Finishing Titanium Medical Implants

A. I assume you are referring to polishing of the wear surfaces. If so, electropolishing the titanium is probably the most cost effective as the usual 'hand' polishing although inexpensive, becomes very expensive if the operator is not properly trained.

A. Cheap depends on what kind of surface finish you are looking for. If my memory serves me correctly, medical implants or any implant for that matter requires a very smooth surface finish. The finer the better. Porosity can be a breeding ground for bacteria plus. Anyway, if that is your situation, I would look into mass finishing systems. You have your choice of barrel, vibratory, and high energy in that order of equipment cost. For efficiency and speed, I suggest a centrifugal barrel machine system. Volume of parts to be processed will determine size of machine and cost.

A. Vibratory finish with porcelain media, and then anodise with "Coca-Cola". You can even offer a choice of colours .

A. Hi David. Vibratory finishing is one process and anodizing is another. In vibratory finishing, the parts are put into a tub full of appropriately selected media, and a vibrator attached to the tub causes the media to rub against the parts and polish them.

Yes, decorative anodizing can be done in Coca-Cola or other mild acids, although proprietary anodizing solutions may work better. The coloration is not a dye or pigment; rather it is a diffraction effect. The titanium oxide film is almost transparent, so some light bounces off the outside of the anodized film, and some goes into the film and bounces off the part itself (or depending on how you think of it, the inside of the anodized film). The film is a fraction of a wavelength thick, and when the reflection from the outside of the film combines with the reflection from the inside, the interference cancels out some of the colors of white light, causing the part to look red, green, blue, or violet depending on the thickness of the anodized film.

But you are with a medical parts supplier, and general hobbyist-level decorative anodizing may not be what you are looking for; please take a look at ASTM F86 first.

Regards,

A. The cheapest way is to passivate the surface per ASTM F86. This will meet the requirements for implants. Smooth, pretty and colored are another subject. We Chemical Polish for a good finish which also removes burrs and leaves the surfaced, passive, bright, smooth and ready for color anodizing, Coke will work some, but we use something different to achieve a rainbow of biocompatible colors, most useful for size coding.

adv.

Contact me to discuss environmentally safe technology and equipment to buy for electropolishing titanium, stainless, etc. medical implants. Polishing process takes few minutes, uses safe electrolytes, surface is mirror-surgically clean, free from any burrs and organic and inorganic residue.

A. Electropolishing and hand polishing are good for the exposed abutments of dental implants but, a smooth surface on an in-bone implant may not be the best choice. The controlled surface roughness of titanium implants during osseointegration to ensure the maximum surface area for bone-to-implant contact can be achieved by deformation (blasting) and/or removal (acid) processes. By combination of different processes and using titanium alloys having aluminum or vanadium constituents different patterns of roughness are possible in order to achieve higher indexes of bone to implant attachment. My company performs etching and certification of titanium implants to meet the cleanliness requirements of ASTM F86 and ASTM B600.

Hi, Dilbagh. If general hints will suffice, we have many threads on line here about electropolishing and color anodizing of titanium, and patience with our search engine will be rewarded. The color is not a dye or discoloration, but a diffraction layer phenomena (like carnival glass or the rainbow sheen of a drop of oil in a puddle) such that the color depends on the thickness of the (almost) transparent film; in turn, the thickness depends on the applied voltage.

You have already read on this page that people earn their living by offering titanium electropolishing and anodizing services based on their years of experience, and that other companies earn theirs by licensing the technology. So, unfortunately, you are unlikely to find "complete information" in an Internet forum. Licensing the technology is usually a good way forward if you want to do it in-house. Good luck.

Regards,

A. Hi Jim,

I think the ultrasonic bath doesn't replace the chemical etch even when the titanium surface is shot blasted. The acid etching has the goal to remove oxide scale in order to obtain clean and uniform surface finishes. I don't know a detergent that can remove those particles. Normally, the etching solution for pickling titanium is with (10-30%) Nitric Acid with (1-3% in volume) Fluoridric acid. The ratio between Nitric Acid and Fluoridric acid can use 12:1. Also, the time of chemical attack with nitric acid is very long. The combination with nitric acid and fluoridric acid can remove aluminum particles or residues from shot blasting.

Any question?

A. Hi Parth. Make sure you're complying with ASTM F86 and/or other applicable specs for these components first. Many people consider the formulation of the alkaline anodizing solution for titanium per AMS 2488 to be their trade secret, so I'm not sure whether anyone will offer recipes.

Regards,