Heavy-Duty 21V Rotary Hammer for Concrete, Granite and Chiselling Work
Hangzhou Xinabo Intelligent Electromechanical Technology Co., Ltd is the XJ.728 21V Lithium-Ion High-Magnetic Brushless Rotary Hammer (Heavy-Duty) — 2.8J Impact Energy for Hard Materials manufacturer, building cordless power tools and pipe fabrication equipment at our factory in Hangzhou, Zhejiang. The XJ.728 sits at the heavy end of our 21V rotary hammer range: a 2.8J high-magnetic brushless machine intended for sustained drilling and chiselling in high-hardness concrete, granite and other hard masonry.
We came to cordless tools from intelligent pipe threading, and the same priorities carry across — sealed motor construction, controls that respond to load rather than to a fixed setting, and one battery platform shared across the range so a crew carries a single charger and a small number of packs. Each XJ.728 is delivered with an extended side handle, depth gauge and hard storage case.
- 21V DC with an upgraded high-magnetic brushless motor
- 2.8J impact energy at 0-4500 bpm, 0-1100 rpm no-load
- 28mm maximum drilling diameter in hard masonry
- SDS/round chuck with three-mode switching
- Load-adaptive intelligent control with triple safety protection
Where the XJ.728 Earns Its Place
The tool is specified where the hole is the bottleneck and the material resists the bit — high-strength concrete, granite kerbs and stone, reinforced load-bearing walls. Three duty groups cover most of the work we quote against.
Engineering construction
Large-diameter concrete drilling, stone chiselling, road repair and bridge reinforcement drilling, where the hammer runs for long stretches and heat build-up decides how many holes a shift delivers.
Renovation and structural alteration
Load-bearing wall drilling, tile channelling and marble drilling, where trigger control and the drill-only mode matter as much as raw impact energy.
Outdoor and yard work
Steel structure installation, yard stone work and outdoor equipment fixing, where there is no mains supply and the battery platform becomes the deciding factor.
Reading the Specification
Each figure below answers a different site question. Impact energy governs penetration in hard aggregate; impact frequency governs how quickly that energy is delivered; the chuck and diameter ceiling define the tooling set.
| Parameter |
XJ.728 rating |
What it means on site |
| Rated voltage |
21V DC |
Shared platform with our other 21V cordless tools; packs swap without adapters. |
| Motor type |
Upgraded high-magnetic brushless |
No carbon brushes to wear; sustained load does not erode motor life the way brushed designs do. |
| No-load speed |
0-1100 rpm |
Variable trigger lets the operator start a hole cleanly and slow down for tile and marble. |
| Impact frequency |
0-4500 bpm |
Blow rate under load; the upper band drives mid-range bits through hard aggregate. |
| Impact energy |
2.8J |
Single-blow energy — the figure that decides penetration in granite and high-strength concrete. |
| Max drilling diameter |
28mm |
Upper boundary for TCT bits; core drilling and larger anchors belong to a different tool class. |
| Chuck type |
SDS/round |
SDS shank bits and chisels locate and lock without a key; round-shank accessories where fitted. |
| Standard accessories |
Extended side handle, depth gauge, hard case |
Site-ready on delivery; the depth gauge holds consistent anchor embedment across a run of holes. |
Three-Mode Operation and Load-Adaptive Control
Mode switching covers rotary hammer drilling, hammer-only chiselling and drill-only rotation. That single selector lets one tool handle a concrete anchor, a tile channel and a marble cut without a second machine on the floor — useful where a crew works across finishes in the same room.
The built-in intelligent control system reads load resistance and adjusts power output to match it, so the hammer does not sit at full demand in soft plaster or bog down in a hard aggregate seam. Triple safety protection is built into the same circuit, covering the conditions that damage cordless hammers in daily site use.
Chuck, Tooling and Accessory Scope
The XJ.728 is listed with an SDS/round chuck, which keeps the tooling decision practical: crews can run the SDS shank bits and chisels already in the store, and round-shank accessories where the holder is fitted.
