Applying toolroom automaton.
Everything is slick, polished, refined--except off in one dark corner, where a caveman is swinging a large club. He's setting cutting tools.
It's not quite that bad, but in the course of our travels, we often encounter tool-control systems that contrast the sophistication of the plant almost that much.
It's surprising to find shops spending top dollar on the latest CNC equipment, only to waste it with such outdated tool-control practices. The toolroom--one of the last parts of the shop to be critically examined--presents real opportunities to improve efficiency and control for plants of every size. In this article, I'll examine how to update your toolsetting, tool control and tool handling; we'll explore the concept of toolroom automation.
What is toolroom automation? It's much like any other type of automation. By applying "systems" to specific tasks, we make many operations automatic. In the toolroom, there are many ways to apply such systems.
You can keep track of tools using a computer. Using a "smart" toolsetting gage, you can automatically move the gage to the tool point. You can automate tool handling, inventory, and delivery in much the same way other parts of a shop are automated.
Granted, toolroom automation requires more flexibility than a high-volume manufacturing system, but the technology to implement this has existed for some time. It's much the same as that technology required for effective machining cells, FMS, and factories of the future.
In a nutshell, toolroom automation is how to bring tool-control procedures into step with the rest of modern manufacturing. Why automate the toolroom function? Nobody invests in automation for the sake of automation. There must be concrete advantages--either short term or long term. In the toolroom, there are several important ways automation pays dividends.
Better toolroom operations improve tool-setting accuracy and help ensure use of specified tool geometries. With automated toolsetting, greater consistency is achieved, but labor is also reduced. Finally, by tying the tool-control function into other manufacturing-control systems, you're assured the best control of all tool-related variables. Let's look at each issue.
Improved accuracy is one of the best reasons to gain more control of toolsetting. Because toolsetting accuracy directly affects the amount of scrap produced, consistently accurate toolsetting is a must.
Furthermore, with untended machining, there is no operator to check tools before they are used, or check parts during the cycle. That's why consistency of toolsetting accuracy is critical. As more automation is introduced into production, errors are far more costly.
Through automation, the exact information about each tool can be made available to the toolroom operator. A computer can generate the tool layout, indicating every dimension and shape.
Then, two different toolsetting approaches can be used to ensure accurate tool positioning. First, the operator can set the tool exactly as indicated by the layout, critically positioning the tool at the specified zero points and checking its geometry in the process.
An alternate approach can be quicker, but requires a more integrated, DNC-type network. By measuring the tool's deviation from the specified zero point, then entering this data into the computer, the system can feed tool offsets directly to a CNC machine. It actually eliminates the toolsetting function, replacing it with tool offsetting via the machine control.
As a result, this approach limits tool accuracy to the accuracy of the machine's offset system (control, encoders, slides, and ball screws), but it completely eliminates the need for manual tool presetting. It's ideal for turning applications where the tool is stationary, but less effective for rotating-tool setups.
If there's anything predictable about workpiece tolerances, it's that they always get tighter. A good tool-control system should be able to accommodate future tolerance requirements as well as today's.
Labor savings are the second important area where advanced toolroom practices pay off. Toolsetting remains one of the most labor-intensive operations in a modern metalworking system. Accordingly, it stands to gain the most from advances in automation. Toolroom automation can improve worker output and reduce training requirements.
First of all, the labor involved in toolsetting and control is expanding with the increasing popularity of short runs. Here, tools must be set up or verified more often. Even if only a few parts are run, the tooling must be retrieved from inventory, gaged, delivered to the machine, and returned to inventory.
As a result, it's possible that more time is spent handling and setting tools than running parts. The flexibility and time saving gained through an investment in CNC equipment could be completely negated by obsolete manual tool-control practices.
The time savings offered by an automated toolroom can really add up, too. For example, if you have one full-time tooling operator working at capacity, an automated tool-management system can eliminate the need for a second person as you get busier. And, because the toolroom operator can be prompted by the tool-control computer, less specialized training is required.
Less experienced operators can follow the instructions on the screen, and those with more experience can use the computer's prompting as a reminder. In both cases, tool-setting personnel are more productive with computer-assisted toolsetting systems because all necessary information is at their fingertips.
Management and manufacturing information control can both be favorably affected by automated tool-control practices. From a manufacturing standpoint, the tool computer helps guarantee the most up-to-the-minute tool specifications without the need to revise layout drawings. It can help monitor tool usage, compare tool life, and manage tool inventories.
