Robotic Assembly in Medical Device Manufacturing

A Lesson in Extreme Precision

In July 2021, Seymour Advanced Technologies (SAT) embarked on an ambitious project to revolutionize the assembly process for an ophthalmic pharmaceutical company. Tasked with developing a micro needle for ocular surgery, the company faced the challenge of automating the assembly to enhance precision and sterility while aiming for a 70% increase in productivity.

The Challenge

To develop an assembly process that is both automated and precise, capable of inserting a 25 mm long rod into a hollow cylinder with a minimal clearance of just 60 microns (0.0015 inches, or roughly a quarter to a third of a human hair's thickness), posed a significant challenge. In the prevailing manufacturing setup, this delicate task is carried out manually, requiring high-powered magnification and meticulous hand coordination. This method, while precise, is notably slow and labor-intensive, yielding a modest output of only 63 microneedles per hour. Moreover, the manual process is fraught with inefficiencies, notably a high rate of needle breakage and an elevated risk of bioburden contamination due to the inherent limitations of human intervention.

Addressing these challenges, the initiative aims to revolutionize the assembly process for the pharmaceutical company. By automating the procedure, the goal is to significantly speed up production, while simultaneously reducing waste and enhancing the sterility of the manufacturing environment. However, during the development of this automated process, SAT encountered a recurring obstacle: the needle's position varied slightly with each cycle, complicating the precise insertion required. This initiative promises to resolve these critical issues, streamlining the assembly process, minimizing waste and operational costs, and ensuring a sterile production environment.

The Solutions

This is where a precise, engineered approach makes things interesting. SAT created SEYMOUR TRI-21, a semi-autonomous machine that capitalizes on precision, sterilization, and waste elimination. It contains three 6-axis robots with an objective to take the syringe from Point A to Point B, inserting the wire into the needle without fail. What makes the SEYMOUR TRI-21 solution even more reliable is that the company’s microneedle will now be produced in a fully automated environment, versus the manual and semi-automated processes used by other manufacturers.

One of a kind:

This one-of-a-kind process starts out with the object being picked up and placed under a micro resolution camera that uses variable strobing technology, also known as structured light modularization, to detect "shadows" in order to find where physical parts of the object are in a certain vicinity. The thickness, length, and straightness are then calculated. SAT then uses this raw data to calculate the relative positional error and move the robots to a new position that allows accurate assembly. This process is critical as the internal parts "float" inside the shell that is picked up. So, even though they are repeatable, the window in which they repeat is much larger than the tolerance for assembling the parts, without probable interference.

Small footprint:

In the current 1,000 sq. ft. cleanroom space, the company can have a maximum of two people working per 8-hour shift. Each person can produce approximately 63 units per hour (1/min.) during a shift for an average of 500 units per shift. The new 60"w x 42"d x 77"h SEYMOUR TRI-21 and one operator will now be able to produce approximately 250 units per hour (4/min.) during an 8-hour shift for an average of 2,000 units per shift (a 400% increase in production). Additionally, these modular robotic machines can be used for R&D as well as for GMP commercial use. Six different pieces of equipment can now be placed in the same clean room, working independently, having anywhere from two to 10 operators working at one time.

Precision:

As previously stated, the automation process had to be extremely precise due to the properties of the elements being assembled. This is why SAT implemented machine learning. It allows SAT to automatically track data, learn from previous cycles, then adjust and streamline for future cycles—ensuring each needle insertion will align the wire and needle perfectly. The target acceptable success rate is 90% or higher with a 70% increase in productivity, both of which will be achieved with the SEYMOUR TRI-21.

Monitoring:

For a machine tasked with creating parts for another machine, meticulous monitoring surpasses that of its predecessor. Monitoring critical elements—force, torsion, velocity, acceleration, time, pressure, volume, weights and masses, translation, and rotation—is essential.

The seven SI base units crucial for this are:

Length - meter (m)
Time - second (s)
Amount of substance - mole (mole)
Electric current - ampere (A)
Temperature - kelvin (K)
Luminous intensity - candela (cd)
Mass - kilogram (kg)

By keeping track of these units, or a relevant subset, the SAT system ensures the product's consistency and predictability, facilitating technological advancement and evolution. SAT's approach includes comprehensive monitoring and data provision to support operations. Despite numerous variables influencing product quality, only a narrow "quality window" exists for consistent operation. Achieving a measurement resolution tenfold that of the requirement ensures the veracity of these measurements. For this project, a precise quality window of 60 microns was necessary—equivalent to roughly 0.0105 inch or 1/25 of a human hair's width.