SD520 Label Counter: Rewinding Guide by Southern Machinery

What is the SD520 Auto Label Rerolling Counter used for? The SD520 counts labels on a roll while rewinding them from the unwind reel to the rewind reel, then stops automatically at a preset quantity (1–99,999 pcs). Typical uses in the source manual: warehouse label issue by quantity, incoming quality control (IQC) of supplier rolls, shipment sampling, inventory counting and splitting large rolls.

Why does a "full" label roll still come up short?

Most factories trust the number printed on the roll box. Then a line stops on the last 200 labels, a traceability label is missing, and nobody knows whether the supplier or the warehouse caused it.

If you run an EMS, ODM or industrial electronics plant, you know the hidden difficulty: labels are cheap, but a shortage stops a packing station or a serial-numbered build. Counting by hand is slow and nobody trusts it. A label counter turns an argument into a measured number.

What is the framework for controlling label quantity?

Use a four-step loop at the label store and at IQC:

1. Measure the roll with a counter at receiving, not at the line.
2. Record the best speed, pre-stop count and sensor setting for each label type.
3. Issue by exact quantity instead of by "one roll".
4. Rewind the counted roll back to its original state when the labels must stay in sequence.

The manual supports this loop directly: one-key rewind returns a counted roll to its original state, which it notes is required for automatic labelling and serial-numbered labels.

How does the SD520 fit that framework?

The manual lists these features for the SD5xx series:

• Settable target quantity, with audible and visual alarm when reached.
• End-of-roll alarm: the machine stops if the roll ends before the set quantity.
• Pre-stop: it decelerates before the target so labels are not damaged by an abrupt stop.
• Leader-label compensation for labels between the sensor and the rewind core.
• Multi-column counting, up to 4 label columns at once.
• Dual-shaft tension adjustment, a KEYENCE (Japan) fibre-optic label sensor and a 4.3-inch colour touch screen (Chinese / English).

Selection parameters from the source manual

| Item | Value in source manual |

|---|---|

| Count range | 1–99,999 pcs |

| Maximum running speed | 60 m/min (±30% depending on model, material and load) |

| Counting rate | Up to 10,000 pcs/min under the stated test labels (varies with speed) |

| Counting accuracy | 99–100% under stated test conditions (varies by model) |

| Roll diameter | Up to 200 mm standard; 250 / 300 mm optional |

| Label width | Up to 120 mm |

| Core | 76 mm standard; 45 / 28 mm optional |

| Roll weight | Not more than 3 kg |

| Label thickness | Not more than 1 mm |

| Power | 220 V AC, 50 Hz, single phase, 150 W maximum |

| Size | 526 × 305 × 368 mm; SD5xx approx. 15 kg net |

| Environment | 20–30 °C, humidity below 75% |

All figures are test results with standard labels; other samples may differ and that does not indicate a defective machine. Optional items (customized) include transparent or metallic-print label counting, automatic cut-off, coreless rewinding and a built-in UPS.

Which labels will count accurately?

The sensor reads light transmittance, so this is the main buying question. According to the manual:

• Labels above 80% transmittance are treated as transparent and need a customized machine.
• Liner transmittance below 20% may give inaccurate counts.
• Only rolled labels work; sheet labels cannot be processed.
• Rolls must be wound neatly. Rolls above 3 kg need a customized high-load machine, to be agreed with Southern Machinery sales in advance.
• Re-adjust sensor sensitivity whenever the liner or label material changes, using the SET key procedure in the manual.

Check these four points with your actual label samples before ordering.

How do you set it up so counts stay accurate?

The quick procedure in the manual: place the machine on a stable level bench, earth it, load the roll, enter the leader-label count, running speed, pre-stop quantity and deceleration speed, set the sensor, then press Start.

The manual's pre-stop example: set quantity 1,000, pre-stop 5, running speed 10,000, deceleration speed 1,000. The machine runs at 10,000 until 995, then counts the last 5 labels slowly and stops gently. It advises a deceleration speed of 10–30% of running speed, and a pre-stop of 1 for quantities of 20 or less.

Safety points: use a leakage-protected supply, wear gloves (Class C sharp edges), keep loose cloth 1 m away and lift the machine with two people.

Does a label counter belong in an SMT or THT line project?

It is a standalone bench tool, not a line machine, and the source does not describe line integration. Its value sits around the line: traceability labels, packing and warehouse control for PCBA output. For the machines that do the assembling, see the THT machine range, board handling systems and inspection equipment from Southern Machinery, founded in 2011 in Shenzhen and serving 237+ global customers.

How do you estimate the value?

Formula (example only):

Monthly value = (rolls checked × shortage rate × cost per stoppage or relabel) − counter operating cost

Example, depending on configuration and subject to final technical confirmation: if your own data show a given shortage rate and stoppage cost, plug them in. The source gives no price, lead time or guaranteed savings, so contact Southern Machinery to confirm.

FAQ

Can the SD520 count transparent labels? Not as standard. Transparent labels need a customized machine.

Can it rewind a counted roll? Yes, one-key rewind returns the roll to its original state; do not press it while counting.

What happens if the roll ends early? The end-of-roll alarm stops the machine after a set time.

How many columns can it count? Up to 4 columns at once.

Can it run without mains power? Only with the optional built-in UPS (runtime more than 5 h at maximum load).

What power does it need? 220 V AC, 50 Hz single phase, 150 W maximum.

What should you read next?

Next in this series: how to choose between standard and customized label counter models (SD5xx, SDC5xx, SD6xx/SD7xx). Bookmark this page and check back.

Ready to match a counter to your labels? Send your label samples and roll data through Get a Quote or contact Southern Machinery. Global service, spare parts support and training are available.