If not now, when? It may be hard to believe, but in spite of the economic and manufacturing trauma of the last 2 years, the time is right to consider robotic automation for metal machining operations. As we emerge from our economic troubles, which all indicators say is occurring, we can no longer go back to business as usual.
In the past, the approach to manufacturing along with automation capabilities and cost, limited the use of robotic automation. Machining operations were generally lumped into two categories—high volume runs with relatively few part changes and low volume runs with many part changes. Normally, it was only the high volume operations that were automated.
The trend for machining operations post-2009 is going to continue towards lower volumes and higher mixes of work. Because of this, successful shops need to be leaner, more agile and overall more efficient than they ever have been. A significant key to this success may be implementation of robotic automation. But how does a shop get started?
Perhaps the easiest way to address robotic automation is to break down various line items that pose challenges in the shop, and then discuss, point by point, potential robotic automation solutions. Then we look at the benefits of robotic automation and some incentives for implementing it sooner rather than later.
Here are some typical challenges to implementing robotic automation in a machining process.
Part Presentation. Often, parts are presented in bulk and need to be channeled so that individual components can be consistently presented for robotic handling. This may require manual staging or some type of automatic feeding method.
Pre- and Post-Operations. These may include inspection, manual gaging and deburring, to name a few. Recording, processing and transfer of the data to the machine are often required. Automating these processes would be required to allow robot tending.
Machine Access. Access to the machine tool for setup and tool changes is critical. In an automated process, the robot system needs to be stopped to allow safe access. If the robot is tending more than one machine, production would be stopped on both machines. Depending on frequency of tool changes, this can limit the viability of robotic automation.
Chip Management. Machining processes may require clean-out of chips and stringers from the workholding and cutting tool areas of the work zone. This process would need to be automated to allow for robotic loading and unloading. Depending on the severity, chip related issues can be one of the bigger challenges to automation implementation.
Process Rates. In all machining operations, shorter load/unload time is important. In smaller part, shorter cycle operations, it is critical. It is difficult to justify automation if machine usage or piece rate are reduced from what is currently being produced.
Available Space. Most shop equipment is positioned for manual operations and to maximize machine density. Creating operational space for a robot to load and unload parts as well as a safety fence can be difficult.
Cost. In North America, robotic automation is primarily justified based on labor reduction. This is also usually coupled with a short-term view of return on investment.
The robotic solutions available to shops in 2010 are far better at addressing these challenges than even those of only a few years ago. Here are some ways those same challenges can be met.
Part Presentation. While conventional vibratory solutions may work for some applications, there are many where they do not. In those cases, fixtured trays and/or conveyors can be used as a staging area for the robot. Because of recent improvements in technology, for many cases a vision based solution proves to be the most flexible, lowest cost solution.
Parts can be loosely positioned onto a tray, belt conveyor or vibratory belt where the vision system will determine the part location and orientation. The vision system then transfers the information to the robot, allowing it to pick up the part. The vision system eliminates the need for part locating details or precision transfer devices and reduces the cost of processing a new part.
Pre- and Post-Operations. In many machine loading applications, the cut time is much longer than the machine load/unload time. This provides opportunity for the robot to process the part through secondary operations. The cost and capability of automatic gages continues to improve.
Single point lasers, scanning lasers and contact gages are frequently used in robot machine tending systems. As with part presentation, vision based solutions are also proving to be a viable solution. For other secondary processes, such as deburring, the robot can present the part to a bench mounted device and be programmed to mimic the motions of the manual process.
Machine Access. With the large variation of robot configurations available, many alternative system layouts are possible. An overhead robot can be a good solution for tending multiple machine tools and, with proper guarding, can allow manual access to each machine without shutting down the robot system. Many types of robot mounts, bases and positioners can also be designed to allow temporary repositioning of the robot for machine access.
Chip Management. Many chip issues can be taken care of by adding high pressure coolant flush and blow-off processes in the machine or by adding blow-off capability to the robot tooling. For the more serious cases, working with an automation supplier that understands machining processes as well as tooling and workholding design is beneficial. That supplier may be able to determine a better way to process the part and incorporate chipbreaker inserts.
Process Rates. Piece rate is only one measure of an automation system. A more important measure of capability is net throughput. Robotic machine loading systems have proven to have a much higher percentage of uptime than the comparable manual process. This additional uptime creates more available hours of operation per shift than the manual process, and even a robot system with a slower piece rate can have a much higher net throughput. Robots also continue to improve in terms of speed, reach and payload capabilities. Today’s robot may be more than 20 percent faster than a comparable model from 5 years ago.
