Double-Dipping with Micro Motion® for Increased Product Quality and ProfitabilityBENEFITS• Increased product consistency and quality
• Increased throughput
• Increased process flexibility
• Reduced material waste
• Reduced manual labor and labor costs
PROCESSA leading manufacturer of premium rubber, coatings, and gaskets for the industrial world is developing a new business in coated parts for gate valves, with plans to expand the process into related parts.
Manufacturing coated parts is a multi-step manual process. Parts are prepared for the injection molder one part at a time. Preparation includes suspending the part, cleaning, priming, and spray-coating. Correct preparation is crucial: Poor or inconsistent preparation can degrade the performance of the rubber when molded onto the part.
CHALLENGEDifferences between operators in each of the preparation steps produced an unacceptable degree of variation in the product. Some parts were not completely cleaned; other parts were coated too lightly or too heavily, or not coated evenly on all sides. Operators did not always make the necessary adjustments for different types of part coming down the line. The manufacturer needed a method to increase the proportion of on-spec product in this process.
In addition, the material costs of the spray-coating step were high: Approximately 50% of the coatings was wasted into the fume collection system.
Finally, because each part was prepared individually, throughput of the preparation step was low, limiting the overall production and profitability of the process. To ensure that the injection molder was used efficiently, the schedule had to allow enough lead time for the preparation process to produce a sufficient stock of prepped parts.
Cleaning Tank
Priming Tank
Final Coat Tank
Suspending Parts
To Injection Molding
Pump Filter F100 Agitator
Pump Filter F100 Agitator
Dry
er
Doubled throughput and halved material waste, for a savings of more than $100,000 per year
CROSS-INDUSTRY
Dip tank system replaces manual preparation
CROSS-INDUSTRY
SOLUTIONThe manufacturer invested in an automatic dip tank system with three stations: Cleaning, Priming, and Final Coat. Each station includes a drying bay. Because the control program can be set for each part type, this process eliminates two sources of variation: operator variation and part variation. The one remaining manual step – suspending the part – no longer affects product quality.
With the new system, throughput increased immediately, minimizing the issues with scheduling. In fact, throughput increased so much that a second injection molder was purchased to keep up with the preparation line, and prepped parts are now being stockpiled.
However, a new challenge appeared: ensuring that the priming and coating fluids were coating parts evenly and to the correct thickness. The density of the fluids is a good indicator of their coating properties. If the system had accurate online density measurement of both fluids, it would be able to monitor and adjust the mix as needed. Temperature data was also required because temperature affects drying time and can affect product quality if it goes out of range.
The manufacturer purchased Micro Motion® F-Series meters with Model 2700 transmitters for the Priming and Final Coat tanks. With these meters, they can measure density and temperature with a single instrument, feed data into the control system, and make immediate corrections to the fluid mix. Although flow is less critical for product quality, flow variables are still monitored because loss of flow indicates pump failure, filter plugging, or other system problem.
The manufacturer is also taking advantage of the Modbus digital communications capabilities of the transmitter. One pair of wires brings all process variables into their control system and data collection system. With this complete set of data, they can use the process as a test line as well as a production line – changing parts, changing product requirements, and developing new parts.
The end result is increased product quality, increased product consistency, increased flexibility, and increased efficiency. Additionally, the amount of coating material lost in the spray-coating step has been reduced from 50% to 20%, for a savings of $100,000 per year, and throughput has increased by more than 100%.
