SPC and MTConnect®

SPC: Saving Process Parameters

Statistical process control (SPC) is a software/hardware feature that saves selected program parameters in real time as a part program is executing. Desired parameters, which may include time and date, position, commanded and/or actual laser power, pulse conditions, etc., are automatically written to a designated hard disk file (see Figure 1).

The G80 command enables SPC and signifies what data should be saved. To save data in a file of your choosing, program G80 “FNAME”, where FNAME is any desired part and file name accessible from Windows (if no directory is specified, the file is written to C:\Cnc-Share\Output). The system first goes to the end of that file (if it exists), then writes a blank line, the time and date, and the SPC data. If no file name is specified, data is written to file Cnc-Share\Output\Process.

Note that although the $ parameters shown below can be used, the newer system parameters that begin with ‘?’ are preferred.

The data in Table 1 can be selectively saved by programming G80 followed by text containing appropriate $ commands. Text in a G80 block without $ commands is also transferred to the output file. G58 messages can also include $ commands to display data in the S94P message window.

 

Table 1 – Statistical Process Control (SPC) Data

$T	Time
$D	Date
$B0	Breakthrough Detection logging off
$B1	Breakthrough Detection logging on
$E0	Do not log system errors
$E1	Log system errors with time and date
$E2	Log system errors without time and date
$F	Commanded federate (inch/minute or mm/minute)
$Vn	System variable value (n=variable number)
$P0	Laser commanded power (watts)
$P1	Actual power at laser
$P2	Actual power at workstation (requires optional power meter)
$Q0	Override summary
$Q1	Feedrate override (%)
$Q2	Power Override (%)
$M	M-function report; lists those functions that are on: M200-M211 M300-M330
$M9	System model number (430, 795, etc.)
$L5	Laser block number executed
$L9	Laser type number

The functions of the following $ commands are dependent on the laser type (CO2, fiber, or Nd:YAG) (see Table 2 and Table 3):

Table 2 – CO2 and Fiber Laser Commands

Command	Function
LAS_NAME	Laser name
LAS_TYPE	Laser type number
LAS_DB-REC	Database record
LAS_SHUTTER_OPEN	1 if shutter is open
LAS_PULSE_MODE	1 if laser is in pulse mode
LAS_AVE_POWER	Average power
LAS_PULSE_FREQ	Pulse frequency
LAS_PULSE_WIDTH	Pulse width

Table 3 – Nd:YAG Laser Commands

Command	Function
LAS_NAME	Laser name
LAS_TYPE	Laser type number
AS_SHOT_COUNT	L Shot count
LAS_DB_REC	Database record
LAS_ACTIVE_PULSE	Active pulse tool
LAS_ACTIVE_WAVE	Active wave tool
LAS_SHUTTER_OPEN	1 is shutter is open
LAS_PULSE_MODE	1 if laser is in pulse mode
LAS_DCRAIL1_VOLTS DC	Rail 1 voltage
LAS_DCRAIL2_VOLTS DC	Rail 2 voltage
LAS_LAMP1_CURRENT	Lamp 1 current
LAS_LAMP2_CURRENT	Lamp 2 current
LAS_LAMP1_VOLTS	Lamp 1 voltage
LAS_LAMP2_VOLTS	Lamp 2 voltage
LAS_HIGH_VOLTAGE	1 if high voltage on
LAS_LAMP1_POWER	Lamp 1 power
LAS_LAMP2_POWER	Lamp 2 power
LAS_DCLINK1_VOLTS DC	Link 1 voltage
LAS_DCLINK2_VOLTS DC	Link 2 voltage
LAS_AVE_POWER	Average power
LAS_POWER_DENSITY	Power density
LAS_BEAM_DIA	Beam diameter
LAS_PULSE_FREQ	Pulse frequency
LAS_PULSE_WIDTH	Pulse width
LAS_PULSE_ENERGY	Pulse energy
LAS_DI_WATER_RES DI	Water resistance
LAS_COOLANT_TEMP	Coolant temperature
LAS_SECTOR_HGT	Sector height
LAS_CT_POS CT	Position
LAS_VSM1_POS VSM 1	Position
LAS_VSM2_POS VSM 2	Position

Output from $W5 consists of one line for each defined sector. The line contains sector number, sector width (ms), and sector height.

