Pick and Place Application Guide
Building out your pick and place application consists of gripper selection, robot selection, and a few other components. In this guide we will go over the best practices, considerations and the main technical details needed to successfully deploy a Pick and Place Application
We’ll start with the gripper selection.
Gripper Selection
Our go-to end of arm tooling vendor is OnRobot. They have an excellent gripper lineup and are made for collaborative / light industrial robotic applications. We will be using their grippers for examples and product information in this guide. They manufacture a complete suite of flexible grippers that can be used for a wide range of product sizes and shapes. These plug-and-produce fully electric grippers reduce programming time and can be quickly deployed, making them ideal for pick-and-place applications.
Gripper selection is critical because the gripper is the interface between the robot and the task to be performed, making it critical to the success of any robotic application. To select a suitable gripper, start by analyzing the following four characteristics of your workpiece:
Shape
Weight
Size
Material
Your next step will be to determine if the gripper will handle one, or a mixture of products in the cell environment and if the part is delicate and must be handled with care. There are many terminologies used in the industry to name the different types of grippers but in this guide we will differentiate them by their method of grasping the part.
Finger grippers (also called jaw grippers) use their fingers to firmly grab a workpiece. They commonly come in two or three finger configurations. The two-finger (RG2 and RG6) grippers are ideal for applications that will handle a mix of products where the part often changes, as they can be easily programmed to a wide range of gripping forces and widths. Their customizable fingertips and embedded rotation bracket make them suitable for grasping many different workpieces with minimal downtime.
To handle fragile parts, or for when very precise gripping forces are needed, the RG2FT gripper with its embedded proximity, self-centering, and forced torque sensors provide advanced intelligence and sensing capabilities to any pick and place application. The 2FG7 parallel gripper is perfect for tight spaces and demanding gripping payloads. Rated IP67, it can withstand wet and dirty conditions. Its Clean Room ISO Class 5 Certification ensures it can also operate in a wide range of environments.
To firmly grasp around or cylindrical parts, a three-finger gripper would be the recommended choice. OnRobot’s 3FG15 gripper can handle a wide range of cylindrical objects. It has a high gripping force, large stroke range, adjustable fingers, and is also IP67 rated.
Vacuum grippers grasp products by creating a pressure difference between the inside of suction cups and the environment. OnRobot’s vacuum gripper line is fully electrical and requires no external air supply or compressor to generate vacuum. It offers interchangeable suction cups, independently operated air channels, many customization capabilities, and incorporates vacuum and object detection sensors to add reliability to any application. The VG10 has configurable arms that allow it to quickly and easily handle objects of various sizes. Smaller in size, the VGC10 has unlimited customization possibilities with the same payload. The VGP20 electric vacuum gripper is the most powerful internal vacuum generation gripper on the market, making it ideal to handle payloads up to 20 kilograms for low porosity products.
For some products, specialized grippers must be used to obtain the best performance or to comply with strict environmental or certification needs. the MG10 magnetic gripper is ideal to handle ferromagnetic parts. Its magnetic strength can be easily configured to only de-stack one part, rather than picking the entire stack. It's IP67 also makes it suitable for harsh environments.
The on robot Soft Gripper is a food grade, FDA certified, silicone molded gripper that can handle irregular and delicate items commonly found in the food and beverage, cosmetics, and pharmaceutical industries. It operates without the need of external air supply, reducing costs and complexity.
The Gecko Single Pad Gripper uses gecko inspired adhesive technology to pick up flat, smooth, and also perforated objects. It is a non-marking gripper that does not need air supply or electrical power to operate, making it a cost effective, truly plug and play solution.
After finding a suitable gripper for the part, it is important to decide early on if one or two grippers will be used. Using a dual gripper configuration will greatly reduce the cycle time, but will add complexity to the robot program.
Let's now move on to the robot selection.
Robot Selection
When considering the robot speed, the main goal is to minimize the overall cycle time of the application. The number of products that can be handled per minute will mainly depend on the speed of the robot. Keep in mind that the robot speed will be dictated by the risk assessment.
Make sure the robot can handle the required payload. To calculate it, we just need to add the weight of the following components
Mounting Bracket
End Effectors
The Workpiece
The reach of the robot needed for the cell will depend on the position of the infeed and outfeed systems and the mounting of the robot. Let's look into the infeed strategy and how the parts can be presented to the robot. The selection of the infeed system will most likely depend on the current application setup. The first infeed strategy is to always present the product in a fixed and repeatable position for the robot to pick it up. This can be achieved by stopping the product at the end of a conveyor belt, using a manual feeder where gravity slides the part to the fixed position, or using a vibratory feeder with an attached hopper. A presence sensor is commonly used to detect the parts.
Another infeed strategy is to arrange the products in uniform patterns. Fixtures, trays, boxes or containers are usually used to facilitate loading, transporting, and placing the parts.
The next infeed strategy is for the robot to track and pick up a product that is moving on a conveyor belt. An encoder and presence sensor or camera are required to detect and track the product. In the case that the parts cannot be presented on repeatable positions, or they will continuously change, a vision system can be used to quickly identify their exact location. The OnRobot Eyes provide efficient 2.5D vision that can easily detect, sort, and locate the parts. With its simple one-picture calibration, fast programming, depth perception, and seamless gripper integration, adding a vision system to a pick and place application has really never been easier in our opinion.
The outfeed is the system area where the robot places the parts. The options are similar to the infeed ones, but will also depend on what the next process for the parts will be.
If you’re building a pick and place application and would like insights from a team of experienced engineers who have seen nearly everything, then send our team a message. We’ll be happy to speak with you about the details of your project, the hurtles, and potential solutions.
