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Title: Blasting nozzles: how long they last and how to tell when one is worn Slug: blasting-nozzles-wear-replacement Meta description: The nozzle is the cheapest part in the installation and the least monitored. How it wears, how to measure it, and why a worn one costs you electricity. Category: Blasting

A nozzle costs about a day of labour. It is the only part every gram of abrasive passes through, at over 100 metres per second. And in most workshops it is the one part nobody ever measures.

The result is always the same: output drops slowly, air consumption rises, and the operator compensates by spending longer on each part. Nobody connects the dots, because nothing broke — a hole just got two millimetres wider.

Why it wears

A mix of air and abrasive passes through the nozzle at high speed. The particles strike the inner wall at a shallow angle and erode it. The wear is not uniform: it starts at the inlet, where the jet has not stabilised yet, and works towards the outlet.

The effect is that the bore grows. An 8 mm nozzle becomes 9, then 10. From the outside it looks the same.

The lining material matters by an order of magnitude

What the nozzle is lined with decides how long it lasts. The ranking is constant, even if exact figures depend on the abrasive and the pressure:

Material	Relative life	When it makes sense
Hardened steel	baseline, shortest	occasional use, low pressure
Tungsten carbide	several times better	small batches, mild abrasives
Silicon carbide	well above tungsten	everyday use, best price per hour
Boron carbide	longest by far	continuous production, hard abrasives

The practical rule: the harder the abrasive, the more the lining choice matters. With steel shot, a silicon carbide nozzle holds up well. With corundum, the same nozzle wears noticeably faster, and boron carbide starts to pay for itself despite costing several times more.

Straight bore or venturi

A straight-bore nozzle has the same diameter throughout. A venturi narrows, then widens towards the outlet.

The difference is physics, not finish: the venturi profile accelerates the mix and spreads it over a larger area. At the same pressure and the same air consumption, it covers more per minute. It costs more and it is longer, so it needs room to manoeuvre — but on an installation running daily it pays for itself.

Straight bore stays the right choice in tight spaces or on small parts, where the extra length gets in the way more than it helps.

How to tell it is worn

Measure it. That is the only method that will not lie to you. A caliper or a set of plug gauges, once a month, written on a sheet next to the machine. Thirty seconds.

The indirect signs show up later, once you have already lost money:

pressure at the nozzle drops although the compressor works the same
the jet widens and loses its sharp edge
you cover less per hour at the same settings
the compressor runs longer between breaks

Why a worn nozzle costs real money

This is the part most people underestimate. The air passing through a nozzle grows with the square of the bore. Not proportionally — squared.

An 8 mm nozzle worn to 9.5 mm consumes roughly 40% more air at the same pressure. The compressor works 40% harder, draws 40% more electricity, and output does not rise at all — it falls, because particle velocity is lower.

You pay more to work slower. And if the compressor was sized tightly, at some point it stops holding pressure, and someone calls service for a problem a few hundred lei of parts would have solved.

The replacement rule

Replace the nozzle once the bore has grown by roughly 1.5 mm over nominal. Past that point, the lost efficiency and the extra air outweigh the cost of a new nozzle.

For a workshop running shifts, it is worth keeping two spare nozzles and a gauge in plain sight. It is the cheapest preventive maintenance in the whole installation.

What to specify when ordering

nominal bore, matched to your compressor and your parts
lining material — matched to the abrasive, not to the budget
profile, straight bore or venturi
thread type and gasket, so it fits your nozzle holder
length, if you work in tight spaces

Replacement nozzles, in every bore and lining above, are part of our consumables and spare parts range.

If you are not sure what you have now, measure the old nozzle and send us the dimension. It is faster than digging through the documentation.