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Auger Flighting Design Considerations
Auger Flighting Design Considerations: American Society of Agricultural Engineers
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ANSI/ASAE EP389.2 JUN00
Approved JAN 1994; reaffirmed JUN 2000 by American National Standards Institute
Auger Flighting Design Considerations
Developed by the Auger Flight Subcommittee of the ASAE Power and Machinery Division Standards Committee; approved by the Power and Machinery Division Standards Committee; adopted by ASAE December 1977; revised editorially December 1980, January 1982; reconfirmed December 1982; revised March 1988; reaffirmed December 1992; revised June 1993; approved as an American National Standard January 1994; revised editorially by ASAE May 1997; reaffirmed by ASAE December 1998; reaffirmed by ASAE December 1999; reaffirmed by ANSI June 2000; reaffirmed by ASAE for five years January 2001.
1 Purpose and scope
This Engineering Practice is a guide for designing conveyor augers using steel helicoid flighting and for specifying helicoid flighting as generally used in agricultural equipment.
2 Normative reference
The following standard contains provisions which, through reference in this text, constitute provisions of this Engineering Practice. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this Engineering Practice are encouraged to investigate the possibility of applying the most recent edition of the standard indicated below. Standards organizations maintain registers of currently valid standards. ANSI B32.3, Preferred Metric Sizes for Flat Metal Products
3 Flighting material
3.1 Physical properties generally limit the number of materials that can be formed into helicoid flighting.
3.2 Present day helicoid manufacturing machines are designed for ferrous metals that are ductile and are therefore generally not used in manufacture of auger flighting from non-ferrous and plastic materials. Other means, such as molding, extruding, forming, and casting, must be developed for these materials. The heavy deformation of the material as it goes through the forming rolls of the flighting machine demands a material that is very ductile and which will stand large amounts of elongation and bending without fracture and wrinkling.
3.3 Hot rolled and cold rolled carbon steels with specifications in the area of AISI (American Iron and Steel Institute) 1006, 1008, 1010, and 1012 and hardnesses of no more than 115 to 140 BHN (Brinell Hardness Number) may be used satisfactorily. The more difficult the flighting is to make, the lower the carbon content must be in the strip. In many cases, it is necessary to use fully killed, fine grained steel. Stainless steel requires special consideration. Consult manufacturer before designing.
4 Flighting dimensions
4.1 Illustrations and standard tolerances for appropriate dimensions are shown in figure 1 and table 1.
4.2 Inside diameter, I.D. The selection of the nominal inside diameter will depend on the type of fit desired. Inside diameters less than 1/5 of the outside diameter should be avoided. Tolerance of shaft diameter used must be considered in determining the inside diameter.
4.3 Outside diameter, O.D. The outside diameter is determined by adding 2 times the strip width to the I.D. The O.D. is not specified except as a reference dimension for the loose helicoid flighting. O.D. tolerances on the completed welded assembly are given in table 1.
4.4 Pitch of flighting. The most economical pitch is equal to the flighting outside diameter. Pitches shorter than 0.9 O.D. and longer than 1.5 O.D. are generally not recommended. Pitches shorter than 0.9 O.D. or longer than 1.5 O.D. should only be used after verifying that the
supplier has the capability of making the part.
4.5 Strip thickness. The strip thickness may be determined from the outer edge thickness desired. The outer edge thickness is approximately
Figure 1 – Standard auger flighting features
ASAE STANDARDS 2003 261
