Machine Design

The good stuff may cost less

Manufacturers often try to cut the number of automation-component suppliers on their approved vendors lists, and for good reason.

Steve Nylund
Delta Computer Systems Inc.
Vancouver, Wash.

Edited by Lawrence Kren

They have learned that it is usually false economy to shop around for the lowest prices. When the bookkeeping cost of adding a new vendor doesn't eat up the savings, higher vendor-qualification and maintenance costs usually will.

Many large automation suppliers take advantage of this vendor-reduction trend by offering one-stop shopping. Assuming available components from different vendors have comparable performance, the savings realized by buying from a single vendor can outweigh modestly higher costs. And minimizing maintenance training brings additional savings with automation components that use software, such as HMIs, PLCs, and drives.

However, there are cases when using best-of-class components make sense. For example, motion controllers are one of the most important components in automation systems. Commodity drives or PLC motion cards can typically handle simple motion applications. But demanding applications may need such special capabilities as tight synchronization between axes, pressure-force control, quick program changeover, precise hydraulic control, or flexible control of servoelectric, hydraulic, and pneumatic systems. In these cases, a full-featured motion controller is key to best performance. It is unlikely that a one-stop-shopping automation supplier has a motion controller up to the task.

Even in simple applications, the savings can be significant. Case in point: A specialty press manufacturer upgraded the motion controller and added a pressure-limit capability to a bushing press. Production defects shrunk nearly to zero, saving hundreds of thousands of dollars in time and replacement costs. As a bonus, the upgrade dramatically shortened changeover time.

In another case, retrofitting the motion control on an injection-molding machine slashed cycle-time variations from seconds to milliseconds, boosting quality, raising throughput, and slashing downtime by a factor of 10. Payback in this case was six months.

The message: Best-of-class motion controllers cost more initially, but can quickly pay for themselves through improved process efficiencies.

Delta Computer Systems Inc. ( is a maker of motion controllers and related equipment.


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