Festo Pneumatic Cylinders DSBC, DNC, DSNU and ADVU, New Zealand

Festo / Pneumatic cylinders

Two cylinders can be identical in bore, stroke, mounting and appearance, and one will not work on your machine. The difference is a magnet in the piston, it is a few characters in the type code, and without it the position sensors see nothing.

Cylinders are the highest volume Festo enquiry we get. Most of them can be quoted straight off a photo of the label.

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Reading a cylinder type code

Take DSBC-32-100-PPVA-N3. It reads left to right.

Field	Means
DSBC	The family. Standard cylinder to ISO 15552
32	Bore, in millimetres
100	Stroke, in millimetres
PPV	Cushioning. Adjustable pneumatic cushioning
A	Position sensing. A magnetic piston is fitted
N3	Further options

Bore and stroke are the two numbers in the middle and they read directly in millimetres. That alone answers most sizing questions without a catalogue.

The letters after them are where the money and the mistakes are.

The magnetic piston decides whether sensors work

The most important thing on this page.

Festo position sensors detect a magnet embedded in the piston. No magnet, no signal, regardless of how good the sensor is.

	With magnetic piston	Without
Cylinder moves	Yes	Yes. Perfectly
Sensors detect position	Yes	No
Looks different	No. Identical from outside
Can be added later	No. The piston is inside the cylinder

So the failure looks like a sensor fault or a PLC fault. The cylinder strokes correctly, the machine sequence hangs waiting for an end-of-stroke signal, and everybody looks at the sensor.

It is not repairable and it is not an accessory. The cylinder has to be the right one.

Two rules that prevent it entirely:

If there are sensors clipped to the cylinder, the replacement needs a magnetic piston. Look at the barrel before you order.

And send us the full type code rather than bore and stroke. Bore and stroke describe a cylinder that fits. The rest of the code describes one that works.

Cushioning

Worth understanding, because it is both an ordering option and a free adjustment.

Type	What it does
Adjustable pneumatic cushioning	Screws at each end, set on site
Self adjusting cushioning	Sets itself, no screws
Elastic cushioning	Rubber buffers. Small cylinders and light loads
No cushioning	Short stroke or externally stopped

A cylinder that slams at the end of stroke is usually a cushioning adjustment rather than a fault. On the adjustable type there is a screw at each end, and they get wound fully open during commissioning and never touched again.

Slamming destroys the cylinder and everything it is bolted to, so it is worth fixing before it becomes a repeat order.

Note that the cushioning type is part of the specification. An uncushioned cylinder fitted where a cushioned one was will hammer, and nothing on the outside tells you which you have received.

The families, and what became what

Family	Standard	Notes
DNC	ISO 15552	The long serving standard cylinder. Enormous installed base
DSBC	ISO 15552	What DNC became. Same standard interface
DSNU	ISO 6432	Round body cylinder, smaller bores
ADVU, ADN	ISO 21287	Compact cylinders. Short overall length
DFM		Guided, resists side load and rotation
DGC		Rodless. Long strokes in a short footprint

The ISO standard is genuinely useful here

DNC and DSBC are both built to ISO 15552, which standardises the mounting dimensions, the port positions and the rod thread for a given bore.

So a DSBC will normally go where a DNC was, on the same mountings, with the same fittings. That makes cylinder replacement far less painful than it is on brands with proprietary dimensions.

It also means another manufacturer's ISO 15552 cylinder will physically fit. We will say so where that is the cheaper or faster answer, though the sensor slot arrangement and the cushioning behaviour are not standardised, so it is not always a straight swap on a machine that uses sensors.

Mountings are separate parts

The most common omission on a first order.

Mounting	Notes
Foot mount	Bolts to the cylinder body
Flange mount	Front or rear
Clevis, swivel and trunnion	For cylinders that pivot
Rod eye and rod clevis	On the piston rod end
Sensor brackets	Where the cylinder has no integral slot

A cylinder arrives as a cylinder. On a like-for-like replacement the existing mountings normally transfer, so you need nothing else.

On a new installation, or where the mounting is damaged, they all have to be ordered. Tell us which and we will quote the set rather than leaving you a part short on the day.

Sensors

	Reed, SME	Electronic, SMT
Mechanism	Mechanical contact	Solid state
Life	Finite switching cycles	Much longer on fast machines
Typical failure	Intermittent first, then stuck	Less common
Fits	The cylinder slot, on cylinders that have one

An intermittent end-of-stroke signal on a high cycle machine is very often a worn reed switch. It works when tested slowly and fails in production, which makes it look like a control problem.

