Weight per meter
The quantity under control, in kg/m: how much material each meter of cable consumes. A process figure, not a piece of equipment.
Weight-per-meter Controller and Inline Closed-loop System
Built for wire and cable extrusion lines, it puts the two metrics that most directly affect cost and quality — weight per meter and wall thickness — under continuous watch by the system.
Terminology
What a weight-per-meter controller is, and how it relates to the system
These three terms get used interchangeably, but they are not the same thing. Telling them apart tells you whether you need a device, a scheme, or simply a better figure for your own line.
Weight-per-meter controller
The device itself. It reads the weight and speed signals, works out the deviation, and sends the correction to the extruder and haul-off.
Weight-per-meter control system
The complete scheme: controller plus actuators, HMI and data logging, able to run the full measure–judge–adjust–recheck loop on its own.
Reference wall thickness · compensation
1.650mm
System Overview
Why extrusion lines need closed-loop control
Extrusion is a coupled multivariable process: fluctuations in hopper feeding, drift in screw speed and changes in haul-off speed all show up in the final weight per meter and wall thickness. Periodic manual sampling with hand-adjusted screw speed carries an obvious lag — by the time a problem is spotted, a considerable length of out-of-spec product has usually already been produced.
This system uses inline gravimetric weighing to obtain material consumption per unit length continuously, converts it into weight per meter and compares it with the setpoint, and then has the control unit adjust screw speed and haul-off speed to bring weight per meter back into the target window. At the same time the control target is corrected against the reference wall thickness and compensation value, so that wall thickness settles down as well.
- Less lag: continuous sampling replaces manual periodic weighing, so a deviation is caught the moment it appears
- Stable gram weight: weight per meter converges around the setpoint, cutting the material loss caused by running at the upper limit
- Less dependence on experience: no need to rely on a veteran operator's feel when changing specifications or shift teams
System Principle
A weight loop that runs without interruption
The system does not change the structure of the extruder itself; it inserts an uninterrupted weigh–compare–adjust loop between feeding and haul-off.
Inline weighing
The weighing module continuously measures material consumption at the hopper (or metering section) and converts the weight change into an electrical signal that can take part in control.
Weight-per-meter conversion
Combined with the haul-off line speed, material consumption per unit time is converted into weight per meter and compared directly with the setpoint on the HMI to give the real-time deviation.
Synchronized adjustment
According to the direction and magnitude of the deviation, screw speed and haul-off speed are trimmed together to pull weight per meter back into the target window.
Repeat check
Sampling and adjustment continue as a loop; deviations are corrected again and again, and the whole process leaves a trace on the trend curves for review at any time.
System Composition
Four parts, installed on the production line
Each unit has a clear role; the system can be supplied as a whole or retrofitted onto an existing line.
Gravimetric weighing unit
Weighs the hopper or metering section inline and converts the material weight into an electrical signal that can take part in control.
Control and computing unit
Performs weight-per-meter conversion, deviation calculation and control output, and sends adjustment signals to the screw and haul-off drives.
Touchscreen HMI
The on-site operating and monitoring entry point: parameter settings, status display and function buttons are gathered on one screen.
Actuation and synchronization
Works with the extruder's variable-frequency drive and the haul-off drive for start/stop interlocking and continuous speed adjustment.
Functions in Detail
What the system actually does
Each function below corresponds one-to-one with a button or parameter on the HMI; there is no purely decorative functionality.
Real-time weight-per-meter control
The HMI shows the current weight per meter and the setpoint weight per meter side by side (for example 0.1413 kg/m); the difference between the two determines the direction and magnitude of control. Once auto control is engaged, the system continuously trims screw speed to hold weight per meter near target, and the operator can watch the convergence on the trend curve.
Wall thickness compensation
The reference wall thickness (for example 1.650 mm) and the compensation value (for example 0.1 mm) are entered per product specification, and the system derives the control target from them. For products with strict insulation layer thickness requirements, the compensation value can be trimmed manually or left to the system for automatic control.
Screw & haul-off synchronization
Screw speed and haul-off speed are adjusted as a pair. The panel provides a synchronized start/stop operation and distinguishes automatic from manual mode, making it easy to switch to manual intervention during tuning or in abnormal conditions.
Specification confirmation & material usage statistics
When the specification changes, Specification Confirmation loads the matching process parameter set so that the previous specification's settings are not used by mistake. Material Usage Statistics accumulates length, weight per meter and output per take-up reel, giving the shift team a basis for accounting and quality traceability.
Process trend logging
The lower part of the HMI logs several curves on one screen: weight per meter, output, haul-off speed, screw speed, throughput, hopper weight, screw signal, haul-off signal and more, making it easy to review the stability of the shift's production.
