OPTOFORM® 30
The last OPTOFORM 30 was shipped in December 2000 and it was replaced by the OPTOFORM 40.
The main advantages of the 40 over the 30 are (a) hydrostatic air slides on both axes vs. the self-adjusting, self
lubricating contacting turcite ways of the 30 and (b) linear motors replaced DC servos and ballscrew.
ENGINEERING SPECIFICATIONS
October 20, 1993 (last revised 6 May 2004)
The OPTOFORM® 30 is a precision, two axis, continuous path CNC contouring and
edging lathe for the direct machining of spherical, multi-curve, and aspheric contact
lenses. Non-rotationally symmetrical designs (including all torics) can also be machined
with a Fast Tool Servo attachment such as the VARIFORM, VARIMAX, or FTS-1000
generator attachment.
Scope
The OPTOFORM® 30 is a precision two axis, continuous path, computer controlled
contouring machine for the direct lathing of spherical, multi-curve or aspheric Contact
Lenses. In addition, any user defined edge configuration can be specified, incorporated
into the lens design, and directly machined. Aspheric surfaces can also be machined
with the aspheric Lens Design Software (LDS version 3).
The machine utilizes precision dovetail slides and a high speed air bearing spindle. The
slides are mounted on a natural granite base and are positioned in a "T" configuration.
The X-axis slide represents the cross arm of the T and carries the dual tool holder
assembly, as well as the optional front surface probe. The Z-axis slide represents the
stem of the T, and carries the high-speed air bearing spindle. The workpiece is
mounted in an air actuated collet mechanism within the air bearing spindle.
Utilizing continuous torque DC servo motors, combined with precision linear glass
scales, any axis symmetrical shape which can be mathematically defined as a surface
of revolution can be generated by continuous path Computer Numerical Control. These
surfaces can range from flats, to spheres, to aspheres with up to 14th order polynomial
departures, or any combination of these.
Machine base
The machine base is made from a 150mm thick piece of laboratory grade natural
granite. It provides excellent thermal stability and good vibration dampening
characteristics.
The base is isolated from its fabricated steel frame by a passive, three point, vibration
isolation system.
Machine slides
Both the X and Z linear axes utilize a precision contacting way slide design. These
slides combine high stiffness with smooth linear motion. The slides are driven in
translation by preloaded ballscrew assemblies which are directly coupled to DC servo
motors. Slide positioning is controlled by linear glass scales attached directly to the
slide carriage.
The total slide travel is 150mm (6") on the X-axis, and 100mm (4") on the Z-axis. The
slide feed is bidirectional and infinitely variable up to 1500mm/min. (60"/min.).
Spindle
The OPTOFORM 30 is equipped with a high speed air bearing spindle with an integral
AC Drive Motor. Spindle rotation is infinitely variable from 5,000 to 10,000 RPM with
acceleration and deceleration times of less than 5 seconds. The spindle design
accommodates air actuated collets for holding the lens button or block (arbor) during the
machining cycle.
Optional collets can be supplied with various bore diameters in standard or fixed-stop
configurations.
Tooling package
The machine can hold up to three dual tool holders. In its standard version it is
equipped with one dual Tool Holder Assembly which facilitates the mounting and fine
height adjustment of up to two diamond tools. Two additional dual Tool Holder
Assemblies may be added as options to accommodate any combination of roughing,
finishing and edging tools (up to a total of 6 cutting tools, allowing simultaneous set-ups
for concave and/or convex surfaces).
High pressure air jets below the cutting tools provide cooling and assist with swarf
removal. A vacuum chip extraction tube is included with the standard tooling package to
provide adequate chip removal during cutting.
Optional Front Surface Probe
An optional LVDT probe can be mounted in a fixture on the X-axis table next to the tool
holder. This LVDT is used to automatically establish the relative Z axis position of the
lens prior to machining, thereby assuring precise and repeatable center thickness from
piece to piece.
Tool set station (optional)
A spindle mounted L.V.D.T. Tool Set Station is also available as an option. It
kinematically mounts to the face of the spindle and is completely interchangeable from
machine to machine. Therefore, only one Tool Set Station is needed to service any
number of machines.
Calibration Artifacts are included with this unit to quickly and easily qualify the tool set
station each time it is placed on the machine. This insures consistent repeatability from
one set-up to the next.
