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Cylinder Hone Proves its Value for Field Repairs

20 November 2014

Damaged, scarred cylinders repaired in field using flexible cylinder hone.

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 be an indispensible tool for field repairs.  

Using this relatively inexpensive tool, parts such as carbide bushings, bore sleeves, hydraulic and pneumatic cylinders, and other cylindrical cavities can be resurfaced using a standard drill.

For two industrial equipment manufacturers, it was precisely this type of field repair work that allowed them to salvage equipment that was damaged – through no fault of their own – and save their customer tens of thousands of dollars in replacement parts.

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 the customer $30,000 in damaged valve housings after unexpected damage was caused 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.  

The 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.  

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 had fallen 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 the 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 was $60,000.

“In this case, the machine hadn’t even run its first product yet,” says 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 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 the valve bodies.  In the past, they had used the Flex-Hone, specifically, in the field to hone out undersized or out-of-tolerance cylinders from time to time.  

The Flex-Hone, from Los-Angeles-based Brush Research Manufacturing, is a highly specialized abrasive tool that is instantly recognizable by its unique appearance.  

Characterized by the small, abrasive globules that are permanently mounted to flexible filaments, the product is a flexible, low cost tool.  

Versatile and easy-to-use, the cylinder hone 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 ideal for field applications because it is self-aligning and self-compensating for wear, which facilitates close-tolerance finishing work.

To assist in the repair, Dahlquist travelled to the customer’s site with several 2.25” Flex-Hones.  The total cost of the hones was less than two hundred dollars. 

In just over 4 hours, Dahlquist was able to hone each of the 45 housings to the appropriate specifications.  To achieve the tolerance required between valve and housing, he utilized a dial bore gauge. 

“With the Flex-Hone, drill and a drill holder, we were able to rework each of the valve housings on the machine by hand,” says 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.

“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,” adds Dahlquist.

Poorly Machined Cavities
For Vektek, 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 & die and mold industries, Vektek must rely 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 very serious since these Vektek devices hold workpieces stationary on machining fixtures. If the 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,” says Rod Nelson, Vice President of Vektek International Sales.  “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 solved at the customer’s site or these very expensive fixtures would not be useable.”

Vektek advised technicians at the manufacturing plant in China to use the Flex-Hone Tool to properly surface finish the cylinder cavities so that the sealing problem would be eliminated.

Nelson says the flexible hone is so useful to his customers in properly preparing cavities for his company’s products that Vektek has for many years specifically recommended the Brush Research tool in its product catalog and data sheets.

“In all, 300 cavities were Flex-Honed, and 299 of the 300 cavities were saved and polished exactly to specification,” explains Nelson.  “One cavity was slightly out of spec, but it also provided an adequate seal. So, in the end, we saved 300 very expensive holes.”


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