NOTE: This portion of the documentation covers the advanced topics of the WT6000 Weld Control. This section of the manual is geared towards line builders, maintenance personnel and welding engineers to assist with procedures related to programming the weld control.
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Constant Current Welding
C-Factor (or Capacity Factor) is a parameter, which is used to track changes in the weld tooling. C-Factor is calculated by determining the amount of total capacity utilized to create the target current and dividing this value by the actual current created.
The C-Factor feature can be used as a maintenance tool to monitor the following:
C-Factor is calculated by the weld processor after each weld and is displayed in the Weld Data Display of the DEP-300s.
Perform the following steps on the DEP-300s to navigate to the Weld Data Menu.
STEP |
DESCRIPTION |
01: |
Press Status Mode (F3). |
02: |
Press More (F5). |
03: |
Press Weld Data (F3). |
04: |
Press ENTER. |
Below is an example of the Weld Data Menu. The C-Factor parameter is circled in red.
As the weld tooling degrades over time, its resistance (either primary or secondary) increases. As the resistance increases, the weld control must compensate for this change, otherwise the welds would gradually grow colder. Weld tooling degredation can be caused by the following conditions:
As the resistance of the weld tooling gradually increases, the weld control gradually increase its "on-time" (or use more of its available capacity) to deliver the requested target current. This gradual decrease in available capacity of the weld control is reflected by a gradually decreasing the C-Factor parameter.
Current shunting (either primary or secondary) is essentially an unintended, alternate path of current flow occuring in the weld tooling. Current shunting causes the overall resistance of the weld tooling to decrease. As current is shunted across the alternate path, less current passes through the work piece, resulting in colder welds. Secondary current shunting paths can be caused by the following conditions:
As the resistance of the weld tooling gradually decreases, the weld control gradually decrease its "on-time" (or use less of its available capacity) to deliver the requested target current. This gradual increase in available capacity of the weld control is reflected by a gradual increase in the C-Factor parameter.
NOTE: Function #92 must be inserted in the weld schedule before function #85 (PROCESS WELD FAULTS).
FUNCTION NO. FUNCTION NAME 00:START OF SCHEDULE # 1 82:LINEAR STEPPER #1 ASSIGNED (0=0FF) 92:C-FACTOR LIMIT: HI= 220 LOW= 150 76:SEC. CURR LIMITS: HI=00 LOW=99990 81:TRANSFORMER TURNS RATIO 73:1 88:TURN ON ISOLATION CONTACTOR 58:TURN ON WELD IN PROGRESS 01:SQUEEZE 30 CYCLES 30:WELD 10 CY. 10000 AMPS 85:PROCESS WELD FAULTS 03:HOLD 5 CYCLES 63:TURN ON WELD COMPLETE 59:TURN OFF WELD IN PROGRESS 75:EXTEND UNTIL NO INITIATE 64:TURN OFF WELD COMPLETE 89:TURN OFF ISOLATION CONTACTOR 100:END OF SCHEDULE # 1
NOTE: The following instruction provides a starting point for the C-Factor HI / Low limits. These values will require adjustment as the user becomes more familiar with the weld tooling and what the C-Factor parameters are when weld quality issues occur (caused by either weld tooling degredation or current shunting).
LOW C-FACTOR LIMITThe Low C-Factor Limit is used to detect an increase in resistance in the weld tooling, which is caused by cable and connection degredation. See Decreasing C-Factor above.
To calculate the Low C-Factor Limit value, subtract a 20% margin from the reference (tip-to-tip) C-Factor parameter for a known good weld tool.
For example, if the reference C-Factor parameter is 200: 200 *.80 = 160. Therefore, the Low C-Factor Limit would be 160.
HIGH C-FACTOR LIMITThe High C-Factor Limit is used to detect a decrease in resistance in the weld tooling, which is caused by shunting paths. See Increasing C-Factor above.
To calculate the High C-Factor limit value, add a 20% margin to the reference (tip-to-tip) C-Factor parameter for a known good weld tool.
For example, if the reference C-Factor parameter is 200: 200 * 1.2 = 240. Therefore, the High C-Factor Limit would be 240.
FAULT NAME VALUELOW C-FACTOR LIMIT (ALERT)HIGH C-FACTOR LIMIT (FAULT)
- Gradual weld tool degradation is an expected process. Therefore, Low C-Factor is set as an ALERT.
