Initially, Showmark focused solely on developing fiber optic winders. Whereas most fiber optic winding systems require dedicated floor space in the production facility, the Showmark system was designed as a "benchtop" model. The reason for the compact design was based on both hunch, and market research conducted by Showmark founder, Scott Markovitz.

While attending the Optical Fiber Conference (OFC) show, Markovitz interviewed users of fiber optic winders. He was not surprised to discover most fiber optic winding machine prospects expressed a desire for a winder that was simpler to operate, more compact, and less expensive than those available at the time. "We estimated that about four times as many of our prospects preferred a compact, less sophisticated winder, as opposed to the large, floor-mounted machines."

Showmark Machines' debut product (shown in Figure 1) weighed about 70 pounds (32 kg). The winder utilizes a three-axis servo controller to coordinate the precision movement of the linear traverse, as well as to control the tension in the fiber. A tension sensor is attached to one of the bottom rollers. The signal from the sensor is continuously monitored by the servo system. Corrections to line tension are performed in real time by advancing or retarding the motion of the payoff reel.

Figure 1 caption:

The benchtop Showmark unit was released at roughly half the selling price of its larger counterparts. The lower cost is due partly to the company's controlled manufacturing processes. Savings also were derived from the fact that Showmark targeted applications for which no pricing precedents had been established.

"Our main market," said Markovitz, "is for very simple general-purpose respoolers which can be used for breaking down bulk spools into smaller spools for distribution."

Previously, the only choice was to use the same spooling equipment that was being used for high end applications such as fiber test proofing, coating, and fiber coloring. Showmark Machines provided a more practical machine offering basic features for every day use.

"When we first opened the doors at Showmark," said Markovitz, "fiber optics was a hot topic. And it was technology we found interesting."

Showmark's first customer was a company in the telecom industry whose fiber optics were doped with erbium, a soft, malleable metal which is fairly stable in air, and not prone to oxidize as rapidly as other rare-earth metals.

Special spools are used for winding erbium doped-fiber (EDFAs) and fiber optic gyros (FOGs). There can be no crossover on the take-up spool, which typically has a very narrow core width. Also essential is proper line tension.

Precision winding of any material, including fiber optics, requires the designer to be aware of general winding application requirements and available equipment. For example, the basics of a winding system include a take-up spool, usually driven by a DC motor. A payoff system feeds the fiber, or other material, onto the rotating take-up spool. The payoff may feed directly from the production line.

Also needed is a linear traverse or traversing nut, which is a linear drive assembly that guides the fiber back and forth as it is wound onto the spool. Figure 2 shows the components in a traditional winding system set-up.

Figure 2 caption:

Deepening on the diameter or thickness of the material being wound, the traverse must move back and forth at a set linear pitch. This is the linear distance the traverse travels per one shaft revolution. The pitch differs for each different diameter of material that is to be spooled. Proper pitch setting is required to assure even placement of lines on the reel. Therefore, there is a requirement to synchronize the rotational speed of the take-up reel with the linear speed of the traverse.

Additionally, the linear drive system moving the traverse must posses enough axial thrust to overcome feed line tension. In the Figure 3, thrust increases as angle M increases. When the traverse reaches the flange of the spool, the thrust requirement is at a maximum.

Figure 3 caption:

With optical fibers, other unique design issues must also be considered such as the minimum bend radius of the fiber. The material is easy to stress if too much line tension is applied during the winding process. If bending occurs, the fiber's light transmission properties can be affected.

Some fiber optic materials must be wound at extremely slow take-up rates. As the take-up spool fills up, its rotational rate must be reduced to compensate for the increasing circumferential length the material is being wound around. Additionally, the linear traverse must slow down to keep the material even and smooth. Special motion control is required over the traverse guide moving the fiber back-and-forth as it is wound onto the spool.

Precise constant tension control while winding the fiber is often needed, usually in the 10-30 g range (0.35 to 1.1 ozf). If the payoff system is feeding out product at a slower rate than the rotation of the take-up reel, too much line tension can result. Conversely if the take-up drive is running faster than the payoff, it will pull the line increasing the tension. A linear traverse with too much thrust can also create line tension levels that can damage fiber optics.

The coating on doped fibers is easily damaged. This can have adverse affects on the performance characteristics. To prevent this, the surface area of the fiber needs to be friction-free during the winding process. To assure smooth, frictionless take-up, the bearings in the winding assembly must be highly efficient. Also, winding fiber optic material typically requires precision placement of the fiber on the take-up spool in perfectly even rows and smooth layers. Consequently precise synchronization of the take-up spool rotation with the movement of the traversing material guide (Figure 4) must be achieved. If the system slows down or speeds up, this synchronization must remain constant.

Figure 4 caption:

"We found the traditional controls and components required for controlling the motion of the traverse guide made the machines larger and more complicated to operate," said Markovitz. Showmark engineers had considered ball screws and belt drive assemblies for their winder. These methods required stepper or servo motors to control the movement of the traverse.

Also needed was a separate motor for the spool drive. Examining other types of linear drive systems Showmark found that the requirements for multi-speed, direct-braked reversible motors, valves and solenoids, gear head assemblies, and so forth added significantly to the size and complexity of the machine design, and significantly increased operating and maintenance expenses.

Showmark's strategy was to simplify machine design to cut costs, conserve space and facilitate operation and maintenance. Showmark engineers came across Uhing’s US-Agent Amacoil and found that company's reciprocating linear drive provided automatically reversible linear motion control without the complex controls, components and programming. Additionally, an Uhing system isn't screw-based. The shaft is smooth so it won't trap dirt and debris which can lead to clogging and jamming.

Showmark went with the Uhing system because it eliminated the need for extra motors, controllers, electronics and programming from the machine design. Figure 5 shows a typical Uhing/Amacoil winding assembly set-up in a custom Showmark winder. "We were able to use a single DC motor to drive both the take-up spool and the linear traverse," explained Markovitz, "which made the controls much simpler." The Uhing drive also enabled Showmark to design a more compact unit which was even lighter-weight than the original benchtop winder.

Figure 5 & inset caption:

Additional features attractive to Showmark designers were adjustable pitch and variable stroke length. "The variable pitch makes the system flexible," said Markovitz. "It means the customer can fine tune the winding procedure to enhance a level, smooth wind. It also lets the customer wind fiber of different diameters on the same machine – without having to change gear heads or invest in electronic controls."

Incorporating the Uhing/Amacoil system led to the release of Showmark's second generation machine seen in Figure 6. This model permitted linear pitch adjustment without adjusting controls or changing gear assemblies. "The new unit was more general purpose. Many different types of fiber could be spooled using a single unit because the pitch and travel direction of the traverse guide could be mechanically controlled," said Markovitz.

Figure 6 caption:

Showmark also found that, with simple modifications, they could configure the general-purpose unit meet many of the precision winding requirements. "Our design is flexible and modular so we can rapidly modify machine design to meet specific winding requirements," said Markovitz. Showmark has already sold a modified version of the general winder to a manufacturer who is using it to spool FOGs. Markovitz sees few obstacles to design the winder to meet virtually any fiber optic spooling demands presented.

Recently Showmark Machines has been using its technology to develop equipment for new markets such as winding magnet wire. Magnet wire is often fragile and the Showmark winder provides the steady movement and smooth reversal needed to make sure the wire doesn't twist or snap.

Markovitz says, "We are planning to introduce even simpler models of our winder. We'll also be designing units to meet high precision applications in the aerospace market."

For more information, contact Showmark Machines. Phone: 610-644-5915.

Fax: 610-644-8073. email: info@showmarkcorp.com

web site: www.showmarkcorp.com