Transcript Milling VS Micro Milling - Washington Asphalt Pavement

Milling & Micro Milling
Mike Bussard
General Superintendent,
P.R. Systems, inc.
The Heart Of Cold Milling Machines
A cold milling machine's most important tool is
the milling drum.
Rotating point-attack cutting bits are inserted in
toolholders that are fastened onto the drum
body.
The texture of the milled surface is determined
by the bit spacing, which is the distance
between one cutting bit to the next.
The Milling Drum:
Standard Drum
Micro Drum
Standard milling drums with a tool spacing of
5/8”.
Ideally suited for the removal of individual
layers or complete pavement structures.
This drum is used 99% of the time
Micro fine milling drums with tool spacing's
of up to 1/4”.
Ideally suited to remove a very thin layer of
the surface to restore the pavement`s
evenness for thin lift overlays.
Skid Resistance
Surface Comparison
Standard Milled Surface
Micro Milled Surface
Standard Drum Pattern
5/8” Bit spacing
Can be used for complete removal up to 14”
Most common practice in todays mill & fill
Traditional Mill Process
What is Micro Milling?
Roughly 3 times the cutting bits of a standard
drum
Best if used from 0”-2” milling depths
Used when surface texture matters the most
Micro Mill Process
Ridge To Valley Depth (RVD)
Traditional Drum RVD 5/16” or 8mm deep
Micro Drum RVD 3/32”- 1/8” or 3 – 4mm deep
Micro Milling Results
Up Close Micro Milled Surface
RAP From Micro Milling
Micro Mill Advantages
Shallow grooves and small vertical edges allows
you to open to traffic
Can grind entire job complete before paving
Creates a smaller RAP size
Bump Repairs
Research shows better adhesion for asphalt
When applied correctly micro milling can put IRI
values in bonus $$$ Range
Determining Factors For Surface
Texture/Surface Pattern
Bit Spacing (From 1/4” to 5/8”)
Wrap Configuration
Forward Speed
RPM
Diameter of Drum, (Typically set by
manufacturer)
Drum Maintenance (Very Important)
Cutter Drum Maintenance
Keep from hitting structures!!
Do not use to remove boulders (3” or Larger)
Don’t Replace used holders with new holders
Maintaining Cutter Drums
New Toolholder vs Used Toolholder
Micro Mill With Multi Plex Sensing
Multiplex systems are used to measure sustained, stretched-out unevenness
and combine multiple sensors on one or both machine sides (e. g. cable,
ultrasonic, cylinder sensor). Using the average value of the connected
sensors, the current milling depth is calculated with high precision.
Longitudinal waves can thus be highly compensated for. The system is
especially suited towards fine milling work.
With the Multiplex levelling system, sensor signals are calculated to arrive at an
average differential value. This enables unevenness to be smoothed out considerably.
Questions?