Machines Focused on Light Management Applications

Dr. Jeff Roblee, Divisional Vice President of Technology at Precitech, talks to AZoM about their new fleet of machines focused on Light Management applications.

Could you provide our readers with some examples of the typical applications of Light Management?

Light diffusers for interior lighting with LED’s, light pipes for solar lighting, backlighting of display screens, films to enhance the brightness of displays, highly reflective signage and tape, solar concentrators, and many more.

What is the typical manufacturing process used in a Light Management application?

The most critical step is the production of a master from which the final product is replicated. Precitech’s machines are used to make these masters. They are usually made of copper or nickel alloys which can be machined to optical quality surface finishes with a high quality diamond tool.

The diamond tools can either spin, as in milling or flycutting, or they can translate while the work piece spins or translates, such as in turning or ruling/shaping operations. The quality of the master is totally dependent on the accuracy and vibration level of the machine tool.

How are the new machines which Precitech has released useful in these applications?

These new machines have achieved new levels of accuracy and vibration levels for machines of these sizes and number of axes of motion. The speeds of these machines have also increased, making them more productive.

Why does the Micro Groove Generator (MGG) have Freedom in its name?

In the past, most groove generating machines made only constant depth grooves on a flat blank. Therefore, they only needed a relatively crude position and hold axis to control groove depth.

On our latest MGG, we decided to replace this vertical axis with our proven, ultra-precision axis from our Freeform product line. This vertical axis can position just as well as the two horizontal axes.

They all use oil bearing slides driven by linear motors. Consequently, this machine can make many of the same freeform shapes as our FF ML machine, but much bigger.

Precitech Freeform MGG micro-groove generator

How is this machine different to other MGG’s available on the market?

Besides a contouring vertical axis, this machine shares the advantages of other Precitech machines, such as a custom made controller with many special features to ease the use the manufacture of masters and world class vibration isolation from our sister company, TMC.

Also new to this machine is our patented oil bearing rotary axis that has been proven on our line of lathes and freeform machines. The stiffness and accuracy of this rotary axis is unmatched in the industry. The flycutting spindle is also a Precitech design with ultra-precise air bearings with optimized water cooling for stability.

Finally, both horizontal slides have extremely straight motion over a long travel of 650 mm. They are water cooled as well.

Can the MGG be configured for other applications apart from making grooves?

Yes - with a radiused tool, the MGG can raster flycut, with a spinning tool, or rule/shape with a non-rotating tool, a true freeform surface. A vertical acting Fast Tool Servo can also be employed to add micro-structures to surfaces, and finally an 80,000 rpm milling spindle can be mounted vertically to transform the machine into a traditional milling machine configuration.

How does the MGG allow customers to produce grooves on flat mold masters?

Either a tool is fixed to the vertical axis, and grooves are ruled, or the tool can spin with a spindle mounted to the vertical axis.

In either case, the work piece translates under the tool for each rapid pass.  Between passes, either the tool can index laterally or the work piece can be indexed rotationally.

Why has Precitech chosen to release three different versions of the Drum Roll Lathe (DRL)?

Each one is optimized for different drum lengths and weights, and each one has a different footprint as well.  This way our customers have a choice of a machine to match their particular needs.

Could you explain the benefits and drawbacks associated with using either air bearing spindles or oil bearings when designing the DRL?

Air bearing spindles have much better error motions and thermal growth than oil bearing spindles, but they have much lower stiffness, damping and load capacity than our oil bearing spindles. The cost difference is significant as well.

What are the benefits of Precitech’s manually adjustable tailstock?

This enables us to easily accommodate a variety of drum lengths without the need for shaft extensions.

What types of patterns can be made on drums using Precitech’s DRL?

Many, many types are possible, but some of the most common are circumferential, spiral and axial grooves.  In combination with our X, Z, B and C axes, these grooves can have varying depths and varying angles as the groove progresses around the drum and along its length.

Multiple passes can also be done on the same drum, which allows complex, intersecting groove patterns to be created.  With the addition of a Fast Tool Servo, a wide variety of micro-structures can also be created, which is particularly important for light diffusers.

Precitech DRL 2000 drum-roll lathe

What is the fundamental difference between a DRL and Freeform MGG? Why would customers choose one over the other?

It really depends on the customer’s preferred manufacturing processes. The MGG is typically used to make fairly flat masters, which are then replicated to make a metal tool.

These replicas can be used directly for compression molding of flat plastic substrates, or many replicas can be attached to a drum that can then be used in traditional roll-to-roll processing of light management films.

Where can our readers find out more information about Precitech’s new fleet of machines focused on Light Management applications?

On our web site, give us a call, or see us at one of the many trade shows we will be exhibiting at in the near future.

About Jeff Roblee

Dr. Jeffery Roblee joined AMETEK Precitech in 2002, and he is the Divisional Vice President of Technology. Dr. Roblee began his engineering career at Lawrence Livermore National Laboratory in 1977.

Dr. Roblee holds a number of patents and awards, and he has presented numerous papers on temperature control, machine dynamics, air bearing design, optics fabrication and optomechanics.

He is an active member of the European Society of Precision Engineering and Nanotechnology, and the American Society of Precision Engineering.

From 2007 to 2009, he has been a member of the Board of Directors of ASPE, and he served as its President in 2008. Jeffrey W. Roblee has a M.S. and Ph.D., both in mechanical engineering, from the University of California at Berkeley.