Automation on demand it’s not just for automotive

Automation has long been associated with high-volume automotive manufacturing, but what about using a robot to run low volumes, even as low as one item? In today’s just-in-time manufacturing environment, automation on demand is an ideal complement. Just as a lathe outfitted with quick-change jaws on the chuck facilitates quicker changeovers, there are many ways to outfit a machine tool automation system to allow it to effectively process low-volume parts and process parts on demand.

Robotics, just like machine tools, are configurable in many ways. True automation on demand has the system decide what part to process, tooling up the robot and machine, based on part identification in the queue. Traditionally, automotive automation in machining is not flexible, but designed to perform one task on one part very quickly. Automotive automation has received much attention, which has skewed perceptions of automation. Few parts justify making an automation system that can only perform one task or process one part. Fortunately, as the knowledge of the technology grows, more end users are working with suppliers to develop flexible systems.

Developing an automation-on-demand cell usually involves a family of parts or parts that are similar. Often a cell will work with a common blank or a few similar blanks to make many different parts. To make a project work for this type of cell, minimize the number of different blanks. The smaller the number of different-size parts that need grabbed, the easier the solution. However, not every part or every family of parts will work in an automation-on-demand cell.
 

Which part to run?

There are typically two different types of automation-on-demand cells: those based on the identity of the incoming parts, or those based on a list of jobs in a job scheduler. Whichever method, the automation system and machine tool will be directed to the part and use the appropriate program for both the robot and machine to process those parts.

The job scheduler software allows programming a list of the jobs to be performed. In this type of cell, different blanks are located in the cell, so the cell is ready to run any of the jobs it was set up for, when directed to do so. This list of jobs can be inserted manually, read off barcodes from a job traveler, or come directly from a company ERP system.

The other type of system will evaluate the next incoming part and call up the programs and processes that are required, based on that part’s identity. When using pallets, the pallets can be marked using RFID or barcode. The robot can bring the incoming pallet to the reader station for identification, sending the proper programs to the automation system and machine based on pallet identity.

Evaluating can be based on the incoming blank, with detection of the incoming parts’ differences made via a photo or proximity switch. Other parts can be more subtle and may require a vision system to detect differences.
 

The deciding factor

Workholding needs to accommodate all the parts the cell will process. If parts are coming from a standard blank, then workholding is not a concern. But often, workholding is the deciding factor on whether a group of parts will be a candidate for an automation-on-demand cell. Robots can change out the end of arm tooling (EOAT) automatically to grab different parts. In machine tool workholding, there may be lot of quick-change options but not many options that automatically change.

Workholding milling – While a myriad of custom solutions exist for special situations, several are more common. Vises are considered the most basic: step jaws can handle different sized parts, or several vises on the table each can be set up to handle different sized blanks.

Workholding milling pallets – Small, automatically clamped pallets allow anything bolted on the pallet to clamp on the machine table with an appropriate clamping unit. These frequently used types of systems allow many different methods to secure the parts to the pallets, enabling a large range of different parts to be included in the cell. Since the pallets are the same, the workholding and EOAT are a common solution in the machine.

Workholding turning – Just like vise jaws, chucks jaws can accommodate different parts. Solutions that are more flexible include systems where collets, jaws, or even the entire chuck changes automatically with the robot to accommodate different parts that may need to be processed.
 

EOAT strategies

Having flexible EOAT is important to handle a series of different parts or a family of parts. Pneumatic grippers are a typical method of choice for picking up metal components. To maximize this choice, there are long stroke grippers to grip a wider range of parts than standard grippers. Two alternatives that allow more flexibility without changeover are magnetics and vacuum. Using vacuum cups to pick up metal parts may seem far-fetched in the machining world, where the tendency is to use grippers that mimic vises and chucks. However, vacuum is very popular in plastics where the surfaces seem smooth, but there are cups that mold themselves nicely to saw-cut surfaces. A pneumatic gripper with a specific range of motion will use gripper fingers to pick up parts with a range of sizes. A vacuum cup can pick up many different parts while only relying on the flat surface and not the size of the part to pick.
 

Infeed/outfeed

Just as workholding can be a limiting factor in the machine, the infeed/outfeed can be the limiting factor in automation. With the goal of these cells being work on demand, infeed/outfeed systems tend to be moderate in size. Conveyors can work well but tend to require a vision system to find the different sized parts on the belt. Racks of parts holding positions around the automation system may also be a good choice. These can be made so that certain positions can be designed for different parts. For example, there are rack positions for smaller and larger parts.
 

Measuring, cleaning, marking

Ancillary processes are popular in automation-on-demand cells. When a cell is making one or a few specific parts and then automatically changing over to the next part, measuring the parts makes sense. In addition, if you’re going to consider measuring the part, then you will need to consider cleaning the parts first for more accurate measurements. Other operations, such as part marking and/or deburring, may also be advantageous.
 

Efficient production

Medical devices, cutting tools, and firearms are industries benefitting from automation-on-demand cells. A basic search of most tooling company catalogs yields multiple choices, and it is obvious how convenient and cost-conscious it would be to have only a few small-volume parts in stock and the ability to make more as needed.

While an automation-on-demand cell is not for every part and every industry, many parts can lend themselves to this style of production.

Methods Machine Tools Inc.
www.methodsmachine.com

About the author: John Lucier, automation manager at Methods Machine Tools Inc., can be reached at 978.443.5388 x5426 or jlucier@methodsmachine.com.