Choosing the Right Industrial Robot

The main selection criterion for an industrial robot is the field of application.

Depending on the robot’s ultimate task, there are four main types of robots to choose from: articulated, Cartesian, SCARA or parallel.

Each of these robots has its own advantages and constraints such as the number of axes, maximum load (called payload) and range.

Each of these criteria will allow you to refine your choice.

An example of a WITTMANN BATTENFELD Cartesian robot

Cartesian robots can only move along linear axes, making them very profitable and easy to program. They are perfectly suited for repetitive tasks, such as unloading machines.

Their main advantage is that they allow a high level of positioning accuracy throughout the working area. For example, most coordinate measuring machines are manufactured with this structure. Additionally, the modularity of the structure makes it possible to produce large robots that can, among other things, control all the machines on a production island.

Some examples of applications include using Cartesian robots for assembly operations that require very precise positioning, for machine tool control (workpiece loading/unloading and tool change) and pick-and-place operations for injection molding machines.

If you work with loads that are heavier than average, you should consider Cartesian gantry robots. This type of robot is larger and has a higher payload and range.

An OMRON SCARA robot

SCARA robots work along vertical axes by rotating on the same plane. They are faster and more flexible than Cartesian robots.

They are especially notable for their ability to carry out vertical insertion operations by only using movement of the Z axis.

The configuration of this robot allows for simple and inexpensive structures. Most SCARA robots are manufactured with only four degrees of freedom and are used for simple assembly operations that do not require complete part orientation capability. For these tasks, SCARA robots will be more precise (repeatability of tasks) and less costly than articulated robots.

However, if you require six degrees of freedom for complete part orientation, an articulated robot would be a more practical option as it will offer greater operational flexibility.

A KUKA articulated robot

The articulated robotic arm is built on the principle of a human arm. It is made up of a series of joints, each joint giving it a degree of freedom (from 4 to 7 DOF). This very flexible structure gives it the ability to reach any position and orientation in its work envelope, in spite of obstacles.

This robot structure is used for a wide range of applications:

– arc welding
– spot welding
– material handling
– machine feeding/loading

They are however more difficult to program than other robots and are also more expensive. They are increasingly available in a collaborative version (cobot).

A PANASONIC parallel robot

Parallel robots are constructed from articulated parallelograms connected to a common base.

In the parallel robot category you will mainly find Delta robots, also called Spider robots. This robot configuration is capable of delicate and precise movements.

They offer very dynamic movements and are the ideal solution for assembly and packaging tasks with a low payload, or for pick-and-place operations on light objects (from 10 g to 1 Kg). These industrial robots are frequently used in the food industry as well as the pharmaceutical and electronics industries.

Most robots are designed to be flexible and carry out various functions.

However, most manufacturers offer lines of robots dedicated to particular applications.

These specific lines have specialized equipment. For example, welding robots are generally equipped with welding torches; painting robots are especially waterproof and have special protection; palletizing robots are designed with a more rigid structure, etc.

The maximum load (payload) of a robot is measured in kilograms. It is the weight a robot can lift. It includes the tool weight (EOAT).

Maximum payloads vary greatly depending on the application, product and robot used. They are therefore very important for accurately calculating the dimensions of a robot. DirectIndustry makes choosing easier by offering you a filter for robots by maximum load.

A robot’s range is measured in millimeters. A robot’s maximum range is measured from the center of the robot to the longest extension of its arm. The maximum range varies for each robot model, it is fundamental in order to adapt the robot to what it is used for. The work space the robot operates in is called the working envelope. This depends on the range and the conception of the arm.