Hilti AG 4D-22 Cordless 125 mm Angle Grinder

The Hilti AG 4D-22 is a compact cordless 125 mm angle grinder on the 21.6 V Nuron platform with a dead-man paddle switch. Hilti says its brushless motor delivers as much power as a 1000 W corded grinder, and it weighs 2 kg with a body of 295 x 85 x 135 mm.

Cord-free cutting of rebar, pipe and sheet metal

Listed applications include cutting rebar, pipes and sheet metal, cutting and grinding steel and other metals, cutting concrete, masonry, stone and roof tiles, and notching, grinding, deburring and finishing metal surfaces. The 125 mm disc and 34 mm maximum cutting depth match the AG 125-13S.

Hilti highlights a quick-acting brake that stops the disc in under 2 seconds, three-dimensional Active Torque Control for protection against kickback in any direction, an integrated dead-man switch with a slim grip, and an auto-restart function that restarts the disc if it stops under pressure and the pressure is released within 2 seconds.

Technical specifications

Wheel limits and ordering notes

The operating instruction requires resin-bonded, fibre-reinforced wheels with a maximum diameter of 125 mm approved for at least 11,000 rpm and 80 m/s peripheral speed. Abrasive cut-off wheels are listed up to 3.2 mm thick and diamond cut-off wheels up to 6.35 mm, and abrasive cut-off work needs the standard guard with the additional front cover or an enclosing dust hood.

The tool, batteries and charger are separate items, so state battery size and charger in the enquiry. Within Hilti’s cordless grinders the AG 4S-22 offers six speed stages with a lockable on/off switch, the AG 6D-22 is a further 125 mm cordless model, and the AG 30D-22 takes 230 mm discs.

Hilti quotes 92 dB(A) sound pressure and 5.4 m/s2 vibration for angle grinding; feed these into your site noise and vibration exposure assessment together with the expected daily trigger time.

Hilti angle grinder range at a glance

Corded and cordless grinders listed by Hilti, with the disc size and maximum cutting depth each is built around.

Preparing the AG 4D-22 for site work

Before the first use, read the operating instruction and fit the guard that matches the job: grinding, cutting with abrasive wheels and cutting masonry each need the guard arrangement described by Hilti. Check that the wheel is the correct diameter, rated for the tool speed, undamaged and within its expiry date where one is printed, then mount it with the correct flange and clamping nut and tighten it as instructed. Insert a charged Nuron battery only after the wheel and guard are fitted, and run the tool briefly with the disc pointed away from people to confirm it runs smoothly without vibration or wobble.

Safe working practice

The paddle switch with dead-man function means the motor stops when the grip is released, which helps on scaffolds, in trenches and in other awkward positions. Hold the grinder with both hands using the side handle, keep the body out of the line of the disc, and let the tool reach full speed before contacting the work. Clamp loose pieces such as short lengths of pipe or rebar rather than holding them by hand. Wear eye and face protection, hearing protection, gloves and suitable clothing, and use dust extraction or respiratory protection when cutting concrete, stone or masonry, because mineral dust from these materials can be harmful to health.

Working in Oman and GCC site conditions

Construction and maintenance sites across Oman expose cordless tools to high temperatures, blowing sand and fine cement dust. Avoid leaving batteries and the tool in direct sun, on hot steel decks or in closed vehicles during the day, and allow a hot battery to cool in the shade before charging it. Charge batteries indoors in a ventilated, dust-free place where possible. Dust drawn into the motor housing through the cooling vents is a common cause of wear, so blow out the vents with dry compressed air while wearing eye protection, and keep the tool in its case when it is not in use. On coastal and marine projects, wipe off salt spray and moisture at the end of the shift.

Routine checks and care

At the start of each shift, inspect the guard, side handle, wheel flange and battery contacts for damage or looseness, and confirm the brake stops the disc promptly when the switch is released. Discard any wheel that has been dropped, cracked or soaked. Have the tool inspected by a qualified service centre if it runs roughly, overheats or shows damage to the housing. Keeping a simple log of battery condition and tool inspections makes it easier to manage a fleet of grinders across several sites.

Matching the grinder to the task

Choose wheels for the material being cut: abrasive wheels for steel, diamond blades for concrete and masonry, and flap or grinding discs for finishing. Plan battery capacity according to how long each cutting task runs.

Documents and quotation

The attached PDF is the manufacturer’s operating instruction for the AG 4D-22 in several languages, and it carries the safety instructions and the technical data quoted above. Item numbers, kit contents and voltage or plug versions change, so confirm them against the Hilti product page and in your enquiry to Seven Star LLC, an independent Muscat supplier. See the Material Handling & Lifting Equipment category for other grinding and cutting equipment.