EXPERT ADVICE
MILLING
BEST PRACTICE
Defining good operational practices
By Jeff Winke
T he asphalt milling machine — also known as a cold planer , pavement planer , pavement recycler , or roto-mill — is a construction machine used to remove bituminous pavement or asphalt concrete from roadways and other pavements . The result is a somewhat rough , but even surface , that can immediately be opened to traffic .
The milled surface is accomplished by bringing a rotating mandrel or “ head ” into contact with the pavement at an exact depth or slope . The mandrel has hundreds of hardened spikes or teeth on its surface , which bite and cut away at the pavement ’ s surface .
“ Make sure the milling teeth are appropriate for the pavement ,” stated Bill Bethards , OEM sales manager , RoadHog , Inc ., Brownsburg , Indiana . “ Many factors can affect tooth life , such as depth of cut , aggregate type , remaining oil content and pavement density .”
Bethards continued , “ Make sure the teeth , and their holders , are in good condition . Examine tooth wear early in the job , to determine tooth life characteristics , and check regularly during production . Make sure the teeth rotate freely in their holders , so that they can self-sharpen . Frozen teeth will result in flat spots and ultimately wear to the point of damaging the holders .”
The material that is removed during milling is normally fed by conveyor into a dump truck or semitrailer , but can be left in place or windrowed to be removed or recycled later . A water spray system provides cooling for the mandrel , as well as dust management .
In the 1970 ’ s , Galion Iron Works , based in Galion , Ohio , manufactured the first production milling machines , which were called Galions . These first units resembled motor graders in shape and size . The difference was there was a 760 mm-wide ( 30-inch ) milling head where the scraper blade would normally be . The cutter drum was set into action by a large hydraulic pump .
Asphalt milling is the process of grinding up asphalt that can then be recycled . The process came about because many streets were getting layered higher and higher as new surfaces were added , thus reducing the curb height and creating roadway drainage problems .
1.800.210.5923 [ 17 ]
August 2021