CONVERGENT LASERS P50L Nd:YAG Laser
The CONVERGENT LASERS P50L has been specifically designed for laser hole drilling with both percussion and trepanning techniques. This combination of peak power, high brightness (beam quality), high average power and power density required to produce deeper holes, with less recast and micro-cracking, will result in faster production. The P50L also gives the user the broadest operating range of any laser used in aerospace drilling today.
Most importantly, the P50L incorporates a unique tunable resonator. LASERDYNE and CONVERGENT engineers have worked together to produce the first closed loop drilling system. A motorized Internal Cavity Telescope ( ICT) provides constant beam divergence from the laser independent of lamp power and output power. The Variable Spot Module (VSM) controls the beam diveregence and size of the beam entering the focus lens. Both modules are motorized and are under the control of the LASERDYNE S94P.
Drilling At Focus or drilling at the center of the laser beam focus range is one important way to ensure hole-to-hole consistency. The combination of the ICT and the VSM movements, controlled by the S94P, provides the required beam diameter at the focus lens which in turn controls the spot size on the work piece and therefore the hole size.
Auto Flow Compensation adds an alternate to the traditional approach for controlling hole size in laser drilling. The traditional method involves using a fixed beam diameter and changing the position of the focused beam relative to the workpiece surface (defocusing) to adjust hole diameter. This approach of arbitrary adjustments from the focus position, can produce significant changes in hole size and taper. Defocusing is a ‘trial and error’ method inconsistent with the need for a repeatable and tightly controlled process.
S94P Laser Process Control
The LASERDYNE System 94P Control continues our philosophy that the most productive laser materials processing systems are those in which all laser, motion, workpiece, and process sensing functions are integrated. This control has evolved through an intimate understanding (often provided by our customers) of the applications for laser drilling systems.
The modern hardware of the S94P includes two Pentium processor based industrial computers and digital servo control. One of the computers is dedicated to controlling and coordinating the laser, motion, and sensing at speeds required for precision drilling. The second provides the user interface. The S94P includes a pendant mounted operator console with full travel keyboard, touch screen with CCTV or other camera image, CD-ROM drive, USB port, and floppy disk drive.
Summary of LASERDYNE S94P Hardware Specifications
| Computer | Pentium 3, 850 MHz (standard) |
| Operating System | Windows 2000 Professional (user interface)
Linux (operating system) |
| User Program Size | 10 Mb |
| Hard Disk | 40Gb |
| Floppy disk storage | One 3.5 inch disk drive (1.44 Megabyte capacity) |
| CD-ROM drive | 24X (minimum speed) |
| USB | One USB 1.0 port |
| Keyboard | Industrial QWERTY keyboard with integral touchpad |
| Screen | Flat panel, 15 inch (380 mm) diagonal active matrix touch screen |
| Network interface | 10/100 network card |
| Inputs/Output, typical | Eight 24V inputs and eight 24V outputs available for general purpose.
Optional I/O boards are available for adding I/O in blocks of 16 inputs and 16 outputs |
The System 94P features a 200-microsecond servo update time for the five axes. In addition, the command position is updated every one millisecond to further ensure accurate contouring motion.
The System 94P is programmed using G and M codes commonly used by machine tool CNCs (e.g. G0 = Rapid Traverse, G1 = Linear Interpolation). This shortens the learning curve for operators and programmers familiar with conventional CNC machine tools.
Software Features Important for Laser Drilling Systems
The S94P control contains a number of features for maximizing accuracy, throughput, and process repeatability. Key features used in laser drilling turbine engine components are summarized here.
• AFC™ Automatic Focus Control AFC provides capability for maintaining a fixed distance between a copper gas assist nozzle and the workpiece in order to maintain a constant calibrated distance between the focusing lens and workpiece. Feedback from the AFC sensor is used to drive the system linear axes. The feedback can also be used in an ‘open loop’ mode in which the feedback is used in measuring the position of the surface of a workpiece feature or tooling feature. For additional information, see the section entitled ‘Workpiece/Fixture Sensing’.
