WIRTGEN: Key impact of cold milling machines on road rehabilitation quality.Cold milling is one of the first measures taken when a roadway or traffic area needs to be rehabilitated.  Market-driven innovations for all applicationsWirtgen offers the most extensive line-up of cold milling machines in the industry, with milling widths of 14 mm to 4.40 m. Customers can choose from over 30 different machine types, each also available with a variety of milling widths. The lower performance class starts with the small 45-kW milling machines and extends through compact machines with engine outputs of between 257 and 298 kW to large milling machines in the upper performance class offering power reserves of up to 753 kW. The high level of customer-oriented design expertise guarantees market-driven innovations. The new solutions developed at the brand headquarters in Windhagen are founded on practical know-how and core competencies in leveling, control and cutting technology. Always on the levelTeamed with a wide range of sensors, the Wirtgen Multiplex leveling system can do much more than simple copying. Three sensors on each side of the machine scan the height at wide intervals along the same reference line. The automatic leveling system averages the three measurements to create a perfectly even milled surface, while meeting the target milling depth. This is a highly effective way of leveling out longitudinal undulations. What’s more, defined surface profiles can be created, such as specified cross slopes or crowns. Completely new surface profiles can be created by means of 3D milling. A new digital surface profile generated on the computer can be transferred directly to the Wirtgen cold milling machine using 3D leveling systems. Increased quality and cost-effectiveness are major benefits offered by 3D milling technology.Milling layers separately, recycling economicallyThe progressive automation of technical processes, in particular, plays a key role in optimising the milling result. To achieve optimum results, the leveling parameters for the respective machine are saved, linked to the LEVEL PRO automatic leveling system and retrieved during the working process. Due to the shallower milling depth, the cold milling machines work more quickly when removing the individual layers than when removing the complete pavement at maximum milling depth in a single pass. Milling off surfaces in two or three layers can sometimes be just as fast – in some cases even faster – than complete pavement removal, depending on the type of machine and pavement and on ambient conditions. Modern cold milling machines also have been specifically tuned to typical selective milling.Cutting technology: A wide range of efficient applicationsThe powerful “heart” of the cold milling machine – the milling drum assembly with all the cutting technology components – also has a critical bearing on the quality, costs and performance of the milling process. Here too, as technology leader, Wirtgen is continually developing cost-efficient solutions. Different milling drums support a wide range of milling applications on different road surfaces. The standard milling drums, for example, offer tool spacings of 12 mm, 15 mm or 18 mm. Fine milling drums usually have a tool spacing of 8 mm; in micro-fine milling drums the tooling space is 6 mm. The ECO Cutter milling drums developed by Wirtgen are designed for maximum milling output. They can even mill extremely hard materials such as concrete or rock cost-efficiently.Precise specification of the required qualityModern cold milling machines have a significant influence on the quality and cost-effectiveness of the overall rehabilitation measure, explains Bernd Holl, Product Manager for Cold Milling Machines at Wirtgen GmbH.(Communication by the management of the company)