In 2015, one of McLanahan’s customers in the salt industry challenged the company to develop a set of rolls for their Roll Crushers that would allow them to produce a more consistent product size. The original roll shells they had in their crushers were not achieving their goal of a large percentage passing a certain product size.
“We started looking at different ideas on what we could do, what kind of rolls we could make to achieve a tighter roll setting, which would allow them to produce a more consistent product size,” said Dan Holes, Director of Parts and Service for McLanahan’s North America facilities.
The customer had tried beaded roll shells, which are typically used for processing salt because they can achieve a tighter setting and therefore produce a smaller product. However, roll shells with welded beads produce a lower throughput than those equipped with teeth.
“The challenge was to produce a roll design with small teeth where we could get a tight body-to-body setting and still meet the customer’s throughput requirements,” Holes explained.
Body-to-body setting describes the distance between the body of one roll and the body of the opposite roll. The closer the roll bodies are to each other, the smaller the product that can be produced.
“We researched all different kinds of options,” Holes said. “We spent several months looking at the different design possibilities, casting pieces for trial fit, and through all that, our flat bottom segment was born.”
As the name implies, McLanahan’s flat bottom roll segment features a flat bottom and rests on a hexagonal or octagonal roll body. They’re intended use is in applications that require a consistent minus 1/2" to 1” material size, and the segments are small enough and light enough for one person to handle.
Holes said the benefits of this style of roll segment are threefold.
First, flat bottom roll segments can be produced with teeth. Roll segments equipped with teeth grab material quicker, process it quicker and size it better than the standard beaded rolls that are typically used in salt crushing machines.
The second benefit of the flat bottom roll segments is that they allow for a much tighter body-to-body setting. Because the segments are cast using a method that can achieve tight tolerances and the roll bodies are machined to be concentric and symmetrical, a much tighter roll setting can be achieved across the width of the rolls.
“We can achieve the smaller product sizes desired and a much higher percentage with the flat bottom roll segments,” Holes explained.
The third benefit of flat bottom roll segments is they are maintenance-friendly. The segments are heat treated to various hardness levels, depending on the application, for maximum longevity.
“The wear resistance on these segments is quite remarkable,” shared Holes.
Maintenance, when required, is fairly easy. Because the weight of the flat bottom roll segments is so low, one person can replace them when necessary.
“We’re quite proud of the fact that the flat bottom roll segments weigh less than 40 lbs,” Holes said. “In addition to finding a solution for producing a smaller product more consistently, we also took into account ergonomics and safety.”
Pleased with their design and the results of the tests, McLanahan shipped the new flat bottom roll segments to the customer.
A few months after the flat bottom roll segments were installed on the crushers, the customer called McLanahan to report on their performance. The rolls were performing so well that the customer was talking about removing the recirculation system they had installed to account for the percentage of oversize material passing through the previous set of crusher rolls.
The customer was so pleased with the flat bottom roll segments that when they ordered a replacement Triple Roll Crusher in 2019, they insisted that both the primary stage and secondary stage be equipped with the flat bottom segments.
“We had to get a little creative with our design to get primary segments on the top stage, but we were able to provide what they requested,” Holes said. “It’s running today, and they’re very happy.”
Since then, McLanahan’s flat bottom roll segments have been used in a variety of mining industries, including limestone, taconite and talc applications. Besides benefitting from McLanahan’s robust equipment, these applications benefit from partnering with a knowledgeable company that has been providing tailored, field-proven processing solutions since 1835.
“In addition to the mining-duty equipment that we provide, we’re always there to listen to our customers’ needs. We’re more than willing to make modifications to our existing equipment to suit those needs, so much so that we’ve gone to the drawing board and completely redesigned a roll for inside one of our crushers per the request of a customer,” Holes said. “They saw a need for something better; we recognized that need and produced something that was far beyond their expectations.”