LPDC thermocouple layout, temperature measurement point location, closed-loop control of mold temperature, avoidance of false temperature and temperature differ

LPDC thermocouple layout, temperature measurement point location, closed-loop control of mold temperature, avoidance of false temperature and temperature difference misjudgment
The mold temperature is the core of sequential solidification, and many production lines only look at one mold temperature point. The thermocouple is placed in the wrong position, buried at the wrong depth, or near the waterway, and the displayed temperature is a false value. The process personnel misjudge the mold temperature, resulting in repeated looseness, aluminum adhesion, and cold insulation.
1、 Thermocouple type, burial depth, and point quantification standards
Low pressure casting molds prioritize K-type armored thermocouples with a maximum temperature resistance of 800 ℃; Measurement point burial depth: 8-12mm away from the molding surface of the cavity; burial depth is too shallow, subject to the impact of aluminum liquid flushing, and the temperature fluctuates violently; Buried too deep, response lag.
Required locations: sprue hot spot area, distal filling end, thick walled T-shaped hot spot, slider forming surface; Add 2-3 thin-walled monitoring points to the thin-walled shell.
The thermocouple should avoid the cooling water circuit and be at least 10mm away from the water circuit; the temperature measured closely to the water circuit is the water temperature, not the working temperature on the surface of the mold cavity.
Target temperature range for mold (A356 conventional): 380-440 ℃ in the gate area; The distal thin wall is 260-320 ℃, forming a stable temperature gradient to achieve sequential solidification.
Xinfeng Machinery reserves thermocouple countersunk holes during the mold processing stage, and the point map is delivered with DFM, accompanied by PID temperature control table parameters.
2、 Wiring, compensating wires, spot checks, drift calibration
Using K-type specialized compensation wire, ordinary copper wire will cause temperature drift; The wiring terminals should be kept away from the heating coil and waterway to prevent interference.
Inspection cycle: every 7 days, compare and recheck the infrared temperature measurement; Thermocouple aging drift, low temperature reading, mistaken for insufficient mold temperature, continuous heating caused aluminum adhesion.
Single point temperature measurement risk: only monitoring the gate, remote cold isolation; Only monitor the remote end, if the gate cools too quickly, cut off and compensate for shrinkage.
Closed loop temperature control: The cooling water circuit solenoid valve is linked with a thermocouple, and if the temperature exceeds the limit, the water will be automatically supplied for cooling. If it falls below the lower limit, the water will be stopped for heat storage.
3、 Differences in mold temperature control for overseas customers
Southeast Asia mostly relies on single point temperature measurement, and even relies on infrared estimation by operators. The mold temperature fluctuates greatly, and defects vary with shifts.
Tier 1 multi-point mold temperature closed-loop in North America, with temperature upper and lower limits locked at each point, automatic alarm and shutdown for out of tolerance, and synchronized archiving of mold temperature and pressure curves.
European customers use infrared and thermocouple dual verification, regular comparison, to eliminate process deviation caused by thermocouple drift.
The environment temperature in the Middle East workshop is high, and there is significant thermal radiation interference. Therefore, adding insulation sleeves to thermocouples can reduce environmental interference.
4、 Temperature measurement failure defect chain
The thermocouple is buried too shallow → aluminum liquid impact, temperature jump → misjudgment, frequent water circuit start stop;
The measuring point is close to the cooling water circuit → the reading is low, virtual temperature → continuous heating, the mold cavity is overheated and sticky with aluminum;
Only single point temperature measurement → unable to identify cavity temperature difference, remote cold isolation or premature solidification and looseness of gate;
Thermocouple drift not calibrated → temperature reading distortion, whole batch process deviation.
5、 Long tail traffic layout ideas
Low pressure casting mold thermocouple, mold temperature closed-loop control, K-type thermocouple temperature measurement, aimed at process engineers.
keywords LPDC mold thermocouple placement、mold temperature closed loop control low pressure casting；
Question type: Thermocouple depth from casting cavity surface;
Comparison category: contact thermocouple vs infrared thermometer for die temperature.
Suitable for mold temperature control and sequential solidification special pages.
6、 Common misconceptions in the industry
Misconception 1: Thermocouple bonding cavity surface temperature measurement is the most accurate. If it is too shallow, it will be impacted by aluminum liquid, causing severe temperature fluctuations and unstable readings.
Misconception 2: One thermocouple is enough to monitor the entire mold, the temperature difference in the mold cavity is huge, and a single point cannot represent the whole situation.
Misconception 3: A high temperature reading indicates overheating of the mold cavity. It is necessary to first confirm whether the thermocouple is close to the waterway and whether it is drifting.
FAQ
Q: What is the burial depth of the armored thermocouple from the cavity surface?
A：8–12mm。
Q: What is the mold temperature target for the gate area?
A: 380-440 ℃.
Q: Thin walled distal mold temperature?
A: 260-320 ℃.
Q: What is the minimum distance between a thermocouple and a waterway?
A：≥10mm。
Q: What are the requirements for temperature measurement wires?
A: K-type compensating wire, no ordinary copper wire is needed.
Q: How long does it take to recheck thermocouples?
A: Infrared comparison review every 7 days.
Q: What is the biggest problem with single point temperature measurement?
A: Unable to identify the temperature difference in the mold cavity, resulting in uncontrolled sequential solidification.
Q: Model temperature closed-loop logic?
A: Automatic water supply and cooling for overheating, and water storage for low-temperature shutdown.