MTConnect®: Getting Real-time Visibility On Laser Processes

MTConnect® is a communication standard used in the manufacturing industry for reporting the current status of a machine tool. MTConnect is an open protocol for integrating machine data into various ERP and manufacturing floor software applications where real-time or near real-time information is being reported. MTConnect will not interfere with workpiece processing but rather streams machine parameters through the MTConnect agent to plant management software.

The standard strives toward supporting a plug-and-play environment to reduce the cost of integration associated with real-time machines status reporting. It is built upon more prevalent standards within the manufacturing and software industry. The MTConnect standard defines a common interface supporting the ability to transfer data via a standard protocol which includes:

• A device identity (i.e. model number, serial number, calibration data, etc.).
• The identity of all the independent components of the device.
• A possible device’s design characteristics (i.e. axis length, maximum speeds, device thresholds, etc.).
• Most importantly, data captured in real or near-real-time (i.e. current speed, position data, temperature data, program block, etc.) by a device that can be utilized by other devices or applications (e.g. utilized by maintenance diagnostic systems, management production information systems, CAM products, etc.).

The types of data that may need to be addressed in MTConnect includes:

• Physical and actual device design data
• Measurement or calibration data
• Near-real-time data from the device

The S94P control supports MTConnect and will automatically connect to any MTConnect® reporting software package that requests a connection, and stream the current state of the machine to it. The process is designed to be seamless, with no input required from the machine operator.

The data stream may be monitored from the MTConnect screen in the Maint94P application (see figure 2).

The reporting software packages require setup files, which are unique to each machine. These files may be generated from the MTConnect screen by pressing the “Make Config File” and “Make Device File” buttons. The files are stored in the MTConnect subfolder in the c:\cnc-share\system folder.

The variables/parameters, which are streamed and through the agent are identified in Table 4. Any of these variables can be reported and used to help monitor and improve the laser processes.

Table 4 – Data Variables/Parameters

Data Variable	Definition	Units
Program name	The name of the program in execution	text string
Program in operation state	If the machine is currently executing a program (Ready/Active)	value
Program running state	The current execution of the program (Ready/Stopped/Active/Completed)	value
Machine power on time	Accumulated time of the machine running (processing a workpiece)	seconds
E-Stop state	Has machine hit and maximum movement of the axis.  (Value: Armed/Disarmed)	value
Control ON state	State of the axis drives	on/off
Program name	The name of the program in execution	text string
Program in operation state	If the machine is currently executing a program (Ready/Active)	value
Program running state	The current execution of the program (value states: Ready/Stopped/Active/Completed)	value
Program checksum	The checksum of the NC text	Hex Number
Axes strokes (X, Y, Z, C, D, A, B, U)	The physical processing length of each axis	(X, Y, Z) millimeters (C, D, A, B, U) degrees
Axes commanded positions	Commanded axis positions	(X, Y, Z) millimeters (C, D, A, B, U) degrees
Axes actual positions	Actual axis positions	(X, Y, Z) millimeters (C, D, A, B, U) degrees
Feedrate commanded	The commanded path speed	millimeter/second
Feedrate actual	The actual path speed	millimeter/second
Feedrate override	The current setting of the feed rate override knob.	percentage
Laser ready state	If the laser is ready for use	on/off
Laser shutter enabled state	If the laser shutter is enabled	on/off
Laser shutter state	The current state of laser shutter	on/off
Laser beam state	If the laser is creating a laser beam	on/off
Laser power commanded	Reports the commanded laser power from the laser unit	watts
Laser power actual	Reports the actual laser power from the laser unit (measured by the laser unit at the input to the feed fiber)	watts
Gas port states	The state of the gas ports	on/off
Gas pressure commanded	The commanded gas pressure at the gas valve	pounds/inch2
Gas pressure actual	The actual gas pressure at the gas valve	pounds/inch2
Focus sensor type	Which type of sensor is presently enabled	AFC/OFC
Focus sensor state	If the enabled sensor is active	on/off
Focus sensor position error	The sensor position error from nominal	millimeters
Lens number	The number of the selected lens	integer
Error numbers	The numbers of the active errors	integer
Warning numbers	The numbers of the active warnings	integer

By using MTConnect to monitor a given set of machine parameters, one can gather real-time updates on job-status, run parameters, downtime, and machine information, which can be used to make the overall plant, machines, and maintenance more efficient.

 

If you are interested in the learning more about using MTConnect or SPC with your LASERDYNE® system, please contact lds.sales@primapower.com.

References: MTConnect Standard Parts 1-5, MTConnect Institute, March 2018
MTConnect is a registered trademark of AMT – Association for Manufacturing Technology.