- Secondary current shunting is not an expected process and requires immediate attention. Therefore, High C-Factor is set a FAULT.
Function #87: SET SPC OFFSET TO nn
For the purpose of statistical data collection, each weld is assigned a data storage bin number (00-99). This function establishes the starting bin number for SPC Indexing. Consider the following example:
CAR TYPE #1 |
|
---|---|
Weld Schedule #20 | SET SPC OFFSET TO 01 |
Weld Schedule #01 | 15 Welds Made (Bins 1-15) |
Weld Schedule #02 | 15 Welds Made (Bins 16-30) |
Weld Schedule #03 | 15 Welds Made (Bins 31-48) |
CAR TYPE #2 |
|
---|---|
Weld Schedule #21 | SET SPC OFFSET TO 51 |
Weld Schedule #04 | 12 Welds Made (Bins 51-62) |
Weld Schedule #05 | 12 Welds Made (Bins 63-74) |
Weld Schedule #06 | 15 Welds Made (Bins 75-88) |
After establishing a bin number, the processor stores the data for each weld made in its own individual bin. The bin numbers increase by one each time a weld is made. This will continue until another schedule containing function #87 (SET SPC OFFSET) is executed.
Bin #99 is the last usable bin. If the weld processor reaches bin #99 and is still collecting data, the data for each weld will be stored in bin #99 until a new offset is assigned, therefore making the data unsuitable for analysis.
NOTE: This function does not tell the weld processor to collect weld data. It only assigns a data storage bin number. To setup SPC data collection parameters, see SPC Setup Parameters below.
Function #88: SEND ALL SAMPLES UNTIL NEXT SPC OFFSET
This function is useful to verify tool conditions after a tip-dress operation.
This function tells the weld processor to collect and sample 100% of the weld data within the schedule. It overrides the "global" Data Collection Sample Size and Data Collection Sample Frequency setup parameters, described in SPC Setup Parameters below.
Function #87 (SET SPC OFFSET) should be inserted before #88 in the weld schedule, to ensure the data is sent to the appropriate bin. Otherwise, it will be sent to default bin #0.
The processor will continue collecting and sampling 100% of the weld data within the schedule until the weld processor executes another weld schedule containing function #87 (SET SPC OFFSET). At which point, the "global" Data Collection Sample Size and Data Collection Sample Frequency setup parameters regain their hierarchical priority.
For more information, see SPC Data Collection and Binning.
PARAMETER |
RANGE |
---|---|
DATA COLLECTION SAMPLE SIZE: 5 | (1-99) |
DATA COLLECTION SAMPLE FREQUENCY: 100 | (1-9999) |
These two parameters set a global command, which allows the weld processor (WCU) to sample data for analysis at controlled intervals.
For example:
Let's assume function #87 (SET SPC OFFSET) is inserted in the weld schedule and set to bin #1:
87 |
SET SPC OFFSET TO 01 |
Let's also assume in the Setup Parameters, the Data Collection Sample Size is set to (2) and the Data Collection Sample Frequency is set to (8):
DATA COLLECTION SAMPLE SIZE: 2 |
DATA COLLECTION SAMPLE FREQUENCY: 8 |
By setting the Data Collection Sample Size to (2) and the Data Collection Sample Frequency to (8), the WCU will collect data for the first two consecutive welds (in bin #1) and flag the WebView to retrieve the data. It will then collect data for the six remaining welds (without flagging the WebView) before repeating the process.
The following table illustrates the example above:
BIN #1 |
||
---|---|---|
SAMPLE / FREQUENCY |
WCU PROCESS |
WEBVIEW PROCESS |
1/8 | Data Flagged for Retrieval | Data Uploaded |
2/8 | Data Flagged for Retrieval | Data Uploaded |
3/8 | Data Collected | Data Ignored |
4/8 | Data Collected | Data Ignored |
5/8 | Data Collected | Data Ignored |
6/8 | Data Collected | Data Ignored |
7/8 | Data Collected | Data Ignored |
8/8 | Data Collected | Data Ignored |
1/8 | Data Flagged for Retrieval | Data Uploaded |
2/8 | Data Flagged for Retrieval | Data Uploaded |
3/8 | Data Collected | Data Ignored |
4/8 | Data Collected | Data Ignored |
5/8 | Data Collected | Data Ignored |
6/8 | Data Collected | Data Ignored |
7/8 | Data Collected | Data Ignored |
8/8 | Data Collected | Data Ignored |
NOTE: Weld data collection is bin dependent. Each bin has its own independent counter and is uploaded to the WebView separately.
