Robot Arm Viscosity Measuring Station
Modular Viscosity Measuring Station for Investment Casting
Overview
As part of the manufacturing process at PCC Structurals, there is a robot arm that does investment casting coats on a number of high-volume parts. Investment casting involves the use of a proprietary slurry to build up the coats on the parts. Like many slurries, there is a consistency where it flows the best. To maintain optimal consistency, PCC Structurals requires a method of testing the viscosity periodically. In the past, this was done by shutting down the robot arm periodically and an operator would manually do the test to ensure it was at the optimal consistency. In order to increase the volume of the parts that could be produced and to extend the life of the slurry, PCC requires a method for the viscosity test to be done without shutting down the robot arm.
Requirements
Washing station
Weighing station
Footprint of 4ft x 4ft for each of the stations
Transportation of the wastewater due to the lack of plumbing in the room
4-20mA PLC communication
High precision with a high weight capacity
Design
The first selection is finding a scale that would have a high weight capacity and high precision to accurately measure the viscosity of the slurry. The scale I selected needed high weight capacity as many different adapters will be used to make the viscosity measuring tool. Additionally, it would be able to measure the small changes in the weight due to the viscosity of the slurry. Furthermore, I required a method of doing the measurement below the balance, unlike the typical method of weighing which is above the balance.
Next, I needed to determine how it would be best to wash the viscosity measuring device. I required a way for the PLC to control the flow of water to wash the measuring device. I selected 30° nozzles that would be wide enough to cover the whole surface area of the measuring device. I included several of the nozzles to ensure that the measuring device would be washed clean even if it was rotating inside of the washing station. The method of controlling the flow of water would be the use of a PLC-controlled pneumatically actuated valve. This way, the whole washing process could be automated.
The original idea was to create two separate washing and measuring stations for different purposes. During the brainstorming process, I noticed that the small-scale viscosity measuring station had created a lot of mess due to the slurry. I took the initiative and decided to take the project in a different direction and combine the two stations into a singular station and still be within the 4ft x 4ft footprint.
At the very top of the station, it would house the high precision balance to do the viscosity measurement. The hole at the top of the station is where the hook for the below balance weighing would enter. The entrance of the station was designed so that it would have enough room for the robot arm to articulate inside. This was a requirement for the design of the station because the deep funnel at the bottom of the station housed several 30° nozzles that would spray down the viscosity-measuring device. The deep shape of the funnel was done to ensure there would be no splash-back of the water into the slurry as it would cause the whole slurry to seize. The funnel would then expel the wastewater into a tilt truck that would be used to transport the water outside of the room.
Results
The implementation of the Viscosity Measuring station and De-ionized Drip System saved the facility over 100k in downtime for the robot arm due to it being able to run 24/7. Additionally, due to the small footprint of the station, it could be implemented in other PCC facilities to save the corporation even more money and increase volume.
For additional information on the De-ionized Drip System:
Auto DI-Water Drip SystemLast updated