Understanding Vertical Linear Stage

Understanding Specifications

 Specifications  Description
Model Number ZA07A-W2C01  1. Kohzu's significant alpha-numeric model numbers offer quick product insight.
Mirror Model Number ZA07A-W2C01-R  2. Mirror symmetry of standard stage.
Table Size 70mm×70mm  3. Table size refers to the stage's valid mounting table size.
Guide Mechanism Cross-Roller Bearing 4. Type of guide mechanism used on this stage.
Motion Range ±2.5mm  5. Stage travel range in the positive and negative directions from it's centered or neutral position.
Lead Mechanism 1/4-Wedge, Ball Screw, Lead 1.0mm 6. Feeding Mechanism and lead screw pitch.
Resolution Full/Half Step 0.25μm/0.125μm  7. Variation of the stage resolution which is defined by microstep division.
Micro Step (1/20 div) 0.0125μm 
Maximum Speed 1.25mm/sec  8. Maximum Speed of standard stage (half step, 10kpps).
Repeatability ≦±0.5μm  9. Refer the "Inspection System"
Lost Motion ≦0.3μm  10. Refer the "Inspection System"
Vertically ≦5μm/5mm  11. Vertically is measured relative to mounting surface.
Load Capacity (Horizontal) 49N(5kgf)  12. Maximum load capacity is for a horizontally orientated stage with load centered on top-plate.
Material Aluminum Alloy 13. Material specification is for stage's main body components only. 
Finish Clear-Matte Anodizing 14. Surface finish type and color.
Weight 1.15kg  15. Stage weight includes all components depicted in product photograph.
Standard Motor Five (5) phase stepper motor (Oriental Motor: PK544PMB)Phase Current 0.75A, Basic Step Angle 0.36° 16. Motor type of standard stage.
Standard Connector 20Pin Round (Hirose: RP13A-12RA-20PC) 17. Connector type of standard stage.
Stage Wiring Type V3 18. Wiring type is connection between stage and stepper motor, and photo-sensor.
Price(JPY) ¥230,000  19. Catalog price in Japanese currency. 
Overhaul Price * ¥48,000 〜  20. Overhaul price in Japanese currency.
Clean Room Lubricant Change Price ¥36,000  21. Clean Room Lubricant change Price in Japanese currency.
Vacuum Lubricant Change Price ¥36,000  22. Vacuum Lubricant change Price in Japanese currency.
Same Size Motor Change Price ¥12,000 〜  23. Change price of same size motor's mounting as standard motor's in Japanese currency.
Different Size Motor Change Price ¥30,000 〜  24. Change price of different size motor's mounting as standard motor's in Japanese currency.

* Parts price is not included overhaul price.


Guide Mechanism Type

●Cross-Roller Guide

In cross roller guides, quench hardened and precision ground bearing surfaces move upon loose hardened steel cylinders (rollers) with rotation axes oriented in alternating 90 degree angles. 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(same as 1/2 type). Figure-1


●Tetrahedral Flat Roller

Tetrahedral Flat Roller is guide mechanism, put the ground bearing on to four-way of transfer post, and set the four guide plate on the outside of bearing. The transfer post and guide plate are finished highly flatness, squareness and toughend by quench ground method. Compare with cross roller guide, longer than length and more quantity of the ground bearing, then bearing area is large. It is superior in terms of stiffness and angular stability as bearing contact area is large that's why longer and more quantity of the ground bearing than cross-roller guide.

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 spindle, a nut, and a ball between them. When the screw is rotated, the ball rolls and moves between the ball screw spindle and the nut, and then returns to its original position. Since a ball is rolled, the friction is low, a high transmission efficiency 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.


Resolution of standard stage is calculated based on the following formula.


ΔX =( p・Δθ / 360n・m)

ΔX: Resolution *
Δθ: Basic step angle of motor
p : Feed screw pitch
n : Reduction ratio of belt drive / Reduction ratio of Wedge
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. The 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).

Maximum Speed

Maximum speed depends on motor torque characteristics in higher speed area. However, we calculate maximum speed at 10kpps with motor in half-step mode. Except of 10kpps, the value is fill in each specification.


●About the table drop

The motorized vertical stage which of lead mechanism is ball screw, there is possibility to drop the stage table when motor's current is turned off. As an option extra, electromagnetic brake is possible to equip. Contact us for further information.

Reverse Stage (Mirror Model)

Upon request, we can supply reverse arrangement specifications in which the connector and the sensor are mounted in reverse.
* Except model ZA07A-W2C and ZA10A-W2C, only connector part is mounted in reverse.