How to crimp a hydraulic hose: cut, skive, crimp, check

Crimping a fitting onto a hydraulic hose takes five steps: cut the hose square, clean the bore, skive the cover if the hose needs it, mark the insertion depth, and crimp with the right die to the table diameter. Then check the mark and measure the diameter. Send your hose type and size and we will suggest the machine.

What should I settle before I start?

Settle three things: the hose type and inner diameter (for example 4SH, 3/4″), the fitting maker and code, and the die set you will use. The fitting maker’s table gives the crimp diameter and it changes with each hose and fitting pair, so do not mix hose and fittings from different makers. The press must also be strong enough for your hose size and type.

1. How do I cut the hose?

Mark the hose to length and cut it square to its axis; a square cut lets the hose seat properly inside the fitting. After cutting, remove burrs and blow the debris out of the bore with compressed air, because particles left inside end up in the system oil. Our bench-top Hose Cutting Machine cuts hose up to and including 2″ and has a 400 mm blade.

2. When do I skive the hose?

Skiving means removing the outer cover over a set length so the fitting can grip the hose; not every hose needs it. Multi-layer spiral-wire hoses such as 4SH and R15 are usually skived, while braided hoses such as 1SN, R1 and R2 depend on the fitting type. The length to skive is in the fitting maker’s table; do not cut the wire itself, take off the cover only. Our Hose Skiving Machine skives 3/8″, 1/2″, 5/8″, 3/4″, 1″ and 1 1/4″ hose and has 6 dies; on the MT 30, 3/8″–2″ skiving dies are standard on the press.

3. How do I mark the insertion depth?

The hose must go into the fitting up to its shoulder. Measure from the end of the ferrule (the outer sleeve of the fitting that gets crimped) to that shoulder, transfer the distance onto the hose from its end, and mark it with a line or chalk; when you push the hose in, the mark should show at the mouth of the ferrule. If the mark still sits at the mouth of the ferrule after crimping, the hose did not slip during the crimp.

4. How do I pick the right die?

The die follows the hose and fitting pair: the fitting maker’s table gives the crimp diameter, so use the die set that produces that diameter. The press’s maximum opening diameter and main die length decide whether the die can be used on that press. We also make dies in the form and diameter you ask for; send us your size.

5. How do I crimp the hose on the press?

Centre the fitting in the die, support the hose and check that the mark shows at the mouth of the ferrule. Run the press and crimp to the diameter in the table. Crimping too far damages the braid and body of the hose; crimping too little can let the fitting pull off the hose.

6. What do I check after crimping?

The mark: if it still sits at the mouth of the ferrule the hose has not slipped; if it has opened up, the crimp is not acceptable however tight it looks.

The crimp diameter: measure with calipers on the flat part of the ferrule without touching the ridges; the reading must be within the tolerance in the table. Our article “How to measure hose crimp diameter” goes through it step by step.

The look: no cracks in the ferrule, no bulging or crushing in the hose.

A pressure test: we recommend pressure testing hydraulic assemblies before they go into use.

What equipment do I need to crimp hose?

Cutting: a hose saw or the Hose Cutting Machine.

Skiving: the Hose Skiving Machine or skiving dies, if your hose needs skiving.

Crimping: a METflex press and a die set that suit your hose and fitting size.

Measuring and marking: calipers, chalk or a paint marker, a gauge.

Cleaning and testing: compressed air and a pressure test rig for the assemblies.

Common mistakes

Choosing a die that does not match the hose and fitting pair.

Not cutting the hose square or not cleaning the bore.

Not skiving a hose that needs it, or skiving deep enough to cut the wire.

Crimping without marking the insertion depth; slip goes unnoticed.

Crimping hose and fittings from different makers to one table.

Putting the assembly into use without measuring the crimp diameter.

Which press suits my work?

Choose by your hose type and your largest diameter:

MT 11: portable and manual, 110 tons; 4SH hose from 3/16″ to 1″.

MT 12: 130 tons, 4 kW electric motor; 4SH hose from 3/16″ to 1″, 1SN hose up to 1 1/4″.

MT 30: 300 tons; R1-R2-4SH-R15 from 3/16″ to 2″, industrial hose 3–4″.

MT 35: 350 tons; R1-R2-4SH-R15 from 3/16″ to 2 1/2″, industrial hose 3–6″.

MT 55: 550 tons; hose and pipe up to and including 10″.

Send us your hose type, largest diameter and daily volume and we will choose the model with you. A WhatsApp message or an e-mail is enough for a quote.