Use of machine monitoring is the 21st century method to efficiently and automatically “data mine” information from a CNC operation.
It provides a continuous stream of data regarding the overall equipment utilization and the labor that operates it. Very little human intervention is required other than analyzing the data it provides (in real time).
Reports can be generated regarding:
- Cycle Time
- Cycle Time Discrepancies
- Load / Unload
- Down Time
- User Defined Issues
- Good Parts versus Bad Parts per Shift per Operator
Statistical data provides operational histories on every job processed because the data is from every shift of every day. The information enables more informed decisions based on factual data not guesswork. Email or text messages can be sent automatically by the system to alert the responsible party. Information includes:
- Efficiency weaknesses
- Quotes inadequacies
- Production load imbalances
- Performance & Warranty Issues
- Shop personnel become “productive” with less supervision as they become aware that the equipment activity or inactivity is being recorded.
- Inactivity emails to supervisory personnel prompts investigation.
- Cycle time changes (caused by feeds and speeds modifications) alerts engineering via email
- Tooling evaluations (allow engineering to quickly assess its performance benefits).
- Equipment problems alerts maintenance personnel to respond
There are a number of reports are included with the software. Generated reports can be configured to be automatically transferred via email to management. The data within the monitor file is in an ASCII form consisting of a series of date and time stamp records per machine, per shift which are in a comma delimited format. The monitor data can be exported to a spreadsheet program where customer specific performance formulas can be applied.
Manual equipment or inspection processes can also be monitored (by installing a trigger device). Other business intelligence can be acquired by adding user definable codes to identify just about any track-able item. Multiple user definable codes can be configured to address a host of other events.
ACTIVATION & OPERATION
Installing the Monitoring option requires a software upgrade of the DNC Server and device hardware installed on the CNC or process.
Option A: A custom interface is retrofitted to the CNC that provides a signal output to the DNC software about cycle activity. During operation the “on and off” state of the equipment is recorded in a file on the DNC server with a time and date stamp. In certain cases the machine cycle LED cannot be used because it never turns off. It is then that the spindle drive can be used to identify a cycle condition (such as when a pallet shuttle system is in use). There are many machine configurations used in factories that must be addressed increasing the difficulty in determining a valid cycle on and off condition. In these circumstances, only the spindle on / off signal is available and it may start/stop several times during a program cycle (i.e. during a tool change). The Monitor software has timers that can be configured to compensate for the spindle stoppages. (If the spindle stops for less than the specified number of seconds, the cycle is considered to be continuous).
Option B: If the CNC is capable of outputting ‘DPRINT’ statements they can be used to indicate the start and end of a part program. Cycle accuracy problems can arise however if a part program is not started from its beginning and executed to its end. When DPRINT is used exclusively for all CNC equipment a USB security dongle must be installed ot the DNC Server’s USB port to activate the MONITOR software.
When a CNC machine stops unexpectedly during a cycle the operator manually transmits an event code to explains the production stoppage. This is done by activating a pre-defined program that describes the problem. eLAN returns an acknowledgement message confirming the condition and a timer records the condition until the machine returns to production.
Another method to activate an event is by use of an optional device called an “eTerminal”. Operation is similar to the above except the operator selects the monitoring event from a list, sends it, and receives an acknowledgement. The eTerminal also enables use of a bar code scanner hardware.
THE MONITOR DASHBOARD
A user may also specify a monitoring event by accessing the ‘monitoring dash-board’ of the software using an Internet browser. A screen similar to the one shown will appear in the browswer. There are two predefined monitoring events: Production and Setup.
- PRODUCTION is determined when Cycle ON/Cycle OFF conditions alternate on the machine
(See “Cycle ON/Cycle OFF” section).
- SETUP is determined when a CNC part program is down loaded. At the same time a new part number may be specified (See “Part Number” section).
In addition, there are eight additional “Main” monitor events and sixteen “Extra” configurable monitor events. Each Monitor event has a user specified ‘timeout’ and ‘email slot’ associated with it that, when ‘activated”, start the timer. When the ‘timeout’ specified expires the software can be set to send an email notification to a specific email or group of email addresses. The differences between Main events and Extra events are as follows:
- A ‘Main’ event may or may not terminate an ongoing event. A ‘Main’ event can be terminated by cycle count. For example: The number of ‘good’ cycles that must occur can be specified before a machine is returned to “Production”. This is referenced in the “Part number”section).
- An ‘Extra’ event always terminates any ongoing event.
Part number tracking can also be performed. Each part number is associated with a Minimum / Maximum (‘ideal’) cycle time with a tolerance. Should the actual cycle time of the machine fall between the minimum / maximum limits, the part is considered to be ‘good’. If the cycle is outside the set tolerance then it is considered to be a ‘bad’.
- A part number can be input manually using the monitor dashboard.
- A part number can be embedded as a comment within in the program code. When the program is down loaded the software will activate / display the current part number on the dashboard.
- A look up table can be created to specify part numbers, run time, and ideal cycle time. When the part program is downloaded the look up table will be referenced.
- Each method requires the user to maintain the part program or the look up table.
Machine status is recorded for each predefined work shift. Flexible shift settings allow separate shift times for an individual machine or shift times for a group or groups of machines. A maximum of three shifts can be defined per day. Different shift settings can be specified for each day of the week (including Saturday and Sunday). A user may place the machine into a specific monitoring event while there is no valid shift in effect, however Cycle ON/Cycle OFF events will be ignored. Other monitoring events plus the part number will also be inherited even through there is no shift times specified, so a new shift will start with the last set monitoring event and part number.