• Automatic Alignment This routine is used to establish the relationships between the motion axes and specific lens/gas assist assembly as required to make use of Part Surface Coordinate programming. Automatic Alignment is used to identify the location of the tool center point (laser beam focal point).
• Drilling macros Simplifies programming of drilling routines involving percussion and trepan drilling of shaped and cylindrical holes and PosiPulse? Drill-on-the-Fly.
• Laser Process Manager This software provides capability for capturing, saving, and analyzing laser process data for use in process control, process trend analysis, and for process documentation. Parameters which can be collected using this software include time, date, laser parameters, and axes positions.
• Materials Processing Database The system contains a database structure for storing laser processing parameters unique to the laser and specific drilling requirements. These parameters include settings for the laser ICT and laser output beam diameter.
• PresSure? This software is used in conjunction with a programmable valve to provide the user capability to set and adjust assist gas pressure manually (MDI) or from within the part program.
• Rotary/Tilt Part PSC Simplifies programming by allowing programs to be written in terms of hole locations and orientations on the workpiece, rather than requiring the programs to be written in terms of machine axes positions.
LASERDYNE offers an optional five axis PC-based CAD/CAM system for editing design files and for preparing programs offline. The system features a postprocessor that is developed in conjunction with the S94P software so as to take maximum advantage of control capability and, in doing so, maximize system throughput and quality in laser drilling.
OFC™ Optical Focus Control
OFC™ is a unique means of controlling the location of the laser beam focal point relative to both metal and non-metal (not electrically conductive) surfaces. OFC is the result of LASERDYNE working with a customer to solve a real-world need for laser drilling of TBC (thermal barrier coated) components.
OFC uses a visible (red) laser beam coaxially aligned with the P50L laser beam to provide an absolute measurement of the distance between the focusing lens and workpiece surface. Performance specifications for OFC are shown in the following table.
OFC is complementary to AFC with each having unique advantages. The operator can alternate between AFC and OFC from the S94P keyboard or using G codes within the part program. Changing between the two requires no physical adjustment to the system. While AFC operates in closed loop control mode to maintain a calibrated distance between the sensor (copper tip of the nozzle) and workpiece, OFC operates as a true measurement device. It is not necessary for the nozzle to be positioned relative to the surface for it to provide information about the surface position – OFC can make measurements and correct for surface errors even with a large standoff. This avoids extra moves for ‘finding the surface’ common when using AFC. As a result, OFC often contributes to significantly faster processing.
Other features of OFC for drilling applications include:
• Precise OFC senses only at the drilling location, thereby providing accurate measurements of part surfaces inaccessible to conventional AFC nozzle. It avoids “side sensing” associated with capacitance (nozzle based) sensors.
• Fast Greater sensing speed allows OFC to follow a surface under closed loop control at 2-4 times the speed compared to when using AFC.
• Flexible Can be used with or without nozzles. For applications requiring a nozzle, OFC allows PTFE (Teflon) nozzles to be used. A wide range of materials, colors, and finishes can be sensed and processed.
• Reliable High immunity to electrical noise. No external cables.
Workpiece/Fixture Sensing
A number of patented features have been developed around the capability of AFC (capacitance sensing) and OFC (optical sensing) to sense the location of key workpiece and fixture features.
• AutoNormal™ Automatically determines the position of a surface and orients the workpiece perpendicular (normal) or at any user programmable angle to the laser beam. This process, which takes a few seconds, involves measuring the location of three points on a surface and calculating the plane and normal vector of the surface. Spacing of the points is user programmable making it useful for sensing a wide range of surface radii.
• Feature Finding™ Determines the actual location of key workpiece and tooling features (e.g. tooling balls). These measurements are typically used to adjust the reference positions and/or orientations from which program locations are based.
• In-Fixture Gauging™ Used to compare the location of reference points on the workpiece to those expected for a correctly fixtured workpiece. Logic within the part program detects fixturing errors before the workpiece is processed.
• Mapping Used to measure the profile of a cylindrical workpiece, such as a combustor, to increase throughput and hole position accuracy.
