What are miniature XY tables and why are they used?
XY tables are very common industrial machines and can be abundantly found in mechanical workshops, assembly lines, manufacturing units, fabrication factories, and research facilities all over the world. An XY table is essentially a range enhancement and position control machine which provides an additional range as well as accurate positioning for the tools and jobs which are mounted on top of these machines. XY tables can either be manual or automatic, depending on the nature of the drive system of the machine. XY tables are being manufactured for all types of applications ranging from very large to very small. Due to this fact, XY tables are available in a vast range of sizes, weights, capacities, and features.
Miniature XY tables are a subclass of XY tables which are specifically designed for very small sized tools, job pieces and applications. They are utilized in the work environments where the work area is very limited and the job piece needs a great deal of accuracy and precise positioning. These systems have a typical resolution in the order of the fraction of a micrometer. Hence, these machines are used in micro level tasks such as micromachining, micro-drilling, micro-milling, micro-gauging, and micro-assembling. Miniature XY tables are ideal for jobs which need intricate work on a micro level.
The miniature XY tables are also called as XY translators or miniature XY cross-slides. The reason behind this naming is the fact that these tables provide a linear translator motion in the crossed XY plane. The X and Y axes are orthogonal to each other and so are the linear sliders of the XY tables. Due to this, they are also known as cross-slide work tables.
Figure 1: https://www.newport.com/p/MS-500-XY
Working of a miniature XY table?
XY miniature tables are a subcategory of regular XY tables and therefore, their working principles are similar. However, there are some differences as well. The miniature XY tables are very small and compact in size therefore, the design of these tables requires extra considerations. Special design, fabrication, and manufacturing techniques are employed for the construction of these miniature tables. Out of all the XY table variants, miniature tables are the most accurate and precise ones, therefore, special attention is paid to the design and development of these machines in order to achieve maximum performance and efficiency.
The miniature XY table consists of a moving platform on top of which, the tool or the job is mounted. This mobile platform moves in the horizontal plane over the linear sliding bases. This motion is made possible by the crossed frictionless roller bearings. The platform can be advanced in the XY plane by means of a mechanical or electrical drive mechanism. The drive mechanism of the table can either be manual or motorized.
In case of manual drive systems, rotary hand knobs or wheels are provided on the machine on each linear axis. By means of these handles or knobs, the motion of the table surface along that particular axis is being controlled. The motion is very precise and is usually in the order of a fraction of a micrometer. A scale is also provided on the machine to measure the rate of advancement of the moving platform.
The automatic motorized variants of the machine are even more accurate and precise due to the electronics and sensors embedded into the machine structure. Special miniature servo/stepper motors are used for controlling the platform positioning. The speed, acceleration, resolution, accuracy, and precision of these types of miniature XY tables is very high.
The mounting platform has holes or t-slots milled or drilled into them to attach the tool or job on the platform surface. Various types of adapter plates are also used for different types of applications.
The miniature XY tables are constructed from stainless steel alloys or aviation grade aluminum. Aluminum makes the machine structure very lightweight and strong. The outer frame of the machine is often anodized to make it corrosion resistant. Miniature tables are also coasted with ESD resistant materials. The reason for this is that these tables are widely used in electronic assembling and testing applications and the electrostatic discharge can cause harm to the electronics. Due to this reason, ESD resistance is provided.
Electronics in the miniature XY tables
The motorized versions of the miniature XY tables have very high performance and accuracy index. The reason behind this is the employment of the digital control system and digital electronics for the machine. The highly accurate control system of the machine controls the motion and positioning of the linear servo/stepper motors.
Several sensors provide feedback to the electronic control system. These sensors include highly sensitive optical encoders, homing sensors, and reflective type limit sensors. These sensors keep the controller updated about the position and status of the machine parameters. Based on this feedback, the controller adjusts the motor torque and speed. This setup results into a very powerful, accurate and efficient control scheme for the tool positioning.
Figure 4: https://www.pololu.com/product/2333
Industrial applications of XY miniature tables
XY miniature tables are used in applications where the job piece as well as the working envelope, are very small. Some of the popular applications where the miniature tables are used include electronics testing, electronics assembling, SMT soldering, laser cutting and engraving, material inspection, semiconductor assembling, and photonics.