DIN 76-A is a specific form designation within the German institute for standardization (), specifically under the DIN 76-1 standard. This standard dictates the dimensions, shapes, and surface configurations of thread undercuts for components featuring external Metric ISO threads.
For internal threads:
: While undercuts allow for flush seating, they can also act as stress concentrators. Engineers must use the dimensions in DIN 76 to balance assembly needs with the fatigue life of the part . din 76a pdf
when you require a tight, flush assembly with zero gap between the component shoulder and the mating face. It is ideal for precision machinery, fluid fittings, and adjusting screws. However, be aware that the reduced diameter ( DIN 76-A is a specific form designation within
: In many modern applications, DIN 76 is cross-referenced with international standards like ISO 4753 (for thread ends) and ISO 3508 (for thread run-outs), though DIN 76 remains the preferred choice in European automotive and heavy machinery sectors. Engineers must use the dimensions in DIN 76
The angle leading from the undercut back up to the thread major diameter, typically designed at 30∘30 raised to the composed with power to accommodate standard machining inserts and tool paths. DIN 76-A Technical Data Reference