Bar Feeders Provide New Paths to Productivity

From all reports, inventories of finished goods will soon be at an all-time low. This means that when the long winter of our economic discontent ends, pent up demand will push manufacturers to ramp up production.

As always, those shops that can respond quickly and with more cost efficiencies will have a decided advantage over their competitors. To achieve this, forward thinking operations will use the current downtime to enhance their manufacturing processes by investing in the newest generation of automation products, including bar feeders.

The obvious reasons to couple bar feeding systems with CNC machine tools are to reduce the cost of making parts, increase output and reduce time-to-market. Regardless of the ups and downs of the economy, these fundamental concerns haven’t changed since bar feeders first gained popularity more than 30 years ago. What is continuously changing is the way in which bar feeding systems deliver these benefits.

Continuous Development

There have been a number of significant technological advancements in bar feeding throughout the years, beginning with the introduction of the hydrodynamic system, pioneered by LNS, that uses oil within the guide tube to support a 12-foot length of barstock and enable vibration-free turning at higher spindle speeds. Additional bar feeder innovations followed, including fully automatic bar feeders, “short-loaders” for spindle length barstock that require no guide tubes or oil, servomotors for better control and faster change-overs, and many other refinements.

The latest productivity-enhancing bar feeder innovation builds on these operational developments by improving the interaction between the bar loaders and the CNC turning machines or the multi-station machining centers they serve. For example, LNS recently introduced the first Advanced Ethernet Interface (AEI) for this purpose.

Although the initial thought was to reduce interface costs and make change-overs quicker and easier, it soon became apparent that the interface could improve productivity in a multitude of ways. Working with the leading CNC machine tool OEMs, and using input from many end users, AEI is evolving into a multi-faceted communication system.

More Flexibility

A key benefit of this communications interface is the ability to more efficiently complete a high mix of long or short production runs, a complex family of parts and even a variety of unrelated parts with little or no operator intervention. Here’s how it works: The operator programs the machine tool for the series of runs to be performed. As each job is ready to begin, the machine’s controller selects the correct tooling from an automatic tool changer (ATC) and uses the AEI to inform the bar feeder of the new job parameters.

On command from the machine tool CNC, the bar feeder then performs any adjustments for such factors as part length and pusher travel that are necessary to accommodate the job. All of these adjustments are performed automatically on select bar feeder models. This enables the machine tool to move seamlessly from one job to another without operator assistance.

In addition to time and labor savings, this communication system can also save materials costs through a unique Library Search feature. For example, if the machine tool finishes machining parts from a length of barstock and the bar remnant is too small for the machine to make another of the same part, the system can electronically search a parts program library to find another part that can be machined from the remnant now in the machine tool. The machine tool then communicates to the bar feeder, the change-over is automatically made, and the new part is machined.

Impact on Untended Operation

Clearly, the advantages of the AEI are well suited to lights-out production. With no operator interaction required, a shop can set up a series of jobs at close of day and find the finished parts in the morning.

However, some shops resist untended operations for fear that something will go wrong, especially over a weekend or holiday shutdown. Because the AEI is Internet-enabled, the process is easily monitored remotely from any computer that has Internet access. It can even be set up to send alerts to a mobile phone if the system is forced to shut down or needs attention.

Connectivity with Other Peripherals

The AEI also has the potential to open communications between the machine tool and other LNS components used in an automation process. One scenario might include the machine tool, the bar feeder, a high-pressure coolant system or a vacuum unloader. As each job comes up in the machine tool’s program, the AEI tells the bar feeder to make the necessary adjustments, the high-pressure system to adjust its stream and the unloader to prepare to accept parts.

Throughout the past 30 years, bar feeders have evolved from simple machines that load barstock into devices that use sophisticated technologies to enable more precise, cost-effective and safer parts production. The next step, exemplified by the LNS AEI, is the ability to seamlessly interface with machine tools and other automation components. By so doing, machine shops of any size will be better able to respond to the next great manufacturing run.

When it's Life or Death, Precision Parts Count

We tend to think of precision machining as a numbers game in which the goal is to hold tolerances within tiny fractions of an inch. However, when you realize that the component you are machining is part of a transcatheter device that will repair a hole in the heart of a child, you see another dimension of your work.

Mendell, a precision manufacturer of custom medical components, uses advanced equipment and automation technologies to keep its processes highly predictable while producing top-quality products. This technology, coupled with the expertise of the company’s 72 employees, enables them to produce medical implants, surgical instruments and other medical components that demand very close tolerances.

The company’s technology extends from sophisticated CAD/CAM systems to high-speed multi-axis milling machines that perform in as many as five axes simultaneously, and Swiss-type CNC machines that operate in as many as 12 axes simultaneously.

Mendell recently upgraded its extensive line of Swiss machines with new Tornos machines that are capable of both high spindle speeds and precision cutting. One is a Micro 8 that can hold tolerances of ±1 micron and rotate at as high as 15,000 rpm. The other is a Delta 20/5 with spindle speed reaching as high as 12,000 rpm.

According to the company’s manufacturing engineer, Mark Luedtke, “One of the issues we faced with these high-performance machines was how to feed and support 12-foot barstock so we can take advantage of the machines’ fast rpm while still holding the close tolerances we require. The problem is to control the bar’s vibration so it doesn’t affect the precision of the cut while maintaining maximum spindle speed. The CNC machine builder recommended we consult with LNS about the bar feeding issues, and they were a big help. They studied our applications and suggested that the company’s Alpha series would be a good fit.

“I’m very impressed with the reliability of these bar feeders,” Mr. Luedtke says. “One of the lines is micro machining very small stainless steel parts that can be a problem to continuously feed without misfires or crashes. We’ve never had such problems with this bar feeder. The other line machines UHMWPE rod stock that has to run oil-free because of the nature of the medical part. LNS worked with us to adapt the Alpha by dialing in the guide channels to allow optimum speed without whip or vibration, and we got a little creative in solving other issues relating to running dry.”

According to LNS, the Alpha machines were clearly the right choice for Mendell’s needs and, coincidentally, are also the most affordable models in the company’s line of automatic bar feeders of this type. The Alpha model ST 320 feeds round barstock from 0.12-inch to 0.78-inch diameter while the model ST 212 loads smaller diameter, round barstock from 0.078 inch to 0.47 inch.

The ST 212 uses a positive mechanical device to advance barstock into the loading position. From this point, a nylon screw and gravity feeds the bar into the channel to eliminate multiple or failed bar loading. It also has an exclusive synchronization system for high-speed sliding headstock machines or for running special materials.

In addition to the LNS bar feeders, Mendell included the company’s high-pressure coolant system for the stainless steel line that helps reduce tool wear, maintain cutting accuracy and improve cycle time.

Mendell’s vice president of sales and marketing, Steve Storlie, sees the combination of automation technology and dedicated employees as the key to having a productive and profitable enterprise. “And, as a result, we get to make medical components that help heal hearts, fix damaged spines and even give legally blind people the possibility of regaining some sight,” he adds. “That’s a great reason to get up every morning and go to work.”