Tool Body and Insert Selection for Advent Tool Replaceable Insert Thread Mill
1. Select the thread form you desire to thread mill. (1.5" - 12UN internal)
2. Choose the tool body that will cut the thread form you need. (tool# 15-TA-01-F5)
3. Check the diameter of tool with inserts. This depends on the thread form on the insert.
4. Compare proper diameter of tool with minor diameter of thread, or drill size. The cutter diameter must not exceed minor diameter of thread, or drill size. (1.5" - 12UN minor diameter = 1.41")
5. Find insert style that fits body chosen.
6. Order insert by applying form to insert style. (insert# ATM-410A12)
Feed Rate Calculation
Due to the circular motion of the cutter as it forms a thread the actual feed rate at the cutting edge will be different from that which is programmed at the center of the tool. For an internal thread the feed rate at the edge increases as the cutter diameter increases. For an external thread the feed rate at the edge decreases as the cutter diameter increases. This can be shown as a direct relation between the size if the circle the cutter moves around, and the size of the circle cut.
Internal thread: F1 = F2 X ((Dw - Dc )/Dw)
External thread: F1 = F2 X ((Dw + Dc )/Dw)
F1 = Programmed feed rate at the tool center (in/min)
F2 = Actual feed rate at the cutting edge
Dw = Diameter of the work piece, or thread diameter
Dc = Cutter diameter
The actual feed rate is calculated using the standard formula : F = (RPM) X (Chip load) X (No. of teeth)
Thread Mill Programming
The simplest method to produce a thread form using an Advent Thread Mill is as follows:
1. The center of the hole being the X-Y zero point. Move the cutter to the center of the hole, then to the thread depth required.
2. Move the cutter over a small distance (usually about .02”towards the three-o’clock position) to call up your cutter compensation.
3. Machine in a counter-clockwise direction generating a 1/2 circle and ending at the full thread depth at the nine-o’clock position. Simultaneously moving 1/2 pitch in the Z direction. The direction of the Z movement will determine the handedness of the thread.
4. Produce your thread by generating 1 full circle (counter-clockwise) around the center, while moving 1 full pitch in the Z direction.
5. After the full form has been machined, return to your starting position near the center of the hole. This is done by generating another 1/2 circle (counter-clockwise) combined with a 1/2 pitch move in Z direction.
6. Return to your hole center, and exit the hole.