Elevator door alignment: design, failure modes, the fix

A landing door that will not close cleanly at handover is usually reported as a panel problem, and it is usually a dimensional stack problem. Elevator door alignment is set by three interfaces: the hanger on its track, the gib in the sill groove, and the meeting edge between the two leaves. Each has a number, and the numbers are small. A 1° slope on the track, a 2 mm high sill at one corner or a 0.14 mm powder film on a meeting edge is enough to turn a door that shut quietly in the factory into one that rubs, drums or drifts open.

This guide is for the manufacturing engineer who has to release the leaf and the frame drawing, and for the site engineer who has to hand the landing over. It works through the failure modes in the order they appear, gives the limits that keep them out, and sets out the adjustment sequence that fixes a door without bending anything.

What decides whether a landing door closes cleanly?

Flatness decides the visible gap, sill level decides the rub, and track level decides whether the door stays where it is put. Everything else is secondary. A door leaf is a 1.5 mm plate hung from two rollers, so it is stiff in its own plane and flexible out of it; the leaf will not fight a bad sill, it will ride over it.

Start with the mass, because every adjustment number follows from it. A 900 mm × 2,100 mm leaf in 1.5 mm CRCA weighs 0.9 × 2.1 × 0.0015 × 7,850 = 22.3 kg. Add the hanger, the roller brackets and the gib and the hung mass is about 26 kg, or 255 N. Two rollers share that, so 13 kg each on a perfect hang.

Now tilt the track by 1°. Over a 3,000 mm track that is 52 mm of fall end to end. The down-slope component of the leaf weight is 255 × sin 1° = 4.5 N. Rolling resistance of a 26 kg load on a steel roller runs at roughly 1% of the normal force, so about 2.6 N. The slope wins. The door creeps open, the closer works against it all day, and the customer reports a door that "does not latch". No amount of panel adjustment fixes a track that is 1° out.

Landing door alignment limits worth putting on the drawing

The table is the working set for a two-panel centre-opening landing door in 1.2–1.5 mm CRCA with a powder finish. Values outside the last column change the route, not just the tolerance, so they need agreement before the leaf drawing is released.

Why a 2 mm flatness error reads as a wedge-shaped gap

A leaf that is 2 mm out of flat over its 2,100 mm height cannot be hung to a parallel gap, because the gap is the difference between two curved surfaces. Hold the bottom of the leaf at 6 mm and the top drifts to 4 mm or 8 mm depending on which way the bow runs. The eye reads that as an out-of-square door, and every site adjustment after that trades one end of the gap for the other.

Flatness has three sources, in order of how often they cause trouble. The first is the coil: CRCA arrives with residual stress from rolling, and a leaf blanked from the middle of a wide coil springs differently from one cut at the edge. The second is the bend sequence: folding the two stiles before the head and the sill locks the leaf into whatever bow the first fold produced. The third is the weld or spot pattern on the stiffener, which shrinks the face and cups it towards the welds.

The countermeasure is process, not tolerance. Cut the blank with the grain direction consistent across the run, form the long stiles first and the short returns last, and keep the stiffener spot pitch under 150 mm so the shrink is distributed rather than concentrated at two points. Leaves that are powder coated after forming also move: the oven runs at 180–200 °C, and a leaf with an unbalanced spot pattern on one face will cup towards the uncoated face on the way out. Check flatness after coating, not before, because that is the condition the fitter receives.

For a clad panel, the numbers change. A 1.2 mm skin on a 1.5 mm core is stiffer out of plane than either alone, but the adhesive layer and the hem at the edge become the flatness risk: a hem that is not closed evenly pulls a wave into the face over the last 40 mm, right where the meeting edge sits.

Sill level and gib engagement: the vertical datum

The sill is the only datum that does not move, so the door is set from it. The gib on the bottom of the leaf drops into the sill groove and stops the leaf swinging; it should sit 5–8 mm into the groove with the door closed and leave 5–8 mm of clear gap under the leaf. Get that pair wrong and the failure is physical rather than cosmetic.

A sill set 2 mm high at one end lifts the leaf through the gib. The bottom clearance closes to zero, the leaf rides on the sill, and the powder wears through at the corner within a season. A sill set 2 mm low does the opposite: the gib barely engages, the leaf swings on the hanger, and the bottom leading edge strikes the frame on closing.

Groove width matters as much as level. The gib needs 2–3 mm of clearance each side in the groove so that a grit of construction debris does not jam the door. Doors that jam "only after a weekend" usually have a groove 1 mm wider than the gib and a sill that has collected plaster dust.

