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Checking the pulse of metalforming.

At AJ Rose Manufacturing Co, Cleveland, OH, there is a distinct feeling that limitations to the precision stamping process have yet to be discovered. Parts that have only recently been the province of casting, forging, or machining are viable candidates for stamping with any one of Rose's battery of 60-ton to 800-ton mechanical presses.

For its high production needs, the company relies on its highly automated Minster HeviStamper stamping presses in sizes from 200 tons to 800 tons, as well as on both automated and manual Bliss presses to produce light and heavy gauge precision stampings from stock up to 5/8" thick. The company routinely holds tolerances on water pump hubs to better than industry standards (e.g. ID to |+ or -~0.0005" for the entire bore length).

Components such as hubs, impellers, and pulleys for automotive and truck pumps crowd one another on a display wall in the quality testing lab along with brackets, oil pistons, backplates, and a variety of retainers, fans, and cam journals that the company has produced. More than 70 different kinds of impellers, for example, have been produced and are testimony to the versatility of the manufacturing processes employed by AJ Rose. Some pulleys that used to be riveted, for example, are now one-piece designs produced by spinning from blanked stampings to produce a perfectly concentric shape. Pulleys run the gamut from single-, double-, and triple-spun groove PolyVee pulleys for almost any application up to eight grooves for passenger vehicles and heavy-duty diesel engine applications.

The company is constantly evaluating new design and process concepts. One new prototype stamped part formed from HSLA steel looks like a miniature steel tire about three inches in diameter. Such concepts are made possible by Rose's innovative approach to tooling, using both transfer-type and progressive-type dies, and to its penchant for careful control of the stamping process.

Checking processes

Process control for AJ Rose has been provided by signature-based control technology that is fast becoming the hottest thing in factory automation for discrete manufacturing. Signature analysis capability has been adopted for two new Minster 600-ton presses, bringing the total of its presses with signature analysis control to seven. A prototype entry-level product called SMART SAM is being evaluated on a manual Bliss press.

AJ Rose has become such a proponent of the new signature-based technology that it has become a partner in a new company called Signature Technologies Inc, a supplier of signature-based hardware and software that was acquired from Johnson Yokogawa Corp's (JYC) Factory Automation Unit. The purpose of the new company is to develop and market STI's technology to discrete manufacturing industries.

The basis of STI's technology is the Statistical Process Controller and a series of product offerings under the SignatureACE name. The opportunity for signature-based process control in the discrete manufacturing industries is tremendous, says Michael J O'Brien, president of STI. The former general manager of JYC's Factory Automation Unit and partner with AJ Rose in the new venture, Mr O'Brien says that AJ Rose came to the control concept more readily than most manufacturers because of its commitment to process engineering.

Mr O'Brien believes that it will be stampers like AJ Rose that will lead to greater acceptance of signature analysis as an important tool on presses for improved quality through greater control of the stamping process. Ultimately, benefits from signature analysis techniques include the ability to verify machine setup, assure continued operation of the process within machine parameters, alert operators to potential quality problems resulting from tool wear, and signal problem areas within the process.

Signature analysis makes these possible because the metalforming process, like any discrete manufacturing process, has its own distinctive signature as force is applied to the workpiece by a tool. "Control engineers can really make a big impact on metalforming operations, especially when you consider that our discrete manufacturing operations call for application of force on a material over a constrained area that is established by a tool," says Mr O'Brien.

But signature analysis goes further than simply and somewhat arbitrarily setting operating limits to the process. Each point in the signature is statistically determined to have its own set of limits. Signature processes that establish limits by devising a constant are doomed to fail, says Mr O'Brien. The STI approach uses statistically derived limits for each point in the machine cycle as the press cycles from zero to maximum force and back to zero.

Quality parameters

In a real sense, signature analysis takes the pulse of the discrete manufacturing process, captures the data for analysis, and alerts the operator to potential problems in the process. "Problems in part quality are often mistakenly identified with one station when, in fact, the problem may be in an adjoining station," says Mr O'Brien. "A scoring problem may not be due to the scoring station at all, but may be traced to misalignment in another station."

As a diagnostic device, signature analysis has been particularly useful to Rose because it can be used to verify that new tool designs do in fact work. Because Rose does a lot of leading edge tool design investigating different ways of making product, the product is successfully used as a debugging device, says Mr O'Brien.

In addition to use as a diagnostic device, signature analysis provides quality assurance by verifying that each part does fall within acceptable tolerance limits. It can also be used as a form of closed-loop quality control where the parts have low cost in a high-speed process.

For this reason, STI's signature analysis products have made their mark in the can-end making operations in the beverage industry or electronic-connector industry. Anything that changes the signature--an improper sealant, debris, or dirt--will be detected, because the signature of the hit is changed. Those parts will be identified and rejected without turning off the machine. In the case of a high-speed can-end making machine, that could save a lot in downtime, which costs upwards of $10,000 an hour.

The cost of getting into signature-based products is dropping. Mr O'Brien says that STI's new PC-based SignatureACE products cost from $15,000 to $20,000 per machine, and that the low end entry-level product SMART SAM, which is currently being tested at AJ Rose, will be available for under $10,000.

Other potential uses include thread making, press brakes and other bending machines, lathes, cutting tools, and a whole series of processes that are not discrete manufacturing but involve determining failure before it happens, such as identifying contactor failure in large motors or improper seating of control valves in process manufacturing industries.
COPYRIGHT 1993 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1993 Gale, Cengage Learning. All rights reserved.

Article Details
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Author:Lorincz, James A.
Publication:Tooling & Production
Article Type:Cover Story
Date:Sep 1, 1993
Words:1097
Previous Article:Value-adding accessories.
Next Article:Stamper leads fight against tooling wear.
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