ASTM F86 — Surface Preparation and Marking of Metallic Surgical Implants

TLDR

ASTM F86-21 is the ASTM International standard practice for surface preparation and marking of metallic surgical implants. It governs the final surface state of titanium, cobalt-chromium, and stainless-steel implants before sterilization and packaging — covering grinding, polishing, passivation, cleaning, and identification marking.

Quick Answer

What does ASTM F86 cover?
ASTM F86-21 defines the surface-preparation sequence and acceptance criteria for metallic surgical implants manufactured from titanium, titanium alloys, cobalt-chromium alloys, and stainless steels. The standard addresses surface finish, residual contaminants, passivation, cleaning validation, and the methods permitted for implant identification marking (without compromising biocompatibility or fatigue life).

Scope

ASTM F86 applies to metallic implants intended for surgical implantation, including:

• Bone plates, screws, and intramedullary nails
• Spinal fixation devices
• Hip and knee joint replacement components
• Dental implants and abutments
• Craniomaxillofacial plates and meshes
• Cardiovascular implants (stents, occluders — by extension)

For titanium specifically, ASTM F86 is typically invoked alongside AMS 2700F (passivation) and ASTM B600 (descaling and cleaning).

Surface Preparation Sequence

The standard prescribes a mandated sequence for implants:

1. Grinding. Remove grinding marks, machining witness, and surface defects using progressively finer abrasives. Final grinding grit ≥ 320.
2. Polishing. Mechanical, chemical, or electrochemical polishing to the required surface roughness. Typical final Ra ≤ 0.8 µm for non-articulating surfaces; ≤ 0.1 µm for articulating joint surfaces.
3. Passivation. Mandatory for all metallic implants. For titanium, per AMS 2700F (citric acid preferred); for stainless, per ASTM A967.
4. Cleaning. Ultrasonic cleaning in non-ionic detergent, followed by deionized water rinse.
5. Drying. Vacuum or forced-air dry in a cleanroom environment (ISO Class 7 or better per ISO 13485).
6. Inspection. Visual under magnification, surface-roughness measurement, residual-contaminant test.
7. Marking. Per Section 6 (see below).
8. Packaging. In ISO Class 7 cleanroom, double-bagged, ready for sterilization.

Surface Roughness Targets

Implant Type	Typical Ra (µm)
Bone plates (non-articulating)	0.4–0.8
Bone screws	0.4–0.8
Spinal rods	0.2–0.4
Hip stem (non-articulating)	0.2–0.4
Hip femoral head (articulating)	0.005–0.05
Knee femoral component	0.01–0.05
Dental implant body	0.4–1.6 (deliberate macro-roughness for osseointegration)
Dental abutment	0.1–0.4

Marking Requirements (Section 6)

ASTM F86 § 6 specifies that implant identification markings must:

• Be permanent under expected service conditions (autoclave, body fluid, fatigue)
• Not compromise fatigue life — preferred methods are laser marking, electrochemical etching, or micro-printing. Stamping, engraving, or impact marking require qualification testing.
• Not create stress risers — markings on low-stress areas only; never on the articulating surface or at the minimum cross-section.
• Be biocompatible — no inks, dyes, or surface contamination
• Include lot traceability — manufacturer code, lot number, material designation (e.g., “Ti-6Al-4V”)

For titanium implants, laser marking is the industry default — it produces a high-contrast oxide-colored mark without removing material and without inducing micro-cracks (when parameters are optimized).

Passivation

For titanium implants, ASTM F86 § 5.2 references AMS 2700 (citric acid passivation preferred). The passivation step:

• Restores the native TiO₂ oxide layer after grinding/polishing
• Removes embedded iron and surface contaminants
• Stabilizes the surface against corrosion in physiological saline

Cleaning Validation

ASTM F86 § 7 requires that cleaning processes be validated for residual contaminants:

• Residual particulates — gravimetric or extraction test
• Endotoxin — LAL test per USP <85>
• Bioburden — per ISO 11737
• Residual detergents — if used

Implants shipped to a sterile-packaging facility must meet pre-sterilization cleanliness levels per ISO 13485.

Inspection Acceptance

• Surface roughness. Per drawing; measured on a representative coupon or 100 % of articulating surfaces.
• Visual inspection. No scratches, gouges, or visible defects under 10× magnification.
• Passivation verification. Water-break test or surface-resistivity test per AMS 2700.
• Mark legibility. All required markings present and legible under 10× magnification.

Typical Applications

• Trauma: Bone plates, screws, intramedullary nails (Ti-6Al-4V ELI / Grade 23)
• Spine: Rods, pedicle screws, interbody cages
• Joint replacement: Hip stems, knee femoral components
• Dental: Implant bodies, abutments, cover screws
• Craniomaxillofacial: Plates, meshes, screws

Related Materials

• Grade 23 Titanium (Ti-6Al-4V ELI) — Most common implant-grade titanium per ASTM F136
• Grade 5 Titanium (Ti-6Al-4V) — Used where higher strength is required
• Ti-6Al-2Sn-4Zr-2Mo — High-temperature / fatigue implants

Related Standards

• ASTM F136 — Wrought Ti-6Al-4V ELI alloy for surgical implants (material)
• ASTM F1108 — Ti-6Al-4V castings for surgical implants
• ASTM B600 — Descaling and cleaning titanium surfaces (pre-passivation)
• AMS 2700F — Passivation of titanium (cited by ASTM F86)
• ISO 13485 — Quality management systems for medical devices
• ISO 5832-3 — Wrought titanium for surgical implants (international equivalent of ASTM F136)