Views: 26 Author: Site Editor Publish Time: 2026-10-20 Origin: Site
When a door closer is specified for a project, closing speed and price usually come up first. The decision that shapes everything else, however, is where the body sits. A door closer can be mounted on the surface of the door, where the mechanism stays in full view, or built into the door frame, where it disappears from sight. Jianlai's aluminum alloy hydraulic door closer line covers both forms, in square, round and slim bodies, with models rated for doors from 25 to 80 kg. This guide explains what each form involves, how the choice affects the door and frame, and how to match a model to the door's weight, width and body shape.
A surface-mounted door closer has its body and arm fixed directly onto the surface of the door and frame. Nothing is recessed: the mechanism remains visible after installation. Models JL-501, JL-502, JL-503, JL-504, JL-505 and JL-506 are all surface-mounted, offered in two body shapes: JL-501, JL-503 and JL-505 are square, while JL-502, JL-504 and JL-506 are round.
A concealed door closer takes the opposite arrangement. The body and arm sit inside the door frame, out of sight, so the door reads as a clean plane when closed. Models JL-509, JL-510 and JL-511 are concealed. JL-509 is square, JL-510 is round, and JL-511 is a slim-profile model.
Both forms use the same hydraulic mechanism with cam action and an arm. The difference lies in where the body is placed, not in how the closing function works.
Day-to-day adjustment is convenient on both forms. On the concealed models, the speed-adjustment valves sit on the side of the body — on the section that stays flush with the door edge rather than inside the frame recess. Opening the door exposes the top edge, and the closing speed can be set from there. On surface-mounted models the body is fully accessible, so the same adjustment takes no extra steps.
A surface-mounted door closer is fixed to the finished surfaces with screws. No routing or recess is required, and the door does not need to be taken down for the body to be fitted. This makes the form practical for doors that are already hanging on site as well as for new installations.
A concealed door closer needs the door frame prepared to house the body and arm. The space for the mechanism is planned before fabrication, and the unit is built in as the frame is made up. In return, nothing shows on the door face once the installation is complete.
One point is worth clarifying, because it is a frequent assumption: door material does not decide the mounting form. Both surface-mounted and concealed door closers are suitable for wooden doors and for aluminum frame doors. The factors that actually separate the two forms are how much hardware the design should show and whether the frame will be prepared with a recess — not what the door is made of.
Where the design calls for hardware to be invisible, a concealed door closer is the natural match. Office entrances, hotel guestroom doors and high-end retail fit-outs often specify concealed models so that the door face stays uninterrupted.
Where visibility is acceptable — or where the hardware is meant to look deliberate rather than hidden — a surface-mounted door closer keeps preparation simple while still offering a tidy, industrial look.
Body shape is a separate decision from mounting form. A square body follows the straight lines of a door frame and reads as a clean block; a round body presents a curved face and sits more softly against the door surface. Where a model is offered in both shapes, the rating is unchanged, so the choice can be made on appearance alone.
Finish is the same across both forms: every model in the range carries a powder-coated surface. Silver, white, black and gold are the popular colors, and the finish can be sprayed in other colors to match a project scheme.
Installation form, body shape and model rating go together in this line: each model is built for one mounting form and one body shape, with its own door weight and door width bands. The table below sets out the current range, one model per row so the shape is unambiguous.
Model | Mounting form | Body shape | Door weight | Door width |
JL-501 | Surface-mounted | Square | 25–45 kg | 500–900 mm |
JL-502 | Surface-mounted | Round | 25–45 kg | 500–900 mm |
JL-503 | Surface-mounted | Square | 45–60 kg | 600–1200 mm |
JL-504 | Surface-mounted | Round | 45–60 kg | 600–1200 mm |
JL-505 | Surface-mounted | Square | 60–80 kg | 900–1300 mm |
JL-506 | Surface-mounted | Round | 60–80 kg | 900–1300 mm |
JL-509 | Concealed | Square | 35–65 kg | 1100–2100 mm |
JL-510 | Concealed | Round | 35–65 kg | 1100–2100 mm |
JL-511 | Concealed | Slim | 30–60 kg | 1100 mm |
The practical way to use the table is to weigh the completed door — leaf plus glass or panel plus fitted hardware — and measure its width, then read off the models whose bands cover both figures. Because the weight ranges of the surface-mounted and concealed models overlap, many doors qualify for both forms: a 50 kg door, for example, falls within the rating of the surface-mounted JL-503 and JL-504 (45–60 kg) and of the concealed JL-509 and JL-510 (35–65 kg) and JL-511 (30–60 kg). Weight and width tell you which door closer models will carry the door; mounting form and body shape then come down to the look of the project and the state of the frame.
The shape pairs share their ratings, so there is no performance trade-off between them. JL-501 and JL-502 cover the same door weight and width, as do JL-503 and JL-504, JL-505 and JL-506, and JL-509 and JL-510. Where a project has already settled on a weight band, the square and round versions can be compared side by side and chosen on appearance. JL-511 stands apart as the slim-profile option, with its own single width band.
Whichever model a project lands on, the fundamentals are shared. Every unit in the line has an aluminum alloy body built around a hydraulic mechanism with cam action and an arm. All models work in temperatures from -40°C to 60°C, and a hold-open function is available. Surfaces are powder-coated in the colors described above. Commercial terms are equally uniform: the warranty is 3 years, the minimum order quantity is 100 pcs, samples ship in 7 days and bulk orders in 30 days, and both OEM and ODM service are supported.
The full line, with its square, round and slim bodies across both mounting forms, can be reviewed on the Jianlai door closer product page. For a specific project, confirm the model's data sheet against the measured door weight and width before ordering.
