Thickness Gauging - Box Gauge

Gapless gauging for aluminium strip

MTG Box Gauge is designed for use in aluminium mills and process lines.
The technology is completely insensitive to anything in the measuring zone, except the metal strip. The gauge will, therefore, measure true strip thickness, unaffected by coolant, dirt, steam, air temperature variations, etc.
Since the MTG Box Gauge is material-independent, there is no need for alloy compensation and calibration.

Increased mill production time
Tighter strip tolerances
No health concerns
Negligible costs for maintenance
Short payback time (ROI)

Our offering

Gauge head

System concept

Cyber Security

Options

Gauge head PMGG201

Due to its heavy duty construction and the stability of its measuring principle, the MTG Box Gauge can be used in locations where it is impossible for other gauges to function.

Function
The MTG Box Gauge is based on PEC technology, which uses magnetic fields for measurement of strip thickness. The interaction between an applied magnetic field and the electrically conductive strip indicates thickness – without influence from the material composition.

The pulsed magnetic field is generated and measured by sturdy electric coils placed just below the cover plate. Since the magnetic field penetrates everything except metal, the coils can be protected by a heavy-duty fiberglass reinforced epoxy plate.

Traceable thickness measurement
The MTG Box Gauge is delivered calibrated and ready to use. Twelve calibration plates are supplied with the system for verification and adjustment of the complete measuring range.

These calibration plates ensure that the gauge measures absolute thickness and thickness deviation according to traceable standards for many years of operation. A normal interval for calibration is 6 months and takes only 20 minutes to perform.

Robust design
The aluminium-bronze housing has superior mechanical and chemical characteristics and provides robust protection for the gauge, making it optimal for harsh rolling mill environments.

The gauge is mounted on a vertically moving frame, automatically adjusting its position to maintain an optimal measuring distance.
The movement is operated with hydraulic valves.

Thickness with lab accuracy

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+ Data

Type	PMGG 201
Minimum/Maximum thickness	0.5 - 8 mm (20 - 315 mil)
High pass mode (for Feed Forward)	0.2 - 0.6 mm (8 - 24 mil)
Measured alloys	Aluminium, clad aluminium and other nonferrous alloys with resistivity range 27 - 65 nΩm
Repeatability	±0.05% (not better than 0.3 μm (12 μin)
Accuracy ¹	±0.05% (not better than 0.5 μm (20 μin)
Total Accuracy ²	±(0.05% +1.5 μm (59 μin)
Total Accuracy clad measurement ³	±(0.05% +2 μm (79 μin)
Oil on strip	No influence
Measuring distance	15 mm (590 mil)
Minimum strip width	500 mm (20 in)
Minimum distance from strip edge	100 mm (4 in)
Measuring area	Ø 80 mm (3.15 in)
Strip position changes > 1 mm/s / >39 mil/s	±5 mm (± 197 mil)
Strip slope	±6°
Gauge holder stroke length	50 mm (2.0 in)
Updating time	5 ms
Operation temperature	+5 to +70°C (+41 to +158°F)
Degree of protection	IP 65
Power supply (from the control unit)	24 V DC, max 3 A (48 V AC, max 5A)
Dimensions
Gauge head	L 352 x W 228 x H 209 mm (L 13.9 x W 9.0 x H 8.2 in)
Gauge head and holder	L 495 x W 228 x H 353/403 mm (L 19.5 x W 9.0 x H 13.9/15.9 in)
Weight
Gauge head	22 kg (48.5 lb)
Gauge holder	48 kg (105.8 lb)

¹⁾ Accuracy = Calibration accuracy, i.e. accuracy after calibration, measured on a calibration plate.
²⁾ Total Accuracy = Accuracy after calibration, measured on an arbitrarily selected plate/strip at normal mill operating conditions, i.e. with mill coolants, temperature variations, pass line variations and alloy composition variations.
³⁾ Provided that input clad parameters are correct.

+ Application

The MTG Box Gauge is designed for use in aluminium breakdown mills and aluminium processing lines. In rolling mills, the MTG systems are connected to AGC systems for feedback, feedforward and massflow control.

Increased mill production time
In a production process running 24 hours a day, every minute of production time is precious. Thanks to its alloy independence, the MTG can increase available production time by eliminating the need to stop for standardization and calibration.

The hydraulic positioning system allows the gauge to measure almost instantaneously when tension comes on, thus optimizing the strip length under thickness control.

Tighter strip tolerances
The ability to produce strip to tighter tolerance maximizes productivity and minimizes the costs associated with non-conforming strip. It also increases the strip producer’s accessible market to include product with tighter tolerance requirements.

+ Pulsed Eddy Current Technology

The MTG Box Gauge, based on PEC (Pulsed Eddy Current) technology, opens up new dimensions in aluminium strip gauging. Weak magnetic fields are used for measurement and the gauge is completely safe to use.

The technology is completely insensitive to anything in the measuring zone, except the metal strip. The gauge will, therefore, measure true strip thickness, unaffected by coolant, dirt, steam, air temperature variations, etc.

Since the MTG Box Gauge is material-independent, there is no need for alloy compensation and calibration.

