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Oct 14, 2024

How a Shear Manufacturer Improved Accuracy While Reducing Costs - Tech Briefs

Wysong USA has been manufacturing industrial press brakes, hydraulic shears, and mechanical shears for sheet metal and plastics for nearly 120 years. Like many companies, their motto was “if it ain’t

Wysong USA has been manufacturing industrial press brakes, hydraulic shears, and mechanical shears for sheet metal and plastics for nearly 120 years. Like many companies, their motto was “if it ain’t broke, don’t fix it,” so their product had remained essentially the same. But during a customer visit that motto clashed with another company saying, “the customer is always right.” This customer had replaced the dry clutch brake for an oil shear clutch brake that was more accurate. “The customer is always right” won, so Wysong updated their product line and increased accuracy while reducing costs, making it a win all around.

Wysong Shears cut sheet metal and sheet plastic for companies making large automotive components, tractor hoods, lawnmower hoods, and more. Often the presses run 24/7, so accuracy, repeatability, and durability are essential. As the business has shifted more toward cutting plastic sheets, customers have been seeking increased accuracy.

During a routine customer visit with Primex Plastics, Wysong Production Engineer Linton Summers noticed that the Wichita clutch brake originally installed had been replaced with a Force Control clutch brake. Summers was impressed with the increased accuracy and repeatability as he watched the machine shear section after section of sheet plastic.

Originally the shear was designed to run even if the mechanism is slightly out of position. “When you told it to go, if it skipped a tooth, it would still go,” said Summers. This breakdown created a scrap part and wasted material — both undesirable outcomes.

Wysong formerly used a Wichita Clutch brake in their shears. Designed to run at 60 strokes a minute, the shears included a flywheel to overcome the inertia and an encoder on the chain drive cam switch. Depending on the speed, the flywheels were quite large, up to 40-inches tall. Because there is inherent fluctuation with a chain drive, the accuracy was not optimal. The encoder certainly helped, but slight inaccuracies over time meant manual adjustments were required, either by an operator or by maintenance personnel. The old-style designs also needed $4700 worth of parts for annual maintenance, plus three hours to change them out. Once re-assembled, the shear had to be manually finessed to ensure it was running properly before production could resume.

The new Force Control clutch brakes do not require flywheels, and one Force Control Posidyne ® model 3 clutch brake replaces a pair of Wichita’s, so the cost savings add up quickly. The old-style design required a D style motor with high slip to allow the motor to accelerate the flywheel up to speed. Eliminating the flywheel allowed the use of a more common (and less expensive) B style motor.

When equipped with Force Control clutch brakes, the shears achieve greater accuracy and repeatability and are far more cost-effective to manufacture and maintain. “The repeatability standpoint is a night and day difference. On the Wichita, you’ve got the brake and then you’ve got the clutch that’s on a flywheel. It’s all one set of air,” said Summers, “so there is only so much adjustment available. With the Force Control, we have the manifold with the air adjustment for the brake and the clutch. You can run more air on the brake and less on the clutch, because its separate. And the Model LC corrects itself automatically.”

The Force Control Model LC is a form of closed loop positioning control. It reads the machine position on each stop and adjusts, in real time, where to signal the stop for the next part/cycle. This compensates for any frictional wear, or thermal changes that occur over time, and significantly improves accuracy. Adding the Model LC eliminated the cam switch and chain drive from the old design, simplifying assembly while improving accuracy.

Designed with low inertia cycling components makes the Posidyne® clutch brake more efficient, requiring less motor horsepower to accelerate the load, and less torque to stop the load. Their totally enclosed design is impervious to dust, chips, chemicals, coolants, caustic wash down, weather, and more, making them ideal for hostile environments.

Their multiple disc design produces high torque from a small package. Re-circulating the fluid dissipates the heat of engagement, which is a common cause of downtime with other clutch/brake assemblies.

A simple actuation system allows torque in the clutch and brake to be precisely controlled. Adjustment for rapid or soft starts and stops is easily accomplished. Manifold mounted control valves reduce response times by eliminating hoses and fittings, and are recommended for high cycle applications. By reducing the high starting inrush currents and the associated power factor imbalance in the motor, these unique clutch/brakes can also reduce energy costs.

The Posidyne® clutch brake can be actuated by air or hydraulic pressure for use in a plant or outside remote applications. The hydraulic actuation package includes a hydraulic pump, solenoid valve, regulators, and a filter. A heat exchanger can be added for additional cooling.

Oil Shear Technology is the reason that clutch brakes by Force Control last up to 10 times longer than standard dry friction clutch brakes and do not need maintenance, adjustment, or disc replacement. Oil Shear Technology is the function of a boundary layer of transmission fluid in shear between the friction discs and drive plates. As the parts come together, the fluid in shear will transmit torque between the two parts, as well as absorb heat. This eliminates direct contact of the friction discs and drive plates during high-speed slip. Heat from the friction surface is dissipated as the fluid circulates to the housing.

Heat dissipation is a major component when selecting a clutch brake. The Posidyne® clutch brake basic unit dissipates heat through a unique internal design pumping system, which causes the transmission fluid to be drawn into the center of the hub, flows through the friction stack, and by centrifugal force is pulled out of the stack to the housing. Cooling occurs as the fluid flows down the housing walls. Additional heat can be dissipated by adding internal water cooling or pulling the fluid out to external-oil-to water or oil-to-air heat exchangers. This also allows for the use of an oil filter extending the life of the fluid. These cooling options allow the same compact size Posidyne ® clutch brake to be used on high inertia loads, or in extremely high or low temperatures.

The Force Control brake also saves money, both in manufacturing costs and ongoing maintenance costs, so it’s a winning proposition not only for Wysong but also for the customers who will be using them. The company has also designed modular retrofit kits allowing older style flywheel models to be upgraded more easily.

This article was written by Tony Stoner, VP of Sales & Marketing, Force Control Industries (Fairfield, OH). For more information, visit here .

This article first appeared in the August, 2024 issue of Motion Design Magazine.

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