Tool setting is accomplished through the use of two air bearing L.V.D.T. probes (linear
variable differential transducers) located on the Tool Set Station. A vertical probe is
used to establish the height of the tool relative to the spindle centerline; and a horizontal
probe is used to automatically establish the X (lateral) centerline position of the tool,
and calculate the tool radius.
Control system
The OPTOFORM 30 is equipped with a PC based computer system and a precise and
reliable motion controller. The front end provides a powerful processing capability
through the use of a Pentium 233MHz CPU with 32MB RAM, 1GB (or larger) hard drive,
3.5" floppy drive, and a high resolution VGA monitor.
The system software monitors and controls all machine functions and provides a
flexible, production-oriented interface for both the machine set-up technician and the
operator. A color assisted Run Cycle screen supports a user-friendly interface for the
operator. Initial set-up is greatly simplified by the use of appropriate Set-Up and Tool
Change screens. Continually updated Production and Maintenance files are optional
and ensure that critical process management information is instantly available. Basic
machine diagnostics can also be checked, by viewing a color-coded I/O Status screen.
Lens surfaces are quickly and accurately machined via continuous path linear
interpolation of the X and Z axes.
Spherical lens design software
A complete standard lens design software package allows the lens designer to create a
job file which incorporates the chosen lens geometry and edge configuration for Soft
Lenses, or RGPs.
Once the basis of the particular lens design parameters have been "locked in" using the
files menu, lenses can be quickly designed by specifying the lens design type and
material by name; and by entering base curve, power and lens diameter. Storing lens
design parameters and recalling them by name de-skills the lens design operation to a
simple task.
Special lens designs can be created using the custom menu which gives lens designers
the full power of 10 spherical curves on either side of the lens. Any user defined edge
configuration may also be incorporated into the lens design. Verification of standard
lenses or special designs can be displayed by pressing the visual hot key.
After defining the lens geometry, the software calculates X and Z data points in 10
micron increments along the specified surface. This information is then utilized to
execute the machine movements by continuous path linear interpolation after modifying
the data points with tool radius compensation values.
Aspheric Lens Design Software is available as an option and allows the creation of
simple aspheric surfaces through the use of conic constants, or more complex
aspherics with up to 14th order polynomial departures. Design modules for Soft
Lenses, and RGP's are included in this software.
Another optional software package is also available for the creation of part programs
from user specified coordinate points or geometrical data. This software is called "Multi
Curve Generator" (MCG) Programming Software and can also be used to program toric
surfaces.
See Software for various other options in lens design and inspection software options.
Acceptance part cutting
On the contoured surface of a typical 12.7mm diameter PMMA blank, Pretitech /
Sterling will guarantee a surface finish of less than 20 nanometers (0.02 micron) RMS
(Rq), as tested on a Taylor Hobson Form Talysurf with a cut-off of 0.25mm. In addition,
form accuracy will be guaranteed to 0.5 micron (20u"), or less, as tested on a Helium
Neon Laser Interferometer operating at a wavelength of 0.6328 microns.
Utilities required
Electrical Power:
230 Volts
50/60 Hertz
Single Phase
3.0 KVA
Compressed Air:
6 bar (90 PSI)
3 liters/sec. (6 SCFM)
Filtered to 0.3 micron solid particle size; and
Dry to 50° F pressure dew point.
Approximate Floor Space: 1000mm x 906mm (40" x 36")
Approximate Weight:
815Kg (1800 lbs.)
Optional equipment

Additional Dual Tool Holder Assemblies

LVDT Tool Set Station with Calibration Artifacts

Front Surface Probe Package

Probing Support Package (required for use of the LVDT Tool Set Station and/or
the Front Surface Probe Package)

Mechanical Indicator to monitor vertical height adjustment of the tool holder
(2.0µm resolution)

Machine mounted flexible Work Light

Various Collets (Standard & Fixed Stop)

Aspheric Lens Design Software with modules for Soft, RGP & IOL designs

MCG Programming Software for the creation of specialized part programs from
user specified coordinate points or geometrical data

Productivity and Maintenance Screens (in the machine control software)

Modem

Refrigerant Air Dryer with 30 gallon air reserve tank and 0.3µm solid particle filter