Thread Milling

Thread Milling

Thread Milling - This process is suitable for work upon which

(1) threads cannot be cut conveniently with the die head during the turning operation

(2) large diameters beyond the capacity of the die head

(3) threads of short length running up to a shoulder, and

(4) internal threads which are unsuitable or inconvenient for cutting with a tap.

Threads of high accuracy, particularly in larger sizes, often are cut by the thread milling process. Either a single or a multiple form cutter can be used.

Thread milling is an established method of producing accurate threads in both small and large quantities of threaded parts. With proper work preparation and rigid work holding and supporting means, accurate threads can be economically produced true, in relation to a specified surface on the work. Class 4 threads can be produced and pitch diameters held to 0.001 in. with surface finish of approximately 55 microinches.

Lead errors can be held to 0.001 in. per ft and spacing errors on multiple start work can be held within 0.0003 to 0.0004 in. Long screws and multiple start work may require rough and finish cuts to overcome distortion. The threads are produced by conventional thread milling and planetary thread milling.