Alarms and user permissions
A prompt is given when a key parameter goes out of range; the HMI provides entries for alarms and user permissions, so that unauthorized personnel cannot alter process settings by mistake.
Core Advantages
What changes on the shop floor once it is installed
Every item below maps to a concrete function in the system, not a general marketing claim.
Advantage 01
No more manual timed sampling
Continuous inline weighing replaces intermittent manual weighing. A weight-per-meter deviation is caught the moment it appears, not at the next sampling round.
Advantage 02
Gram weight tracks the target
Weight per meter converges around the setpoint instead of sitting at the upper limit for long periods. Running at the upper limit means extra material going in every shift.
Advantage 03
Wall thickness controlled to the reference value
The control target is the reference wall thickness plus the compensation value, which reduces the practice of adding a little extra thickness "just to be safe".
Advantage 04
No starting from scratch on a specification change
Specification Confirmation loads the process parameter set for the product, so a shift or operator change does not mean running trials again.
Advantage 05
Production data is retained
Trend curves and material usage statistics keep the shift's records, so there is evidence to check when a customer complaint arises or a review is needed.
Advantage 06
You can take over at any time
One-key switching between automatic and manual lets a person take over during tuning or abnormal conditions, rather than handing the line entirely to a black box.
On-Site Photos
Mounted beside the line, readable at a glance
The system's main unit is installed on the extrusion line, with the touchscreen facing the operator station. The HMI uses a dark background and high-contrast colours, so it stays legible under shop-floor lighting; key values use large type, so whether the current weight per meter is in range can be read from two meters away.
- Process setpoints and measured values on the left, live screw and haul-off speeds on the right
- The hopper animation in the centre reflects feeding and inventory status in real time
- The trend strip at the bottom keeps the process curves for the most recent period
On-Site Readings
Example parameters on the HMI
| Process parameter | On-site reading |
|---|---|
| Weight per meter | 0.1413 kg/m |
| Reference wall thickness | 1.650 mm |
| Wire diameter | 17.50 mm |
| Material density | 1.42 g/cm³ |
| Wall thickness compensation | 0.020 mm |
| Screw speed | 41.24 rpm |
| Haul-off speed | 60.013 m/min |
| Extrusion output | 508.70 kg/h |
Configuration Notes
What we confirm during selection
| Item | Notes |
|---|---|
| Extruder model | Model and screw specification |
| Product specification range | Wire diameter and insulation thickness |
| Material type | Density and process temperature |
| Control mode | Automatic / manual switching |
| Data logging | Trends and material usage statistics |
| On-site installation | Measurement point locations and scope of modification |
Scope of Application
Which production lines it fits
The system addresses the extrusion stage of wire and cable production, controlling weight per meter and wall thickness through inline weighing and screw & haul-off synchronization.
Power cable insulation extrusion
Insulation layer gram weight and thickness are tightly specified, making this the most typical application for a weight-per-meter closed loop.
Control cables and specialty cables
On lines with frequent specification changes, parameter sets reduce the trial material needed for each setup change.
Wire workshop lines
Works with the extruder, haul-off and pay-off/take-up stages, covering the whole run from start-up to reel change.
Retrofit on existing lines
The weighing and control components are added to an existing production line; the whole extrusion line does not need to be replaced.
MV/HV cross-linked cable and high-voltage insulation
Covers 10 kV, 35 kV and 110 kV cross-linked cable lines. Insulation thickness and eccentricity are the control focus on these lines, and parameter sets can be stored per voltage class and construction.
Whether the system fits depends on the extruder model, screw specification, product specification range and on-site installation conditions, as determined by the on-site survey.
Communications and integration
It plugs into the control system you already run
The weight-per-meter control system is not a stand-alone gauge. It provides standard communications interfaces, can join a customer's existing PLC and supervisory system as a Profinet slave, and hands weight-per-meter, haul-off speed and material usage data to MES for digital traceability.
Profinet slave
Joins the customer's existing PLC as a Profinet slave, exchanging weight per meter, haul-off speed, screw speed and run status in real time, with no extra gateway in between.
MES integration and digital traceability
Three options, all supported: publishing data over OPC UA, writing directly to a database, or a custom interface built to the customer's MES requirements. Weight per meter, material usage and process parameters are handed over per reel.
Local records for cross-checking
Material usage statistics and process trends are kept locally and can be cross-checked against the supervisory system. A communications outage does not interrupt local recording; syncing resumes afterwards.
Tell us your machine model and product specification
Based on your existing line, we will propose the measurement point layout, control mode and configuration.