Phase 1: Transmitting

An electric field is generated with a transmitting coil
The field is applied until it fully penetrates the strip
The field "energy" is stored in the air gap and in the strip
The amount of energy stored in the strip depends on the thickness alone - not on resistivity

Phase 2: Distance measurement

Fast air response just after transmit field is swithed off
The measurement of air gap energy corresponds to distance between coil and strip
Pulse time t1 is typically less than 5μs

Phase 3: Resistivity measurement

Response from the surface area of the strip
The measurement starts when the air gap signal has declined
The measurement of the surface response corresponds to resistivity and is dependent on the speed of the field leakage out of the strip

Phase 4: Thickness measurement

Response from the whole strip
The measurement starts when the air gap signal has declined (phase 3 is included in phase 4)
The measurement of the whole strip corresponds to the complete energy stored in the strip, and continues until the strip response has almost declined (t3)
The measurement corresponds to the strip thickness
The resistivity does not affect the level of the whole strip response
The tail part after t3 is calculated with the use of the resistivity part

System concept

Control unit PMGA200

The Millmate Thickness Gauging system is an intelligent measurement system designed for user-friendly commissioning, operation and service.

The control unit is used for integration with other mill systems.
It provides a choice of integration interfaces.
- Profibus-DP fieldbus communication
- Network communication via VIP, OPC DA and Modbus TCP.
- Discrete I/O-signals

The Control unit also handles communication with the gauge.
It communicates measurement data, status control and error handling as well as implementing vertical position control functions.

The control unit is available in either wall or floor mounting cabinets.

+ Data Control unit PMGA200

Type	PMGA200
Operation temperature	+5 to +45°C (41 to 113 °F)
Supply voltage	115 / 230 V +10 / -15%
Power consumption	300 VA

Wall cabinet
Protection	IP 64
Dimensions	H 658 x W 600 x D 200 mm (H 25.9 x W 23.6 x D 7.9 in)

Floor cabinet
Protection	IP 54 or IP 21
Dimensions	H 2225 x W 700 x D 600 mm (H 87.6 x W 27.6 x D 23.6 in)

+ System interface

The Millmate Thickness Gauge System can easily be connected to AGC systems, based on feedback, feedforward and mass flow control.

Network communication
As a complement to I/O signals different Ethernet communication protocols are available.

The Vendor Internet Protocol (VIP) uses predefined data telegrams to exchange information on measurement data, system status and system set-up. The sending procedure is cyclic and the receiving procedure reacts on incoming messages.

Modbus TCP is also an available option for Ethernet communication.
The protocol is used in the same manner as VIP.

OPC protocol is yet another means to connect the MTG Box Gauge to higher level systems via Ethernet. The system supports OPC DA Data Access over an optional Ethernet local network.
To gain access to measurement data and system set-up, a higher level computer with OPC-client functionality can communicate with the Control unit.

Profibus-DP
As an option, the MTG system can be equipped with a Profibus-DP slave interface for communicating with the rolling mill control system.
The Profibus-DP interface provides fast transfer of measurement data. It can also be used for setting up nominal thickness and for remote control of system settings and gauge movement.

HMI on Industrial PC

For data presentation, manual gauge operation, calibration and maintenance.

+ Data Industrial PC

Type	AAEON Boxer 6640
Power supply	24 VDC, 120 W via AC power adapter 100 - 240 V
Protection class	IP 40
Operating System	Windows 10 IoT Enterprise LTSC
Option	KVM extender for extended distance between PC and monitor

Hydraulic Valves

+ Data Hydraulic Valves

Type	Hydraulics
Working pressure	50 bar
Input pressure	max 160 bar
Flow	5 l/min
Pressure switch	40 bar
Pressure fluid	Mineral oil DIN 51524 (HL, HLP) Phosphate ester (HFD-R)
Sealing	Viton

Air regulator

The air regulator filters the air and controls air pressure in the gauge. The air is used for internal temperature control and provides over-pressure to prevent coolant, etc., from entering the gauge.

+ Data Air regulator

Air regulator
Supply pressure	5 to 16 bar (72,5 to 232 psi)
Air consumption	5 dm³/s (11 cfm)
Air quality requirement	Acc to PNEUROP
Particle class 3	Particle size max 1 μm (40 μin), particle content max 5 mg/m³
Oil content class 3	Max1 mg/m³
Condensation class 3	Condensation at +10° C (50 °F)

Cyber security

ABB approach to Cyber Security

ABB provides the defense-in-depth security required for digital solutions in mission-critical applications and industries.
A common standard is applied for all ABB products and system with rigorous testing performed by specialists.

HMI based on Windows 10 IoT

Active firewall configured to block all incoming connections
Hard drive locked down for writing, a reboot resets the HMI
User preferred malware protection to be added
Periodic Windows patch packets service – tested with application software

Controller based on Windows 7 Embedded Compact

WEC7 is a real-time OS - normal Windows program cannot be executed
Much less vulnerable
External communication designed as a normal Firewall
Only 2 available ports for defined external interfaces:
1. Modbus/TCP and OPC DA
2. VIP/TCP