Robots are programmable manipulators that contain rotary and/or prismatic joints in order to perform precise, repetitive movements. They are designed to move parts, tools, materials, and devices through variable, programmed motions.

Types of Robots

The GlobalSpec SpecSearch database contains information about these types of robots. 

• Articulated robots have arms with rotary joints. They provide greater flexibility and dexterity than SCARA robots, and can be used to inspect areas with assembled structures.  Other applications for articulated robots include assembly, welding, weld sealing, and spray painting. 
• Cartesian robots (rectangular coordinate robots, rectilinear robots) have three prismatic joints whose axes are coincident with a Cartesian (X, Y, and Z) coordinate system.  They are used for pick-and-place operations, assembly, handling machine tools, and arc welding. Gantry robots are a type of Cartesian robot that is suspended from an X or X/Y axis beam.
• Cylindrical robots operate in a cylinder-shaped space or coordinate system and have at least one rotary joint and at least one prismatic joint. They are used for handling products at die-casting machines, handling machine tools, and spot welding.
• Parallel robots such as hexapods have multiple arms, each of which has three concurrent prismatic joints.  They have a large working envelope, but are more difficult to program and control.
• SCARA robots are cylindrical and have two parallel joints to provide compliance in one selected plane. They are used for pick-and-place work and assembly operations. SCARA stands for selectively compliant arm for robotic assembly.
• Spherical robots have an arm with two rotary joints and one prismatic joint. The axes of a spherical robot form a polar coordinate system. They are used to handle machine tools and arc or spot welding.

Sprue pickers for removing sprue from molds are also available.

Drives and Mounting Styles

Drive type and mounting style are important specifications to consider when selecting industrial robots. Most large, industrial robots use hydraulic drive systems for improved speed and strength. By contrast, SCARA robots may use electric drives. Smaller robots with fewer axes of movements (such as sprue pickers) use pneumatic drives.

Some industrial robots mount on ceilings or walls to save space. Others are rated for cleanroom applications or can be transported easily from one location to another. Mobile devices use treads, wheels, robotic wheels, and other methods.

Typically, pneumatic robots are less expensive than hydraulic or electric ones.

Additional Specifications

Specifications for industrial robots include number of axes, load capacity, reach, X-axis travel, Y-axis travel, and Z-axis travel. The total number of joints determines the number of axes in which devices operate. Applying force to a prismatic joint creates a linear movement in the positive direction along the axis of translation.  The reach or work envelope determines the maximum distance that industrial robots can extend an arm to perform a task.

Each type of robot has a different work envelope. For example, Cartesian robots work within a cube-shaped envelope while cylindrical robots work within a cylindrical envelope. Polar and articulated robots work, respectively, within envelopes that are partially or completely spherical. X-axis, Y-axis, and Z-axis travel is expressed in a variety of measurements, including inches, feet, yards, millimeters, nanometers, and miles.

Applications for Industrial Robots

Industrial robots are used in a variety of industries. Typical applications include assembling, fluid dispensing, gluing, sealing, inspection, laser integration and processing, material handling, tending, palletizing, metal removal (cutting, drilling, deburring), packaging, labeling, painting, coating, and welding. Industrial robots that are used to inspect pipelines, storage tanks, and boilers are usually mobile and capable of withstanding harsh environments. Painting robots are used in the automotive and aerospace industries or when high volume, programmable, and precise painting is required.

References

AuthorStream – Robotics PowerPoint Presentation

Entrepreneur – Articulated Robots Win Points for Flexibility and Dexterity