Available Space. As with the challenge of machine access, many space and system layout issues can be addressed with the variety of available robot configurations. Recent changes to robotics industry safety standards allow safety rated soft limits. Robots can now dynamically define operating space and restricted space based on the status of safety interlock signals. This allows tremendous flexibility in both system layout and access.
Cost. When justifying robotic automation, more than only the labor component needs to be considered. A thorough return on investment evaluation needs to take into account all associated costs and savings as well as changes in throughput. It can also be difficult to justify robotic automation because we tend to think “one-to-one”—one robot for one machine or one robot to replace one operator.
Instead, we should look at multiple processes in a production area. In many cases, what appears to be a situation of one operator per one machine can turn into one operator per three or four machines when we look at the bigger manufacturing picture.
The challenges to implementing robotic automation are more than offset by the substantial benefits. Here is a list of the most tangible benefits for a machining process.
Process Control. A properly designed automated process ensures that things happen when they are supposed to and how they are supposed to. The result of this process control is reduced scrap, higher quality and more throughput resulting in higher customer satisfaction.
Better Machine Usage. A machine that is not running generates no income for the shop. Typical machine usage for a manual machining process is 65 percent. For a comparable automated process, this number is more than 90 percent. Better machine tool usage results in a faster return on investment for the machine tool.
Higher Production Capacity. Robotic automation can allow the opportunity to run untended operations. This provides additional production increases to those because of process control and machine usage.
Better Use of Labor. The most flexible and most valuable resource in any company is its people. A better use of that resource is not necessarily for machine tending, but for machine setup and other operations that may not be suitable to automation, such as part staging, secondary operations, quality control functions, packaging, and so on.
Flexibility. Quick response by being better able to respond to changing production requirements creates the leaner, more agile and more efficient operation necessary for today’s market.
The benefits of automation listed above tell us why we should automate. Here are two reasons why the time is now to look hard at robotic automation.
Economic Recovery. While most experts agree that the economy is recovering, the question is “how fast?” Most companies feel this uncertainty and, as a result, are reluctant to quickly add to their labor force. This is in conflict with the need to hire to be able to increase production. Robotic automation for machining operations provides a good alternative.
Future Available Labor Resources. In the next 5 to 10 years, it is estimated that approximately 40 percent of our current manufacturing skilled trade labor will leave manufacturing. This wouldn’t be as big of a concern if our upcoming labor force was being trained to fill this gap, but unfortunately, for many years the education trend in our country has not been focused on manufacturing and the associated trades.
In addition to the skilled trades problem, the baby boomer employment bubble is about to burst. It is estimated that throughout the next 10 years approximately 70 million baby boomers will retire and 40 million new workers will enter the workforce. The manufacturing industry will be hit hard.
Keys to Automation Success
Success boils down to common sense. Be careful of what application is selected as a viable automation candidate; be careful who you partner with, and stay committed. Many robotic projects have failed because a first-time user attempted to automate its most difficult operation, partnered with an automation company that didn’t understand machining or didn’t involve and train the shop’s people.
Potential candidates for robotic automation may have one or more of the following characteristics on their shop floor: similar processes for multiple parts or part families; machining areas with inconsistent production (problem areas); machines with poor usage; parts and processes with ergonomic issues; and multiple machine/multi-step production areas. Also, it is important to look at net throughput versus actual piece rate.
To select a partner, don’t look for a component supplier; look for a process supplier. Ideally, it is a company that understands machining processes and robotic automation processes so that it can evaluate processes, tools and workholding that are specific to the shop’s applications. That supplier should have a proven track record of supplying robotic machine tending systems.
Also, the partner should be a company that is willing and able to accept total turnkey responsibility, which includes everything from developing the machining process to complete equipment installation.
It has been a tough couple years, but American manufacturing will recover and compete using its brains more and its brawn less. The time is right.
Shops can easily view chips simply as waste, hardly giving a second thought to the disposal process and the potential related savings. By keeping an eye on the waste and choosing the most efficient methods of chip disposal, a shop can easily add to the bottom line through substantial savings.
Here’s a review of the workholding and workhandling challenges a shop faces as it moves a part through a robotic cell, from serving up the blanks to the transfer of the final workpiece to post processing and gaging. Productivity, Inc. takes the reader through a few of their cells that they've installed using Fanuc robots and a variety of other machine tool equipment.
Urethane spindle liners present a viable option to steel to fill the gap between spindle ID and bar OD. They protect both the spindle and bar stock and increase machine performance.