Issue link: http://read.dmtmag.com/i/266311
HOT-MIX MAGAZINE 20 VOLUME 19 NUMBER 1 T he asphalt milling machine— also known as a cold planer, pavement planer, pavement recycler, or roto-mill—is a construc- tion machine used to remove bitu- minous pavement or asphalt con- crete from roadways. 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 pave- ment 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 roadway's surface. The surface material that is removed is normally fed by conveyor into a dump truck or semi trailer, but can be left in place or windrowed to be removed or recycled later. A water spray sys- tem provides cooling for the man- drel, as well as dust management. IN THE BEGINNING In the 1970's, Galion Iron Works, based in Galion, Ohio, manufac- tured 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 in) 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 road- way drainage problems. Early milling machines were simply a mining mandrel attached to a mobile undercarriage. They were designed to remove a layer of old concrete or asphalt so that a new layer could be applied to a better quality base than resurfacing over the old road surface. MORE MATERIAL REMOVAL From the start, the emphasis for milling machines was to place more power to the cutting drum, which is needed to remove more mate- rial. Thus, the cutter head itself and Roadtec adds flexibility to its machines by manufacturing and assembling the milling tractors and cutters separately. Milling Best Practices Road construction's smooth future 13609_Astec_HotMixV19N1.indd 20 2/18/14 11:24 AM