XY tables are mechanical or electromechanical devices which are widely used in CNC machining, milling, tooling, robotics, and various other industries. These are basically range increasing devices which increase the outreach of the machines mounted on top of them. They are also known as XY linear stages, XY adjustment tables, and XY cross-slide worktables.
The word linear signifies the fact that they provide linear motion in two axes in the horizontal plane. The word cross slide refers to the fact that the two linear sliding motions provided by the XY tables are perpendicular to each other.
XY tables can be used to carry around machines as well as workpieces. These devices are available in a wide range of shapes, designs, configurations, and capabilities.
Figure 1: https://www.excitron.com/webdocs/Items/Details354.cfm
Types of XY tables
In terms of construction and functionality, XY tables have two major types:
- Manual XY tables
- Motorized XY tables
Manual XY tables are usually smaller sized XY tables with limited loading capacity. These types of tables are moved across the X and Y axis by means of hand wheels provided on the side of each axis slide.
Motorized versions of the XY tables are advanced electromechanical systems, which have a motor based drive system. Highly accurate servo or stepper motors are used for driving the linear slides.
Some advanced variants of the XY motorized tables are programmable as well. This means that the motion of the table can be preplanned using a computer program and downloaded to the XY table. The table then carries out the program and moves across the preplanned path. The programming is usually done in G Codes, which is also widely used for the motion planning of CNC machines.
Figure 2: http://www.genericslides.com/x-y_slide_tables.html
Figure 3; http://www.optics-focus.com/motorized-xy-translation-stage-p-861.html#.XNFa6thRXIU
Mechanical construction of XY tables
XY tables are basically flat platforms which are mounted on linear slides by means of roller or ball bearings. The platform slides over the stationary linear base with the help of these bearings. The linear bases have hand wheels or linear motors which are used to advance the platform over the slides.
A single linear base can provide motion along one axis only. To achieve motion along two axes, an additional linear base is stacked on top of the existing one. In this way, the XY table can reach any point within the XY horizontal plane within its limits.
For the mounting of load on top of the XY table, two mechanisms are commonly used.
- Mounting Holes
In the first type of tables, t-slots are milled into the platform surface. The machine can then be mounted on top of the table using T-bolts.
In the second type of mounting mechanism, holes are drilled into the platform surface. The machine can then be fastened to the platform surface by means of nuts and bolts.
The XY tables are constructed using stainless steel or cast iron alloys. Bearings are usually made of chrome steel, martensitic stainless steel or bronze. The device frame is constructed from anodized aluminum which makes it durable, elegant and corrosion resistant.
Figure 4: http://bobsoft.ga/wowy/xy-t-slot-table-1765.php
Figure 5: http://ritmindustry.com/catalog/motorized-2-axis-linear-positioning-stages/linear-positioning-table-motorized-2-axis-xy/
Electrical construction of XY tables
The motorized versions of XY tables are electromechanical devices with an advanced electronic control system and sensors. These types of XY tables are highly accurate and robust due to the feedback from the sensors and encoders.
Highly precise and accurate linear stepper motors or brushless direct driven servo motors are used in these XY tables. The motion of the motors and the positioning of the platform are controlled by a central processor or a microcontroller. The controller and the associated circuitry form an embedded control system for motion control.
Very commonly, limit switches are also installed at the end of the axes to detect the dead ends and to stop the motors from exerting unnecessary force when a dead end is reached.
These types of advanced XY tables are programmable through a computer program. The G Code instructions are downloaded into the machine controller and the motion is carried out according to a preplanned motion path.
Figure 6: https://www.smart-prototyping.com/16-channel-servo-controller.html
Features of XY tables
The features of XY tables are listed as following:
- Highly accurate and precise positioning
- Wide range of loading capacities
- Smooth vibration-free motion
- Typical resolution of 0.001’’
- Typical graduation of 0.05’’ per revolution
- Very less maintenance required
- Lightweight in general
Applications of XY tables
XY tables are widely used in mechanical and heavy mechanical workshops, fabrication facilities, automotive industries, heavy mechanical construction industries, and manufacturing industries. They provide a motion enhancement platform for the CNC machines, tooling systems, milling machines, drilling machines, and robot systems. They are also used in semiconductor assembling and optical applications.
Figure 7: https://velto.ca/mies_portfolio/d-bot-3d-printer/
Selection of appropriate XY table
XY tables are available in a wide range of shapes, sizes, configurations, and capabilities. For the selection of an appropriate device, the customer must take into account the machine features such as dimensions, loading capacity, table weight, drive system, maximum speed, resolution, accuracy, and construction material.