Every week, a factory manager calls me with the same question: "Cylinder's leaking — should I just order a new one?" Nine times out of ten, the answer is repair. Here's how I work it out on the phone, and why the maths almost always favours a rebuild.
Why cylinders fail (and what that tells us about the fix)
Pneumatic cylinders don't really "break" — they wear out in predictable ways, and each failure mode has its own repair path.
- Seal degradation. The single most common issue. Piston and rod seals harden or tear over time — you get air leaking past the piston, slow strokes, weak force. A seal kit fixes this.
- Rod scoring or pitting. Usually contamination in the air supply cuts grooves into the chrome. If the pitting is shallow, we re-chrome; if the rod is bent or deeply damaged, we replace it.
- Bore scoring. High-cycle machines or bad lubrication chew up the barrel bore. Light scoring hones out; heavy scoring usually means the cylinder is done.
- End cap damage. Hydraulic lock or missing cushions can crack an end cap. Replaceable on most ISO 15552 cylinders.
- Corrosion. Common in humid Noida summers and food/chemical plants. If it's surface rust, we clean it. If it's pitted through, we replace.
What a "repair" actually looks like on the bench
If you dropped a faulty cylinder off at our Sector 9 workshop, here's what the repair technician would do:
- Disassemble — end caps off, piston out, parts laid out in order
- Inspect — rod for scoring, bore for scratches, seals for wear pattern
- Clean — degrease barrel and all components
- Re-chrome the rod if it's pitted (sent out to a chroming shop, adds a day)
- Hone the bore if it's lightly scored
- Fit a full new seal kit — piston seal, rod seal, wiper, cushion seals, O-rings
- Reassemble to spec, torque the tie rods correctly
- Pressure test at rated working pressure — usually 7-10 bar
Simple reseal: half a shift. Rod re-chroming job: 2-3 days because the rod goes out to a chroming shop. Most of what we handle falls in the 24-72 hour window.
Repair vs replace — side by side
Lean towards REPAIR when…
- Seal wear is the main issue
- Rod and barrel are in decent shape
- Bore size is 40mm or bigger (more rebuild value)
- It's a tie-rod type (ISO 15552 / 6432)
- Stroke length or mounting is non-standard
- You need it back in days, not weeks
Lean towards REPLACE when…
- Barrel is badly scored or corroded through
- Cylinder body has cracks or impact damage
- Bore is under 20mm (labour ≈ new cost)
- Obsolete seal profile no supplier stocks
- It's already been rebuilt 3-4 times
- You're upgrading to a better spec anyway
The real numbers — repair vs new (Indian market, April 2026)
| Cylinder | New price | Repair cost | You save |
|---|---|---|---|
| ISO 15552, ⌀40 × 150 stroke | ₹3,000–4,500 | ₹900–1,500 | ~65% |
| ISO 15552, ⌀63 × 250 stroke | ₹6,000–8,500 | ₹1,800–2,800 | ~65% |
| ISO 15552, ⌀100 × 400 stroke | ₹14,000–22,000 | ₹3,500–6,000 | ~70% |
| ISO 15552, ⌀160 × 500 stroke | ₹28,000–45,000 | ₹6,000–10,000 | ~75% |
Notice the pattern — the savings go up with bore size. A small ⌀25 cylinder isn't worth resealing because the labour swallows the saving, but anything ⌀40 and above, the maths is obvious. That's why we get called in for the bigger cylinders more often.
Turnaround — repair usually wins here too
New cylinder from a dealer: 3-7 days if it's a standard model sitting in someone's warehouse in NCR. Two to four weeks if it's imported or an unusual bore/stroke. Custom builds can run longer.
Repair at our shop: 24 hours for a straight reseal, 48-72 hours if the rod needs re-chroming. Walk in Monday, most jobs are ready by Wednesday or Thursday. If your production is down, that difference alone pays for the repair.
When I honestly tell people to just replace
I'm not trying to sell you a repair you don't need. I'll tell you to replace if:
- The barrel is cracked or badly corroded all the way through
- The cylinder body is physically damaged (hit by a forklift, dropped, etc.)
- It's already been rebuilt three or four times — the tolerances won't hold again
- It's a micro cylinder (⌀20mm or smaller) — the labour isn't worth it
- The seal profile is obsolete and no one stocks the kit
In those cases we'll source you a matching new cylinder. But honestly — most of what comes through our door is a seal job wearing a panic about replacement.
Send a WhatsApp photo of the faulty cylinder (brand, bore, stroke visible) to +91-9811104037. I'll tell you in one reply whether to repair or replace, and quote either way before you commit.