A common problem with thread turning is chips entangled around the robot, chuck, tool and component. Chips can also get caught in conveyors, causing damage and loss of productive machining time. Successful chip control is key to good part quality when thread turning. Follow our thread turning application tips for good chip control and long tool life.

Light Thread™

Optimal chip control with the OptiThreading™ method. This method enables the tool to perform an oscillating motion, resulting in interrupted cuts on all but the last pass. It provides the highest process control and component quality

Improved side feed

For conventional thread turning applications, use the improved side feed for the best chip control. The improved side feed makes threading more like a normal turning operation. It provides a controlled process that creates fewer chip issues and therefore provides predictable tool life and higher thread quality.

Opposite side feed

With opposite flank infeed, the insert can use the rear flank (opposite flank) for cutting, which means the chips can be directed in the correct direction. This is very important for internal thread turning operations, especially when machining bottom holes. Using this method allows for continuous, trouble-free machining without unplanned stops.

Cutting fluids and coolants

It is recommended to use cutting fluids and tools with precision coolant to optimize chip control and chip evacuation. Precision coolant has the following advantages when thread turning:

Controlled cutting edge temperature

Good chip evacuation

Improved chip control

When using external coolant, usually only a small amount of coolant enters the thread, so a small amount of coolant will have an effect.

When using internal coolant, the coolant jet reaches the cutting edge even in deep threads. The coolant effectively reduces the temperature, which:

Allows the use of higher cutting data or tougher grades

Improves chip control and surface finish

Lower temperatures extend tool life by reducing insert wear caused by, for example, flank wear and plastic deformation. However, too low a temperature can shorten tool life because, with sticky materials such as stainless steel, too much of a temperature reduction can lead to chip buildup.

Diameter inspection

Before turning threads, make sure the workpiece diameter is within specification.

If the external thread diameter is too large, or the internal thread diameter is too small, the first cut will be large and may cause insert breakage.

If the external thread diameter is too small, or the internal thread diameter is too large, the wrong thread diameter may be produced.

A: Turning diameter is too large in case of external thread

B: Correct external thread diameter

C: First pass of thread cycle generation

Tool life

Careful observation of the insert after threading will allow you to achieve the best results in terms of tool life, cutting speed and thread quality.

The two main machining parameters, each of which affects tool life, are feed and speed. Increasing either of these parameters will reduce the time in the cut per component, but will also increase the temperature. Too high a temperature will shorten tool life.

To find the best tool life, it is more advantageous to optimize the feed/chip thickness first. When increasing feed/chip thickness, the temperature increase is less than when increasing cutting speed. On the other hand, too much chip thickness will overload the insert.

Use coolant to reduce temperature. Precision under coolant has the greatest impact.

Effect of increasing cutting speed and feed rate on temperature

Chip thickness

When machining work-hardened materials, avoid small depth cuts that penetrate the work-hardened skin.

If the radial cut is 0.2 mm (0.008 in), the chip thickness on the flank will be:

0.05 mm (0.002 in) at 30° profile

0.1 mm (0.004 in) at 60° profile

Insert nose radius and tool life

The nose radius is the smallest point on the insert and is most susceptible to breaking under the extreme stresses of a thread turning operation.

The nose radius varies greatly between insert types and should be considered with cutting speed and number of passes to optimize performance and process security.

NPT and NPTF thread profile inserts have the smallest nose radius of the standard range. To optimize performance, increase the number of passes and reduce cutting speeds.

The nose radius of an internal insert is significantly smaller than that of an external insert.

Premachining with turning tools

Pre-machining threads with a turning tool with a 55° or 60° insert before finishing with a threading tool can improve productivity and tool life.

When machining threads with small root and crest radii, similar pre-machining can also be done by rough threading with an insert with the same angle but a larger nose radius. Then allowance is left for the remaining finishing pass with the thread turning insert.

Deburring

Deburring the thread start

If burrs occur, they tend to form at the start of the thread before the insert has formed a complete profile. These burrs can cause problems and should be removed, especially in the hydraulic and food processing industries where tolerances and quality requirements are high.

Burrs most often occur in difficult-to-machine stainless steels and duplex materials.

Thread deburring is achieved with standard turning tools. It is important to consider the correct positioning of the deburring insert relative to the thread, pitch and thread cycle.

How to remove thread burrs

1. Use standard threading cycles and recommended feed data. The tool should exit the thread at a 45° angle

2. Use the same threading program, same cutting speeds and half the number of passes for parting and grooving inserts. Program the deburring length before the 45° exit to 1 x pitch and measure the zero point according to the following setup instructions

Setup instructions

Set the zero position of the threading insert

Measure the zero point on the parting and grooving inserts

Offset the parting and grooving inserts by a certain distance

Thread diameter deburring

When turning threads with V-shaped inserts, a burr is usually produced on the thread crest. This burr needs to be removed in order to obtain high-quality threads.

