XY tables are very widely used pieces of mechanical/electromechanical equipment in the machining, tooling, drilling, alignment, gauging, assembling, and fixture applications in a wide range of industries all over the world. Their basic purpose is to provide a stable, smooth, precise, and accurate positioning for job objects. The job piece which needs to be positioned is mounted on top of the table.
As the name points out, XY tables provide motion and positioning in the XY horizontal plane. XY tables come in a huge variety of sizes, shapes, materials, and technical specifications. In this article, we will discuss a particular type of the XY table known as miniature XY table.
Miniature XY tables are specialized pieces of equipment which are specifically developed to provide a very high level of performance, precision, accuracy, resolution, and repeatability. These types of tables are widely used in industries where micromachining, micro-assembling, and micro-positioning is required. Examples of such industries can be electronic circuit board assembling, optical lens alignment, laser cutting, and semiconductor assembling. It is evident from the nature of these tasks that why such a high level of accuracy and performance is required from miniature tables.
Miniature XY tables have very small sizes, form factors, loading capacities, and weights. This makes them very lightweight and easy to transport devices. The miniature XY tables are also sometimes known as XY translators or XY positioners.
Figure 1: https://www.thorlabs.com/NewGroupPage9.cfm?ObjectGroup_ID=1909
How does a miniature XY table work?
The operating principle of a miniature XY table is the same as that of a regular XY table. However, advanced manufacturing techniques and specialized components are used in their construction because of the level of performance demanded from them.
Like regular XY tables, miniature XY tables also consist of two linear sliding bases. A moving surface is attached to the sliding bases by means of crossed roller bearings. The moving surface can slide over the linear bases in the horizontal XY plane by means of the roller bearing. The motion and the position of the mounting surface are determined and controlled either by the manual control knobs or by the specialized servo/stepper motors.
To reduce the overall weight of the device and to increase the coupling efficiency, sometimes both the linear axes of the miniature table are fabricated from a single block of metal. The typical motion range of a miniature XY table lies between 3mm and 150mm. These tables are super accurate and have a resolution value which is a fraction of a micrometer. The loading capacity of miniature tables is typically in the order of a fraction of a kilogram.
The electromechanical motorized versions of these tables are even higher in performance and accuracy. They employ optical encoders for greater resolution and precision. The typical resolution of an optical encoder is around 0.1 micrometer which is an exceptional level of precision. The motorized versions of the miniature XY tables use linear servo or stepper motors. These are specially designed motors which are capable of exhibiting great torque-speed characteristics despite their small size. The microcontroller chip and the associated circuitry form a digital motion control system which controls the position of the motors and interacts with the sensors. The miniature XY table can also be connected to a computer using RS-232 or USB 2.0 interface. A computer program can be used to create a motion plan for the table. The motor then achieves the desired positions using this motion plan program.
The motorized miniature XY tables also have zero and limit position sensors built into the mechanism. These sensors are based on optical reflection or laser mechanisms. These sensors keep the control system updated regarding the limits of the table. When the job piece is at zero level or dead-end position, the motor stops exerting force. This saves the motor from wear and tear.
The mounting surface of the table has holes drilled into it so that the job piece can be fastened to the surface by means of screws or bolts. For different types of applications, different types of adapter surfaces are available from the manufacturers. These plates can be swapped easily when the application demands it.
The mounting surface of the miniature tables have holes drilled into them which can be used for mounting the tools and jobs by means of small screws or bolts. However, different applications require different types of mounting surfaces and holders, therefore various types of adapter plates are also available from the manufacturers of these devices.
The miniature XY tables are widely used for electronics applications. Hence it is important to keep the assembly safe from electric discharges. Hence the body of the table is coated with low ESD materials.
Figure 2: https://www.micromo.com/products/stepper-motors
Figure 3: https://www.elliotscientific.com/Precision-Positioning/Elliot-Martock-Products/Miniature-Stages/187-Small-Stages/Elliot-Martock-MDE258-Dual-Axis-XY-Micropositioner-Stage
Industrial use of XY miniature tables
XY miniature tables are used in the industries and applications where very high performance, precision, and accuracy is needed. Examples of such applications include assembling of electronic components, soldering of microchips and ICs, fiber optics applications, semiconductor material handling, microscopy, biomedical applications, laser engraving, and micromachining.
Figure 4: https://www.aliexpress.com/item/Micro-stepping-motor-cross-platform-small-mobile-digital-microscope-XY-axis-table-experiment-two-slide/32790147861.html