Thinking about investing in a helping hand in the form of a cobot? Plug-and-play cobots offer a perfect transition from manual handling or assembly to more automated operations. But, it is important to choose one with a powerful and safe grip!

Collaborative robots or cobots are robots that have been designed to work alongside humans. Equipped with grippers, sensors and vision technology, this latest robotics technology is safe and easy to use in almost any setting. Little wonder that they are quickly becoming a familiar sight in industry

Cobot equipped with Piab’s piCOBOT®—
a plug-and-play compressed air driven vacuum ejector unit

Plug-and-play models specifically targeted at small workshops or businesses, where so far work has been carried out manually, are being promoted by several different manufacturers. However, depending on their design, the capacity and capability of these different cobots and end-effectors can vary significantly. In fact, some vacuum end-effector grippers have ten times the lifting capacity of others.

The secret behind a successful cobot vacuum gripper is its vacuum flow. Without a powerful and continuous vacuum flow, the cobot vacuum end-effector will fail to grip and securely lift whatever it is you want it to handle. Having a cobot with an insufficient lifting capacity will be both frustrating and unsafe. A “weak” cobot will drop and damage parts, compromising the working environment and increasing the risk of industrial accidents.

This is why it is important to look at how the vacuum is generated in the cobot and gripper unit you are about to choose. However, let’s start from the beginning:

The vacuum does the work

Often thought of as a completely empty space, vacuum is an ideal and elusive state. For practical reasons engineers will instead usually view vacuum as negative pressure, as this describes the force that can be harnessed to do work.

In a vacuum system, it is the difference between the atmospheric pressure (equal to the weight of the air above your head) and the vacuum (negative) pressure that provides the ability to perform actions such as lifting, holding, moving, and so on.

Different cobots use different vacuum pumps

In engineering, vacuum is usually created using a vacuum pump, and although there are several different types of vacuum pumps, two main types are used in cobot vacuum end-effectors – miniature electro mechanical pumps and compressed air driven pumps/ejectors.

Vacuum pumps are rated according to their ability to generate vacuum flow. The vacuum flow is the induced air drawn into the pump’s body from atmospheric pressure. This figure is usually expressed as normal litres per minute (Nl/min) or cubic feet per minute (cfm).

Miniature electro mechanical pumps provide less flow

Some of the plug-and-play cobot vacuum grippers offered on the market today use miniature electro mechanical vacuum pumps. This might be the only alternative in settings without access to compressed air. Or, if the cobot is intended for use on a highly mobile truck.

However, miniature electro mechanical vacuum pumps provide significantly less vacuum flow compared to compressed air driven vacuum pumps.

Better lifting capacity with compressed air

As the lifting capacity depends on the vacuum flow, cobots fitted with compressed air driven vacuum pumps will provide between four and ten times the lifting capacity of cobots that use miniature electro mechanical pumps.

The simplest type of compressed air driven vacuum pump is known as a single stage ejector. Vacuum is generated by forcing compressed air through a small orifice or ejector nozzle at very high speed, resulting in negative pressure building up inside the system. From the outside of the system, atmospheric pressure attempts to balance this negative pressure and reinstate equilibrium. This creates the vacuum flow or induced air flow.

Multistage ejectors are even better

In so called multistage ejector pumps, compressed air enters the pump and is fed through a system of ejector nozzles and chambers of varying sizes that act as a “pressure amplifier”. Multistage vacuum ejectors make optimum use of the energy stored in the compressed air through specially designed air nozzles in a series of progressively larger ejectors that allow the compressed air flow to expand in controlled stages.

Multistage ejector principle.

Multistage ejector vacuum pumps offer many benefits over both single stage ejectors and mechanical or electro mechanical vacuum pumps. They are quiet, have few moving parts, and generate no heat or vibration, resulting in virtually maintenance-free operation.

A wise choice

Plug-and-play cobot vacuum grippers that use multistage vacuum ejectors offer the ultimate vacuum flow, which translates into the best lifting capacity and the ability to handle a large variety of products, including objects difficult to grip, such as flexible packages. This is why choosing a compressed air driven “strong” cobot vacuum end-effector is a wise choice for anyone investing in the latest of co-working tools.

About Piab
Piab provides smart solutions for the automated world, helping thousands of end users and machine producers in e-commerce logistics, food, pharma, automotive and other manufacturing industries to improve energy-efficiency, productivity and working environments. With 430 employees and SEK 1 bn in sales 2017, Piab is a global organization, serving customers in almost 70 countries from a network of subsidiaries and distributors. By leveraging the ongoing technological development in automation and robotics, and targeting high-growth segments and geographies, Piab's vision is to become the global leader in gripping and moving solutions.

The content & opinions in this article are the author’s and do not necessarily represent the views of RoboticsTomorrow

Piab Inc.

Piab provides smart solutions for the automated world, helping thousands of end users and machine producers in e-commerce logistics, food, pharma, automotive and other manufacturing industries to improve energy-efficiency, productivity and working environments. By leveraging the ongoing technological development in automation and robotics, and targeting high-growth segments and geographies, Piab's vision is to become the global leader in gripping and moving solutions.

Other Articles

Reinventing Intralogistics

A comprehensive approach to automation requires networking - not just between the individual components. Because for something really ground-breaking to emerge, already the development must be aligned.

The dm Drugstore Distribution Center Relies on Piab Suction Cups

An average of 3,500 pallets are delivered and picked there every day. A large part of the pallets is depalletized with Piab’s DURAFLEX® suction cups BX52P and fed into the order picking chain.

Automated Palletizing of Sweet Tea and Juice From a Cold Room

While palletizing cartons is a regular automation application, doing so from a cold room that is regularly hosed with water to stay clean is a specific challenge. Motion Controls Robotics overcame these by using vacuum technology from Piab supplied by Neff Grp Dist.

More about Piab Inc.

Featured Product

ElectroCraft's Motion Control for Mobile Robots

ElectroCraft is showcasing its award-winning mobile robot technology including their powerful and compact wheel drives, high-torque-density brushless DC motors, precision linear actuators as well as servo motor drive technology at a variety of conferences and tradeshows including the Boston Robotics Summit. Robotics Summit is the premier symposium for the sharing of ideas, technology, and market developments for robotic technologies across industries. Beyond a showcase and pitch of product, ElectroCraft is eager to participate in the collaborative discussion of challenges and opportunities that will shape the near and long-term robotic marketplace.

More Products

Feature Your Product