3.3.5 Straightness. Machine dowel pins shall he straight 05cr the effective length within an accumulative total of 00005 in. per inch of length for nominal lengths. up to and including 4 in,. and within 0.002 in. total for all nominal lengths oser 4 in.
3.4 Surface Roughness
The surface roughness on hardened ground machine dowel pins shall not exceed K mieroinch 1p.m.) tarithmctical average) on the effective length nor 125 gun. iarithmetical average) on all other surfaces. Refer to ASME 1146.1. For pins having additive linishcs. thcsc liniis shall apply prior to coating or plating.
3.5 Material and Heat Treatment
3.5.1 Steel. Hardened ground machine dowel pins shall be made from any carbon or alloy steel capeble ol’ bemg heat treated to a core hardness of Rockwell C54) minimum and having sulphur and phosphorus content not in excess of 0.05’i and 0.04w. respectively.
3.5.2 Heat Treatment. Pins shall he burdened by quenching in oil (mm the austcniling temperature and tempering to mcci the following conditions. Case Hardened Pins. Pins shall he hardened to a minimum total case depth of 0.010 in. for nominal pin sues % in.. or smaller, and 0.015 in. (or nominal pin sizes in.. and larger. The case shall have a minimum surface hardness of Rockwell C60. or equivalent, and the core hardness shall be Rockwell C47 to 58. The microstructure shall be tempered martensite. Through Hardened Pins. At manufacturer’s option, pins smaller than in. nominal size may be through hardened to a hardness of Rockwell C50 to 58. Ifoweser, in no instance shall the hardness o4’ the pin surface be softer than that of thc core. The p’nicrostruclure shall be tempered martensite.
3.6 Finishes
Unless otherwise specified, machine dowel pins shall be furnished with a ground (as processed) finish or with black oxide coating at the option of the manufacturer. Other protective or decorative finishes, where required, shall be subject to agreement between the manufacturer and purchaser. However. where a finish applied to carbon or alloy steel pins is such that it might produ.e hydrogen embrittkment. the pins shalt be baked for a suitable time at a temperature that will ohs late such cmbnnlcrncn. Baking shall he accomplished as soon as possible following the plating or coating operating inasmuch as delay is detrimental to achieving the desired results. Whcre additivc.typc tinishes are used, the iahulaied dimensions and tolerances shall apply to the pins prior to application or the plating or coating. unless otherwise spccihed by ihc purchaser.
3.7 Workmanship
Dowel pins shall be free front detrimemal burrs. cracks. scams, or nicks and other defects affecting Iheir serviceability or pmpcrtics
3.8 Designation
3.8.1 lbrdened ground machine dowel pins shall be designated by the following data, in the sequence shown:
Product name (noun first), including pin scncs; nominal pin diameter fraction or decimal equivalent): length (fraction or decimal equivalent): material; and protective finish. if required. See the following esamplcs:
Pin. Hardened Ground Machine Dowel—Standard Series. X 1 ‘4 Steel, Phosphate Coated
Pin. llankned Ground Machine Dowel—Oversize Series. .625() X 2500. Steel
3.8.2 For a recommended part idenfifying numbering system (PIN). see ASME Bl&24.3.
3.9 Application Information
3.9.1 Hole Sizes. Because of the wide variety of materials in which dowel pins are used and of the many design requirements which must be considered. i is not possible to provide hole size recommendations that will he suitable for all applications.. However, the suggested hole sizes tabulated in this subparagraph have been commonly used for press-fitting standard series machine dowel pins into materials such as mild steels and cast iron. In soft materials such as aluminum or zinc die casting hole size limits arc usually decreased by 40O5 in. to Increase the press lit.