How to calculate feedrate for drilling

Furthermore, the clearance between the tooth flanks is reduced, which tends to make the entire system more precise. Multi-start threads are often used for high helix threads.

How to calculate FeedRate for lathe

Lead screws are machine elements that convert a rotary movement into a translatory one. Lead screws consist of a cylindrical round rod on which a simple transmission thread is attached. The transmission threads can have, for example, the trapezoidal thread form or the dryspin® geometry designed by igus. We have explained the production of such lead screws in a separate blog post: https://blog.igus.eu/production-of-a-lead-screw/

How to calculate feedrate for milling

But in this post we will deal with the topic of the threadability or single and multi-start threads. What do these terms actually stand for and what is their significance in my application?

When multi-start lead screws are used, the effective support surface increases under the condition of a constant core diameter.

Single-start trapezoidal lead screw units are self-locking in most cases, depending on the coefficient of friction. This effect can only be weakened at a very low coefficient of friction. This means that the flank angle and the sliding friction prevent the nut or lead screw from moving without outside forces being applied. As soon as the static friction is exceeded, the components are no longer self-locking. Multistart trapezoidal screw drives have a “residual self-locking” feature; high helix screw drives have no self-locking feature. More information about self-locking can be found here: https://blog.igus.eu/self-locking-what-is-it/

How to calculate feedrate for turning

For the second lead screw (2nd graph from left) a further thread has been added. This means that with one revolution of the lead screw the two-fold stroke is achieved (lead = 2 x pitch). The start of the thread is offset by 180°, i.e. opposite each other. These are the multi-start threads.

Trapezoidal thread: TR20x8P4Thread diameter: 20mmLead: 8mm Pitch P: 4mmNo. of starts: 8/4=2 (Lead) / Pitch = No. of starts) ► TR20x8P4 = 2-start thread

Turning speedsandfeeds calculator

Single start lead screws (1st graph from left) consist, as the name suggests, of only one single thread (single start). This means that the distance between the flanks, marked by pitch, is also the linear travel (lead) in millimetres per revolution of the lead screw.

The third lead screw in this example shows a 4-start lead screw. This means we have 4 thread starts (orange, green, purple and light blue). For the linear travel the same calculation applies here as for the other examples. My linear travel (lead) is therefore four times the distance between the flanks. The start of the thread is at a position of 90° to each other.

Remaining graphs: looking at the front surface of the lead screw, you can see two or more starts of thread symmetrical to each other. The number of starts of thread defines the number of threads. (Two starts of thread = two-start lead screw)

How to calculatecuttingspeed

First graph from the left: a start of thread can be seen from above. The thread flank distance (pitch) is equal to the lead length of the thread (lead).

Can I recognise a multi-start thread visually and without marked lines? YES! This is done by viewing the front side of the lead screws:

High helix thread: DS10x12Nominal thread diameter: 10mmLead L: 12mmPitch P: 3mmNo. of starts: 12/3=4 (Lead / Pitch) = No. of starts)