Cylinder Hones Provide Slick Solutions

Scored valve bores

For Elmar Industries, Depew, N.Y., a company that designs and manufactures filling machines for the food, beverage, petrochemical, personal care, and pharmaceutical industries, a flexible cylinder hone saved its customer $30,000 in damaged valve housings after unexpected damage was caused prior to production. Elmar offers a variety of models, including rotary piston, bottom fill, gravity and pocket for filling liquids, high viscosity and solid particulates into plastic, glass, composite or metal containers.

The rotary piston models have a large, rotating bowl for product with six to 72 filling stations. Each station is built with a valve housing and rotary valve that dispenses a metered quantity of product. The tolerance between valve and housing must be within 0.001 in. Elmar’s customer used a 45-station piston filler, used for packaging applesauce and other food products.

The food processor had recently taken delivery of the new equipment. However, construction continued within the facility, one floor above. As a result, a small amount of concrete and metal shavings fell into the filling bowl. When the equipment was started, the concrete particles and metal chips moved from the rotating bowl into the rotary valves, scarring the housings and damaging valve plugs. The damage was significant enough that each of the 45 valve housings and plugs had to be replaced.  The estimated cost for replacement: $60,000.

“In this case, the machine hadn’t even run its first product yet,” explained Thomas Dahlquist, special projects manager for Elmar. “When you have a capital improvement project, and the customer is looking at an expensive bill for replacement parts before production even begins, they want a quick solution that is cost-effective.” Unfortunately, the valve plugs were damaged beyond repair.  This comprised approximately half the estimated replacement costs. 

However, Dahlquist suggested an alternative solution. By honing each cylinder to remove any raised lips or high points, then inserting new valve plugs, the customer could save half the cost--approximately $30,000.

Elmar was familiar with cylinder hones, having used them in the past for manufacturing valve bodies. From time to time, they used the Flex-Hone, from Brush Research Mfg. Co., Los Angeles, in the field to hone out undersized or out-of-tolerance cylinders. The Flex-Hone is an abrasive tool characterized by small, abrasive globules permanently mounted to flexible filaments. Versatile and easy-to-use, the cylinder hone can deburr and clean out passages or provide bores with a finish free of cut, torn, and folded metal.  It can also be used for edge blending, plateau honing, polishing, and chamfer operations.

Although the Flex-Hone can be used in automated production equipment, it can also be used with a handheld electric drill.  The tool is well-suited to field use because it is self-aligning and self-compensating for wear, which facilitates close-tolerance finishing work.

To assist in the repair, Dahlquist traveled to the customer’s site with several 2¼-in. Flex-Hones, valued at a total cost of less than $200. In just over four hours, Dahlquist honed each of the 45 housings to the appropriate specifications. He used a dial bore gauge to achieve the tolerance required between valve and housing. “With the Flex-Hone, drill, and a drill holder, we were able to rework each of the valve housings on the machine by hand,” said Dahlquist. “We were able to smooth out all the high points and insert the new valves.” As a result, the customer was able to begin production within a few weeks.

Poorly machined cavities

For Vektek Inc., Emporia, Kan., a manufacturer of hydraulic and pneumatic clamping systems, improperly machined cavities from an overseas third party not only impacted the performance of the product they were providing, but also created a potential safety issue. As a global supplier to the metalworking, tool and die, and mold industries, Vektek relies on their customer to ensure that the cylindrical product they supply is installed into a cavity with a proper surface finish, or it will not seal and function properly. The consequence of a leaking cylinder could be serious because these Vektek devices hold workpieces stationary on machining fixtures. If oil pressure in the cylinders drops due to leakage, the grip on workpieces would fail, requiring the machine to be shut down and production to halt.

This became a very real issue when Vektek began having some problems with a major heavy-equipment manufacturer customer in China that was not machining a cavity suitable for installation.

“The trouble was that the customer’s cavities were not machined suitably for installation, a flaw in their finishing process was missed,” said Rod Nelson, vice president of Vektek. “As a result, it appeared that the Vektek seals were leaking, a problem that was not a shortcoming in the cylinder design or quality, but nevertheless had to be resolved at the customer’s site. Otherwise, these expensive fixtures would not be usable.”