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The Challenge
The client needed to reduce labor and improve safety in a high-risk paste milling operation.
Client Overview
Zaic Design was approached by an international conglomerate with headquarters in Germany to tackle significant challenges with their paste milling process in their Pennsylvania plant.
Paste Milling Explained
Paste milling is a process used to grind and mix paste materials into a fine consistency. This process is commonly used in industries such as manufacturing and pharmaceuticals where precise mixing and grinding are crucial. The paste, which can contain valuable materials like precious metals, is placed into a mill where it is subjected to mechanical forces that break it down and mix it uniformly. This ensures that the paste achieves the desired consistency and properties for further processing or use. The milling process must be carefully controlled to prevent issues such as material loss, contamination, or damage to the milling equipment.
A 25-gallon pot containing precious metal paste. In the legacy system, an operator used a secondary hoist to tilt the pot, pouring the paste onto the rollers, for milling, below.
The Legacy Process
The legacy milling process involved manually lifting a large metal pot filled with up to 1000 lbs of precious metal paste over an expensive milling machine using an electric hoist. The operator had to tilt the pot until the paste slowly spilled into the mill. The paste viscosity varied from caramel to peanut butter, which often required operators to reach into the pot while it was suspended over the mill to encourage the paste to fall.
Safety and Efficiency Risks
This process was not only physically demanding but also posed serious safety risks. The high turnover rate among mill operators was due to the physical demands of the job and the mental effort required to pay close attention to the mill for hours on end. A small lapse in attention could lead to personal injury or damage to the mill, with a single roller costing $200,000 to replace. Risks included letting the mill run dry or dropping a foreign object into the mill, which could destroy a roller.
Material and Cleanup Challenges
Additionally, the paste often contained valuable metals like platinum and silver. Wasting material due to spills was costly, and cleanup was time-consuming. A precision system that was easy to clean to prevent metal loss was crucial.
Custom Fabricated Pots
The client was using custom-fabricated 25-gallon pots that cost $25,000 each. These pots were not uniform and were heavily worn and banged up from years of use. However, it was critical that they be integrated and interface well with a new, more efficient, automated system.
Pressing Ahead
The Solution
Zaic Design developed a custom-designed press-out lid system to ensure safe and efficient paste dispensing.
Investigating Market Solutions
Zaic Design approached the challenge by first thoroughly investigating existing market options to see if any off-the-shelf systems could meet the specific requirements for the 25-gallon pots. After an extensive search and evaluation, it was clear that no existing solutions could adequately address the unique challenges. Therefore, we decided that a custom solution was necessary.
Engineering a Custom Lid
We engineered a custom lid to clamp onto the rim of the existing 25-gallon stainless steel pots. On the upper side of the lid, two jack screws were mounted and belt-driven by a single servo motor, capable of generating 4000 lbs of downward force into the pot. Sensors were installed around the rim to ensure the lid was fully clamped before the pot was lifted, preventing accidents. If the clamps holding the lid to the pot were not fully engaged, power to the hoist lifting the pot would be interrupted, requiring the pot to be lowered for inspection before continuing the process.
A photo of the Zaic Design system lid attached to the hoist. Once clamped to a new pot, the lid ensures safe and secure transport of the heavy pot over the milling operation.
How the System Works Mechanistically
The key to the system is the custom lid and piston assembly. Once the lid is securely clamped onto the pot, and the pot is moved into position by the hoist, the servo motor can drive the jack screws, generating significant downward force. This force pushes a hollow stainless steel piston into the pot. The piston, which is slightly smaller in diameter than the pot, allows for a small gap around its edge.
Ensuring Efficient Paste Dispensing
Inside the piston is an inflatable gasket made from the inner tube of a BMX bicycle. This innovative solution ensures a tight seal against the pot walls, compensating for any irregularities or wear. As the piston descends, the servo motor provides real-time torque feedback. This feedback is crucial as it allows the system to detect when the piston contacts the paste. Initially, the gasket is only partially inflated, allowing air to escape and ensuring smooth movement.
Cost-Effective Innovation
Once the piston makes contact with the paste, the system fully inflates the gasket. This inflation creates a tight seal, preventing any paste from bypassing the piston and ensuring that all the paste is pressed out efficiently. The innovative use of the BMX inner tube came about because off-the-shelf gaskets of the required size didn’t exist, and custom gaskets were prohibitively expensive. The BMX inner tube offered a cost-effective and readily available alternative, significantly reducing both capital and maintenance costs, especially for a client with operations in Germany and potential installations worldwide.
The lid is designed to attach to a pot filled with paste. The pot is then lifted by the hoist and brought into location over the milling machine.
A cross-section view illustrating key components: two jack screws are attached to the piston, extending through the lid. Both jack screws are driven worm-gear mechanisms powered by a single servo motor.
Safety and Efficiency Enhancements
To further enhance safety and efficiency, sensors around the lid ensure it is fully clamped before any lifting occurs. If the clamps are not properly engaged, power to the hoist is cut off, preventing any accidental drops. This feature is critical in avoiding accidents and ensuring the integrity of the milling process.
