Re:Build DAPR successfully designed and built a custom manufacturing machine capable of filling and sealing over 2000 cosmetic capsules per hour.
Location: Boston, MA
Product: Capsule Fill and Seal Machine
Timeframe: 10 months
BackgroundOur client requested an automated process to fulfill their production requirements for filling and sealing small plastic capsules with cosmetic liquids intended for consumer use. The first hurdle we encountered was the capsule delivery system, which required manipulation of the downstream process. We implemented a vibratory bowl feeder, utilizing mechanical features, compressed air, and vibration to sort and orient the capsules onto a linear accumulation track, facilitating bulk loading and delivery to the rest of the automated machine. The second challenge was to ensure accurate filling of the capsules to 0.8mL +/- 0.01 mL of liquid. Failure to meet this requirement could result in either dry aerosolization or leaking of the aerosolizing device when the capsule is removed. We overcame this obstacle by introducing positive displacement pumps, which are highly precise and consistent, and can sustain hundreds of millions of cycles. Finally, we addressed the issue of sealing the capsule. The client’s current process involved heat-sealing oversized foil to the capsule and then trimming the excess foil. We modified the process by pre-cutting the foil and then heat-sealing it, eliminating the trimming step. We incorporated a single heat head with a compliant base on which the capsules rested, allowing for variations in capsule height. Our comprehensive solution met the client’s requirements while ensuring efficient and reliable performance.
Challenges & Solutions
- Sealing issues were encountered due to the higher heat-activation temperature of the sealing foil selected, resulting in the plastic capsules melting and sticking to the foil rather than activating and sealing to the plastic. This caused rejected parts due to “squatting” of the plastic capsules, which affected the inspection station’s ability to differentiate between good and bad capsules. Additionally, squatting led to plastic accumulation on the seal head, causing capsules to be inadvertently pulled out of the nest and disrupted the inspection and rejection process.
- During the initial discovery phase of the project, Re:Build DAPR investigated several operation options, including 3-up rotary, 4-up rotary, and linear operation. After considering the client’s throughput demands and floor space limitations, the 3-up rotary option was selected by both DAPR and the client.
- Foil heating and pressure application testing was then performed to determine the appropriate amount of force and temperature required to adequately seal the capsule. This testing was crucial in ensuring that the capsules were properly sealed and prevented any manufacturing defects.
- After sealing, the capsules were inspected using the Cognex Insight 7800 camera series. This camera series detected bubbles in the foil, which indicated a bad seal, and ensured that the foil was concentric to the capsule for satisfactory placement.
- In addition to the capsule sealing process, preliminary POC testing was conducted on the positive displacement pumps to confirm the accuracy of the pumps for each customer-provided liquid. Some liquids required positive mixing to maintain a homogenous solution, so a secondary pump was used to constantly siphon the liquid from the reservoir tanks through a mixing loop. Additional testing and validation were performed during the Discovery phase to ensure that this approach to mixing was feasible. The successful results were implemented into the final design.
The client’s objective of achieving a production rate of 1950 capsules per hour was exceeded with a sustained throughput of more than 2000 capsules per hour. Additionally, there was a notable reduction in operator involvement from 3-4 individuals required to achieve a production rate of 1300 capsules per hour down to a single operator responsible for maintaining the machine.