The ins and outs of in-line automated inspection

Hommel-Etamic Wavemove

The challenges to manufacturing as it evolves into the 21st century are now familiar, and impact how metrology must contribute. Manufacturers face uncertain production volumes with roller-coaster demand, shorter production runs and faster product development cycles. Automation, while alluring as a way to reduce cost, needs to adjust.

At the same time, the marketplace demands ever higher quality and parts made to more precise tolerances. All these factors, and more, are driving the need for more flexible yet more automated production metrology equipment.

For example, the automotive powertrain production line of the future hardly demands the traditional dedicated hard gauge purpose-built for a single part or subsystem. The traditional concept of 100 per cent hard gauging disappeared along with production runs in the millions.

“Part runs [today] are in the hundreds of thousands, even in automotive. Some companies are configuring flexible production setups to run multiple engine components on the same line: a six-cylinder crank one week, a five-cylinder the next day, and a four-cylinder the next,” agrees Andreas Blind, vice-president of Hommel-Etamic in Rochester Hills, Mich.

Flexible, reconfigurable metrology is the demand of the future. Hard gauges and fixture gauges are still very useful, he explains, but today they may be built to work in conjunction with flexible solutions or with retooling and reconfiguration in mind. There remain tradeoffs between speed, flexibility and cost.

“This does not mean hard gauging fixtures go away,” he explains. “It does mean you build them with more flexibility, so that you can retool them very quickly.”

The company uses three basic kinds of technologies for metrology: pneumatic, tactile and optical. Each is integrated into flexible or dedicated gauging solutions, depending on a customer’s budget and expectations towards flexibility.

At the same time, companies like Hommel-Etamic are expanding off-the-shelf production metrology. A good example Blind points to is its Opticline series of optical metrology systems. These are designed to measure long, round workpieces such as crankshafts, camshafts and driveshafts, directly on the production floor.

An LED light source illuminates a shaft rotating on a fixture. A high-resolution CCD line sensor captures a silhouetted shadow, digitally measuring the contour as the piece rotates. Models in this line measure parts as small as fuel injector nozzles or medical needles, and parts as large as 2,500-millimetre (mm) aircraft engine shafts. Programmers use a teach-in method to create parts programs. They call up programs when needed and workpieces are measured in seconds.

Specifically for Use in Automation

Important for this subject, the company designed Opticline Contour Automatic (CA) 300/500/800 series machines specifically for use in automation for 100 per cent in-line inspection. Accuracy in diameter is (two + D/100) microns and length is (five + L/100) microns, both to ISO 10360. Measurements include lengths, diameters, angles, radii, runout, roundness, eccentricity, cylindricity, straightness, form and profiles.

The Wavemove automated surface roughness and contour measuring system is another measuring device the company released in 2011 and recently introduced to North America to meet the growing need for automated measurements. The device includes up to seven CNC axes for complete high-accuracy measurement and evaluation of complex shaft or prismatic parts such as automotive crankshafts, cylinder heads, engine blocks, or transmission housings.