Consider traditional fixed and new flexible automation systems to achieve reliable, safe, and profitable production of medical devices.
By TOM BEMER AND RAY TYNCZUK
No manufacturer has a greater responsibility than one who creates medical devices for protecting the health and well-being of its customers. If not manufactured properly, these devices can cause harm or death, so designers and manufacturers must take great care that their end products meet the highest quality standards.
One area of consideration is optimizing process control capabilities. Afixed automation technology to accomplish this revolves around the operation of the fixed-stop index cam for manufacturing, assembly, and packaging of medical devices. However, automation advancements have evolved to include flexible systems with a constant-lead cam as their means of controlling the motion.
Fixed-stop cams are mechanical automation components machined for use on an indexer, with two distinct operating periods:
Index period – Number of degrees on the cam that are used for moving the indexer into position
Dwell period – Remaining portion of the cam used to determine the length of the cam’s in-station position where no movement occurs during indexing If an indexing operation calls for the cam to rotate 90° and stop, it’s cut so those operational parameters are always achieved, with no change in or added movement allowed.
By comparison, the index characteristics of the constant-lead cam are not determined by the way the cam has been cut, but rather electronically by a programmable device – usually a servomotor – instead of having the indexing and dwell times built into the cam. Constant-lead cams have a programmable indexing period, but no true dwell period since the servomotor is designed to continually use infinitesimal movements controlled by thousands of encoder points on the motor to seek correct position, even when the cam has stopped.
The subtle differences in fixed-stop and constant-lead cams need to be considered when deciding which technology to deploy.
Fixed automation pros:
Rotary or linear movement
Automation systems are typically available in two configurations: rotary indexers that move in a circle as predetermined movements and tasks are completed, or conveyor systems that move parts or products in a straight line through production. Rotary and linear systems can be outfitted with either fixed or flexible automation systems, and specific considerations must be weighed before choosing fixed or flexible automation for each.
A typical rotary indexing system can feature a six-position dial plate, where the first one loads the product, the second performs gluing, the third performs welding, the fourth drills a hole, the fifth inspects the product, and the sixth offloads the product. Traditionally the sweet spot for fixed automation, these systems can be modified to feature programmable movement through a servomotor, making them a choice for operations where a flexible system can perform well.
For involved processes, the linear conveyor system has typically been the first choice. Technology advances now enable movement of the conveyor by traditional fixed cams or servomotors, allowing use of both automation technologies together for operations requiring a part to be moved 6" one day, and 12" the next day.
Asynchronous movement is accomplished by magnetic conveyor systems to accurately control movement. Benefits of magnetic systems – either synchronous or asynchronous automation – are faster line speeds, more predictive, less frequent maintenance required, significantly smaller size than traditional chain-link conveyors, process programmability, and push-button changeover capabilities that eliminate the need for change parts.
In deciding between fixed and flexible automation systems, consider the design and expectations of the operations, such as:
About the authors:
Tom Bemer, Destaco product applications manager, can be reached at firstname.lastname@example.org or 847.612.9456.
Ray Tynczuk, Destaco application engineer, can be reached at 847.215.5670.