Motorized Stages & Others -CHUO PRECISION INDUSTRIAL CO.,LTD.-

Motorized Stages & Others

Motorized Stages & Others

Accuracy

Positioning Accuracy
Repeatability
Resolution
Maximum Speed
Lost Motion
Backlash
Straightness (Horizontal)
Straightness (Vertical)
Yawing

Pitching
Parallelization
XY Orthogonality
Load Capacity
Moment Rigidity
Allowable Moment
Run-Out
Face Deflection
Center of Rotation Accuracy

Positioning Accuracy [JIS B 6191-1993 Compliant]

位置決め精度

This is defined as “the limiting value of permissible deviation between the position of one point on the moving part after movement and its target position”. This is found by incrementally moving a standard length (angle) specified separately for each model of motorized stage, in a single direction and measuring the various distances between the actual length (angle) moved with the standard length (angle) that one would expect it to move. The largest difference among these values is taken as the “positioning precision”.

Repeatability [JIS B 6191-1993 Compliant]

繰り返し精度

This is defined as “the limiting value of permissible variability of the difference between the target position and its actual position after repeated positioning in one direction”. This is found by repeating positioning at an arbitrary point a total of seven times and measuring the stop position. The maximum value of these measurements is then recorded. These measurements are performed in the middle and on both edges of the device and the maximum value of the resulting differences is given a ±1/2 error confidence interval to give us the final value for the repeatability.

Resolution [JIS Z 8103-1990 Compliant]

This is defined as “for a given input value, the amount in which you can vary the input and still see a discernable change in the output value”.

Maximum Speed [Chuo Precision Industrial Internal Standard]

The maximum speed of a motorized stage can vary depending on the model, the type of controller/driver output used, and the acceleration/deceleration conditions (acceleration/deceleration rate).
Please note that if it is overloaded or the acceleration/deceleration conditions become stricter, the device may not be able to be operated up to its maximum speed.
Our catalogue (General Catalogue No.41) shows the case with the conditions in Table 2.

自動ステージの最高速度

Motorized stage maximum speed

Lost Motion [JIS B 6330-1980 Compliant]

This is defined as "the maximum difference between the stop position for a given point after positioning in the positive direction and the negative direction". This is found by performing positioning of a single point in both the positive and negative directions and measuring the stop positions for a total of seven times. The average difference is then calculated. These measurements are performed in the middle and on both edges of the device and the maximum value is taken as the value of lost motion.

Backlash [JIS B 0182-1993 Compliant]

This is defined as “the clearance that is found in the direction of motion between mating machine components that move in relation to each other, including gaps that cause unintended hindrance to the direction of motion”.
This is found by moving the stage in an arbitrary direction and performing positioning. A load is then applied to the stage at this reference position in the same direction of movement and the difference between the values of the position when the load is removed and the reference position can be taken as the backlash.

Straightness (Horizontal) [JIS B 6191-1993 Compliant]

This is defined as the “the amount of deviation from a geometric straight line exhibited by parts that travel in straight line motion”.
Positioning of a standardized point is performed incrementally in a single direction. Horizontal variations in the lengths for each point are compared with reference positions and the differences is taken as the measured value for that position.
The straightness (horizontal) is taken as being the maximum difference from a geometric straight line that connects the measurement points at the reference position and the final measurement position.

Straightness (Vertical) [JIS B 6191-1993 Compliant]

This is defined as the “the amount of deviation from a geometric straight line exhibited by parts that travel in straight line motion”.
Positioning of a standardized point is performed incrementally in a single direction. Vertical variations in the lengths for each point are compared with reference positions and the differences is taken as the measured value for that position.
The straightness (vertical) is taken as being the maximum difference from a geometric straight line that connects the measurement points at the reference position and the final measurement position.

Yawing [JIS B 6191-1993 Compliant]

This is defined as "the amount of deviation of moving parts that are designed to travel in a straight line. It is expressed as the angular deviation that occurs during straight line motion”.
Positioning is carried out incrementally in one direction from a given reference position. For each position, the maximum value of the horizontal displacement angle in regards to the reference position is taken as the value for yawing.

Pitching [JIS B 6191-1993 Compliant]

This is defined as "the amount of deviation of moving parts that are designed to travel in a straight line. It is expressed as the angular deviation that occurs during straight line motion”.
Positioning is carried out incrementally in one direction from a given reference position. For each position, the maximum value of the vertical displacement angle in regards to the reference position is taken as the value for pitching.

Parallelism [JIS B 6330-1980 Compliant]

When two flat surfaces are placed against each other and one of them is nominated to be the reference surface, the degree of parallelization is defined as “the amount of deviation of the other surface when compared to a geometric plane orientated parallel to the nominated reference surface”.
The degree of parallelization is found my measuring the parallelization between the table and base surfaces of the motorized stage, measured at the central position of the overall movement.