- TCT drill bits up to the 28mm ceiling for concrete, granite and stone
- Flat, point and channel chisels for tile removal, channelling and stone dressing
- Depth gauge for repeatable anchor and fixing depths
- Extended side handle for two-handed control during sustained overhead work
Rotary Hammer Range and Where Each Model Fits
We supply the XJ.728 alongside lighter and heavier rotary hammers on the same 21V platform, so a project can standardise on one battery and one charger set while matching the tool to the duty.
| Model |
Impact energy |
Chuck |
Where it fits |
| XJ.728 |
2.8J |
SDS/round |
Heavy drilling and chiselling in concrete, granite and stone; road and bridge repair. |
| XJ.709 |
1.7J |
SDS-plus |
Lighter fixing work, overhead drilling and maintenance crews. |
| 4.5J 3-mode model |
4.5J |
3-mode drill/chisel/hammer |
Heaviest demolition and chiselling duty where maximum blow energy is required. |
Battery Platform and Fleet Integration
The XJ.728 runs on our 21V lithium-ion packs, the same platform used across our brushless hammer drills, impact wrenches, angle grinders, circular saws and hole punchers. For crews working a full shift away from power, the backpack lithium battery pack in 20Ah and 30Ah versions extends continuous runtime and can feed several tools in sequence.
Because the platform is shared, a project order can be built around one charger type, one pack family and a single spares holding — a practical consideration for contractors standardising a fleet across several sites.
Safety and Operator Protection
- Triple safety protection integrated into the control circuit
- Extended vibration-damping side handle for long drilling runs
- Depth gauge to prevent over-drilling through slabs and walls
- Hard storage case for transport and site storage
- Two-handed operating posture supported by the extended handle layout
Quality Control and Documentation
Production runs in our 10,000 m² factory with incoming material control, in-process inspection and a finished-product check before packing. Hangzhou Xinabo holds National High-Tech Enterprise status and more than 30 patents across its machinery and tool development. Our certificate file includes Machinery Directive and Electromagnetic Compatibility Directive attestation of conformity.
For project handover we confirm mode function, no-load speed and impact operation, chuck locking, battery and charger pairing, accessory count against the order and case packing before shipment. Documentation and labelling can be prepared to the language and format a project file requires.
Information We Use to Configure Your Solution
A workable proposal starts from the duty, not from a model number. These are the inputs that let us confirm the XJ.728 is the right tool and build the supply scope around it.
- Base material and strength — concrete grade, granite, stone, tile or mixed substrate
- Hole diameter and depth range, plus the anchor or fixing system in use
- Chiselling volume and the type of removal work expected
- Shift pattern and holes per shift, to size the battery and pack count
- Existing battery platform in the fleet, if any
- Tooling set required — bit diameters, chisel profiles, chuck interface
- Quantity, packaging format and delivery destination
- Documentation, labelling and language requirements for the project file
Maintenance, Spares and Serviceability
The brushless motor removes the carbon-brush service interval that dominates brushed hammer maintenance. What remains is straightforward: keep the chuck bore and shank clean, check the side handle clamp and depth gauge rod, and store the tool in its case between shifts.
We hold spare parts for our product range and support installers with replacement components. Packs should be charged and stored per the battery instructions, and chargers kept matched to the pack family in use.
Frequently Asked Questions
What materials and hole sizes is the XJ.728 built for?
It is a heavy-duty hammer for high-hardness concrete, granite and other hard masonry, with a maximum drilling diameter of 28mm. Above that ceiling, core drilling or a larger tool class is the correct choice.
What does 2.8J impact energy mean in practice?
It is the energy delivered per blow. Combined with 0-4500 bpm, it sets how quickly a bit advances in hard aggregate and how much the operator has to lean on the tool.
Which battery and charger does it use?
The XJ.728 runs on our 21V lithium-ion platform, shared with the rest of our cordless range. For extended continuous work, the 20Ah and 30Ah backpack packs can power multiple 21V to 60V tools.
Can the tooling set and packaging be matched to our order?
Yes. Bit diameters, chisel profiles and accessory quantities are confirmed against the order, and the tool ships in its hard case with the extended side handle and depth gauge as standard.
How do we get a configuration and quotation?
Send the base material, hole diameter and depth range, expected holes per shift, tooling requirements and delivery destination. We confirm the model, battery and pack count, accessory scope and documentation, then issue the quotation from our Hangzhou factory.
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