Several months ago, ATS Automation Tooling Systems, Inc. surveyed its Innovator e-newsletter audience on “How to Select the Right Robot.” Respondents agreed that robots and related technology have changed in the last decades from a technical, cost, and integration standpoint, making some aspects of selection simpler and others more complex. Here are five areas to investigate when selecting a robot.
Prioritize the Basic Selection Criteria
When embarking on any complicated and multifaceted endeavor, a good place to start is to review the basics, which in terms of robot selection criteria have not changed a great deal over the last decades:
Point-to-point positioning accuracy and repeatability- Axis speeds
- Point-to-point speed
- Environment requirements
- Controls integration requirements or advantages
- Reach
- Payload
- Cost
When asked to rate the above points in order of importance, survey respondents emphasized that all can be equally important and are difficult to rank without an application to reference. By ranking the basic parameters according to the requirements of a specification, the choice of robots will narrow down before a more detailed assessment is initiated.
The cost of a robot is very subjective and dependent on your ultimate goal: do you want it to solve a quality issue with a high-value product caused by manual assemblers, or do you want to drive down the cost of a low-value product in order to compete? In the first example, a robot might be the only choice no matter the cost, but in the second, you might have to consider a variety of options.
Work Closely with the Robot Manufacturer
First and foremost -- remember that robot manufacturers’ specifications are based on average conditions, so it is important to work with the manufacturer to define how a particular robot will perform in your facility with your process. For example, a part with an uneven distribution of weight may have an effect on accuracy and repeatability. In order to achieve those two requirements, you may have to compromise on speed.
Since a robot rarely operates in isolation, additional issues need to be considered:
- Involve all stakeholders early on in the decision-making process because their experience is invaluable in comparing the robot manufacturers’ specifications to the requirements of your process and operation.
- Look at the controls architecture into which the robot will be integrated for both compatibility concerns, and areas where controls can be used for multiple purposes.
- Think ahead about the likelihood of your product changing and how easy it will be to adapt a particular type of robot.
- Ask the robot sales representatives for as much data as you need to help you make an intelligent decision.
Seek Advice on End Effectors
End effectors have tended to be a weak link in robot technology, which survey respondents confirmed. You have a choice of how to get an end effector designed and built, but rarely is the service available through robot manufacturers. Some companies use an internal department; others have their end effectors designed by an automation integrator, while others use suppliers who specialize in end effectors.
One of the main trouble spots mentioned is with the flexible hosing and wiring that is concentrated in the joint between the robot and end effector; the constant movement of the robot can cause both components to wear out prematurely. Service technicians complain that because of the tight space they have to work in, servicing the end effector wiring and hosing can be difficult. However, some respondents noted improvements and one forward thinking individual commented that as wireless technology becomes more common, the problem with wiring, at least, will become a distant memory.
Controls programmers who responded to the survey explained that whether to program an end effector through the robot controller or the PLC is not always a clearcut decision. Also, depending on the complexity of an end effector, which can range from simple pneumatic finger-like grippers to sophisticated electromechanical devices, the end effector can present the bulk of programming and integration challenges in a new robot installation.
From a mechanical point of view, the end effector can have an impact on the robot’s available payload. In order to get greater use out of a single robot, some have automatic tool changing capability and perform a multitude of tasks. However, the more the end effector can do, the heavier it is likely to become. You must be cognizant of the threshold in your application where trying to get too much out of a single robot may end up costing more in controls complications, reduction to payload and speed, and service headaches than dividing the work between two robots.
Don’t Forget Service
While robot manufacturers continue their efforts to promote all of the latest improvements, such as more flexible motion control, user-friendly teach pendants, and easy-access service ports, the survey revealed that end users consider training, service, and support from the robot manufacturers to be a very high priority. Plus, service must be available everywhere, and it must be delivered fast. In order to offset the need for training and service, end users have a tendency to use the same type of robot and controls architecture that they have in the past, suggesting that many of them have not yet experienced the advances in technology.
When engaging stakeholders in the decision-making process, make sure they are aware of the latest technology. Your in-house controls expert might make his decision based on a difficult experience he had reprogramming a particular model of robot in the past without being aware that a lot of the controls platforms are more flexible today. Most robot manufacturers are quite willing to help educate people in your organization.
When service is the only solution, compare the manufacturers’ service and support offering to your requirements based on your operating and maintenance personnel and the regions where your manufacturing facilities are located.
Understand the Total Cost of Ownership
No matter what manufacturing process you use, it is always important to understand the total cost of ownership. In manual operations, consider the cost of ongoing training of personnel. Likewise, automated processes have upfront costs such as training, and the recurring cost of replacing wear parts that the uninitiated might not expect.
If your process has never been automated before, consider facility upgrades that may be needed. For example, a large robot operating at a high speed may require a reinforced floor pad, or the pressurized air system may need to be improved due to the additional requirements of pneumatic grippers.
Once you have solicited input from everyone on the team, asked the important questions, and done the necessary calculations, proceed with confidence, knowing that selecting the right robot will make you as efficient and competitive as you can be.