FINE MILLING and MICRO MILLING…to the next “level”

October, 2015

Why Fine / Micro Milling?

• Remove wheel ruts or uneven pavement surfaces• Roughen pavement surface to improve adhesion of thin wearing course

or seal coat applications• Restore skid-resistance to worn, slippery pavement surfaces• Allow milling crew to operate independently from paving due to surface

texture that allows opening to traffic• Cost savings related to the reduced amount of material needed• Potential to allow traffic to use surface as milled over extended periods• Reduce the amount of tack, as the peak-to-valley ridges decrease

What can it do for you?

Why Fine / Micro Milling?

Material Removed New Material Required Haul Trucks Time Required For Mill & Fill Overall Contractor Costs Overall Cost of Project

What can it do for you?

Plan Work To Meet Job Requirements

Restoring Elevations• Smoothness specification

usually tied to bump detection

• Cold planer should do the bulk of the smoothness improvement

• While also providing good texture

Plan Work To Meet Job Requirements

Creating Profile (Slope)• Cold planer has same

slope capability as a paver

• Whenever possible, cold planer should use automatic slope control to create specified profile

Surface texture• Texture contributes to

smoothness – especially thin lift over milled surface

• Depends on:-- milling speed-- condition of rotor tools-- rotor tool spacing-- cut depth (delamination)

Plan Work To Meet Job Requirements

• Properly milled surface simplifies the paving process

• Improper milling creates problems for the paving process

• What problems do you see?

Condition of Milled Surface

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Scalloping-Too fast forward speed

Best practice- Drum Speed

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Drum speed vs. Travel speed.• Consider a reasonable ratio of Cutter RPM to

Travel speed to maintain quality.• Most cutter drums turn about 100 rpm.• When the Machine moves forward, a tool

striation mark is created approx- 3.5” to 4” long (10 cm)

• When the travel speed exceeds the drum rpm, the machine outruns the cutter.

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Travel speed continued

• When the cutting tools are not overlapping their adjacent tool striation, a very poor quality surface finish results.

• The surface can become scalloped, and /or just individually gouged.

• An acceptable ”rule of thumb” is that the travel speed not exceed 2/3 of the cutter drum RPM.

• EX----100RPM at 66 FPM• This allows a 1/3 overlap in the striations

between adjacent tools.

• Slope does not care about depth

• High spots in the grade can cause the screed to drag

• Depth not always equal across mat width

• Emphasizes the need for quality control during milling step

Paving Under Slope Control

• Standard drum impact spacing is 16 mm (5/8”)

• High density drum impact spacing is 6 mm (1/4”)

• Higher operating cost• Smoother milled

surface• Finer gradation RAP

Want Smoothness?High Density Drum

Smoothness• Milling considered one

opportunity to improve smoothness in most specs

Plan Work To Meet Job Requirements

Worn Drum Cutting a Crown• Worn carbide tool holders can also create another

issue.• Typically, the rotating tools in the center of the drum

will see more material flow.• This can create a crown in the milled surface.• This issue is somewhat corrected by the moleboard,

but the moleboard can then wear to the crowned shape.

Worn carbide holdersImage of a “crown” situation

Evolution of Cutting Tools

• Polycrystalline Diamond Powder• Tungsten Carbide Substrate• Sinter the two elements together using a

proprietary high pressure/high temperature press process to form the StingerTM tip

• Braze together the tip, carbide bolster, and hardened steel body

Microscopic View

Hard Frame Press

Cat® Diamond Bit Anatomy

Each phase of this design acts as building block to provide longer wear through improved thermal characteristics.

540 Asphalt Bit

• ½” diameter carbide bolster brazed to the tip and hardened steel body.

• Application– Asphalt ONLY

625 Extended Life Bit

• Bullet shaped carbide bolster brazed to the tip and hardened steel body

• Applications– Asphalt– Asphalt off of Concrete

STINGER POLYCRYSTALLINE DIAMOND

TUNGSTEN CARBIDE

STEEL

• Asphalt Milling Applications• Proprietary One-Piece Design

− Replaces the need for a tool holder• Non-Rotating Bit

− Because the StingerTM tip is wear resistant there is no need for the bit to rotate and more uniform wear provides a better cut

• Bits available to fit most drumtypes:− Cat− Wirtgen HT11− Kennametal− Sollami− NovaPick

Features

Benefits

NEW ENGLAND

• BODY WASH• SAME FLAT PATTERN• SAME GAUGE HEIGHT

SMOOTHER ROADS, BETTER FUEL ECONOMY, LOWER VIBRATION

Diamond Teeth Stay Sharp• Reduced fuel consumption• Reduced rotor drivetrain

loads• Less vibration• Longer structural life• Component life• Improved operator comfort

Teeth Engage

Additional Benefits

FUEL DATA RESULTS

14.9% Fuel Savings

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Future

• More Fine and Micro Milling requirements

• Growth for Asphalt recycling and related savings

• Improved wear course life• Better Roads for less dollars

Thank YouThank You