On a fast machine, fit electronic sensors. They go in the same slot and they outlast reeds substantially.

Cable length and connector type are part of the sensor order code, so tell us whether you need a flying lead or a plug.

Seal kits before whole cylinders

Symptom	Likely answer
Air escaping at the rod	Rod seal. Kit
Weak or slow, but air supply is good	Piston seal bypassing. Kit
Rod scored, pitted or bent	New cylinder
Barrel scored	New cylinder
Slams at end of stroke	Cushioning adjustment
Drifts under load when stopped	Piston seal, or the valve

Ask for the kit first where one exists. If the rod or bore is damaged a kit will not save it, and we will say so rather than selling you a kit that does not fix it.

A scored rod usually has a cause. Side load, a failed rod wiper letting grit in, or a misaligned mounting. Replacing the cylinder without fixing that just resets the clock.

Sizing a cylinder from scratch

For when the machine is being modified rather than repaired.

Input	Why it matters
Force required	Bore and working pressure decide this
Working pressure at the machine	Not the compressor pressure. The pressure at the cylinder under load
Stroke	Plus any overtravel
Direction	Pull force is lower than push, because the rod takes area off the piston
Mass and speed	Decides the cushioning requirement
Side load	Points at a guided cylinder rather than a standard one

The pull stroke is the one people forget. A cylinder sized on push force can be short on the return, because the piston rod occupies part of the piston area on that side.

Send us the force, the stroke and the pressure available and we will size it.

Before ordering a replacement

Symptom	Check first
New cylinder fitted, sensors dead	Magnetic piston. Check the type code
Slow or weak	Pressure at the machine under load, and the filter element
Leaking at the rod	Seal kit, unless the rod is damaged
Slamming	Cushioning screws
Intermittent signal	Worn reed sensor
Rod keeps scoring	Alignment and side load, not the cylinder
Same cylinder fails repeatedly	Air quality upstream, or a mechanical cause
Will not hold position when stopped	Piston seal, or the valve holding it

What to send us

The full type code. Not just bore and stroke.

A photo of the cylinder on the machine. It shows the mountings, whether sensors are fitted and how it is installed.

Whether sensors are clipped to it. That settles the magnetic piston question.

Whether you need mountings, or the existing ones transfer.

The symptom, because a seal kit may be the answer.

For a new application, the force, stroke, pressure and whether there is side load.

What we can supply

Cylinders. DSBC, DNC, DSNU, ADVU, ADN, DFM and DGC across bores and strokes, with and without magnetic pistons, in the cushioning variants.

Repair parts. Seal kits and service kits where they exist for the family.

Mountings. Feet, flanges, clevises, swivels, trunnions, rod eyes and sensor brackets.

Sensors. SME reed and SMT electronic, in the cable and connector variants.

Equivalents. Where an ISO 15552 cylinder from another manufacturer is faster or cheaper, we will offer it and tell you what differs.

We buy Festo

We buy surplus and unused Festo, particularly cylinders, valve terminals and electric axes from decommissioned lines.

Unused stock in original packaging is worth the most, and mountings and sensors are worth keeping with the cylinders they came with. See Sell To Us.

Common questions

Can you get a part that is not listed on your site?
Usually. The site shows what we hold, not what we can source.

What do the numbers in DSBC-32-100 mean?
32 mm bore, 100 mm stroke.

My new cylinder works but the sensors do not.
It has no magnetic piston. That is in the type code and it cannot be added afterwards.

Will a DSBC fit where my DNC was?
Normally yes. Both are ISO 15552, so the mounting dimensions and rod thread match for a given bore.

Can I repair it instead?
Often, with a seal kit. Not if the rod or barrel is scored.

Why does it slam at the end of stroke?
Cushioning. On the adjustable type there is a screw at each end.

Do the mountings come with it?
No. They are separate parts. On a like-for-like swap the existing ones usually transfer.

What is the lead time?
Ex stock items ship the next working day within New Zealand. We give you a firm lead time with the quote.

Do you quote in NZD?
Yes, in NZD including GST for New Zealand customers.

Send us your type codes

A photo of the cylinder on the machine answers most of our questions at once, including the one about sensors that catches people out. Quotes in NZD including GST.

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Industech is an independent supplier of new, surplus and used industrial automation equipment. We are not an authorised distributor of, approved by, sanctioned by, or affiliated with Festo. Festo and the product type codes named here are trademarks of Festo SE & Co KG. All trademarks, brand names and type codes are the property of their respective owners and are used here for identification purposes only.