Robots invade test labs.

The growing need to ensure zero-defect production through increased statistical process control (SPC) is creating employment opportunities in testing laboratories for "steel-collar workers"--better known as robots.

Use of robot to automate materials testing could make sense wherever a long series of repetitive tests needs to be performed. Resin suppliers and custom or proprietary compounders are logical candidates, as is any processing operation spending a lot of time evaluating different materials and sources of supply.

Two examples of robots being used in quality control are at USI Div. of Quantum Chemical Co. and the Research Div. of Rohm and Haas Co. At Quantum's compounding plant in Crockett, Texas, a robot was installed last fall to automatically measure pigment loadings right on the production line. Rohm and Haas, on the other hand, has been using a robot on a mechanical-properties testing system for more than three years at its Bristol, Pa., research facility. Spokesmen at both companies say the robots have proven beneficial in saving money, increasing productivity and ensuring a consistent product.

GETTING THE RIGHT COLOR

At Quantum's 110,000-sq-ft Crockett plant where 100 million lb of white and black concentrates, wire and cable compounds, and other masterbatches are made each year, the role of the $60,000 robot is to remove samples from a side stream at the extruder and test them right on the spot to ensure proper pigmentation. The robotic test system was designed jointly by Quantum's Quality Methods and Technology Group in Rolling Meadows, Ill., and Zymark Inc., Hopkinton, Mass., which manufactured many of the components. It reduces the process of testing for silica and titanium dioxide content from 20 to 10 min., Quantum says. A programmable sampler probes the transfer line, pulling out a 2-g sample that is moved to the testing area via a pneumatic conveyor. The sample is then ashed in a 10-ml crucible for 3-4 min at 1472 F; it is cooled for 3 min over a stream of dry air before the residual ash is weighed. The system can be used to determine silica and Ti[O.sub.2] contents in a range from 0.1% to 50%.

So far, the system has only beenm installed on a white concentrate line, but Quantum hopes to add another sample station, oven, and cooling station later this year so that both black and white concentrates can be tested simultaneously.

A Quantum spokesman says the installation of on-line robotic testing, which operates 24 hr/day, moves the plant a step closer to achieving real-time product quality assurance. "The robot provides test data in a more timely manner," says Michael Armitage, lab manager at the Crockett plant. "While this is not true SPC, it is much closer to real-time and will better allow operators to relate process information to test data. "Armitage estimates that with the robot, the time from sample to results is between 8 and 10 min, half the previous turnaround time. But the biggest benefit, he says, is the elimination of the need to transport sample batches from the line to the quality assurance lab for analysis.

Couples with a computerized SPC system, this technique allows sampling every 10 min, Armitage says, detecting variations in the process quicker than ever before and allowing process operators to make adjustments prior to offspec product being generated. This then gives Quantum a better handle on the relationship between changes in processing conditions and changes in pigment levels. Armitage estimates the system will save Quantum $30,000-40,000/yr in off-grade production costs.

With the robot now performing what were previously manual tasks, lab technicians can spend more time on other duties such as comparing raw-material data to product data to establish more meaningful material specifications; or looking at formulations and processing technioques in the pilit lab to improve product quality and production rates, Armitage says. (CIRCLE 36)

HANDS-OFF TENSILE TESTING

At Rohm and Haas' research lab, a robot has been part of the facility test system since April 1988. Used as part of an automated tensile testing installation (supplied by Tinius Olsen Testing Machine Co., Willow Grove, Pa.), the robotic system takes test specimens that have been manually loaded into one of four carousels, pushes them to a station where a micrometer measures the samples' minimum thickness and width to an accuracy of 0.1 mil, and then pushes the sample into a manipulator arm that inserts the sample into the tensile-test grips. A computer-controlled extensometer lowers to contact the specimen, and load is applied until the specimen fails. The extensometer then releases the specimen and the crosshead returns to its start-test position. The manipulator arm removes the two halves of the broken sample and picks up the next specimen to be tested. Strain ranges are automatically adjusted by the instrument from 2% to 333% to meet the requirements of each test being performed. The system runs 10 hr/day.

The benefits to Rohm and Haas have been primarily those of better manpower usage and increased productivity. "We've eliminated the need to have a technician constantly at the machine," says George Beswick, testing coordinator at the Rohm and Haas laboratory. "We've also greatly improved our turnaround time." Sometime this year, Rohm and Haas hopes to integrate results from the automated tested into a larger computer that would combine information from numerous test machines into one comprehensive laboratory management database. (CIRCLE 37)