Forstner bits, flat-bottomed to drill holes in wood materials, they can cut on the edge of a block of wood, and can cut overlapping holes; for such applications they are normally used in drill presses or lathes rather than in hand-held electric drills. Because of the flat bottom of the hole, they are useful for drilling through veneer already glued to add an inlay.
The bit includes a center point which guides it throughout the cut (and incidentally spoils the otherwise flat bottom of the hole). The cylindrical cutter around the perimeter shears the wood fibers at the edge of the bore, and also helps guide the bit into the material more precisely.
Forstner bits have radial cutting edges to plane off the material at the bottom of the hole. The bits shown in the images have two radial edges; other designs may have more. Forstner bits have no mechanism to clear chips from the hole, and therefore must be pulled out periodically.
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National Fertilizer Production Increases by 6% in the First Quarter
According to the latest statistics released by the National Bureau of Statistics of China Chemical News, in March, the country produced a total of 5.474 million tons of fertilizer (amount of purification), an increase of 7.7% year-on-year; a total of 14.428 million tons of chemical fertilizer was produced in the first quarter, an increase of 6% year-on-year. In terms of sub-species, the output of phosphate fertilizer and potash fertilizer continued to maintain a high growth trend. In March, the country produced 1.277 million tons of phosphate fertilizer, an increase of 22.9% over the same period of last year. In the first quarter, the cumulative production of phosphate fertilizer was 3.387 million tons, a year-on-year increase of 22.3%. A total of 211,000 tons of potash fertilizer was produced in March, an increase of 41.1% year-on-year; in the first quarter, a total of 589,000 tons of potash fertilizer was produced, an increase of 43.3% year-on-year. The growth rate of nitrogen fertilizer production was relatively small. In March, the total nitrogen fertilizer production was 3.885 million tons, which was a year-on-year increase of 3.5%. In the first quarter, cumulative production of nitrogen fertilizer was 10.441 million tons, an increase of 0.5% year-on-year.