Fast, 5-axis powertrain scanning

Powertrain component manufacturers consider inspection critical. One plant has machined parts in aluminum, cast iron, and steel. There are five critical processes for aluminum and 3x that for steel parts, and all have similar tolerances in microns for form and 0.05mm for true position.

Verifying tolerances falls to quality control departments using environmentally controlled labs, often located adjacent to the machining lines. Parts intended for routine inspection are delivered regularly with critical components hand-delivered for priority inspection during a line changeover or if an operator suspects a problem.

The best way to measure cylinder head flatness and bore cylindricity is to take a large quantity of accurate surface points. A Nikon Metrology coordinate measuring machine (CMM) equipped with a Renishaw REVO 5-axis scanning probe is the best solution. REVO scanning probes installed on Nikon Metrology CMMs slash form-data collection times and feedback to machining cells, reduce CMM fixturing, and cut probe calibration time from hours to minutes. Increased throughput and flexibility allow faster feedback for gears and cam lift inspections.
 

5-axis scanning advantage

Powertrain teams often become frustrated with having to make multiple probe configurations with limitations to what can be done, even with the articulated heads. The number of different probe configurations, each with separate calibration times, could take a 6- to 7-hour bite out of inspection.

The REVO 5-axis scanning probe, mounted on a Nikon Metrology CMM, can collect up to 6,000 data points/sec. Engineered for high-speed, precision measurement of contoured surfaces and complex geometries, it collects the required high volumes of data to validate fit and form. Using two rotary axes, one in the vertical plane and one in the horizontal, it has infinite rotation and positioning capabilities. Five-axis software drives the measuring head and synchronizes its motion with the linear axes of the CMM. Look-ahead algorithms drive the probe path and CMM in coordinated, continuous motion. The head adapts position while measuring on the move, maintaining stylus tip contact with changing contours at scanning speeds of up to 500mm/sec.

With cylinder and crank bores, standard touch probing may be inadequate. Because of the vast amount of data needed to measure the geometry of an 80mm-to-100mm diameter bore, 150mm in length, the SP25 probe limits those inspections to machine setup or special requests. Instead, for every crankcase, the probe does a spiral scan of bores and the system outputs the values to software, sending a graph of the data points to the network, which can help troubleshoot problems on the fly. The REVO scanning heads greatly reduce or eliminate the need for touch probing. The device can also do head-touch probing or be used for traditional machine-touch probing.

With touch probing, it is easy to get a single speck of dirt that causes an out-of-round condition if you are only sampling seven or eight points. That can throw off the location of that circle. With the system, flatness errors that would not have been caught with touch probing – and cylinder bore geometries that would not have been caught with touch probing – are found without the parts becoming scrap when found too late in the process. Scanning inspections provide production and engineering departments with confidence that the data are valid.
 

Fewer probes, more flexibility

With REVO, manufacturers require fewer probe configurations to measure mass production parts, reserving custom probes for a few unique applications. Special configurations for outside parts can also be eliminated due to the infinite positioning angles that allow measuring of a part without special fixturing or consideration of which probe to use. With so few probes, calibration time can drop significantly. Five-axis CMM scanning can be a game-changer in terms of speed, data quality, and inspection capacity.

Nikon Metrology Inc.
www.nikonmetrology.com