Expanding Mandrel for Decoilers | Directory Reference

Product Specifications

Technical details and manufacturing context for Expanding Mandrel

Definition

The expanding mandrel is a critical component of a decoiler or uncoiler system. It is inserted into the center of a coil of material (such as metal, paper, or plastic). Through mechanical, hydraulic, or pneumatic actuation, the mandrel expands radially outward to make firm contact with the inner surface of the coil. This creates the necessary friction and positive drive to rotate the coil and feed the material into a downstream process line in a controlled manner, preventing slippage and ensuring consistent tension. The mandrel consists of a central shaft and multiple movable segments or shoes arranged around its circumference. When actuated (e.g., by a wedge mechanism, hydraulic cylinder, or air bladder), these segments move radially outward. This expansion increases the mandrel's effective outer diameter until it firmly presses against the inner wall of the coil's core (ID). The resulting friction allows torque from the decoiler's drive system to be transferred to the coil, enabling controlled unwinding. Typical specifications include an expansion range of 50–600 mm, expansion accuracy of ±0.05 mm, and maximum radial runout of 0.10 mm per ISO 1101. Load capacity ranges from 10 to 50 tons, and maximum speed from 100 to 300 rpm. Operating temperature is -10 to 60 °C. Materials on file include alloy steel and hardened tool steel, with a reference grade of 42CrMo4 (DIN EN 10083) and surface hardness of HRC 50–55 (DIN EN ISO 6508). Weight ranges from 200 to 1500 kg, and IP rating from IP54 to IP65 (IEC 60529). These values are directory references and must be verified with the manufacturer for specific models and applications. Always confirm model-specific values and standards with the legal manufacturer or supplier.

Working Principle

The expanding mandrel operates by radial expansion of segments or shoes around a central shaft. Actuation via wedge, hydraulic, or pneumatic mechanisms forces the segments outward, increasing the effective diameter until they contact the coil's inner diameter. This creates friction, enabling torque transfer from the drive system to the coil for controlled unwinding. The expansion range and accuracy are critical for proper grip and alignment.

Common Materials

Alloy Steel, Hardened Tool Steel

Technical Parameters

Parameter	Typical range	Notes & selection driver
Expansion Range	50–600 mm	Range of coil inner diameters the mandrel can grip
Expansion Accuracy	±0.05 mm	Radial runout of expanded segments
Max Radial Runout	0.10 mm	Ensures coil alignmentISO 1101
Max Load Capacity	10–50 t	Weight of coil the mandrel can support
Max Speed	100–300 rpm	Higher speeds may cause imbalance
Operating Temperature	-10–60 °C	Outside range may affect seals and lubrication
Material	42CrMo4	High-strength alloy steelDIN EN 10083
Surface Hardness	HRC 50–55	Wear resistanceDIN EN ISO 6508
Weight	200–1500 kg	Depends on size and capacity
IP Rating	IP54–IP65	Protection against dust and waterIEC 60529

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Components / BOM

Central Shaft Part
The main structural backbone of the mandrel, transmitting torque from the drive and housing the expansion mechanism.

Material: Alloy Steel
Expansion Segments/Shoes Part
Movable blocks that slide radially outward to contact the coil ID. Often lined with wear-resistant material or friction pads.

Material: Hardened Tool Steel
Actuation Mechanism
The system (e.g., tapered wedge, hydraulic piston, air bladder) that converts axial or fluid pressure into the radial motion of the segments.

Material: Steel/Alloy
Wear Pads/Liners Part
Replaceable surfaces on the expansion segments that provide high friction and protect the segments from abrasion.

Material: Polyurethane or High-Friction Composite

Application & selection

Application Fit & Sizing Matrix

Operational Limits

pressure:	Max 10 bar hydraulic pressure
other spec:	Coil ID range: 300-1500 mm, Max torque: 5000 Nm, Expansion range: ±5% of nominal diameter
temperature:	-20°C to 150°C

Media Compatibility

✓ Steel coils ✓ Aluminum coils ✓ Paper/plastic film rolls

Unsuitable: Abrasive slurry environments with particulate contamination

Sizing Data Required

Coil inner diameter (ID) and tolerance
Material weight and coil width
Required torque for unwinding force

Risk, maintenance & compliance

Reliability & Engineering Risk Analysis

Failure Mode & Root Cause

Mandrel surface galling and scoring

Cause: Insufficient lubrication during expansion cycles leading to metal-to-metal contact and adhesive wear

Hydraulic cylinder seal failure

Cause: Contamination in hydraulic fluid causing seal degradation and pressure loss

Maintenance Indicators

Irregular expansion pattern or uneven pressure distribution during operation
Hydraulic fluid leakage around cylinder seals or fittings

Engineering Tips

Implement strict lubrication schedule using manufacturer-recommended anti-galling compounds
Install high-efficiency filtration system for hydraulic fluid and conduct regular fluid analysis

Indicative industry ranges for design and RFQ preparation. Confirm the exact figures and applicable standard with the manufacturer before specifying.

Compliance & Manufacturing Standards

Applicable Standards

ISO 286-2:2010 (Limits and fits) ASTM A370-24 (Standard Test Methods and Definitions for Mechanical Testing of Steel Products) DIN 5480-1:2006 (Splined connections with involute splines based on reference diameters)

Quoted from the published standard.

Manufacturing Precision

Bore diameter: +/-0.01 mm
Concentricity: 0.02 mm TIR

Quality Inspection

Dimensional verification with CMM (Coordinate Measuring Machine)
Hardness testing (Rockwell C scale)

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

Check the legal entity, factory address, ownership, certifications, and direct contacts.

Compare the published product scope and source details, then include your specifications and quantity in an enquiry.

Manufacturers of Expanding Mandrel

Manufacturer profiles associated with Expanding Mandrel.

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Frequently Asked Questions

What is the expansion range of the expanding mandrel?

The directory lists an expansion range of 50–600 mm, meaning the mandrel can grip coil inner diameters within that range. However, this is a reference range; the actual range for a specific model must be confirmed with the manufacturer.

What materials are used for the expanding mandrel?

Materials on file include alloy steel and hardened tool steel. A reference grade is 42CrMo4 per DIN EN 10083, with surface hardness of HRC 50–55 per DIN EN ISO 6508. Confirm material and hardness for your application.

What is the maximum load capacity?

The maximum load capacity is listed as 10–50 tons, depending on the model. This is a directory reference; verify the exact capacity with the manufacturer for your specific coil weight.

What standards apply to the expanding mandrel?

Standards referenced include ISO 1101 for radial runout for operating pressure, DIN EN 10083 for material, DIN EN ISO 6508 for hardness, and IEC 60529 for IP rating. These are verification references; compliance must be confirmed with the supplier.

Related equipment

Applied To / Applications

This component is essential for the following industrial systems and equipment:

Decoiler / Uncoiler

View system integration details

Industrial Ecosystem & Supply Chain Structure

Complementary Systems

Downstream Applications

Specialized Tooling

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review · Page last updated 12 October 2026

Expanding Mandrel