For more information, see SPC Data Collection and Binning.
The following is an example tip dress schedule when the weld control is not controlling the tip dress motor.
FUNCTION NO. |
FUNCTION NAME |
---|---|
00 |
START OF SCHEDULE # n |
58 |
TURN ON WELD IN PROGRESS |
01 |
SQUEEZE 30 CYCLES |
93 |
TIP DRESS ADVANCE: GROUP 01 - STEP 2 |
59 |
TURN OFF WELD IN PROGRESS |
63 |
TURN ON WELD COMPLETE |
03 |
HOLD 5 CYCLES |
51 |
TURN OFF WELD COMPLETE |
100 |
END OF SCHEDULE |
The following is an example tip dress schedule where the weld control is controlling the tip dress motor. This feature requires an optional tip dress motor control circuit installed in the weld control cabinet (see note below). This schedule also monitors or "checks" the current draw of the tip dress motor. The purpose of this check is to (1) protect the motor from damage and (2) determine if the weld caps were properly cut.
NOTE: If your weld control cabinet does not have the optional motor control circuit installed and you are interested in using this feature, contact your WTC sales representative for assistance.
FUNCTION NO. |
FUNCTION NAME |
---|---|
00 |
START OF SCHEDULE # n |
16 |
MOTOR CURRENT LIMITS HI=6000 ma LO=1000 ma |
58 |
TURN ON WELD IN PROGRESS |
18 |
START TIP DRESS MOTOR CHECK |
17 |
TIP DRESS TIME 5 SEC BLANK 500 ms |
19 |
STOP TIP DRESS MOTOR CHECK |
59 |
TURN OFF WELD IN PROGRESS |
63 |
TURN ON WELD COMPLETE |
03 |
HOLD 5 CYCLES |
51 |
TURN OFF WELD COMPLETE |
100 |
END OF SCHEDULE |
Description of the special functions (in red above) used in the tip dress check schedule:
NOTE: This function must be inserted in the schedule after function #16 (MOTOR CURRENT LIMITS HI=nnnn ma LO=nnnn ma).
NOTE: This function must be inserted in the schedule after function #18 (START TIP DRESS MOTOR CHECK) and before function #19 (STOP TIP DRESS MOTOR CHECK).
Mode of Operation:
Notes:
The results of the tip dress motor current check are displayed in the Weld Data Menu. Perform the following steps on the DEP-300s to navigate to the Weld Data Menu.
STEP |
DESCRIPTION |
01: |
Press Status Mode (F3). |
02: |
Press More (F5). |
03: |
Press Weld Data (F3). |
04: |
Press ENTER. |
In the example below, the results are displayed in the Sec I column (circled in red) in milliamps. There are three current measurements displayed: MAX current, AVG current and MIN current.
To navigate to the I/O Status Menu, perform the following steps on the DEP-300s:
STEP DESCRIPTION 01:Press Status Mode (F3). 02:Press More (F5). 03:Press IO Status (F2)
04:Press Page 2 (F5) to view more bits (if applicable)
In the example above, the I/O Status Menu shows the mapped bits relating to the application error codes (circled in red). It should be noted this is a simplified example and the customers application requirements may require these bits to be mapped to different I/O locations.
Each bit is represented by a tag. Each tag will have either a "1" or "0" underneath it:
- "1" indicates the bit is HIGH or ON.
- "0" indicates the bit is LOW or OFF.
TAG NAME BIT NAME BIT TYPE FACKAPP ERR ACKNOWLEDGE Input EVALAPP ERROR AVAILABLE Output ER1APP ERROR BIT 1 Output ER2APP ERROR BIT 2 Output ER4APP ERROR BIT 4 Output ER8APP ERROR BIT 8 Output ER16APP ERROR BIT 16 OutputNOTE: For more information on mapping I/O bits, see Reference Chapter E: Inputs and Outputs.
The following example is a robot welding application where the weld processor is reporting three application error codes:
Error Code Fault Family Weld Control Fault 5End of Stepper End of Stepper 7High / Low Current Limit Low Current Limit Fault 19C-Factor Limit Low C-Factor LimitNote: Multiple application error codes are reported in ascending order.
Click HERE to see the Application Error Codes for timer software G08300.