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A machine-tool family.

This is a story of a man and his dream. A man fed up with the Establishment. A man with a better idea, and the guts and perseverance to bring it to fruition. To do that, he had to become a machine-tool company. So he did. The message here is that you can too, if you really want to bad enough.

The scene above was a proud moment for Burton F Lewis and his sons--the shipping of their first machine tool. It was a machine that Burt and sons had spent many years designing and building from the ground up.


Over two decades ago, Burt Lewis was chief engineer at a machine-tool company in Connecticut making high-performance metalforming and metalcutting machines. He was particularly interested in metalspinning machines that could form flat blanks into cup-shaped parts of varying contours much easier than you could stamp them out on a deepdraw press.

Metalspinning technology wasn't going anywhere because it couldn't reach the potentially lucrative job runs of 10,000 to 100,000 parts. For that, you had to use expensively tooled press equipment. Metalspinning machines were too slow--they were single-spindle horizontal machines that were difficult to automate, and they are still to slow today.

So he came up with the idea of using multiple vertical spindles to boost spinning technology into more practical production ranges. With four vertical spindles on a horizontally rotating table, three spindles could be spinning parts while the other was automatically loaded/unloaded.

The idea kicked around in his head for several years without an opportunity to develop it. Then in 1967, he left to start an engineering consulting business, and two years later opportunity did knock. His oldest son alan, a mechanical engineer with a varied background in manufacturing and making precision jig borers, had just changed jobs when a slowdown occurred, and he was suddenly available. He and his dad had often talked about building a spinning macine, so he called Burt up on a Thursday night and asked him if he was still serious. "Yes!" Burt said. "When would you like me to start?" Al asked. "Monday!" Burt replied, and that was how they got started.

Getting rolling

Within a year, they had researched the patent position, invented the machine, made engineering drawings, and gotten strong feedback from a small company in the metalspinning business. The owner had expressed interest in the idea, helped them establish realistic part-size parameters and machine specs, and told them that if they could build one that worked, he would buy it.

Halfway through the development process, they were forced to move because a new highway project came through and swallowed up their property, so they set up operatons on a beautiful 500-acre farm outside of Hillsboro, NH. He had seen it advertised in the Wall Street Journal and they had bought it earlier, never thinking at the time that the farm would become the factory, but that's the way it worked out.

Although they couldn't build the whole machine themselves, they had the small- and medium-sized machine tools to make the small, high-precision machine parts and develop the part-handling mechanisms. By combining their own engineering, tooling, and assembly capabilities with the talents of several job shops, they have put together a team that is hard to beat (and one with a lot of mutual respect).

There were some disappointments, of course, but generally the New Hampshire job-shop people that they worked with were capable, cooperative, and sympathetic. Certainly, the talent is there in New England. There are hundreds of small 15- to 5-man machining and fabrication shops with all the tools and skills to make precision parts.

Disaster strikes

Unfortunately, in 1970, after they had built their first machine and were just submitting initial saamples to their benefactor/customer to prove that it did work, the man had a fatal heart attck. With him out of the picture, the man's family was more interested in keeping their company afloat than expanding business to make use of Burt's machine.

Burt and Al decided they would be better off using the machien to spin parts into money, rather than worrying bout where their next machine customer was coming from. So, they designed a variety of consumer products based on metalspinning shapes. They also kept busy making parts for the next machines, making experiemental tooling and samples for potential machine customers, developing new products for consulting clients, and doing production work in metalspinning.

Understanding the process

Shear spinning or flow forming thins the metal in direct relation to the steepness of the forming. In fact, if you think of the part as basically a cone, the sine of the angle of that cone about its vertical axis is directly related to how much the metal thins down as it is formed about the mandrel. This flow forming creates excellent homogeneous grain structure comparable to what you get in a forging die.

In deep drawing, you progressively draw the metal in from the OD of the blank and seldomly thin the metal to any extent. Because the punch and die work on the full circumference of the part, tremendous forces are required. In shear spinning, forming results from the highly concentrated pressure at the roller nose. Forming starts at the center of the pat and works to the outside, and you can make the metal flow down to a quarter of its original thickness. Going beyond that risks shearing the metal.

Thus, the maximum thinning occurs at an angle of 15 degrees, where the sine = 0.25. You can't make a full-vertical 90-degree bend (a cone with 0-degree angle) because there's no place to get the metal, so you use a combination of a press operation to produce a drawn cup or preform that you finish with metal spinning. There are some exceptions where you can ease up on the roller pressure for part of the forming process and allow the metal to draw in from the OD without wrinkling it or changing its cross section. In cases like this, where you really need to push the process to its limits, trial runs are the best way of finding out whether what you want is possible.

thus, as Burt's sample case shows, the ideal metalspun part is a lighting-fixture reflector where you can take a 10" circular blank and spin it in one operation into a 10" multicontoured lamp shade with no secondary operations required. With his four-spindle machine, he can easily produce 1000 parts/hr. Or, if you don't need to make parts that fast, you can use fewer spindles and save on tooling costs.

