Townley Engineering & Manufacturing Co., Inc., Candler, Florida, a manufacturer of replacement bearing assemblies for large, severe-service “matrix” pumps used in mining, solved a service-life problem with dimensional measurement and inspection. And because short service life was an industry-wide quality control issue in mining, Townley turned the solution into a competitive edge.  The competitive edge was a new 18-month warranty in an industry where some 20-odd competitors, most of them original equipment manufacturers (OEMs) of pumps, offered essentially no warranty.

Caught flat-footed, “our competitors started calling us and saying we must be crazy,” reported Townley Quality Assurance Manager Howard Record. An extension to 24 months is under consideration.  

Dimensional measurement and inspection at Townley is done with a state-of-the-art INFINITE™ portable coordinate measuring machine (CMM) from ROMER Inc., Wixom, Michigan, USA, combined with PowerINSPECT™ software from DELCAM Inc., Windsor, Ontario, Canada. PowerINSPECT is sold bundled with the INFINITE and supported by ROMER.

Matrix pumps get their name from handling semi-liquid flows of ore chunks, other rocks, sand and water—a matrix in mining parlance rather than a slurry. The shock and vibration from chunks of rock—up to nine inches in diameter and weighing several pounds—makes for a harsh environment for pump bearings. In addition, these pumps run 24 hours a day, seven days a week (24/7).  Matrix pumps are widely used in mining phosphate and copper and in dredging. Coal-fired power plants use them for pumping limestone slurries in their emission control systems. Given these harsh environments, even the sturdiest pumps fail regularly, the main reason OEMs shun warranties on their bearings.  

PROBLEM: Lack of Good Data for Machinists
Townley began encountering unexpected field wear issues with its UBD Matrix line of pump assembly bearings in 2002. Among the biggest pump bearing assemblies Townley makes, UBDs are widely used in Florida phosphate mining. By 2004, bearings for as many as one pump in five suffered a failure, Record said, some after just one month’s service.  Careful dimensional measurement quickly pinpointed root causes in concentricity, perpendicularity and bore diameters of the bearing housings supplied by a contract machining company.

The supplier’s management quickly found and fixed the root cause. It was an out-of-calibration horizontal machining center used to machine housing bores. Townley immediately began 100% inspection of all incoming housings (and set up a clean room for assembly). The initial solution was to build an inspection fixture, a replica of the pump’s central shaft with machined and welded steel plates representing the bearings. As in anything that rotates, precise shaft alignment is vital to service life. Townley UBD Matrix bearing assemblies have two double-tapered roller bearings and a tapered-thrust bearing. But the inspection fixture was still a feeler-gauge solution.

“Unfortunately,” said Record, “a feeler gauge generates almost no data a machinist can use to correct a dimensional problem.”  While very accurate in trained hands, feeler gauges give only simple go / no-go determinations.   

SOLUTION: Good Q/A Data And A Speedy R-O-I 
Looking back, Townley actually got a handle on the dimensional problem quickly, in just a few hours. The larger issue was getting good Q/A data to the machinists. For that, the ability of Delcam’s PowerINSPECT to generate IGES files proved invaluable. Combined with the portable ROMER arm, the $70,000 system “paid for itself very fast, in two weeks,” Record said. He based that return on investment (R-O-I) on the warranty cost of replacing a failed bearing assembly. 

The payback period was so short, he noted, “because right away we could give the machinist exact numbers on concentricity and perpendicularity with IGES files.” The IGES data was uploaded to the CAD files used by the machine shops’ programmers. The portability of the ROMER arm lets Record and co-worker Ben Philips bring the entire inspection system right to the bearing housing, or any other large workpiece.  

RESULTS: Taking No Chances with Dimensions
“We overnighted the first inspection results and our new dimensions to the machine shops,” Record said, “and got better housings from them almost immediately. Now that we can give our vendors sound numbers and inspection reports, we can expect them to step up to the plate and help us hit a home run on the success of our bearing assemblies.

In addition, dimensional measurements from the INFINITE Arm and PowerINSPECT verify vibration analyses on full bearing assemblies. Townley does these analyses on a test system called “The Mule.” Fully computerized, The Mule generates physical test data under initial load (pounds of force), revolutions per minute (RPM), time at RPM,  temperature under load, and specific load data. A full test takes 48 hours. All Mule test data plus the ROMER – PowerINSPECT dimensional inspection reports go to the customer.

“That birth certificate is a set of fingerprints for each bearing assembly,” Record pointed out. “The customers know exactly what they are buying from us, a bearing housing that will outperform its competition.”  

BENEFITS: Business Transformed with a New Competitive Edge
Among Townley’s many business benefits from dimensional measurement:

• Better quality parts from its vendors
• Better quality products that keep customers happier and buying more
• Sharply reduced warranty claims
• Reverse engineering, which helps Townley launch new products

“But the real advantage we get from the CMM,” said Townley vice president Randy Arnett “is that it opens people’s eyes, especially for us as a manufacturer bearing assemblies. This is the first time anyone in the matrix pump business has ever stepped out to offer a warranty of 18 months.” Whether rival pump manufacturers will improve their methods, tighten their tolerances, and offer their own warranties remains to be seen.

“The portable CMM offered us a real opportunity for business transformation,” Arnett continued. “We had been looking to take a big step like this, offering a real warranty, for several years. Without this transformation, we might never have had a chance to be a major player in bearing assemblies for mining” because almost all the replacement bearings business went to the pump OEMs.

In a nutshell, Townley can compete more on the basis of verifiable quality and service life, rather than on price, which the OEMs can afford to undercut, or on service, which can be tough sell to new customers.