Common Robotic Machine Tending Applications

Machine tending – the loading and unloading of manufacturing machinery – has historically been one of the most common applications of industrial robots.  That trend continues today, as the International Federation of Robotics reported that 44% of all robots sold in 2022 were used in parts handling applications, more than any other category.

Loading and unloading machinery is considered one of the DDD applications – Dull, Dirty, Dangerous.

Virtually any machine that is manually loaded and unloaded can be automated, but collaborative robots (cobots) are changing how manufacturing and production engineers think about automation.  The typical approaches in the past included gantry robots, traditional (non-collaborative) robots, and dedicated machine specific devices.  All had their limitations:

• Floor space – safety guarding required by traditional automation consumes large chunks of manufacturing floor space, and may require the re-location of machines, power drops and other utilities.
• Complexity – traditional robots are difficult to program, operate and maintain.  Small shops just don’t have the skilled resources to dedicate to traditional automation, and large shops don’t want the expense.
• Lead times – traditional automation lead times are typically 3-5 months, an eternity for any company fighting labor challenges day to day.
• Limited flexibility – traditional automation is difficult to move to a new location, and to re-program for new parts, limiting the overall efficiency.
• Total cost – given all the above points, machine tending with traditional robots is an expensive investment that is difficult to justify.

Collaborative automation offers a uniquely different approach.  With a proper risk assessment, safety guarding and the associated floor space is not required, programming and ease-of-use is simplified and flexible, and total cost is a fraction of traditional automation.

When we look at applications, the common objective is to keep the machine running, actually making parts, as much as possible.  Whether the measure is ‘spindle on time’ in CNC machining, or ‘mold closed’ time in injection molding, the goal of automation is to deliver more productivity and throughput.  Additional benefits such as improved quality and higher employee satisfaction all contribute to the productivity objective.

Machine tending of CNC machine tools is a popular and growing application for cobots, and the most common configuration has 1 robot tending a single machine tool.  The cycle is straightforward, as finished parts are removed from the chuck and a fresh blank part is loaded in.  In single gripper applications, the cobot removes the finished part from the machine tool and places it in dunnage or in an organized fashion on a work table.  The cobot then picks up a blank part and loads it into the tool.

In dual gripper applications, the end of arm tool has a pair of grippers.  The cobot picks up a fresh blank in gripper #1, and carries it into the machine tool.  The second gripper is used to remove the finished part from the chuck, the blank is then loaded and the cobot exits the machine tool to drop off the finished part and pick up a new blank.  The dual gripper configuration is more efficient, as the robot unloads and loads in a single motion without exiting and re-entering the tool.

With the introduction of larger cobots such as the UR20, a single cobot tending 2 or 3 machine tools is feasible.  Each application would have to be evaluated based on average milling cycle time, the weight of the typical parts and the physical layout of the machines.

Cobots are common in 3 applications in injection molding.  The first is the removal of the finished part from the open mold.  In the traditional approach a finished part was ejected off the face of the mold to drop onto a conveyor belt below.  Robot automation allows the part to be carefully handled to protect surface finishes and maintain orientation for secondary processes outside the mold.

The second application is insert loading, where metal parts are molded right into the plastic.  A good example would be automotive or marine battery cases, where the terminal lugs are molded into the sides or top of the battery case.  Depending on complexity, insert loading may be done by the same robot as the unload process, or a second robot.

The third application area in injection molding is secondary processes.  OEM customers are requiring their molders to add more value to the molded parts, including sprue and flash removal, embossing, polishing, assembly and packaging.

Injection molding efficiency is measured by mold closed time, so the objective of any automation is to get in and out of the mold as quickly as possible.

In Circuit Testers

The electronics industry as a whole produces a massive quantity of printed circuit boards, modules, memory and storage devices and interfaces.  And in today’s hyper competitive markets, product quality must be maintained at the highest levels.  Which means testing, at component, module, board and final product levels by sophisticated and expensive test systems.  Manually loading and unloading In Circuit Testers (ICT’s) is similar to machine tending a CNC machine or injection molding machine – dull, demanding and repetitive work that is inefficient.  And the cost of scrap and rework due to handling errors, especially on fully populated boards and assemblies, is extremely high.

UR cobots are a perfect match for machine tending ICT systems.  PCB’s are delivered in totes, trays or racks.  In most application, a dual gripper set up is used to maximize throughput, as the payloads are relatively light.  The cobot pulls a tested PCB from the ICT and loads a fresh untested board.  The tested board is then loaded into the proper tote depending on pass / fail status.

Additional Machine Tending Applications

Any manufacturing process that includes manual loading and unloading of machines or equipment is a candidate for cobot machine tending.  This article introduces 3 common applications, but there are many more!

• Press brakes – loading sheet metal blanks and repositioning as needed to complete the bending process.

• Additive manufacturing – removing completed parts from printers or sintering machines.

• Metrology – loading components into 2D or 3D non-contact or automated CMM machines.

Communications

One of the key elements of any machine tending solution is the robot to machine interface. In some industries, such as CNC machine tools, the interfaces are brand specific to the controller manufacturer.  In this case, the UR+ Ecosystem brings great value, as 3rd party partners have developed hardware and software interfaces to the major CNC controller manufacturers.  In other cases, such as injection molding, the interface is standardized by industry associations.  UR offers a standard interface to injection molding machines – the IMMI option.  And finally, some interfaces are less standardized, and developed along industry standard communication protocols such as Ethernet/IP, PROFINET, Modbus TCP or even digital I/O.

Low risk, rapid deployment cobot machine tending solutions from Universal Robots and our partners – contact us today to see how we can solve your business challenges.