Higher bearing surface area of smaller machinery

A scaling law).
When scaling things down the ratio between surface area and volume changes. Specifically halving the size of an object doubles its surface to volume ratio. This can be easily seen by cutting a cube into eight sub-cubes and calculating the ratio between the surface to volume ratios before and after the cutting. (wiki-TODO: add illustrative image)

As concern in regards to:
"macroscale style machinery at the nanoscale"

The potential consequences of rising surface area are one of the major concerns when it comes to the assessment of the feasibility of macroscale style machinery at the nanoscale.

Potential issues include:

• rising friction power losses
• rising corrosion rates
• dirt and lubricants clogging machinery

Concern: Friction-power losses

There are no less than three factors that work against the growing surface area effect when it comes to increasing friction power losses.

• first and most importantly: the rising throughput per volume scaling law
• second: the superlubricity effect
• and third: infinitesimal bearings (an "invention" of this wikis author)

It should be possible to keep power losses low enough for a practical functioning nanofactory (with large safety margins). Even systems more efficient than biological diffusion based systems may be possible. For details why see here: (wiki-TODO: add link).

Counter-factor: throughput per volume scaling law

This law is less much less known than the scaling law for surface area per volume, but it plays a major role in compensating the rising friction effect of it.

• there is rising throughput-per-volume @ constant operation speeds
• or equivalently constant throughput-per-volume @ falling operation speeds
• this causes falling friction power losses -- quadratically falling :) since it is dynamic friction

Counter-factor: superlubicity

This is not exactly a scaling law but an effect that is only available at the nanoscale in atomically precise systems in dry sleeve bearings with non meshing atomic bumps. The effect is experimentally proven. For more details see the main article: Superlubrication.

Friction power losses can be lowered from three to five orders of magnitude compared to motion in a liquid.

Counter-factor: infinitesimal bearing

These machine elements distribute speed differences equally over multiple coplanar surfaces. Due to friction power falling quadratically with speed this kind of allows one to "cheat" scaling laws a bit.

Concern: Surface oxidation

(wiki-TODO: add details here)

Concern: Nanomachinery getting clogged

(wiki-TODO: add details here)