ROBOTS have earned a respected place in many factories facilitating improved productivity, quality and safety. However, as with other technologies, achieving these outcomes relies on more than simply purchasing the equipment.
According to ABB Australia’s account manager, Andrew Davenport, the first requirement for successful selection and implementation of an industrial robot is a thorough understanding of the process and the potential savings that could emerge.
Robot Technologies-Systems general manager, Trinton Smith agrees assessing the positives robots can bring is important. He told Manufacturers’ Monthly a robotic system should yield a payback period of between 12 and 18 months.
In assessing payback, Smith says non-financial issues, such as health and safety savings should be considered along with direct financial benefits. He claims safety is a major non-financial driver for the automotive industry’s use of robotics.
“It’s to do with repeatability for RSI (repetitive stress injuries) issues, and also danger as car materials are getting stronger,” Smith told Manufacturers’ Monthly.
“With materials getting stronger, it takes longer to weld and there’s more expulsion. The end effect is that you can’t have a guy standing there welding, otherwise he would have to be protected in full leather.”
For materials handling, Smith says restrictions governing the maximum weight operators may lift make automation essential in some processes.
Whatever the process, Smith claims, the main requirement is product consistency.
“Manufacturers need to really analyse what they want to do with the process and what the product tolerances are. If the product is within production tolerance for the year, then you shouldn’t have an issue with putting a robot system in,” he said.
Types of Robots
Many kinds of robots are available, but according to Davenport, articulated robots offer the greatest flexibility.
“You are able to get the [articulated robot] unit to do a number of different tasks and redeploy those tasks quite easily and efficiently,” he said.
Davenport admitted the main shortcoming of articulated robots was that they try to do all things and in some cases dedicated machines may be simpler and more cost effective.
Hawker Richardson’s Jeff Roberts claims articulated robots are less suited to high precision, high speed applications, for example electronic component assembly.
According to Roberts, Cartesian robots can operate more quickly and accurately in such applications because of their structure. Cartesian robots have axes fixed perpendicular to each other, whereas articulated robots’ motions are transmitted via a gearbox which Roberts claims can lead to compound errors.
“As an example, we could ask the robot to pick up 10,000 components in one hour and place those components after looking at them with a camera. That type of application is specific to a Cartesian robot and many anthropomorphic robots could not compete with that,” he said.
Davenport says manufacturers must adhere to specifications when installing robot.
“It’s important to make sure manufacturers’ guidelines are stuck to in terms of concrete thickness and power and air supply,” he said.
A strong base for the robot is needed to provide stability, particularly for emergency stops. “The robot exhibits forces, both linear and rotational. In normal mode of operation that force isn’t too high, but when you have an emergency stop...you have a high amount of force being exhibited and that needs to be held by the robot. The robot is bolted to the floor and the concrete needs to be thick enough to withhold those forces.”
End effectors, cell layout and safety must all be planned, he continued, and the robot must also be programmed.
Davenport claims most recent robotic developments have focused on computing. “On the pre-installation side you now have the ability to do a full 3D moving simulation showing your robot in the plant. That means measuring dimensions and optimising the robot for that particular process is now a lot easier to do.
“When setting up the robots in the factory, again you can take the computer simulated results to reduce your programming time when you’re on site,” he said.
For on-going operation, computer simulations also allow robot cycle time and production to be optimised. “You don’t need to stop the robot to try new things,” Davenport said.