The OEM's Guide to Advancing Life Science and Biomedical Equipment with Linear Motion — Pt 4: Ensure Efficient Integration

This series of articles highlights how next-generation linear motion systems can be specified, designed, installed, and maintained to advance life science and biomedical capital equipment manufacturing.

Ensure Efficient Integration?

Life science and biomedical capital equipment manufacturers must think big, long-term, and preventively to provide their customers with the highest-reliability product. Risk can be eliminated in many situations before a moving part arrives at the loading dock.

Do not think in terms of buying even the best single component. Instead, focus on creating a complete solution from the floor to the measurement point.

Besides the highest-performance cross roller bearings to provide extreme smoothness and speed, seek a solution that takes "ownership" of the entire assembly. This would include the stage and the properly isolated frame to which it is mounted. This also includes state-of-the-art active dampening measures. This integrated technology helps ensure rock-solid control of component movement and any ancillary vibration.

In terms of manufacture, perhaps the process that holds the most potential for causing mishaps down the line is designing and constructing the control element or elements that will direct the linear motion system. Issues such as improper wiring can crop up and must be guarded against, as in other parts of the build. But the myriad steps of programming the control, and integrating the hardware and software demand the most care.

Are all limit switches — with sensors that protectively trigger on or off states when the stage hits a point, such as a hard stop for the limit of travel — ordered as an option if a stage is a stock purchase? Were they all properly set, correctly oriented (with plus or negative limits sent to left or right pins, as applicable), suitably connected to the controller, and appropriately used?

Are limits for the electrical current set to the proper levels? Is the stage correctly tuned? Is the velocity limited so that it never exceeds the specified limits of any component in the system?

At the extreme, a mistake here might even lead to a runaway stage in the application. The moving part loses communication with the controller and starts moving on its own volition, perhaps to the point where it goes beyond the desired end of travel and impacts another part of the machine.

But, in a more likely scenario, a control design oversight could lead to an overcurrent situation and cause motor burnout. Suppose the limits are not correctly specified, and during travel, a motor-driven component such as a stage or table is physically impeded by an unexpected object on the rail (a fallen screw, an operator's hand, its end of travel, etc.). In this case, the motor may draw more and more amperage until it burns out. The results: equipment shutdown, disassembly, and service or replacement — all with significant downtime and costs for that part of the application.

An even subtler problem may arise if the control designers neglect to consider every possible condition during linear motion equipment operation. For instance, a three-axis linear motion component might perform perfectly during all routine operations through thousands of iterations. But in what might be an exceptionally uncommon configuration with no limit switches set (such as when the X, Y, and Z axes all happen to be simultaneously at their very lowest points of travel), the moving component may run into a structure in its surrounding environment. Not accounted for in planning, this could include hitting a nearby post, holder, or dispenser.

The problem is this: Linear bearings are excellent at accommodating continuous dynamic and static loading. But not impact loading. If a linear motion component hits something at high velocity, it generates what could well be an out-of-spec impact load. Potentially a single such hit could destroy every bearing in the system.

Next: Transport, Installation, Lubrication, and a Roadmap

Discover how next-generation linear motion systems can advance life science and biomedical capital equipment manufacturing capabilities and ensure against failures. Get the complete exclusive guide for OEMs now.