Seating control step

This step is specialized for joints with increased rundown friction, such as thread cutting, thread forming screws or joints with sideloads from misaligned parts.

In this type of applications it is common with variations from joint to joint. The main goal of this step is to eliminate floating screws and apply the same clamp torque or clamp angle to all joints even though the joints vary. The step monitors the gradient of the clamp torque over clamp angle and can detect when the screw is seated, that is when the screw head is in contact with the joint surface. From the seating point, the configured torque or angle is applied. The total torque or angle may differ from tightening to tightening but the same amount of clamp torque is used to compress the joint.

The method works as follows:

A torque level, the gradient trigger point, is set for detection of the point where the screw head is touching the work piece.
When the torque gradient exceeds the gradient trigger point, the seating point is detected. The torque gradient can be displayed in the tightening graph in the analysis window.

From this point, where the torque curve starts rising, the Seating point is calculated. This is done by calculating the mean torque from the gradient trigger point and looking back the amount of degrees from seating angle displacement.

This step type allows lower target torque and higher speeds than what the tool is calibrated for. This means that you may sometimes not get the desired results. If this happens, try to change the speed in order to get a more desired clamp value.

Parameter	Description
Speed	The tool speed is programmable within the valid range.
Final tightening method	Decides if the tightening should use clamp torque or clamp angle.
Clamp torque (A) / Clamp angle (B)	Sets the value for the clamp torque or the clamp angle.
Seating angle displacement (G)	Angle window for calculating the seating point from the gradient trigger point.
Gradient trigger point (H)	The torque level when the tool detects that the screw head has touched the work piece. This is the end point of the Seating angle displacement.
Vacuum enabled	Digital output to switch on an external vacuum pump.
Min. torque (L)	If the total torque for a seating control step is below minimum torque, an error message will be displayed.
Max. torque (D)	The Maximum torque value must not be exceeded during this step. If the Maximum torque is reached, the driver will stop and the controller will display an error message.
Min. angle (F)	Angle that must have been reached when the step is finished. If not reached, the controller will display an error message.
Max. angle (E)	Angle that must not be exceeded prior to reaching target torque. If exceeded, the controller will display an error message.
Min. clamp torque	The min. clamp torque can be used to detect joint anomalies.
Max. clamp torque	The max. clamp torque can be used to detect joint anomalies.
Min. clamp angle	The min. clamp angle can be used to detect joint anomalies. If below, the controller will display an error message.
Max. clamp angle	The max. clamp angle can be used to detect joint anomalies. If exceeded, the controller will display an error message and the tool will stop.
Step start delay (M)	Delay from trigger to tool start.
Min. step time (J)	Minimum time for the step. If not reached, the controller will display an error message.
Max. step time (K)	Maximum time for the step. If exceeded, the controller will display an error message.
Seating angle displacement (G)	Angle window for calculating the seating point from the gradient trigger point.
Gradient trigger point (H)	The torque level when the tool detects that the screw head has touched the work piece. This is the end point of the Seating angle displacement.