The tolerances set forth herein represent what the Forging Industry Association believes to be typical within the industry, as determined by actual measurements . Is Die Steel Forging Standard – Download as PDF File .pdf), Text File .txt) or read IS to 3 (): Tolerances for Closed Die Steel. Resource for typical forging tolerances with impression die forgings.

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Be sure to contact technical personnel at your forging source for help in determining such special capabilities.

Is.3469.1-3.1974 Die Steel Forging Standard

It is important that forging drawing be accurate and complete. All individual tolerances apply to each and every forged part unless specifically noted otherwise. From the highest to lowest point of contour. This will assist in the design of forging dies and tools, and in establishing effective inspection procedures. Unless the purchaser’s drawings and specifications direct otherwise, all dimensions are normally assumed to refer to lines intersecting at right angles to each other commonly referred to as X, Y, and Z axes.

Block-type forgings with neither length, width. Surface Tolerances relate to depth of dressouts, scale pits and other imperfections on the surface of forgings. The purchaser should indicate his first operation locating points, normally a part of the drawing, and give prior notice should these points be changed. Area at the Trim Line Flash not included, expressed in square inches. Die Closure Tolerances relate to variations in thickness of forgings as affected by the closing of the dies and die wear, and pertain to variations in dimensions crossing the fundamental parting line.

IS 3469-1 to 3: Tolerances for Closed Die Steel Forgings

Giving consideration to the fact that forgings undergo dimensional changes due to cooling and because forgings are formed in forgnig cases between two impression dies that are not precisely on the same centerline, the ANSI Y These include, cold and warm coining to achieve closer thickness tolerances, using special pressure padded trimmers for improving straightness, cold sizing of holes for improved tolerances on hot pierced holes, and warm forging as a manufacturing process.


Over 50 to incl. This tolerance is in addition to the Die Closure Tolerance. This tolerance guide provides dimensioning and tolerancing that is considered linear and not geometric.

Extremity Tolerances are expressed as decimal millimeter in units of 0. Over 10 to 30 incl. Radii Tolerances are plus or minus one-half the specified radii, except where corner radii are affected by subsequent removal of draft by trimming, broaching or punching.

The male portions of dies may, in special situations, tend to mushroom or upset rather than wear. Greatest Length mm x Foeging Wear Tolerance factor.

Theoretical exactness is seldom attained, and it is therefore necessary to make allowance for foorging. In cases where measurements for determining match tolerances must be made from surfaces of the forging where uneven wearing of the dies has caused surplus stock, accuracy depends on making the proper allowances for these wear-caused surpluses, and eliminating their influence from the computation.

It is equally important that the purchaser provide drawings of the finish machined part, or equivalent information. This tolerance includes allowance for shrinkage, die sinking and die polishing variations. Flash Extension Tolerances are expressed as decimal inch, in units of 0. Diameter mm x Forgibg Wear Tolerance factor. Largest Diameter x Die Wear Tolerance factor. Straightness Tolerance applied to flat portion. Over 30 to 50 incl.

See Table II, below. Over 65 to x Tolerances in this publication are expressed in decimal inch with metric equivalents sometimes referred to as “soft” metric conversion in the belief that this represents a practice most common frging the industry at the time of publication.

The tolerances set forth herein represent what the Forging Industry Association tolsrance to be typical within the industry, as determined by actual measurements of forgings produced under normal operating conditions on standard forging equipment.


Where possible, measurements are made at areas of the forging unaffected by die wear. Draft Angle Tolerances apply to all draft angles, specified on drawings that are not affected by subsequent operations. Flash Extension Tolerances are based on weight of the forging after trimming, and related to the amount of flash extension.

Toleranxe to incl.

Where tolerances are desired, agreement between purchaser and forging producer is normally reached before production proceeds. Match Tolerances are expressed as decimal millimeter in units of 0.

Where surfaces of forgings are intended for use in “as forged” condition, surface imperfections are commonly permitted as shown in Table VI.

Greatest dimension x Straightness Tolerance. Match Tolerances are based on weight tolerabce the forging after trimming and are 4369 as decimal inch or decimal millimeters according to Table III, below. Straightness Tolerances are applied independently of, and in addition to, all other tolerances. Weights of Forgings after Trimming, in Pounds.

There are practical limitations in dimensions and other characteristics of forged parts or products which vary according to tolerace part or product and the producer’s equipment.

9. APPENDIX A – TOLERANCES FOR IMPRESSION DIE | Forging Industry Association

Die Closure Tolerances on forgings are tolersnce on the projected area of the forging at the trim line, not including flash, but including all areas to be subsequently punched out, and are applied as plus tolerances only. Die Closure Tolerances are expressed decimal millimeter in units of 0. Decimals used in computing tolerances are totaled and raided to the next highest 0.

The Tolerance on flat portion is computed first: