Age of the machines: automated manufacturing23 July 2012
For medical device manufacturers the use of robotic technology to automate manufacturing operations is in its infancy. Mike Wilson of the British Automation and Robot Association explains why its potential is slowly and surely beginning to be recognised.
One of the greatest challenges to the growth of robot use in medical device manufacturing is the perception that robots are special, complicated and require experts to operate them. In reality they are only a type of automation, a very flexible form of automation, but automation nonetheless. Medical device manufacturers have been using automation for years and the move to robots is the next logical step.
Automation can help manufacturers to meet the stringent requirements imposed on medical devices. It provides consistent production of high-quality products, not only meeting product conformance requirements but also allowing for traceability of manufacture. Companies in this sector are now facing ever-increasing commercial pressures, particularly relating to cost reduction and delivery performance, and automation is helping to meet these challenges.
Traditional automation solutions have often been developed specifically for individual products. These solutions can be very effective because the design and operations are optimised for the production of a specific part; as a result, they provide consistent quality and often high production rates. However, these dedicated automation solutions can be expensive and have little capability to accommodate changes in product design. It is often the case that a completely new system is designed when new products are introduced.
Today, commercial pressures demand much greater flexibility, shorter product lifecycles and small batch sizes. Traditional automation systems are not appropriate and manufacturers are turning to robot-based automation systems instead. These solutions provide the ability to process different products through the same system and are also reconfigurable for new products, thereby reducing costs and improving delivery flexibility.
Polishing orthopaedic joints
The inherent dexterity of robots makes them suitable for manufacturing operations that are very difficult to automate by other means. One example of this is the production of orthopaedic implants, such as knee and hip joints. These are manufactured from high-strength, biocompatible materials such as titanium and stainless steel, and the surface finish is critical. Irregularities can lead to excessive wear and reduce joint life.
Six-axis robots are used by a growing number of implant manufacturers for grinding, polishing and buffing operations. These often present the implant to a series of belts, with varying grades of structured abrasives, to remove material and achieve the required shape and finish, before polishing mops complete the part.
The combination of automation and enhanced abrasives achieves a more consistent finish and extends media life. It also, in comparison with manual production, reduces the number of individual finishing operations, typically from eight to six. The major benefit is an increase in productivity. Manually, it can take 45-90 minutes to hand-polish and buff a hip implant whereas a robot system can achieve the same result within eight minutes.
Assembly and testing
The assembly of medical devices covers a very broad range of products from sutures and cannulas to inhalers. Traditionally, these assembly systems are often high-volume, dedicated machines based on a linear index or circular rotary table approach. Items such as syringes and needles can be produced at 1,000ppm. More difficult parts, such as catheters, are typically assembled at about 60ppm. Inspection and testing, often at 100% of production, is incorporated within the system. There is often very little flexibility built into these systems as the life of the product is expected to be a number of years.
However, the initial design of these machines presents a problem. A new product must undergo a lengthy and stringent testing programme before it is approved for sale. A significant number of sample parts, which could be of the order of 200,000, is required for testing by the company as well as various approval agencies. It is not cost-effective to build the final assembly system for this limited
run-off and in this instance manual production is not an alternative.
Therefore, lower-volume pilot manufacturing systems are being built that are increasingly reliant on robots. Although robots are slower than dedicated automation, they are more easily set up to perform multiple tasks and are therefore much better suited to these lower-volume pre-production systems. Even in some high-volume applications, robots provide a cost-effective alternative to the design of special-purpose automation.
Robot motion is defined in software, whereas the motion of special-purpose automation is normally defined by the mechanical design. The robot therefore enables late changes and provides a lower-risk alternative catering for product design changes as well as errors in the system design.
There is widespread use of automation for final packing operations. Packaging is not subject to the same approvals as the actual products and can change much more frequently to meet customer demands. These packing systems often include robots because of the flexibility they provide. For example, a system based on robots automates the pick-up of flow-packed droppers from a conveyor, using vision to identify the positions of the droppers. The robots then place the droppers in a carton along with a bottle containing penicillin. These packing systems are relatively standard robot applications and therefore proven solutions are commonly available.
Automated system design and implementation
There are companies that specialise in automated systems for medical device manufacture; however, they typically have more experience of high-volume, dedicated systems rather than robots. There are many robot system integrators although they often have less experience of the various requirements associated with the medical device sector.
For an end-user to obtain the optimum solution, it is important they discuss their requirements with a range of suppliers. To achieve good communication with the suppliers it is imperative that the end-user develops a detailed user-requirements specification. This must provide the appropriate information, including details such as the tasks to be performed, the required throughput, product details including tolerances, and details of the component input methods and required presentation at the output.
The development of the specification can often be time-consuming but it can provide the key to a successful system implementation. Of those systems that have not performed to the expectation of the end-user it is often due to a lack of understanding between the system supplier and the client arising from the lack of a clear and detailed specification.
A good specification also provides the opportunity to include potential suppliers who may have less experience of medical device manufacture but may have gained experience in other sectors that could provide valuable insights and new ideas, resulting in a better solution. They may need additional support during the project to ensure they understand and achieve the relevant standards, but, if they have a better solution, this time-investment may still result in a lower-cost technology.
To ensure compliance with the standards and validation required for medical devices, automation is almost becoming mandatory. Medical device manufacturers are also facing increasing cost pressures and the need to provide for shorter product lifecycles. The most cost-effective solutions to these challenges will increasingly be flexible systems based on robots and may well be delivered by integrators new to the sector.
This article was first published in our sister publication Medical Device Developments.