Through a central computer, you can track tool usage and forecast when you will need to have certain tools delivered. When inventories drop below a specified quantity, an order flag can be raised. This helps minimize tool inventories, yet assures timely replacement of spent tools.
When comparing tool life, statistical analysis can eliminate the variation associated with irregular tool wear. The analysis shows underlying tendencies that more accurately reflect typical tool-wear characteristics. As a result, you can evaluate the cost effectiveness of different cutting-tool options and make better selection decisions.
From the product-design side of things, computer-aided toolsetting also can improve responsiveness of manufacturing to part-design changes. Through an integrated CAD/CAM system, every design change can be immediately reflected in tool changes. Whether new tools or different tool settings are required, an automated tool-control system can respond equally fast.
For shops of any size
The concept of toolroom automation works on nearly any scale, whether you've got three NC machines or 300. And benefits begin immediately.
In big shops, centralized tool control reduces inventory, labor, and cost of engineering changes. If computers are already used, a computerized tool-control system can tie directly into them, painlessly. Further, the toolsetting volume of a large shop can mean fast payback.
For shops with as few as three NC machines, the same holds true. More small shops are using computerized programming systems that make toolroom automation a natural.
Many computer-aided programming systems generate tool layout and dimension drawings electronically. Transferring this information to the toolroom computer eliminates drawings and endless drawing revisions. One person can handle far more of the overall manufacturing-management operation.
Such systems also can accommodate shop expansion. A modular system like Royal's Variset gaging system lets you add capabilities as needs develop.
Basically, there are four areas where automation can help the toolroom: Toolsetting, tool storage, tool handling, and tool information. The requirements of each are simple.
The toolsetting gage must be accurate, efficient, and impervious to hazards of the shop environment. An effective gage is the most essential element of an efficient toolroom.
The gaging system must have resolution greater than the closest tolerance measured. Specifically, better than 0.0002" for typical machining operations. (The better the tool-setting accuracy, the better the accuracy throughout the shop.)
When comparing noncontact with contact gaging systems, noncontact systems generally will result in better accuracy over the life of the gage. They reduce the likelihood of problems caused by wear and contaminants. Toolsetting gages that rely on mechanical contact can require more frequent mastering and adjustment.
Whatever feedback system is used (glass scales, optical encoders, magnetic encodors, etc), it should be sealed against chips, oil, and contamination. Ideally, the entire gage should be protected from the environment.
Some gages allow automatic positioning to the recommended tool zero point via servomotors. The computer-stored dimensions are relayed to the gage, and it automatically moves to those coordinates. These systems are efficient because the operator doesn't have to manually position the gage. Over the years, they will pay for themselves many times over in time savings.
Storage, transfer, and control
Effective tool storage is another important part of an automated toolroom. Tool-storage systems must meet the same requirements as any storage system: The tools must be protected, organized so you can find them, and accessible to appropriate personnel. A variety of tool-storage systems meet these requirements with capabilities ranging from simple drawers and cabinets to fully computerized and automated storage and retrieval systems.
Tool transfer is fairly easily automated with existing technology. Tools must be transferred between the gage, storage system, machine tool, and the repair and sharpening area.
The most basic tool-transfer system uses tool-handling modules that hold and organize several related tools.
These same modules can simplify storage. With tools in place, modules can be transferred from storage to machine, either by hand, push cart, conveyor, or automatic guided vehicle. The more automation used in tool transfer, the better control you'll have over tools, and the lower labor requirements will be.
Tool-control systems are extremely important. Increased degrees of automation require more and more sophisticated control systems. Information and control needs will vary dramatically, based on your own shop situation and requirements. For example, various printers and plotters can produce valuable management reports or tool-layout drawings, but they add to the overall cost of the system. Whatever criteria are used to evaluate the toolroom control package, allow for system growth.
Control communication capabilities are also important to allow the toolroom control system to interact with other control systems and computers. By linking to a host computer, CNCs, material-handling PCs, and plant-floor feedback devices, an automated toolroom has the potential to become an integrated part of an entire manufacturing system.
The concept of toolroom automation is fairly new, but the skills and equipment required to implement it are available. The costs are insignificant in light of the returns. Even a partially automated toolroom can pay for itself through improved control, reduced scrap, and more effective use of existing personnel and tool inventories. For information on automated toolsetting equipment and systems, circle E66.
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|Publication:||Tooling & Production|
|Date:||Mar 1, 1985|
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