Three Step

The Three step strategy adds a loosening step between the first step and the final step, to overcome short-term relaxation effects due to embedment, and reduce preload scatter. This is sometimes used to condition the joint. This can be useful in, for example, joints with many adjoining surfaces and will have a greater effect on new parts than on reused ones, due to the smoothing of surfaces, which reduces embedment.

Conditioning the joint is done by tightening the first step to a given torque, First torque, and then releasing the load by turning the nut a specified Conditioning angle and then re-tightening the nut to its Target torque.

Tightening strategy three step

The table below lists all the parameters for the Three step tightening strategy. Some parameters are mandatory, some are optional and some are conditional.

The conditional parameters are not shown in the configuration menu if the condition is not valid, this is also the case when certain functions are disabled.

The table below is valid for Final target = Torque.

When the First target is reached and the conditioning step is entered, the tool makes an immediate stop and reverse before it continues with the final step. This conditioning step may need to be fine-tuned to improve ergonomics for hand-held tools.

Parameters for a torque value as the final target.

Parameters for Three-step tightening with Final target = torque.

Parameter name

Condition

Description

Default value

Target

 

Torque or Angle can be selected from a shortcut menu

 

First torque

Target = torque

 

 

First speed

 

Selected by radio buttons.

First speed can be Automatically or Manually selected

 

First speed

First speed = manual

Specifies the tools speed during the first step

 

Conditioning angle

Strategy = Three step

Angle to turn the socket backwards during the conditioning step

180°

Conditioning speed

Strategy = Three step

Target speed for the backwards rotation during the conditioning step

345 rpm

Target speed

 

Selected by radio buttons.

Target speed can be Automatically or Manually selected

 

Target speed

Target speed = manual

Specifies the tools speed during the final step

 

Target Torque

 

Defines the target torque of the final step of the tightening

 

Torque limits

 

Selected by radio buttons.

Torque values for max and min can be Automatically or Manually selected

 

Torque min

Torque limits = Manual

Torque value for the lower limit

95% of target torque

Torque max

Torque limits = Manual

Torque value for the upper limit

120% of target torque

Angle limits

 

Angle limits is activated through shortcut menu.

Off: No angle limit monitoring.

From rundown complete: The monitoring window is set from when the Rundown complete torque is reached.

From first torque: The monitoring window is set from when the First torque is reached.

From torque: The monitoring window is set from when the specific torque value is reached.

 

Final angle monitoring torque

Angle limits = from torque

Torque value from when the angle limits are monitored

 

Angle min

Angle limits = on

Angle value lower limit

324°

Angle max

Angle limits = on

Angle value upper limit

396°

Time min

Angle limits = on

Minimum time for the step

Range 0 - 99999 ms

0 ms

Time max

Angle limits = on

Maximum time for the step

Range 1 - 99999 ms

1000 ms

Measure torque at

 

Selected from a shortcut menu:

Max torque value: Measures the highest torque value during the tightening.

Value at peak angle: Measures the torque value at the highest angle value.

Shutoff: Measures the torque value before starting the stop step.

 

Torque compensation

 

Selected from a shortcut menu:

On: Compensating the final torque value with the measured torque during rundown at the torque compensation point.

Off: No torque compensation value is applied.

Off

Torque compensation point

Torque compensation = On

The torque compensation point is set by referring back to a specified angle from Rundown complete.

 

45°

Measure angle to

Angle limits = on

Or final target = angle

Selected from a shortcut menu:

Value at peak torque: Measures the angle value at the maximum torque during the tightening.

Max angle value: Measures the maximum angle value during the tightening.

Shutoff:Measures the angle value before starting the stop step.

 

Premature torque loss detection time

200 ms

Current monitoring

Selected from a shortcut menu:

On: The current monitoring is enabled.

Off: The current monitoring is disabled.

The current monitor is used as a redundancy check for the measured torque to give reasonable confidence that torque readings are accurate.

Shutoff current high limit.

Current monitor = On

The current value must be above 0 and below tool maximum current.

Shutoff current low limit.

Current monitor = On

The current value must be above 0 and below the current high limit.

The table below lists all the parameters for the Three step tightening strategy. Some parameters are mandatory, some are optional and some are conditional.

The conditional parameters are not shown in the configuration menu if the condition is not valid, this is also the case when certain functions are disabled.

Parameters for a torque value as the final target.

Parameters for Three-step tightening with Final target = angle.

Parameter name

Condition

Description

Default value

Target

 

Torque or Angle can be selected from a shortcut menu

 

First torque

Target = angle

 

 

First speed

 

Selected by radio buttons.

First speed can be Automatically or Manually selected

 

First speed

First speed = manual

Specifies the tools speed during the first step

 

Conditioning angle

Strategy = Three step

Angle to turn the socket in reverse during the conditioning step

180°

Conditioning speed

Strategy = Three step

Target speed for the reverse rotation during the conditioning step

345 rpm

Target speed

 

Selected by radio buttons.

Target speed can be Automatically or Manually selected

 

Target speed

Target speed = manual

Specifies the tools speed during the final step

 

Torque min

Torque value for the lower limit

95% of target torque

Torque max

Torque value for the upper limit

120% of target torque

Target angle

 

Target value for the final step

 

Angle limits

 

Angle limits is activated through shortcut menu.

Auto: Set automatically by the algorithm.

Manual: The limits are set manually.

 

Angle min

Angle limits = Manual

Angle value lower limit

324°

Angle max

Angle limits = Manual

Angle value upper limit

396°

Time min

Angle limits = Manual

Minimum time for the step

Range 0 - 99999 ms

0 ms

Time max

Angle limits = Manual

Maximum time for the step

Range 1 - 99999 ms

1000 ms

Measure torque at

 

Selected from a shortcut menu:

Max torque value: Measures the highest torque value during the tightening.

Value at peak angle: Measures the torque value at the highest angle value.

Shutoff: Measures the torque value before starting the stop step.

 

Torque compensation

 

Selected from a shortcut menu:

On: Compensating the final torque value with the measured torque during rundown at the torque compensation point.

Off: No torque compensation value is applied.

Off

Torque compensation point

Torque compensation = On

The torque compensation point is set by referring back to a specified angle from Rundown complete.

 

45°

Premature torque loss detection time

200 ms

Current monitoring

Selected from a shortcut menu:

On: The current monitoring is enabled.

Off: The current monitoring is disabled.

The current monitor is used as a redundancy check for the measured torque to give reasonable confidence that torque readings are accurate.

Shutoff current high limit.

Current monitor = On

The current value must be above 0 and below tool maximum current.

Shutoff current low limit.

Current monitor = On

The current value must be above 0 and below the current high limit.