Two rules keep the sill workable:

• Level the sill to ±1 mm across the full opening before the frame is packed, and re-check after the frame bolts are torqued. A frame pulled to a 3 mm out-of-plumb wall drags the sill with it.
• Cut a debris relief at both ends of the groove. A 10 mm wide, 3 mm deep relief lets the gib push grit out instead of compacting it.

The hanger, the track and the adjustment order

Alignment is a sequence, and doing it out of order is why doors get adjusted twice. The order that works is: sill, frame plumb, track level, hang, gap, close force.

Track level comes before hanging because the leaf cannot be levelled against a sloping datum. Set the track to 0.5 mm/m with a digital level on the track face, not on the ceiling bracket. Then hang the leaf and set the meeting gap with the hanger's vertical screws, using a feeler gauge at three heights: top, middle and bottom of the stile. If the three readings disagree by more than 1 mm, the leaf is twisted and no screw will fix it.

Closing force is last, and it is a safety number rather than a comfort number. A 26 kg leaf travelling at 0.7 m/s carries ½ × 26 × 0.7² = 6.4 J of kinetic energy. The cap that applies to power-operated landing doors is 10 J, which that leaf reaches at 0.88 m/s. Heavy clad leaves get there sooner than the drawing suggests, so the mass on the drawing should be the finished mass, coating and hardware included, not the blank mass.

Roller load is the other number to check. A leaf whose centre of gravity sits 25 mm off the midpoint between two rollers at 120 mm centres does not load them equally: the leading roller takes 26 × (60 + 25) / 120 = 18.4 kg and the trailing one 7.6 kg. The leading roller wears first, the leaf drops on one side, and the gap opens at the top. Put the hanger bracket so the centre of gravity falls within 10 mm of the roller midpoint, and the pair wears together.

What Ganesh runs for landing door leaves

Landing door leaves, returns and frame sections are cut on the 12 kW fibre laser with the 40 ft × 16 ft bed, which takes a 900 mm × 2,100 mm blank and its roller and gib holes in one pass. Folding runs on the 200 T, 5-axis CNC press brake with the 4,450 mm bed, one programme per part number so the stile angle repeats from release to release. Where a leaf is stainless faced, the die needs a protective film and lower tonnage to keep the grain unmarked, and that is a tooling decision made at quotation.

Coating is where the gap allowance is won or lost. Every frame and leaf goes through seven-tank pretreatment, then powder in the 18 ft × 14 ft booth with the gibs, roller faces and mating edges masked. Film thickness is checked with a DFT gauge on each significant face and adhesion by cross-hatch to ISO 2409 on a coupon from the same batch, which is the evidence a lift installer asks for when a door edge shows a witness mark six months after handover.

The elevator parts range covers door leaves, frames, sills and counterweight frames, and the rest of the family sits under the elevator components hub. The panel side of the same problem, where the skin thickness and the fold return decide flatness before alignment even starts, is covered in the elevator car door panel design guide. The bending tolerances and inspection article sets out how the stile angle and the leaf squareness are checked at the machine.

What to put on the landing door drawing

1. Finished leaf size and the thickness, with the grain direction noted if the finish is visible.
2. Meeting-edge gap and leaf-to-frame gap as finished dimensions, with the coating system and nominal DFT beside them.
3. Flatness as mm per metre, with the measurement method and the condition (after coating).
4. Hanger mounting holes with their position from the leading edge, and the permitted centre-of-gravity offset.
5. Sill groove and gib dimensions, including the debris relief and the bottom clearance.
6. Masking schedule: gibs, roller faces, mating edges, earth points and any tapped insert.
7. Mass of the finished leaf, since the closing-energy and roller-load checks both start from it.

The quote request route takes the drawing and returns the flatness capability, the fold sequence and the coated-gap allowance with the price.

When alignment cannot be adjusted out

Three situations are outside what a door set can absorb, and the honest answer is a site fix rather than a drawing change.

The first is shaft plumb beyond the hanger's ±15 mm of travel. If the frame has to be packed 20 mm off the wall to bring the track level, the landing needs a survey before the next door is hung, because a 20 mm packer changes the frame-to-wall gap and the architrave.

The second is a sill cast or set out of level by more than 3 mm. Grinding a sill flat on site removes the groove depth and the gib then has nothing to run in; the sill has to come out.

The third is a leaf that is twisted rather than bowed. A twist is locked in by the fold, and site force either springs back or cracks the powder along the fold line. That leaf goes back for a replacement, and the drawing needs the stiffener pattern and the grain direction reviewed before the next batch.

One more limit belongs on the record: fire rating. Where a landing door carries a fire rating, the leaf construction, the intumescent seal and the hardware are part of a tested assembly, and we build to the released drawing and coating specification without issuing fire test certificates. The alignment numbers above still apply, but no slot, gap or stiffness change is available to fix a fit problem once the assembly has been tested.