Whether for smoothing out rough areas and high points, deburring, edge blending, cross hatching or removing cut, torn or folded metal, a flexible cylinder hone can prove a useful tool for field repairs. Parts such as carbide bushings, bore sleeves, hydraulic and pneumatic cylinders, and other cylindrical cavities can be resurfaced using a standard drill.

Scarred valve housings

For Elmar, a food processing company that designs and manufactures filling machines for the food, beverage, petrochemical, personal care and pharmaceutical industries, a flexible cylinder hone saved a customer $30,000 in damaged valve housings after unexpected damage occurred prior to production. The company 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.  

Rotary piston models have a large, rotating bowl for product with 6 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 1/1000th of an inch. 

It was this type of machine, a 45-station piston filler, that Elmar sold to a customer for apple sauce and other food products. Construction was still going on within the facility, one floor above and, as a result, a small amount of concrete and metal shavings had fallen into the filling bowl.

When the equipment was started, concrete particles and metal chips moved from the rotating bowl to the rotary valves, scarring the housings and damaging the valve plugs. The damage was such that each of the 45 valve housings and plugs had to be replaced at an estimated cost of $60,000.

Thomas Dahlquist, special projects manager for Elmar, says: “In this case, the machine hadn’t even run its first product. 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.”  

The valve plugs were damaged beyond repair. This comprised about half the estimated replacement costs. However, Dahlquist suggested an alternative solution. By honing each cylinder to remove any raised lips or high points and then inserting new valve plugs, the customer could save half the cost – approximately $30,000.

The company was familiar with cylinder hones, having used them in the past in the manufacturing of valve bodies. It had used the Flex-Hone from time-to-time in the field to hone out undersized or out-of-tolerance cylinders.  

The Flex-Hone, from Los-Angeles-based Brush Research Manufacturing, is a highly specialised abrasive tool characterised by the small, abrasive globules that are permanently mounted to flexible filaments.

Versatile and easy-to-use, it can deburr and clean out passages or provide IDs with a super-smooth plateau 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 suitable for field applications, is self-aligning and self-compensating for wear, which facilitates close-tolerance finishing work.

Dahlquist travelled to the customer’s site with several 2.25in Flex-Hones and in just over 4 hours, he was able to hone each of the 45 housings to the appropriate specifications. The total cost of the hones was less than two hundred dollars. To achieve the tolerance required between valve and housing, he used a dial bore gauge. 

He says: “With the Flex-Hone, drill and a drill holder, we were able to rework each of the valve housings on the machine by hand. We were able to smooth out all the high points and insert the new valves. This was a unique application that saved a customer a lot of money. They were very happy and were able to get on with their production.”