Common Signal Matching Issues in Multihead Weighers: Troubleshooting Guide for Accurate Packaging

Q1: Why does the combination scale discharge only when the request signal disconnects?

Explanation:
Kenwei combination scales offer four request signal detection modes:

• 0: Pulse with memory

• 1: Pulse without memory

• 2: Level with memory

• 3: Level without memory

Pulse signals are valid on the falling edge (when the signal changes from ON to OFF), while level signals are valid on the rising edge (when the signal turns ON).

If the scale discharges only when the signal disconnects, the detection mode is likely set to 0 or 1 (pulse mode).

Solution:
Set the detection mode to 2 or 3 (level-based) for continuous operation.

Q2: Why does the combination scale discharge material when the packaging machine stops, or why does it sometimes pause?

Explanation:
The difference lies between memory and no-memory modes:

• Memory mode: The system immediately prepares for the next discharge upon receiving a request signal.

• No-memory mode: The scale waits until it’s ready before accepting the next signal.

In Mode 2, if the packaging machine issues the next request signal before stopping, the scale will still discharge. In Mode 3, if the scale isn’t ready, it won’t process the signal, leading to occasional pauses.

Solution:
Adjust the packaging machine’s signal program. When stopping, ensure the machine checks for pending signals:

• If a request has been issued, finish that cycle before stopping.

• If not, stop immediately after the current cycle.

Q3: Why does material sometimes fall during sealing?

Explanation:
This occurs when the discharge signal delay is too short. This parameter ensures that materials completely fall into the bag before the packaging machine seals it.

Solution:

1. Reduce the packaging speed to prevent overlap during material drop.

2. Increase the discharge signal delay so sealing occurs after all material has entered the bag.

Q4: Why do some bags contain two portions of material or experience entrainment?

Explanation:
This usually happens when the packaging machine sends two consecutive request signals quickly (multi-interval mode), and the scale is in memory mode operating at high speed. The second signal is processed immediately, causing two discharges into one bag.

Solution:
Switch the detection mode to no-memory and use high-precision mode instead of high-speed mode. This prevents duplicate discharges and ensures stable operation.

Kenwei’s Commitment to Excellence

Kenwei designs every machine with precision, stability, and efficiency in mind. By understanding these common signal matching issues and applying the recommended solutions, you can optimize performance, minimize errors, and achieve seamless integration between combination weighers and packaging systems.