How precision machining is impacting the future of medical device fabrication
Unlike conventional manufacturing, precision machining produces parts with submicron accuracy. For medical applications, this brings the crucial benefits of miniaturisation, personalised fit, and high performance. Ralph Zoontjens, product designer who specialises in 3D printing, shares his insight on how precision machining is impacting medical device manufacturing.
Manufacturing Revolution
Industry 4.0 is in full gear, and more and more companies are making the step toward digital manufacturing. CNC machines are chipping away material at blazing speeds with enhanced artificial intelligence and accuracy, ensuring that the product meets the intent of the design engineer.
With precision machining, the struggle for geometric dimensioning and tolerancing is over, since parts will be consistent with the 3D model to the micron.
This is a considerable achievement, since deviations are often visible across parts of the same batch, causing high scrap rates and failures to meet performance requirements.
Computer numerical control (CNC) does not hold onto heat-affected zones or other mechanical flaws of 3D printing, which is more suitable for prototypes and preoperative planning models. By milling the material as-is, it retains its homogeneous mechanical properties for meeting higher quality standards.
Precision technology is not just an incremental improvement. It has a radical impact on medical applications.
It’s capable of making long-lasting parts that can be carried on or inside the body for a good part of a lifetime. Solutions that were hitherto impossible can now enable new forms of microsurgery, such as on embryonic infants, blood vessels, or the brain.
Miniaturisation
A collection of devices rely on precision machining:
Insulin pumps
Defibrillators
Heart monitor implants
Pacemakers
Drug delivery systems
Kidney dialysis machines
Biometric trackers
MRI scanners
With precision technology, the product casing, internal architecture, electronics integration, and cabling solutions for your biometric tracker or digital X-ray are optimised. For wearables like heart monitor implants or pacemakers, their minimally invasive form factor with ultra-thin walled micro moulded enclosure is game-changing both in terms of comfort and aesthetic sensibility.
The instruments it makes also enable robot-assisted surgery like heart valve surgeries. And we witness great growth for tiny parts like septums, sensors, microelectronics, microneedles, stents, and micro-machined screws. Needless to say, this requires great specialisation on the part of the supplier.
Personalised Fit
Precision machining creates the perfect fit for critical applications like prostheses and orthoses. Thanks to these technologies, people do not simply feel supported, but more abled.
The following replacements are typically milled using multi-axis CNC machines out of titanium or cobalt-chrome with some polyethylene, acrylic, polyethylene terephthalate, or polyether ether ketone plastic components:
Major joint implants for the shoulder, hip, or knee
Implants for the hand, ankle, or elbow
Cranioplasty implants
Spine implants
Cerebral spinal fluid shunt systems
Phakic lenses
Implantable catheter ports
Cochlear implants
Based on body scans, these complex solutions can be machined to be exactly attuned to the patient’s biomechanics. This stands in stark contrast to traditionally hand-made components. With a precision-machined product, there is no more human error, no patient dissatisfaction, no second operation.
Professionals like surgeons and dentists benefit from having access to precision manufacturing. To their preference, they can now develop custom tools such as cutters, biopsy needles, implant holders, forceps, nebulisers, and blade handles, or outfit the robotic assistant with custom grippers.
In the future, medical professionals will use digital customiser apps to create bespoke components to spec, locally, and on demand.
Besides functional benefits, there are social acceptability factors as well — bringing hip hearing aids, canes and crutches, thin-wall machined biometric rings, and other wearable medical devices to the fashion-savvy.
Ultra-Performance
Stepping from traditional to precision manufacturing feels like turning a wheelbarrow into a race car. Electrical drive, oil-free equipment prevents contaminants as well as particle and fastener-free joining with laser welding and overmoulding.
Digitally-driven, AI-enhanced control software provides optimal dimensional accuracy to allow for intricate design features.
One benefit over other processes is the myriad of biocompatible materials it allows. Because of high spindle speeds, this requires very specific control parameters for each material. For example, polypropylene, polyethylene, and polyoxymethylene are best for thin-wall sections.
Nylon can be used as well but has a small processing window, while polycarbonate and PET require delicate temperature control. For high-strength applications, consider a glass fibre-filled ABS.
Medical-grade metal components like guidewires, screws, implants, and brackets are made of titanium, stainless steel, aluminium, copper, as well as Kovar, Invar, and Inconel alloys. Nitinol, a smart material with shape-memory behaviour, is an upcoming option for its kink and fatigue resistance.
For efficiency reasons or complex geometries, a hybrid approach is sometimes deployed. 3D metal printing can be used to develop organic internal lattice structures for lightweight components to be in-tolerance post-finished using CNC.
Devices like the Apple Watch thank their supreme finish to combining aluminium extrusion with precision milling and laser equipment in a process that leaves no edge and surface burrs, even inside the device.
For silicone parts like membranes, valves, and seals, micro moulding allows for parts just a few millimetres in size while retaining full detail as required for specific structural zones. And with optical liquid silicone rubber (LSR), glass-like transparency can be achieved.
A Clear-Cut Choice
Medical devices have to meet strict standards for durability, safety, biocompatibility, and sterilisation, and key mechanical requirements for flexibility, lubricity, buckling resistance, and torque transfer.
Cutting-edge precision machining is the way to go in almost all cases, allowing full control and a vast range of materials, with the perk of enabling ultra-personalised products.