ShopSolutions Case Histories of Manufacturing Problem Solving Marine Final Inspection Gets CMM Thrust T
hrustmaster of Texas Inc. (Houston), a leading manufacturer of marine application thrusters, devel- ops all of its products in-house. Almost every order is unique to the customer. Thrustmaster manufactures heavy-duty commercial marine-propulsion equipment, including deck-mounted propulsion units, thru- hull azimuthing thrusters, retractable thrusters, tunnel thrusters, Z and L drives, and the patented Portable Dynamic Positioning System. Thrustmaster’s product lines include fixed- pitch propeller hydraulic and mechanical thrusters with direct engine drive, electric drive or hydraulic drive, and underwater mountable thrusters for the largest marine applications. Heavy-duty thrust- ers for marine applications are rated from 35 to 10,750 hp (26-8000 kW).
Thrusters are used for main propulsion, slow- speed maneuvering, and dynamic positioning of barges or displacement hulls. The propulsion units can also be fixed or azimuthing and close fitted to the hull such as with Z or L drive propulsion. Or they can be stem-mounted and tiltable with lengths up 35' (10 m) for the 2000-hp (1500-kW) hydraulic thrusters. All products are developed in-house by a complete engineering department for mechanical, hydraulic, electrical, and electronic design. Tooling includes state-of-the-art computer equipment with software packages for CAD, vessel resistance and propulsion, 3-D mathematical modeling, and ANSYS Finite Element Analy- sis (FEA). Applications like modal analysis, stress and strain analysis, as well as rotor dynamic analysis of drive trains and transmissions, are major fundamentals required to ensure the reliability and quality of Thrustmaster’s products. When it came to final inspection of the lower and upper outdrive housing components used in the thrusters, measure- ment was done manually on the CNC machines themselves, using a portable measuring arm. With a recent increase in engineering and manufacturing capacity, one challenge for Thrustmaster was the need to free up the CNC machines
for manufacturing instead of measuring. Machines could be occupied for hours measuring, delaying production of other parts and increasing costs. To achieve a leaner quality inspec- tion process, the company began a search for a dedicated CMM to handle final inspection.
Thrustmaster of Texas purchased a Zeiss gantry CMM, a MMZ-B 25/60/20 model, to fit its quality inspection needs for final inspection of the lower and upper outdrive housing components used in marine thrusters. Measurement was previously done on the CNC machines, tying them up from production.
Because of the size of the parts, a large CMM would be needed, and the best way to find the right solution was to have one of its parts measured on the system as part of a demo. Thrustmaster sent one of its parts to be inspected at the Carl Zeiss IMT Corp. facility for a remote live demonstra- tion on a large gantry CMM. Impressed with the inspection reports and quality of information received, Thrustmaster purchased a large gantry MMZ-B 25/60/20 CMM. “A Zeiss CMM was our first choice based on performance, price, and availability,” says Paul Martin, Thrustmaster of Texas quality manager. The large gantry system has the 2.5-m Z axis they wanted and was also available in a short lead time.