System Combines Surface Finish and Profile Measurement

Lemforder Corp. is a Lancaster, South Carolina-based supplier of steering components and suspension systems for trucks and buses. Being a quality systems supplier, several of the company's machines feature bearing surfaces that will come into moving contact with mating parts made of metal, plastics or powder metal. These bearing surfaces, which can have complex geometrics, must meet certain surface finish requirements to ensure product functionality and durability.

Lemforder machines contain many round components with varying diameters, complex surface contours, tight surface roughness specs and internal features. The company's previous surface measuring machine, although capable of performing satisfactory surface measurements on round parts, had several limitations. "It was beyond the capabilities of the machine to measure straight or nonround surfaces," comments Sri Burugapalli, quality manager at Lemforder. "In some cases, we had to inspect blind holes and internal threads destructively."

Testing protocols required technicians to run the surface-measuring probe across a reference standard that matched the particular surface finish that was being inspected. The quality laboratory maintained a number of these reference standards. To identify surfaces of blind holes or through holes and internal threads, quality technicians were required to "feel" for the features using a probe, a lengthy method requiring both patience and skill. Additionally, surface inspection had to be performed on another machine, and occasionally, quality engineers needed more information than the surface-finish machine and comparator could provide. That meant sending the part out to an inspection vendor.

The measurement of surface finish and part profiles usually requires two separate pieces of equipment. However, after researching a number of suppliers, Lemforder discovered Surftest SVC524 from Mitutoyo Corp., which combines both tasks into one system. "It offered us both these measuring functions in a small footprint, had more capabilities than the other systems and represented a $20,000 savings over the cost of having to buy two different machines," notes Burugapalli.

To perform both measuring functions, Surftest requires only two interchangeable heads. Changing over from one inspection method to another requires a simple switch of probe heads and telling the computer which head is installed.

Surftest features custom screen building, allowing most operators to control what data, information, charts and reports appear on the screen. The system creates computerized reports of inspections, displays the results on the computer screen and gives profile information and other measuring data at any time. Also, the data are capable of being networked, so they can be accessed from anywhere.

Technicians at Lemforder use the Surftest to measure threads and conduct surface measurements of corners, radii and merging arcs. "We can measure exact profiles of these types of parts," says Burugapalli. "If we have three or more circular features in a small area, a wave feature for example, the Surftest measures it very accurately." Because Surftest can inspect all surfaces -- whether straight, round, contoured or wavy -- technicians at Lemforder can perform linear checks regardless of the surface's shape.

Mitutoyo's Surftest SVC524

Benefits

• Performs both surface-finish and part profiles
• Probe heads are easily switched.
• Data are capable of being networked.

www.mitutoyo.com