Controllers advance micro-manufacturing

I recently spent several weeks abroad studying micro-manufacturing in a U.S.-government-sponsored technology review. The goal was to assess and understand what is happening globally in micro-manufacturing. The final report is being generated; initial findings are online at—a site hosted by the World Technology Evaluation Center.


I recently spent several weeks abroad studying micro-manufacturing in a U.S.-government-sponsored technology review. The goal was to assess and understand what is happening globally in micro-manufacturing. The final report is being generated; initial findings are online at —a site hosted by the World Technology Evaluation Center. I highly recommend this site, as it has several studies of great interest to the controls, manufacturing, and micro-manufacturing technology communities.

My role on the WTEC micro-manufacturing team was to evaluate advances in controls, metrology, and sensors for micro-machining. I learned quite a bit—some of which was surprising. My next few columns will impart what I learned. This month, I will discuss new controllers being used for micro-manufacturing.

In past articles, I mentioned that controls being used for ultra-high precision applications need to be fast to track small distance increments (on the order of nm) while moving relatively fast (10-100 mm/s). Also, I mentioned that large counters are critical, as ultra-high resolution feedback requires the ability to count many small increments over the stroke of the machine. These two capabilities are prevalent in all control systems I observed on micro-machine tools, in industry as well as in research and development efforts.

Critical capabilities

Two other capabilities were identified by all controller manufacturers and users as critical in micro-machine tool motion control. The first is spline interpolation, which is critical in generating smooth tool trajectories when cutting micro-component surfaces. Spline interpolation has been shown to generate significantly improved geometries and surface finishes over conventional G01, G02, and G03 linear and circular trajectory commands. The second capability is controlling higher order motion trajectories. Traditionally, these systems control position, velocity, and acceleration.

This new generation of controllers for the micro-manufacturing arena also control the time derivative of acceleration known as jerk , to smooth tool trajectory. In many cases, the machines we reviewed produced very small-scale optical components (for example, lenses for next-generation optical drives or molds for producing those lenses). The combination of spline interpolation and jerk control was extremely beneficial in successful implementation of these machines.

Pushing the frontier

Most controllers we saw on a variety of micro-machine tools had the basic capabilities discussed here. In addition, many machines are reconfigurable and can therefore be used as a lathe, a mill, or a grinder, etc. However, controllers' openness varied substantially from system to system.

I believe these new controllers are going to be very impressive and offer significant capabilities. They will push forward the frontiers of micro-manufacturing, and enable cost-effective advances in manufacturing in general.

The next column will discuss trade-offs between open and closed architecture controllers. Following that, I will address controls designed for reconfigurable machines.

Author Information

Thomas Kurfess is a professor at Georgia Tech's George W. Woodruff School of Mechanical Engineering.

No comments
The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by...
The System Integrator Giants program lists the top 100 system integrators among companies listed in CFE Media's Global System Integrator Database.
The Engineering Leaders Under 40 program identifies and gives recognition to young engineers who...
This eGuide illustrates solutions, applications and benefits of machine vision systems.
Learn how to increase device reliability in harsh environments and decrease unplanned system downtime.
This eGuide contains a series of articles and videos that considers theoretical and practical; immediate needs and a look into the future.
System integration: Best practices and technologies to help; Virtualization virtues; Cyber security advice; Motor system efficiency, savings; Product exclusives; Road to Hannover
Collaborative robotics: How to improve safety, return on investment; Industrial Internet of Things, Industrie 4.0: World views; High-performance HMI, Information Integration: OPC and OMG
9 tips: How to integrate a servo system; Process control mathematical models; Serial network grounding; Engineers' Choice Awards; Learn from cyber security mistakes
This article collection contains several articles on the Industrial Internet of Things (IIoT) and how it is transforming manufacturing.
PLCs, robots, and the quest for a single controller; how OEE is key to automation solutions.
Learn how Industry 4.0 adds supply chain efficiency, optimizes pricing, improves quality, and more.

Find and connect with the most suitable service provider for your unique application. Start searching the Global System Integrator Database Now!

Getting to the bottom of subsea repairs: Older pipelines need more attention, and operators need a repair strategy; OTC preview; Offshore production difficult - and crucial
Digital oilfields: Integrated HMI/SCADA systems enable smarter data acquisition; Real-world impact of simulation; Electric actuator technology prospers in production fields
Special report: U.S. natural gas; LNG transport technologies evolve to meet market demand; Understanding new methane regulations; Predictive maintenance for gas pipeline compressors
click me