walled micro-molded medical merchandise will probably be underneath the rhetorical microscope throughout a session on the co-located Plastec West and Medical Design & Manufacturing (MD&M) West occasion in Anaheim, CA, subsequent month. Patrick Haney, R&D Engineer at MTD Micro Molding, will focus on the requisite traits of varied polymer classes to satisfy the calls for of thin-wall molding and find out how to decide the optimum supplies for a particular software. He’ll lean on real-world examples as an example his factors.

Haney is scheduled to talk on this matter on Tuesday, Feb. 7, at 1:30 pm within the Design Alley part of the present ground, however he graciously agreed to share some insights with PlasticsToday forward of the occasion.

Plasticc West different Medical Design & Manufacturing (MD&M) West return to the Anaheim Conference Heart in Anaheim, CA, on Feb. 7 to 9, 2023.

Patrick Haney, R&D Engineer, MTD Micro Molding.

PlasticsToday: In an article in your web site, it says that probably the most widespread questions you hear from medical OEMs is: “How skinny are you able to go?” So, let’s begin there: How skinny can you go? And what are the first advantages of thin-wall units?

patrick haney: In the case of achievable skinny partitions, the reply is, “It relies upon.” One of many most important components is materials alternative. Can your design use a thermoplastic materials that’s higher suited to ultra-thin partitions, like liquid crystal polymer (LCP)? Or does your half performance require different materials traits, just like the rigidity of PEEK, which is far more difficult for thin-wall molding? Or does your thin-wall design require a number of supplies for an over-molded part?

LCP and PP are recognized for his or her thin-wall molding capabilities, being able to fill partitions of about 0.002 in., relying on geometry. Polyesters and nylons are additionally nice choices.

The primary advantages of thin-walled medical system elements and implants are affected person consolation, and the smaller an element can get, the smaller areas it might probably successfully monitor and deal with. Miniaturization can broaden capabilities of those medical units, and that goes hand in hand with thin-walled designs.

PlasticsToday: What are the first concerns when trying to realize thin-walled options in a micro-molded half?

Haney: The 2 major issues to consider are materials alternative and half design. In case you are pressured into a fabric household because of the software of the system, you could be restricted in how one can design sure options, like wall thickness.

The opposite facet to contemplate is an element design because it applies to injection molding. Ask your self when you can change half options to raised accommodate plastic half design for manufacturability. Though generally you might be pressured to interrupt guidelines to realize your purpose. For instance, if there’s a difficult half design that forces a lower than ultimate gating location, that may trigger extreme stress loss or fast movement entrance cooling, which may make it tougher to fill skinny partitions. Simply because you could have a fabric that’s greatest for filling skinny partitions doesn’t suggest it’s going to fill if the design shouldn’t be optimized.

PlasticsToday: Which medical supplies are greatest suited in these functions, and which of them could also be tougher?

Haney: Supplies which are greatest suited are those who have a extra linear polymer spine. When they’re flowing, the diploma of entanglement is way much less, which promotes decrease viscosity. One instance is nylon 6/6.

The tougher supplies are those who have larger levels of entanglement or larger glass transition temperatures and melting factors. In different phrases, it takes extra warmth to decrease the viscosity. An instance of this can be polycarbonate.

PlasticsToday: Do materials properties change when they’re utilized in micro-molding functions?

Haney: The molding course of exposes supplies to very excessive velocities, pressures, and shear charges for a really quick time frame. This additionally implies that the cooling charges a fabric is uncovered to are extraordinarily fast and these circumstances may end up in distinctive microstructures that may sometimes have an effect on mechanical and thermal properties. Nonetheless, with the appropriate instruments and information, anticipating that phenomena may end up in the fabric demonstrating fascinating properties, as supposed.

Probably the most widespread errors in micro molding is assuming that non-Newtonian conduct will display the identical traits as in macro-molding conditions.

PlasticsToday: What different components ought to be thought of when specifying thin-walled micro components?

Haney: Contemplating the ultimate system’s intent and software circumstances are actually vital for micro half design. Some issues to contemplate embrace, however usually are not restricted to: What’s the software temperature? Does the system require any mechanical efficiency? How lengthy is the system supposed to carry out its perform? These questions are all crucial as a result of they might all influence the best way the half is designed and manufactured. For this reason working intently together with your micro molder early about materials choices and achievable tolerances can arrange a venture for achievement.

PlasticsToday: What do you hope that convention attendees come away with out of your presentation?

Haney: We wish to stress the truth that getting concerned together with your micro molder as early as potential is in the most effective curiosity of this system going as easily as potential. There are a variety of questions that should be answered when designing a tool and lots of supplies to select from. I imagine that somewhat little bit of upfront schooling can go a great distance in the case of giving system designers the information to ask the appropriate questions and higher equip them to take their packages in the most effective route potential.

For a half century MTD Micro Molding has created a few of the world’s smallest elements for difficult functions. It’s solely centered on medical functions and supplies medical system OEMs with a single supply for micro molding initiatives from preliminary design to meeting and packaging.

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