Multiple start threads

具有三个启动的多启动线程

A thread with two or more parallel thread grooves requires two or more starts. The lead of this type of thread will be twice that of a single-start screw.

The lead increases relative to the pitch by a factor equal to the number of starts:

• Single start thread - lead and pitch are equal

  
  

  Double start thread - lead is twice the pitch

  
  

  Triple start thread - lead is three times the pitch, etc.

To produce multiple-start threads, machine one thread groove with multiple passes, then a second thread groove with multiple passes, then a third thread groove with multiple passes.

It is important to select the correct shim. Use the lead value to calculate the correct inclination (helix angle) and select the shim accordingly.

First thread groove

Second thread groove

Third thread groove

Thread turning application skills

A common problem with thread turning is chips entangled around the robot, chuck, tool and component. Chips can also get caught in conveyors, causing damage and loss of productive machining time. Successful chip control is key to achieving good part quality when thread turning. Follow our thread turning application tips for good chip control and long tool life。

Light Thread™

Achieve optimal chip control with the OptiThreading™ method. This method enables the tool to perform an oscillating motion, resulting in interrupted cuts on all passes except the last. It provides the highest process control and component quality.

Improved side feed

For conventional thread turning applications, use the improved side feed for the best chip control. The improved side feed makes threading more like a normal turning operation. It provides a controlled process that creates fewer chip issues and therefore provides predictable tool life and higher thread quality.

Opposite side feed

With opposite flank infeed, the insert can use the rear flank (opposite flank) for cutting, which means the chips can be directed in the correct direction. This is very important for internal thread turning operations, especially when machining bottom holes. Using this method allows for continuous, trouble-free machining without unplanned stops.

标准修正侧向进给	进给方向	对侧进给
切屑方向		切屑方向

Cutting fluids and coolants

It is recommended to use cutting fluids and tools with precision coolant to optimize chip control and chip evacuation. Precision coolant has the following advantages when thread turning:

Controlled cutting edge temperature

Good chip evacuation

Improved chip control

When using external coolant, usually only a small amount of coolant enters the thread, so even a small amount of coolant has an effect.

When using internal coolant, the coolant jet reaches the cutting edge even in deep threads. The coolant effectively reduces the temperature, which:

Allows the use of higher cutting data or tougher grades

Improves chip control and surface finish

Lower temperatures can reduce insert wear caused by, for example, flank wear and plastic deformation, thereby extending tool life. However, too low a temperature can shorten tool life, because with sticky materials such as stainless steel, too much temperature reduction can lead to built-up edge (BUE).

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Diameter Check

Before turning threads, make sure the workpiece diameter is within specification.

If the external thread diameter is too large, or the internal thread diameter is too small, the first cut will be large and may cause insert breakage.

If the external thread diameter is too small, or the internal thread diameter is too large, the wrong thread diameter may be produced.

A: Turning diameter is too large in case of external thread

B: Correct external thread diameter

C: First pass of thread cycle generation

Tool life

Careful observation of the insert after threading will allow you to achieve the best results in terms of tool life, cutting speed and thread quality.

The two main machining parameters, each of which affects tool life, are feed and speed. Increasing either of these parameters will reduce the time in the cut per component, but will also increase the temperature. Too high a temperature will shorten tool life.

To find the best tool life, it is more advantageous to optimize the feed/chip thickness first. When increasing feed/chip thickness, the temperature increase is less than when increasing cutting speed. On the other hand, too much chip thickness will overload the insert.

Use coolant to reduce temperature. Precision under coolant has the greatest impact.

Effect of increasing cutting speed and feed rate on temperature

进给，p	后刀面快速磨损 内置边缘 不经济	失去切屑控制 表面光洁度差 月牙洼磨损/塑性变形 高功耗 芯片锤击 崩刃/刀片破损
切削速度，vC	内置边缘 不经济	后刀面快速磨损 失去切屑控制 表面光洁度差 月牙洼磨损/塑性变形 高功耗

Chip thickness

When machining work-hardened materials, avoid small depth cuts that penetrate the work-hardened skin.

If the radial cut is 0.2 mm (0.008 in), the chip thickness on the flank will be:

0.05 mm (0.002 in) at 30° profile

0.1 mm (0.004 in) at 60° profile

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Insert nose radius and tool life

The nose radius is the smallest point on the insert and is most susceptible to breaking under the extreme stresses of a thread turning operation.

The nose radius varies greatly between insert types and should be considered with cutting speed and number of passes to optimize performance and process security.

NPT and NPTF thread profile inserts have the smallest nose radius of the standard range. To optimize performance, increase the number of passes and reduce cutting speeds.

The nose radius of an internal insert is significantly smaller than that of an external insert.