Content
Understanding Vertical Linear Stage Specifications
Specifications | Description | |
Model Number | ZA07A-R3S | 1. Kohzu's significant alpha-numeric model numbers offer quick product insight. |
Table Size | 70mm | 2. Table size refers to the stage's upper-most mounting surface. |
Guide Mechanism | Cross-Roller Bearing | 3. Type of guide mechanism used on this stage. |
Motion Range | ±12.5mm | 4. Stage travel range in the positive and negative directions from it's centered or neutral position. |
Lead Mechanism | Rack & Pinion | 5. Feeding Mechanism and lead screw pitch. |
Ideal Resolution | 0.25μm / step (Half Step) | 6. Ideal Resolution of standard stage (half step). |
Maximum Speed | 2.5mm/sec | 7. Maximum Speed of standard stage (half step, 10kpps). |
Repeatability | ≦ ±0.5μm | 8. See "Kohzu Stage Inspection Standards" |
Lost Motion | ≦ 3μm | 9. See "Kohzu Stage Inspection Standards" |
Vertically | ≦ 8μm / 25mm | 10. See "Kohzu Stage Inspection Standards" |
Load Capacity (Horizontal) | 10kg | 11. Maximum load capacity is for a horizontally orientated stage with load centered on top-plate. |
Material | Aluminum Alloy | 12. Material specification is for stage's main body components only. |
Finish | Clear-Matte Anodizing | 13. Surface finish type and color. |
Weight | 2.2kg | 14. Stage weight includes all components depicted in product photograph. |
Standard Motor | Five (5) phase stepper motor PX533MH-B | 15. Actuator type. |
Standard Connector | RP13A-12RA-20PC | 16. Connector type and pin quantity of standard stage |
Guide Mechanism Type
Cross Roller Bearing
In cross roller bearing guides,,, quench hardened and precision ground bearing surfaces move upon loose hardened steel cylinders (rollers) with rotation axes oriented in alternating 90 degree angles (Ref. Fig.1). Having rollers arranged in an alternating cross pattern allows preloading and operation at any angle. The roller bearings are held apart from one another by a bearing cage, which prevents adjacent rollers from touching. Since cross-roller bearing have little difference between static and dynamic friction they minimize start-to-stop slip-motion typical of other bearing types. The line contact of roller bearings along with precise roller-to-race gap management provide larger load bearing surfaces, higher preloads and meet very tight runout and stiffness specifications.
Wedge Type Cross Roller Guides
One set of wedge type cross roller guides are mounted on the horizontal plane and the other set of guides are tilted so that tangent is 1/4 (approximately 14 degree) (see Fig. 1). If the wedge is pushed in from one side, the table fixed to the central axis moves vertically. Since the tilted cross roller guide supports the horizontal component of force, the moment load rigidity on the table top face is reinforced.
Feeding Mechanism
Ground screw, Ball screw + Timing belt
Ground screw: The ground screw is ground at high precision and is held in place by a female screw. Since the ground screw and female screw are in contact each other over a wide area, the friction is high.
Ball screw: The ball screw consists of a screw axis, a nut, and a ball between them. When the screw is rotated, the ball rolls and moves between the ball screw axis and the nut, and then returns to its original position. Since a ball is rolled, the friction is low, a high transmission effect is obtained, the difference between static friction and dynamic friction is small, and stick-slip does not easily occur.
Ball screw + Wedge
Since the vertical-to-horizontal of the wedge is 1:2 and 1:4, the vertical movement distance is 1/2 and 1/4 of the push-in depth.
Rack & pinion + Worm shaft and worm wheel
With these stages, the motor driving force is decelerated by a worm shaft and worm wheel and is converted to vertical force by means of the rack and pinion system (see Fig. 2).
Ideal Resolution
Ideal Resolution of standard stage is calculated based on the following formula.
ΔX = ( P・Δθ / 360 n・m ) | ΔX： Ideal Resolution※ |
Δθ： Basic step angle of motor |
p ： Feed screw pitch
n ： Reduction ratio of belt drive / Reduction ratio of Wedge / Reduction ratio of Worm shaft and worm wheel
m： Division number of micro-step
※ Kohzu uses two motors with basic step angles of 0.36° / pulse and 0.72° / pulse, which is combined with Feed Screw and Timing belt, or Wedge, or Rack & Pinion plus Worm shaft and Worm wheel. The minimum resolution described in this catalog is calculated with two (2) divisions of the standard motor step (half-step, where the value of m is 2).
Timing belt type
Model number | Screw pitch (mm / p) | Reduction ratio of belt drive | Basic step angular of motor (° / p) | Micro-step | Resolution (μm / p) |
ZA05A-V1 | 0.5 | 1 | 0.36 | 2 | 0.25 |
ZA07A-V2 | 1 | 1 | 0.36 | 2 | 0.5 |
ZA10A-V1 | 0.4 | 2 | 0.36 | 2 | 0.1 |
Ground Screw Type
Model number | Screw pitch (mm / p) | - | Basic step angular of motor (° / p) | Micro-step | Resolution (μm / p) |
ZA05A-X1 | 0.5 | - | 0.36 | 2 | 0.25 |
ZA07A (F)-X1 | 0.5 | - | 0.36 | 2 | 0.25 |
ZA10A (F)-X1 | 0.5 | - | 0.36 | 2 | 0.25 |
Wedge type
Model number | Screw pitch (mm / rev.) | Reduction ratio of Wedge | Basic step angular of motor (° / p) | Micro-step | Resolution (μm / p) |
ZA07A-W2, | 1 | 2 | 0.36 | 2 | 0.25 |
ZA07A-W2C, | 1 | 4 | 0.36 | 2 | 0.125 |
Rack & Pinion plus Worm shaft and Worm wheel
Model number | Screw pitch (mm / rev.) | Reduction ratio of Worm shaft and worm wheel | Basic step angular of motor (° / p) | Micro-step | Resolution (μm / p) |
ZA07A-R3, | 24 | 48 | 0.36 | 2 | 0.25 |
Maximum Speed
Maximum speed depends on individual motor torque characteristics. However, we calculate maximum speed at 10kpps with motor in half-step mode.