Road Maintenance Means Millers Keep on Churning

Aug. 24, 2016

Things are looking up for the milling machine market and manufacturers continue to invest in technology to make cold planing more efficient and cost effective.

“The market for milling machines is up from 2015 across each size class, with a slightly larger increase in the high horsepower class,” says Kyle Hammon, product manager, Mills, Stabilizers, Booms, for Roadtec. “I believe this is a function of increased funding for road construction and the resulting increase in milling projects.”“The milling machine market is generally experiencing slow, positive growth,” says Dave Peterson, North America marketing consultant, Cold Planers, for Caterpillar. “It fluctuates a bit due to budgeting and some of the general market volatility caused by the commodities market and the price of oil. As RAP becomes more valued and existing roads mature, the need for milling will increase.”

Cost of Ownership

Size class (inches) Avg. price Hourly rate*
26-49.9 $468,428 $283.10
50-71.9 $501,686 $336.54
72-87.9 $656,319 $471.87
88 & over $794,482 $645.29

*Hourly rate represents the monthly ownership costs divided by 176, plus operating cost. Unit prices used in this calculation: diesel fuel at $2.36 per gallon; mechanic’s wage at $56.67 per hour; and money costs at 2.5 percent.

Jeff Wiley, SVP, Wirtgen America, agrees. “Cold planing fits squarely into the growing trend toward programmed preservation of pavements,” Wiley says. “When you are preserving an existing pavement, you will be repairing it. Sometimes you’re cutting out a patch, sometimes you’re cutting out wheel ruts, sometimes you’re re-sloping the road to get better drainage, sometimes you’re creating a crown in the cross section, or using a fine-textured milling machine to flatten out asphalt shoving problems prior to opening the pavement back up to traffic.”

For the purchase process, as with most iron, managers should focus on the exact applications.

“Consider what your primary application is, such as mainline milling, urban streets, perhaps resurfacing,” Peterson says. “This can dictate what the ideal machine configuration will be or what features you will need. Some features can be scaled up as needed, allowing you to purchase additional features as required rather than up front.”

Hammon also keys on application. “What cut depths will the machine typically be required to perform?” he says. “What cut width and work speed range will the machine need to achieve in order to maintain a schedule with the other activities within the project? Also, if a specified surface pattern is required, the spacing of cutter drum tooling is a very critical component.”

Because of wear, heat, and dust, serviceability is another important consideration.

“Servicing the machine should be a big concern—can you freely access the primary maintenance and service areas?” Peterson says. “If not, you may experience downtime simply by needing to remove other systems to access the areas you need to get to. The machine should be easy to use and the controls should be easy to understand,” Peterson says. “This will minimize training and optimize efficiency.

“Also, visibility and safety are primary concerns. Check to see if there is good visibility and options to enhance awareness around the machine,” Peterson says.

Flexible machines seem to be in demand, according to Wiley.

“Every job is different, and the biggest thing that operators benefit from is flexibility of machine application,” he says. “The operator today has the opportunity to select the type of grade-control system he or she wants to use. It could be a laser system, running off stringline, GPS, dual-grade, grade-and-slope, averaging, averaging with three sensor heads, or seven sensor heads. The owner can have anything and everything he or she needs to perform the most precise job.”

But managers have to demonstrate ROI on the cost of all that technology.

“Some of the highest technology grade-control systems can be quite expensive,” Wiley says. “You have to justify it on the job. But having the technology enhances the performance and flexibility of the milling machine.”

Also, managers should think about keeping a crew and a machine together to promote familiarity with the technology.

“It’s important that an owner keep his crew with a machine as long as he can,” Wiley says. “It’s not a good idea to send the crew back to the union hall at the end of year, and get a new operator and crew the next year that has to be trained all over again on that machine.

“When crews stay on a machine month after month, year after year, they understand it, they know what to do on the machine to keep it up and running, they have memory and records of any issues or problems with the machine,” Wiley says. “Having new crews all the time is not good for a milling operation. The best crews are those that have been with the machine for the life of the machine.”

To keep costs down, Caterpillar’s Peterson suggests following maintenance plans, and checking maintenance points and wear parts daily.

“Sharp cutting bits, or even better, diamond bits, reduce the load on the machine, minimizing fuel consumption and machine wear,” he says.

“Equipment maintenance is key,” Wiley says. “To me, it doesn’t matter how old the machine is, or how many hours are on it, or what model it is. What matters is the condition of the machine and how well it’s been maintained.

“If a machine is ‘tight’ and not ‘loose,’ every time the grade control calls for an adjustment, the milling machine will respond and not create ups-and-downs due to the way it’s been maintained,” he says. “A tight machine like that will achieve as good a pattern as a brand-new machine. That’s why the machines need to be kept in a good operating condition.”

Peterson advocates planning planing and using additional technology to minimize possible downtime. “Pre-plan to minimize the risk of hitting unseen obstructions, which can stop production and possibly damage the machine,” he says. “Metal detection and ground penetrating radar are seeing more use for this purpose.”

Also, managers and users should pay attention to milling speed. This is another area where planning ahead can be beneficial.

“Milling speed is often misunderstood,” Peterson says. “It’s often assumed that faster ground speed means more production; however, this can have a negative effect in terms of wear on the machine and expedited wear of bits and other consumables, which will cause part replacement costs and downtime for service. It also affects the quality of the milled surface, which can have a negative effect on meeting the final specification for the application.

“An optimal speed can often be determined with detailed pre-work planning,” Peterson says. “A good rule of thumb is that the ground speed [feet per minute] should not exceed 75 percent of the rotor speed.”

Wirtgen’s Wiley stresses that consistency of speed is important. “The more consistent a machine’s speed, the better off the operator will be,” he says.

“It doesn’t make sense to run at full speed, slow down and stop, change trucks, and run at full speed again. That changes the milling pattern significantly; you are better off running at a slower, more consistent speed, as it will result in a lot more precise pattern or texture of cut, and that will benefit the paving operation.

“Another way of keeping the machine moving is adding water, used to cool the drum and suppress dust, ‘on-the-fly,’ without stopping,” Wiley says. “While the mill moves forward, a water truck moves parallel with the machine, filling its water tank.”

“During operation,” Roadtec’s Hammon says, “proper use of the machine’s water system can minimize wear of the drum tooling—and time devoted to maintenance.”

Suppressing dust has become much more of a concern since NIOSH released its guidelines in 2015. The major OEMs in the category were ready.

BOMAG’s BM2000/75 counts a dust suppression system as standard equipment. Its smaller, 300-horsepower class BM1200/35 can have a dust suppression kit added at the manufacturing plant or in the field by technicians.

Caterpillar’s PM620 and PM622 models have a primary water spray system augmented with a vacuum system to control dust to meet the NIOSH standard. An optional secondary water spray system can be added to the primary system to increase the level of dust control.

Wirtgen offers an optional Vacuum Cutting System that extracts fine material particles right at the cutting drum, promising better air quality and visibility in the working environment for both operators and ground crew members.

“Roadtec began adding a dust extraction system to all half-lane and full lane milling machines as a standard feature in January of 2015,” Hammon says. “Retrofit kits will be made available for older Roadtec models.”