The recent addition of the latest in programmable controls permits tailoring pneumatic forming-roll pressure and timing to adapt to changing contours of a part. Maximum operating air pressure is only 100 psi, but by using some fairly large air cylindes, pressures are high enough to form 1/6"-thick stainless steel blanks into 30-degree (60-degree total included angle) cones.

Round and round

"Try taking that 6"-dia stainless blank 1/6" thick to the owner of a presss shop," Burt says, "and ask him to thin it down to a 1/32" thick in a 60-degree cone. He'd throw up his hands! He wouldn't have the press tonnage to do it. but with metalspinning's concentrated forces you can form parts that would require presses running into hundreds of tons capacity."

One of Burt's main missions in life is to sell the idea that "round and round goes great with up and down," meaning that spinforming and presses make a good production marriage. A flat blank or a drawn cup prepared in one shot on a press can be finished to a complex conical or contoured shape by one spinning operation, usually without need for a final trimming operation. This can replace a complicated five- or more-step deepdraw and trim operation and a lot of die expense.

This also saves material because as the part is flow formed to match the mandrel, the metal is also thinned an amount corresponding to the steepness of the form. The result is a 25- to 35-percent material savings over normal deep-draw and trimming operations on a press. Where once you needed an 11" blank to make an 8"-dia part, now you do it with an 8" blank.

Another advantage is quick prototype parts. "Soft tooling, mandrels cut from ordinary carbon steel, can be used to form initial samples for a tenth of the time and money it takes to punch out samples on a press. Samples can be produced in days for a few hundred dollars versus weeks and tens of thousands of dollars to do the same part on a press.

And the hard tooling, the mandrel, isn't that expensifve either--usually less than $1000/spindle. also, a basic form can be used to make a variety of parts of different sizes by using different portions of the mandrel. Fast changeover and setup time are other obvious advantages.

You use the same basic carbide form rolls for all part shapes, and if, after 100,000 parts or so, they wear or are damaged on the surface, they can be easily redressed since their diameter is not critical.

Back on track

After supplying lanters and planters to local gift and garden shops, Burt and his son finally got into some of the larger New England retailers with some nice repeat business. But they seemed to be moving in the wrong direction. They had to decide whether to expand that side of the business or get back to their original plan of developing their spinning machine.

Having gained considerable experience producing a variety of commercial pats, they saw many features to incorporate in an expanded machine. The first machine could handle up to 10" blanks and parts up to 4" high. The newer machine can handle up to 11.5" blanks and parts to 6" high. they have had people express interest in much larger machines--large reflectors for the lighting industry and cooking utensils, for example--but so far the production quantities involved have not justified developing such a machine.

"So we designed a machine that would fit in well in most stamping-shop operations," Burt explains, "where the volumes we can produce would be practical. Also, we fully automated loading/unloading operations."

Number two son

Meanwhile, a second son, Bill, caught the bug and joined them in 1976, adding critical skills in tool development and electronic controls. "We have people we're working with," Burt adds, "who have shown interest in helping us with the marketing end of the business and some of the tooling. We are now following up on the many proespects outside New England. This potential business is substantial. The people we've done work for are still hepped up about our machine, but theese business prospects need to be cultivated.

"We've got machines in the field that are performing well, standing up against any of the foreign machines we've seen," Burt reports. "We're currently running some large production orders for people who are good prospects to get machines of their own. Repeat production for past customers is also growing. Even though we may not accomplish all that we'd like to as soon as we might wish, the growing demand for our services should keep us busy for years to come.

"Looking back, if that fellow who had the heart attack hadn't shown the enthusiasm he did for our machine, there wouldn't have been a machine. Or if my son Al, whom I had never had plans of being in business with, hadn't become available and worked with me to take the basic idea and develop it, there wouldn't have been a Spinamatic. And now with Bill and others who are anxious to help put this show on the road, the future looks promising.

"So many people today don't want to take that big step--to go out on their own like we did. They want the security of a steady income. In our case, it wasn't a lot of smart planning on our part, we just took things a step at a time. It's hard to explain how we made some of the basic decisions. The only answer is that Somebody else is running the show. The Man Upstairs."

If you'd like more information from Burt's company, BFL Associates, Hillsboro, NH, on their metalspinning capabilities, circle E22. (The BFL could stand for Beautiful Farm Land, but it is simle Burt's initials. It also represents the philosophy displayed on his office wall: By Faith Live!)
COPYRIGHT 1985 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1985 Gale, Cengage Learning. All rights reserved.

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Publication:Tooling & Production
Date:Sep 1, 1985
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