Tumble machines

Typically, dry potassium nitrate is pulverized in a ball mill. Sulfur is milled into cellular charcoal to form a uniform mix in a separate ball mill. The nitrate and the sulfur—charcoal mix are screened and then loosely mixed by hand or in a tumbling machine. Magnetic separators may be used to ensure the absence of ferrous metals. The preliminary mix is transferred to an edge-mimer wheel mill with large, heavy cast iron wheels. A clearance between the pan and the wheels is required for safety purposes. The size of this gap also contributes to the density of the black powder granules obtained. Water is added to minimize dusting and improve incorporation of the nitrate into the charcoal. The milling operation requires ca 3 to 6 h. 

The parathion was removed from the surface of the fruit with benzene (redistilled) in an end-over-end type tumbling machine at a speed of 72 revolutions per minute. All samples were washed in this manner for a period of 0.5 hour. Reagent blanks and unsprayed fruit blanks were run with all samples. All results, as reported, have been corrected for reagent and fruit blanks. 

TABLE 12.13. Moisture Requirements for Successful Granulation in Tumbling Machines... 

The primary classes of FW are hoop, polar, and helical. The simplest is hoop or circumferential winding, in which fibers are wound approximately normal to the mandrel axis of rotation with the fiber payout head advancing one band width for each revolution of the spindle. Hoop winding is usually combined with helical winding in more complex parts. Polar or tumble machines are used for parts wound using a planar winding path (such as for a short closed-end pressure vessel). These machines normally have the mandrel mounted vertically, over which a rotating arm wraps fiber onto the mandrel. 

For smaller parts, tumble machines can be used to rotate the part about a fixed arm. Helical winding machines give greatest flexibility and are most common. There is a wide variety of machinery and control systems and these machines can be used to wind fi om simplest to most complex shapes. 

A typical enzymatic stone-washing process (76) is as follows load garments into industrial laundry machine, add water, and heat to 50—60°C. Adjust pH to 6.0 with acetic acid or buffer. Desize garment with a-amylase for 10—15 min, and drain water. Add new water, heat to 55—60°C, adjust pH to 6.5—7.0, and add ceUulase. Tumble for 20—90 min, drain, rinse twice, and dry. 

The availability of more powerful, continuous machines has extended the possible applications to both lower- and higher-size ranges, from 5 to 200 [Lm product size, and to feed size as large as 5 mm. The energy density may be 50 times larger than in tumbling-ball mills, so that a smaller mill is required (see Fig. 20-37). Mills range in size from 1 to 1000 L, with installed power up to 320 kW. Specific... 

Surface preparation, e.g. polishing, tumbling, blasting, etching or a machine process, may be required due to the nature of the process or due to surface contamination. This can be an added source of variability. 

After degreasing, metals have to be blasted with a sufficiently abrasive material to remove the surface oxidation layer. Application of the abrasive to the metal surface to be cleaned depends very much on the dimensions and type of metal. Large dimensioned metals and interiors of such articles as tanks, will require application of the abrasive by means of air blasting techniques. Smaller metals of suitable strength can be treated in rumbler machines where the metals are tumbled whilst being blasted by the abrasive carried in an airstream. 

A loose abrasive powder can be used to impinge on the rubber rather in the manner of a shot blasting machine, or tumbled with the rubber test pieces in a rotating drum. These are logical ways to simulate the action of sand or similar abradants impinging on the rubber in service, as may be the case with conveyor belts or tank linings, but this type of test is not very common. 

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