SHIFT VIEW DETAIL
Detailed shift view is presented via saved monitoring data. The picture below is a typical graphic display in one second resolution. This ‘shift data’ is stored and available from the day the monitoring system was installed.
eLAN features a built in weekly report generator. It will display a summary report for each day of the week in a compressed graphic as shown in the machine oriented report below. Users can generate custom reports with the eViewer – see below. In addition, the data collected by our MONITOR system is in an ASCII form so it can be easily exported to any spreadsheet program where the user can apply or run their own calculations and reports.
eViewer is a Crystal reports based report generator. One eViewer program is included in the purchase of our Monitor software. The user can use eViewer to automatically generate a Machine Status, Part Number, Operator or a combined Machine/Part number oriented report. Examples are shown below.
Machine Status Report
Part Number Oriented Report
What is Overall Equipment Efficiency (OEE)?
Overal equipment efficiency is an evaluation method that checks the performance of a production line. Once a baseline is established the OEE calculation can be used to verify corrective actions to verify performance improvement. Production data can be gathered using Monitoring hardware and software. Real time statistics compare events with causes to assist managers to gain control over operational procedures to improves quality and output.
The basic measurements required to calculate OEE are;
Availability – The percentage of time that a machine is available for operation i.e. “uptime” is calculated as a ratio of available time divided by schedule time.
Performance- This is calculated by multiplying the number of parts produced within the ideal cycle time and then dividing the quotient by the available time.
Quality – Measures the percentage of good parts out of the total part run and is calculated by dividing the number of good parts created by the total number of parts run.
- The equation for OEE is therefore Availability x Performance x Quality
If a machine has the following characteristics: 95% Availability, 85% Performance, 93% Quality then OEE = 0.95 X 0.85 X 0.93 = 0.75, or 75%.
It is virtually impossible to achieve a perfect OEE percentage as even small reductions are multiplied through the equation. A best case scenario for many manufacturing operations is an OEE of 85% however, many manufacturing operations are thought to have actual OEE levels around the 40-50% range.
Another factor in the OEE equation is use of ‘Event” codes. These represent direct feedback from machine operators on the line. The vital data received consists of the;
A part number identifier string is embedded into the CNC program as a comment. The comment identifies the part number to eLAN. When a request is sent from the CNC the program is queued causing a “SETUP” event timer to activate. The active part number will appear on the eLAN dashboard.
Cycle information is stated in comment form and includes the ideal time with a plus and minus tolerance.
When the part time falls into the tolerance then it will equal Good Part cycles. If the cycle time exceeds the tolerance the cycle is considered a bad cycle.
A “CALL” program could be formatted and sent to the eLAN system as follows:
|O5555||This program is identified in the eLAN configuration as a command to find and queue a file.
|(1234)||The data following the open parenthesis character (comment) is the filename being requested and queued by the eLAN software.|
|(NEW-PART,30,40)||The data following the open parenthesis character (comment) is the part number ID which is necessary when using OEE to evaluate the machining cycle. Also within this comment appearing after the comma is the minimum cycle time (specified at 30 seconds) and again after the next comma appears the maximum cycle time is at 40 seconds. A comma is used as the delimiter between values.|
|M30||End of Program / Memory Reset|
Event Code (SETUP, PRODUCTION, MAINTENANCE, INSPECTION and etc.)
Event codes are sent by the operator whenever a production stoppage occurs. These codes provide the detail information to the software about the interruption along with the amount of time used to resolve the problem. This is vital to the OEE performance calculation.
End of Shift
The cycle count is sent from the machine tool at the end of each shift in the following format:
O5555 Program command identifier
(PC,22,1) PC = the total CYCLE COUNT, 22 = total actual parts made, 1 = is the number of BAD parts
The cycle count i.e. Good vs Bad parts is used in the OEE Quality calculation.
- The eLAN / Monitoring feature is activated either via a USB key or by the installation of at least one eMONITOR interface board within the network.
- The true CYCLE On / Off signal condition must be analyzed to determine what constitutes a “valid” CYCLE ON condition.
- Cycle on and off signals to the Monitor software must be accurate to attain valid data.
- Machines equipped with pallet shuttles typically remain in the Cycle ON state continuously after the start of the initial cycle. Determining the end of one pallet cycle and start of another requires pairing the CYCLE ON LED with a SPINDLE ON L.E.D. (or some other device to determine the end of a cycle and beginning of another).
Software Setup Considerations
- Are emails to be sent for certain conditions?
If the answer is yes, then the email server and email address must be set up.
- What are the email server settings?
- What event types are to be recorded?
- Setup the list of events, including the commands, to be used to notify the MONITOR software.The descriptive names must be entered. The information includes:
the termination sequence set, the time out required before an email is sent and shift, and to whom the email is to be sent.
- How are CNC headers to be formatted?
The part number, file storage name to be used, the minimum and maximum cycle time to be used.
- How many cycles must be run before the machine event changes from SETUP to PRODUCTION?
The default value is three cycles…
- What delay time is set and for what event before the system sends an email to a supervisor?
- The software is extensively tested and continuously updated.
- Enhancements are made available via the internet thru this website. Software updates posted on our website can be downloaded to update the software to the most recent version.
- There are no yearly user maintenance fees.
- The labor warranty is one year excluding travel and shipping.
- No changes are required to existing wired or wireless devices however, a software upgrade is required along with an e-Monitor interface installed at each CNC.