Richard Comely, Director of Product Management at Ransomes Jacobsen, looks at Frequency of Cut (FOC) and its importance to the quality of cut on fine turf
For FOCs Sake! T
o begin this article, I would like to quickly review the theory and fundamentals of the cylinder mowing process. I may be teaching
many of you to suck eggs but, understanding the principles of mowing fine turf, is a good starting place. A cylinder mower cuts grass with a scissors-
like shearing action between the rotating cylinder blade and the stationary bottom blade (also known as a bedknife). The cylinder has a number of helical knife-like blades, evenly
lawns, parks, athletic fields, and golf courses. Mowing to a schedule with correctly adjusted and sharpened cylinder units is the most important factor in maintaining healthy, well- groomed turf.
Quality of cut refers to how well the individual grass blades are cut. A properly adjusted and sharpened cylinder mower cuts grass cleanly without tearing, shredding or bruising the grass
Poor Quality of Cut
Grass, cut with dull blades or improperly adjusted cutting units, has poor colour, slow
growth recovery, and a ragged appearance. This increases drag, resulting in a slower playing surface. Shredded and torn grass blades also tend to require more water and fertiliser and, therefore, cost more to maintain.
Frequency of Cut
spaced and maintained at the same cutting angle on round support members called spiders, webs or collars. The cylinder shaft is driven by drive gears, belts, or motors. Below the cylinder is a flat, stationary bottom blade mounted rigidly on a solid backing plate. The bottom blade holds the grass erect and, as the rapidly rotating cylinder blades pass over the bottom blade, they cut the tops off the grass blades. This cutting action is referred to as “shearing,” “clipping,” or “scything” by various mowing and sharpening equipment manufacturers.
Quality of Cut
Cylinder mowers have always provided the most effective means of maintaining well groomed
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blades. In addition to the sharpness of the blades, the adjustment of the cylinder blades to the bottom blade and the gap (clearance) between the cylinder blades and bottom blade are crucial to the quality of cut. The bottom blade must be flat and true where it meets the bottom blade backing, with no distortion or gaps
Good Quality of Cut
Grass, cut with sharp blades and properly adjusted cutting units, has good colour, rapid growth recovery, and a sharp, clean, uniform appearance.
Having looked at the theory and fundamentals of mowing, now let’s take a closer look at Frequency of Cut (also sometimes expressed as either Cuts per Metre or Clip Rate) and the consequences of correct and incorrect clip rates.
Frequency of Cut: FOC (expressed as cuts per metre or clip rate)
Frequency of cut is the rate at which the cylinder blades cross the bottom blade. In the US, this is quoted as the clip rate, and is expressed as either a decimal of an inch (0.15”/mph), or in millimetres (3.81mm/km/h). To determine the actual clip rate, simply multiply the rate by the speed. In Europe, FOC is often expressed as cuts per
metre. Here, a metre (1000mm) is divided by the clip rate, giving the number of cuts per metre. This, typically, shows the number of cuts per metre at the highest forward speed, therefore the lowest standard of finish likely to be achieved. This measurement is much easier
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