The short answer
A decoiler holds a steel coil and pays off strip into a production line. Decoiler, uncoiler and payoff reel are three names for the same machine. Decoilers differ in two ways: how they grip the coil, by manual, pneumatic or hydraulic expansion, and how they are laid out, as single-head, double-head or double top-cone machines.
Choose by coil weight first, then check strip width and thickness, then decide the layout from how often you change coils and how you load them. Light coils and narrow strip suit manual or pneumatic decoilers; heavier coils need hydraulic expansion; wide, heavy coils, such as master coils for a slitting line, suit single-head hydraulic or double top-cone machines. This guide gives the overview. For the details, see our guides How a Hydraulic Expanding Uncoiler Works: 1:3 Wedge Mandrel and Single- or Double-Head Uncoiler: Coil Weight and Strip Width.
Decoiler, uncoiler, payoff reel: what the names mean
All three names describe a machine that carries a coil on a mandrel, or between cones, and lets the strip unwind under control. You will meet all three in quotations, catalogs and line drawings; our own catalog uses "uncoiler". In Chinese the same machine is called 开卷机 or 放卷机.
This guide covers decoilers for tube mill, slitting and roll-forming lines. Combined decoiler-straightener-feeders for press lines are a different machine and are not covered here.
Three ways to grip the coil: manual, pneumatic, hydraulic
The mandrel expands against the inside of the coil to hold it. What drives the expansion is the first way to tell decoiler types apart:
- Manual decoiler: the operator expands the mandrel by hand. It is the simplest type and suits light coils and narrow strip.
- Pneumatic decoiler: an air cylinder expands the mandrel, which saves manual effort. It suits light to medium coils on narrow-strip lines.
- Hydraulic decoiler: a hydraulic cylinder expands the mandrel and grips the coil firmly. It is the usual choice for heavier coils and wider, thicker strip. How the hydraulic mandrel turns cylinder stroke into grip is explained in How a Hydraulic Expanding Uncoiler Works: 1:3 Wedge Mandrel.
A double top-cone decoiler works differently: instead of an expanding mandrel, two cones clamp the coil from both sides.
Three layouts: single-head, double-head, double top-cone
- Single-head: one cantilever mandrel. The next coil goes on after the current one has run out. Simple, and the usual layout for heavy coils, which are loaded with a coil car.
- Double-head: two mandrels back to back on a rotating base. While one pays off, the next coil is loaded on the other; at coil change the base turns 180 degrees. It removes the loading wait and suits narrower strip and lighter coils.
- Double top-cone: the coil is clamped between two cones. It suits wide, heavy coils.
Whether single-head or double-head suits your coils, and how coil weight, OD and width limit the choice, is covered in Single- or Double-Head Uncoiler: Coil Weight and Strip Width.
InGen MillTek decoiler types at a glance
InGen MillTek builds uncoilers in seven arrangements. The ranges below are from our April 2025 catalog. Widths and thicknesses are upper limits for each type, not a combination reached at the same time. A T in a model name gives the rated coil weight in metric tons; numbers in other model names are not tonnage.
- Single-head manual (DTKJ150): strip width up to 250 mm, thickness up to 3 mm
- Double-head manual (STKJ150, STKJ300): strip width up to 120 or 250 mm, thickness up to 4 mm
- Single-head pneumatic (QDKJ150 to QDKJ500): strip width up to 100 to 450 mm, thickness up to 3 or 4 mm
- Double-head pneumatic (VKJ1.5T to VKJ3.5T): coils of 1.5 to 3.5 t, strip width up to 100 to 300 mm, thickness up to 3 or 4 mm
- Single-head hydraulic (YKJ3T to YKJ15T): coils of 3 to 15 t, strip width up to 450 to 1,200 mm, thickness up to 4 to 12 mm
- Double-head hydraulic (YKJ3T to YKJ15T): coils of 3 to 15 t, strip width up to 450 to 1,200 mm, thickness up to 4 to 12 mm
- Double top-cone (DYKJ10T to DYKJ30T): coils of 10 to 30 t, strip width up to 800 to 2,000 mm, thickness up to 10 to 18 mm
The full model table is on our Uncoilers & Decoilers page.
Brakes, powered payoff and other options
In normal production a decoiler does not drive the strip. The strip is pulled by the next machine, and a band or disc brake keeps back tension on the coil so the wraps do not loosen. Options reduce manual work and help with heavy coils:
- Coil car: lifts a heavy coil, lines it up with the mandrel and pushes it on. A coil car is available as an option supplied with our uncoilers, in classes from 5 t to 30 t.
- Coil support arm: supports the free end of the mandrel under heavy coils.
- Powered base swivel: turns the decoiler on its base under electric control instead of by hand.
- Powered unwinding kit: turns the mandrel under electric control to help find and thread the strip head.
- Assisted unwinding kit: an electrically controlled pressure head drives the strip to ease unwinding.
Which decoiler for which line?
These are typical starting points; the final choice follows your coil data and is confirmed in the proposal.
- Tube mill with narrow strip and frequent coil changes: a double-head decoiler, pneumatic for light coils or hydraulic for heavier ones, so the next coil is ready during payoff. The line still needs a spiral accumulator to keep the mill running while the strip ends are joined; see What Is a Spiral Accumulator?
- Tube mill with wide strip or heavy coils: a single-head hydraulic decoiler with a coil car and support arm.
- Slitting line: wide, heavy master coils, usually on a single-head hydraulic or double top-cone decoiler.
- Replacing the decoiler on an existing line: any type, matched to the line's pass line height, feed direction and the space available.
What to send for a decoiler proposal
Decoilers are configured to order and quoted individually. Please send:
- Maximum coil weight, coil inside diameter (every size you use) and maximum outside diameter
- Strip width and thickness range, and material grade with yield and tensile strength
- How often you change coils, and how coils are loaded (crane or coil car)
- For a replacement: the pass line height and feed direction of your line (left-hand or right-hand), and the space available
- Local supply voltage and frequency
Frequently asked questions
Prepared by the InGen Engineering Team. Values are reference values and are confirmed in the technical proposal and technical agreement.
- Is a decoiler the same as an uncoiler? Yes. Decoiler, uncoiler and payoff reel are names for the same machine.
- Manual, pneumatic or hydraulic: which do I need? It depends mainly on coil weight and strip size. Manual and pneumatic decoilers suit light coils and narrow strip; hydraulic decoilers suit heavier coils and wider, thicker strip.
- What does the T in a model name mean? It is the rated coil weight in metric tons, so YKJ10T is a 10 t class hydraulic decoiler. Numbers in model names without a T are not tonnage.
- Does a decoiler drive the strip? Not in normal production. The next machine pulls the strip, and the brake keeps back tension. A powered unwinding kit helps with threading.
- Can I buy a coil car on its own? A coil car is supplied as an option with our uncoilers.
- Can you supply only a decoiler for my existing line? Yes. Decoilers are supplied as single machines too. Tell us the pass line height, feed direction and space available.
- What does a decoiler cost? It is configured to coil weight, strip size and options, and quoted individually.
About this article
Prepared by the InGen Engineering Team. This is a general technical guide, not a specification or performance guarantee for any project. Final parameters are set in the project's technical proposal and technical agreement.