• Selectable Seek™ Used to program the direction which the system moves to follow the surface. This feature is especially important for maintaining accurate location of holes produced at an angle to the surface, that is, on a ‘waterline’.
• Probing Uses a combination of built-in measurement devices (AFC?, OFC?) to identify the actual positions of reference locations (datums) to correct for misalignments and part-to-part variations in order to achieve required precision in hole location.
BreakThrough Detection
LASERDYNE Breakthrough Detection is another of the tools for maximizing throughput and quality in laser drilling turbine engine components. It accomplishes this by compensating for variations in material thickness and material removal rates.
BreakThrough Detection monitors progress of laser drilling for each hole to determine the pulse at which breakthrough first occurs. Once breakthrough has been detected, a user-defined number of additional pulses (any number from 0 and higher) are delivered to the workpiece. The number of additional pulses is determined by factors such as proximity of the surface being drilled to an adjacent back wall, hole size and taper consistency (see graph at the right), and air flow tolerance.
Multiple Levels Collision Protection
The 450 continues the LASERDYNE tradition of producing systems with the most comprehensive collision protection. Multiple level collision protection includes:
• Spring loaded nozzle assembly, which disables axes drives when a collision occurs from any direction. The assembly is designed for repeatable positioning after a collision has been cleared.
• All servo axes are current limited, which protects servo amplifiers and motors.
• All servo axes have circuit breakers, further protecting motors and amplifiers.
• Software compares the command position with actual position. The motion system is disabled if a pre-set limit is exceeded.
• Double over travel limit switches protect the system from extreme cases of over travel.
Restarts after a collision are made simple because the system remembers the position at which the collision occurred.
LASERDYNE® 450 Laser Drilling System
• Five axis workstation
• Three linear axes with 14 x 14 x 14 inch (355 x 355 x 355 mm) X-Y-Z travel
• Rotary and tilt axes mounted on the X-Y axes,
• A (rotary) 360 degrees continuous, B (tilt) +/- 135 degrees
• CDRH Class I enclosure with two manual sliding doors
• Multiple levels of collision protection
• Sealed and pressurized beam delivery
• 200 mm Quick change 15O shallow angle cutting/drilling head assembly – other focal lengths are also available
• Programmable assist gas pressure
• BreakThrough Detection
• OFC™ Optical Focus Control
System 94P Laser Process Control
• Windows 2000 Professional operating system
• 40 Gb (minimum) hard disk
• 1.44 Mb 3.5 inch floppy disk drive
• 24X (minimum) CD-ROM drive
• QWERTY keyboard and pointing device
• 15 inch active matrix flat panel touch screen
• 100 Mb Ethernet Network card
• Expandable digital I/O
• Industrial enclosure
• Electrical box air conditioner
• Exclusive features for multi-axis laser drilling and contouring
CONVERGENT LASERS P50L Laser
• 200 Watts average power
• Advanced solid-state design
• Tunable resonator: Motorized Internal Cavity Telescope, ICT
• Motorized Variable Spot Module, VSM
| Standard – Motor Encoder Feedback | Linear Scale Feedback |
Axes Travels |
Linear X, Y, Z | 355 x 355 x 355 mm (14 x 14 x 14 inch) | |
Rotary A | 360º continuous | |
B | ±135 Degrees | |
| | |
Feedrate | | |
Linear X, Y, Z | 0-15 m/minute (0-600 inch/minute) | |
Rotary A | 0-40 rpm | |
B | 0-10 rpm | |
| | |
Accuracy | | |
Linear X, Y, Z | +/-13 µm/300 mm (+/-0.0005 in/ft) | +/-2.5 µm/300 mm (+/-0.0001 in/ft) |
Rotary A | +20 arc-second | |
B | +6 arc-second | |
| | |
Repeatability | | |
Linear X, Y, Z | 13 µm/300 mm (+/-0.0005 in/ft) | 2.5 µm/300 mm (0.0001 in/ft) |
Rotary A | within 15 arc-second | |
B | Within 6 arc-second | |
Weight Capacity | 18.2 kg (40 lb) total of workpiece and fixturing |