XY Orthogonality [JIS B 7440-1987 Compliant]

“The squareness between two straight axes can be taken as the amount of deviation between the actual linear motion and a line at right angles to the geometric line that is used as a straight reference for motion.”
The reference axis is set to be a geometric straight line indicating the level of straightness (horizontal) of the X stage reference position and the final measurement position.
The XY orthogonality is defined as the maximum horizontal error that exists from a Y stage reference point on a geometric straight line that is perpendicular to the X stage reference axis, to the final measurement position.

Load Capacity [Chuo Precision Industrial Internal Standard]

The load capacity is defined as the maximum distributed load that can be handled by stage surfaces that are able to be mounted onto the stage.

Calculation of the dimensions of objects that can be loaded onto the stage

Even when it is within the load capacity, for the motorized stage to operate sufficiently, the dimensions of the work piece must be limited.
As a general measure, the length and width of the work piece must be no more than approximately 1.5 times the dimensions of the stage surface; and the height approximately the same dimensions of the stage surface.
Please use a motorized stage with a larger stage surface if you wish to load objects with dimensions in excess of this.

　Example: If the stage surface = 200mm × 200mm
　　　　　 Work piece length and width dimensions
　　　　　 = 200mm × 1.5 = Approx. 300mm or less
　　　　　 Work piece height dimensions = 200mm × 1
　　　　　 = Approx. 200mm or less

Unbalanced work pieces

If the work piece is unbalanced, there is a limit to the moment that can be handled by the motorized stage.
The standard amount tolerated must be within the value of the moment generated when a load equal to the load capacity is applied at a center of gravity position which is located one quarter of the stage surface length from the center of the stage surface.
However, this excludes special cases such as when the motorized stage is orientated vertically or upside-down.
Please use a motorized stage with a larger load capacity if you wish to load objects that are more unbalanced than this standard.

　Example: If the motorized stage load capacity
　　　　　 = 490N, and the stage surface = 200mm
　　　　　 Allowable moment = 490 × 20cm × 1/4 = 2450N" cm or less
　　　　　 ≒ If the center of gravity is a point 10cm
　　　　　 from the stage surface center,
　　　　　 the weight of the work piece must be 25kg or less

Moment Rigidity [JIS B 6201-1993 Compliant]

The moment rigidity is defined as the displacement angle (sec) of the motorized stage for the moment load per 1N•cm.
There are different categories of moment rigidity depending on the direction of the moment load, and this can vary depending on the motorized stage model. X, X•Y, and Z stages have three types; yaw, pitch, and roll rigidity. Rotation stages have one type. Tilt stages have two types; yaw and roll rigidity.
As the value of the moment rigidity becomes smaller, displacement of the motorized stage due to the moment load is reduced which indicates that the device has superior rigidity.

X, XY, and Z stage moment rigidity

Note: In the case of an X•Y stage, a downward facing axis is standard.

1. Moment rigidity (Yaw rigidity)
2. Moment rigidity (Pitch rigidity)
3. Moment rigidity (Roll rigidity)

Z elevating stage moment rigidity

1. Moment rigidity (Yaw rigidity)
2. Moment rigidity (Pitch rigidity)
3. Moment rigidity (Roll rigidity)

Rotation stage moment rigidity

1. Moment rigidity

Tilt stage moment rigidity

1. Moment rigidity (Yaw rigidity)
2. Moment rigidity (Roll rigidity)

Allowable Moment [JIS B 6201-1993 Compliant]

The allowable moment is defined as the moment load that can be handled by the stage(s), or when a work piece is placed upon the stage(s).
There are different categories of allowable moment depending on the direction of the moment load, and this can vary depending on the stage model.
X, X•Y, and Z stages have three types; allowable moment (yaw), allowable moment (pitch), and allowable moment (roll). Rotation stages have one type; allowable moment. Tilt stages have two types; allowable moment (yaw) and allowable moment (roll).

Run-Out [JIS B 6194-1997 Compliant]

This is defined as “the difference between the radius of the maximum and minimum concentric inscribed circles that can enclose the actual observed route. Or the difference between the largest and smallest radius circles that are concentric with the smallest least squares circular approximation of the actual route”.
The run-out value is taken as the maximum amount of variation in the radial (horizontal) direction from the axis of revolution of the rotation stage surface.

Face Deflection [JIS B 6191-1993 Compliant]

This is defined as “the amount that a the actual axis of rotation of the face deviates from a plane perpendicular to a reference axis of rotation”.
The face deflection value is taken as the maximum amount of variation in the thrust (vertical) direction of the rotary stage upper surface.

Center of Rotation Accuracy [Chuo Precision Industrial Internal Standard]

Taking the position from the upper surface of a goniometer stage to the ideal center of rotation as a reference, the maximum deviation from the ideal center of rotation during stage positioning is measured. The center of rotation precision is taken as the diameter of a sphere with its radius given as this maximum deviation.

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