Rapid Design and Deployment of Special-Purpose Automated Product Inspection Systems
by Ross Burchard
Sandia National Laboratories
Sandia's Intelligent Systems and Robotics Center (ISRC) has proven its capability to develop and deploy automated inspection stations. ISRC designers meet with customers to compile a list of requirements, specifications, and hardware and software needs. From those requirements, a cost-effective system is developed to meet their special needs.
As part of its mission for the Department of Energy, Sandia manufactures neutron generator subassemblies whose exterior is coated with special metallic materials. This process uses a gas torch and high-pressure air to blow melted material onto the surface of cylindrical production components rotating at high speed. New surfaces are built up when molten material solidifies on the component's surface. This thermal spray process requires several passes of the spray gun to build up sufficient material thickness.
In the past, the only way to verify that the proper amount of special material was adhering to the surface was to accurately weigh each component. However, there was no way to determine whether the material was being distributed in a uniform manner. When new production requirements made it necessary to accurately measure the thermal spray material thickness and determine its uniformity, Sandia's manufacturing organization tasked the ISRC to develop an automated inspection station.
Obtaining accurate thermal spray thickness measurements is difficult because of the material's rough texture. After examining the thermal spray material, it was concluded that taking physical or optical measurements would not be feasible; a totally new approach was required. Within nine months, the ISRC developed and deployed an automated Thermal Spray Inspection Station (TSIS) that electrically measures the amount of material deposited per unit area rather than physically measuring the material's thickness.
From the list of requirements generated by the manufacturing organization in November 1997, ISRC created a preliminary conceptual design and developed an extensive software requirements specification. In July 1998, ISRC delivered a complete software package, all of the hardware, an operating procedure, an alignment procedure for calibration, and a complete mechanical and electrical drawing package for this first-of-a-kind automated system.
Sandia's manufacturing organization used the Thermal Spray Inspection Station to qualify 23 units as part of a critical October 1999 product certification deadline. The success of this project has resulted in a number of follow-on projects. For instance, the first TSIS works so well and is so cost effective that the manufacturing organization funded development of a second system. This unit will be used in tandem with the first unit to increase throughput. It will also serve as a backup should the first one need to be serviced.
ISRC is now working with the Thermal Spray Research Laboratory to develop an Automated Thermal Spray System (ATSS).The ATSS will permit manipulation of the component for uniform coverage, and will make it easier to change components, thus allowing the process to operate continuously. The ATSS will couple Sandia's R&D 100 Award-winning motion planning software with computer analysis of the spray process to eliminate the traditional "cut and try" method of programming an automated coating system. The entire process design will be able to be evaluated in a simulated environment so that potential problems can be mitigated before the actual thermal spray procedure begins. Development will begin in October 1999 with deployment and operation expected within 18 months.