by
Jianzhong Xing
Engineer, Shanxi Diesel Engine Plant and Technical Specialist,
DEA CMM Users' Association,
People's Republic of China

The Shanxi Diesel Engine Plant in Datong, People's Republic of China, is a specialized engine production facility with the largest aluminum alloy foundry in China - and some of the most advanced manufacturing equipment and research instruments in the world.

To improve the speed and accuracy of inspecting complex workpieces ... the company replaced surface plate tools with two DEA coordinate measuring machines.

Throughout its history, the company has developed a range of products that are sold not only in China, but throughout the world as well. These include the 150-Series diesel engines, GF-Series generators, the high-powered 396-Series diesel engines which were imported from MTU in Germany and are manufactured under license, and the 492QS "Jet-Flow" fuel-economizing gasoline engine.

In order to improve the speed and accuracy of inspecting complex workpieces such as engine blocks, cylinders, crankshafts, and fuel-injection pumps, the company replaced surface plate tools with two DEA-Brown & Sharpe coordinate measuring machines, an IOTA and an OMEGA.

Shanxi Diesel Engine Plant's foundry produces aluminum alloys for use in manufacturing a variety of engine components.

The OMEGA is one of the largest CNC bridge-type coordinate measuring machines available with an X-axis stroke of 1,499 mm to 3,302 mm, Y-axis stroke of 1,499 mm, and Z-axis stroke of 1,016 mm to 1,346 mm. Its aluminum alloy bridge provides a high stiffness to weight ratio, and aluminum construction minimizes structural stress and deformation from temperature gradients. The result is a CMM that provides a volumetric accuracy of 0.013 mm with a resolution of 1 µm and repeatability of 2 µm, even in harsh shop environments.

The IOTA is an older design CMM that engineers at the plant upgraded, with the help of DEA applications engineers, by modifying its control system, adding gage attachments and the TUTOR™ for WINDOWS™ software system. Now both CMMs have the same functions and share TUTOR for WINDOWS measurement software.

TUTOR for WINDOWS includes multi-tasking capabilities, a standard operator interface, a high-speed point-to-point scanning function, and feature oriented measuring and programming along with a large library of fully integrated application programs and more than 100 canned cycles.

The open architecture of TUTOR for WINDOWS allows great flexibility in developing in-house programs for special measurement tasks. During the past dozen years, more than 200 gaging and utility programs have been written.

For example, the company developed a software program for the IOTA that puts a floating pen on the Z-axis for the production of precision drawings. Not long after the company began using the OMEGA, programmers developed an automatic coordinate-fixing and correction program in DEA/PPL for operating PH9/PH10 star contact probes in the TUTOR for WINDOWS environment.

This greatly facilitates coordinate-fixing and correction of the probe contact point. At the same time, this program makes use of graphic parameters for man-machine communication.

A 150-Series diesel engine block undergoes dimensional inspection at the Shanxi Diesel Engine Plant. Use of coordinate metrology for both quality control and process control has helped the facility build its position as one of China's leading large-scale state enterprises.

The Shanxi Diesel Engine Plant has inspected nearly 30,000 workpieces with the CMMs. Accurate gaging has provided a reliable basis for adjustment of machine tools and verification and revision of numerical-control programs.

As a result of 10 years of practical application, the coordinate measuring machines have become highly-effective precision testing instruments. Together with more traditional inspection tools such as out-of-roundness indicators, contour indicators, and laser interferometers, they have become an important part of production, scientific research, and technical progress at the Shanxi Diesel Engine Plant.

Everyone has come to know from personal experience the value of coordinate metrology. The CMMs are capable assistants for scientific and technological development.