The Piston Cap
To protect the inflatable gasket and facilitate paste recovery after dispensing, we created a custom-molded cap that slid over the piston assembly. This cap not only protected the inflatable gasket but also served as the physical contact surface between the press-out piston and the paste material. Initially, the piston cap design included a lip at the top to prevent it from slipping off the piston once installed. However, this design proved problematic as it made installation difficult.
During the initial development phase, one of our young engineers, a woman in her 20s, could install the cap quickly but with some effort. Initially, we assumed that the burly male operators would manage it easily after training, but they struggled with the installation. It turned out that the young engineer had exceptionally strong grip strength due to her advanced rock climbing experience. Realizing the discrepancy, we created a new mold for the piston caps that allowed easy fitting and cinching after installation to prevent slippage.
Smooth Operation
The Outcome
The project resulted in improved safety, reduced labor, and increased efficiency in the milling process.
Client Testimonial
Kurt, Process Improvement Manager, highlighted, ‘With the automated press-out, we can now have one operator run two mills at the same time. This scenario allows us to accommodate increased volumes/capacity with the existing headcount in production. More press-out units definitely support future growth and increased volumes for us.’
Exceptional Results
After the successful installation and testing of the first unit, the client promptly requested a second unit. The new system not only reduced labor and improved safety but also minimized the risk of damaging the mill, ensuring efficient and controlled paste dispensing. Currently, Zaic Design is fabricating a third unit for a different milling application.
Independent Control Systems
A key decision made early in the project was to keep the press-out controls completely independent from the mill’s controls. This approach increased redundancy and ensured that any failure in the operation of the press-out system would not interfere with the mill’s safety features.
Advanced Sensing and Control
The mill maintained its own sensors to monitor the process, while Zaic Design installed an additional laser sensor to monitor the buildup of paste in the mill. This sensor controlled the flow of paste in real-time using a PID loop to regulate the piston feed rate.
Autonomous Operation
The result was a highly efficient system where operators could set specific dispensing parameters via a touch screen interface and allow the system to function autonomously. This design not only enhanced safety by reducing the need for manual intervention but also optimized the overall efficiency of the paste dispensing process.
The film thickness on the first roller of the mill is measured by a laser sensor, which feeds data into a PID loop to control the paste flow rate. The red dot, highlighted and enlarged in the detail view, shows the light beam from the sensor measuring the film thickness. A red line indicates the location of the laser sensor.
Benefits of the New System
The new press-out lid system offers several significant benefits over the legacy process, addressing the major challenges faced by the client:
Enhanced Safety: The use of sensors to confirm the secure clamping of the lid before lifting significantly reduces the risk of accidents. Automated processes minimize manual intervention, further enhancing operator safety. This improved control over the pot handling reduces the likelihood of damage to the expensive rollers, ensuring the integrity of the milling equipment.
Increased Efficiency: Real-time torque feedback and a fully inflatable gasket ensure that paste is dispensed efficiently and consistently, reducing the need for manual intervention. The automated system allows for continuous operation without the need for constant supervision, optimizing the paste dispensing process and minimizing errors.
Cost Savings: The new system significantly reduces operational costs by minimizing paste wastage and improving material recovery. Innovative solutions like using a BMX inner tube for the inflatable gasket help keep capital and maintenance costs down. The precision of the new system reduces cleanup time and material loss, leading to substantial cost savings.
Ease of Use: The system is easy to clean and maintain. The user-friendly touch screen interface allows operators to dial in specific dispensing parameters, simplifying the operation and reducing the mental load on operators.
Improved Productivity: The automated system optimizes the paste dispensing process, leading to significant improvements in operational efficiency and productivity. The reduced need for manual supervision allows operators to focus on other critical tasks, further enhancing overall productivity. The system’s improved control also prevents costly downtime and potential damage to expensive rollers, ensuring consistent and reliable operation.
Pushing Boundaries
Future Development
Zaic Design is exploring larger press-out units and new custom solutions for specialized paste formulations.
We have developed concepts for a larger 50-gallon press-out unit, potentially for installation in a German facility. We continue to seek opportunities with companies that create specialized paste formulations and may need custom dispensing solutions. We provide a wide range of innovative and custom automation solutions in the manufacturing industry.
Our dedication to innovation and excellence makes Zaic Design a strategic partner for companies looking to enhance safety, reduce labor, and improve efficiency in their paste milling operations.
With a strong foundation in product design, precision engineering, and creative solution development, we excel in tackling sophisticated manufacturing challenges.
Optimize your manufacturing processes with custom automation solutions tailored to meet the unique challenges of your industry. Whether you need advanced precision instruments, integrated firmware solutions, or automated work cells, Zaic Design has the expertise to transform your operations and enhance productivity.
Schedule your free consultation today and take the first step towards revolutionizing your manufacturing capabilities with Zaic Design.
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