March 7, 2012

5 Min Read
Ten Tips for Medical Device Assembly Automation

The below ten tips for assembly automation in medical device manufacturing follow the progression of a machine project from product development through machine definition and selection to completion of the part automation.

Concep Machine1. Design Parts for Manufacturability. If the parts do not join together in a robust manner, the automation will not be reliable and will not provide high-quality completed assemblies. The fit of each part to another is critical for a successful automation process. It is very important to consider designing in features that help guide the parts together; lands, chamfers, and assembly guides go a long way in supporting the assembly process. It also helps for designers to consider parts for assembly in a manner that allows the part to go together without special tooling considerations.

2. Establish Stable Dimensional Quality of Parts. It is often said that assembly automation is the most demanding inspection machine that you can buy. This is often the case because of the need for stable dimensions to build the machine tooling around the parts.  If dimensions are not within the tolerance range that has been provided to the automation supplier, parts can jam in the machine. Therefore, it is helpful to dimension and tolerance the part prints to reflect what can be achieved in real production.

3. Prototype High-Risk Processes. Sometime during product design or the beginning of the development of a machine user-requirement specification (URS), vendors may identify areas of the assembly process that demonstrate a high risk or require a new concept for tooling. In such instances, the development of a prototype can be used to confirm the process or tooling approach. These prototypes are most helpful if the part samples of the assembly components are in a stable design stage. Developing the production tooling at this stage with a simple prototype can confirm key data such as the feasibility of the process, as well as whether it will work within a cycle time window, generate any particulate, or damage the assembly.

4. Identify Automation/Production Processes. The next step after obtaining feedback on the assembly processes is to make some fundamental choices regarding the type of machine that is desired. Feed rate becomes an important factor at this stage of the development. For example, the use of pneumatics for actuations in the machine are a good choice; however, they are limited to speeds that do not cause premature wear of the devices. Cam-actuated processes, on the other hand, will provide much higher machine speeds but  require a higher investment than pneumatics do.

5. Develop a Detailed and Complete URS. The URS is an important guide for the automation project as it will enable the suppliers to provide accurate and complete proposals for the equipment. The manner in which customers write the URS varies widely; some are very detailed while others are intentionally vague and open to interpretation. In either case, the "must haves" for the machine project must be clearly defined to ensure project success.

6. Choose a Vendor Through Thorough Review. Supplier selection for an application should be determined through a systematic comparison; each supplier should be evaluated based on the strengths and weaknesses of its approach. Careful weighting needs to given to various aspects of the proposed machine, from cycle rate to needed floor space to the inclusion of various quality inspections.

7. Develop a Robust Process Failure Modes and Effects Analysis (PFMEA). A complete and detailed PFMEA provides invaluable information about the machine process. High risk priority numbers (RPNs) are a strong indication that a process is not going to be robust in a machine, or that it will be a high-maintenance area once the machine enters production. Modification of the process or detection methodology is a low-cost, low-risk solution for the automation at this phase of the project. Making these changes early in the engineering design of the machine also lessens the cost impact to the overall project.

8. Develop a Project Plan. The project plan should contain key data points that relate to the project schedule and show both supplier and customer key inputs for the project. It is important for all parties involved to see such milestones, including when the customer needs to supply parts in quantity and the date of "power on" for the system from the supplier, for example.

9. Monitor the Project Plan-Often. Once the project plan has been developed, it needs to be reviewed and maintained as a living document. It should be reviewed whenever the project team has a major meeting or review event. Adjustments need to be made that show both the original base line and real-time adjustments that have been implemented to accommodate changes in the project schedule. This approach becomes vitally important during the de-bug phase of machine development. De-bug is the phase when unexpected time may need to be allocated in the schedule to solve a problem on the machine that could not be foreseen and is not apparent until the system is under power and beginning to cycle.

10. Take Ownership. The ultimate owner of the machine process is the customer who purchases the equipment. Therefore, the earlier that the customer's team takes part in machine development, the smoother the transition to ownership will be. Working side by side with the supplier gets the engineers and technicians that will maintain the equipment completely involved and comfortable with the machine.

Concep Machine (Northbrook, IL) specializes in the design and manufacture of special-purpose machinery and factory automation systems for use in medical device assembly and test applications.

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