Aluminium Profile Sliding Door 40 Series 8 mm Slot for Machine Enclosures

OEM / ODM Available Free Sample Available Material declaration, RoHS and REACH on request; guard assessment is the machine builder's scope

Sliding door leaves framed in 40 series aluminium profile for machine enclosures. Top hung or bottom rolling, captive bottom guide, brush or EPDM seal, supplied as a cut list with the rail and stops.

Wholesale Price Quoted per door set against leaf size, rail section, seal and quantity per piece

Material	Aluminium
Alloy Grade	6063-T5
Temper	T5
Section Size	40 x 40 mm leaf frame, 40 x 40 rail minimum, deeper rail above 1.2 m span
Slot	8 mm slot, M6 T-nut fixing, four faces
Length	Cut to the door drawing; leaf and rail supplied as one cut list
Tolerance	Cut length +/-0.5 mm; rail straightness to EN 755-9; guide position set on assembly
Surface	Mill finish / clear anodised / black anodised
MOQ	No fixed minimum; priced per door set
Lead Time	2 to 3 weeks for mill finish, plus about a week for anodising
Loading Port	Shanghai / Ningbo
Supply Ability	Leaf frame, rail, guides and stops cut and kitted from one drawing
Payment Terms	T/T 30% deposit + 70% before shipment \| L/C at sight
Trade Terms	FOB \| CIF \| EXW
Certifications	Material declaration, RoHS and REACH on request; guard assessment is the machine builder's scope

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Sliding leaves on a 40 series frame. The track is where the design decisions concentrate — everything else is a rectangle.

01How wide does the leaf have to be for a given opening?

A 40 series aluminium profile sliding door is not sized from the opening, it is sized from the opening plus the overlap. The leaf has to travel past the frame on both sides, or it leaves a gap that no seal will close.

Configuration	Leaf width	Net opening	Overlap per side
Single leaf, opening 1000 mm	about 1120 mm	about 1000 mm	about 60 mm
Two leaves bi-parting, opening 2000 mm	2 x about 1060 mm	about 2000 mm	about 60 mm each
Single leaf with a full perimeter seal	opening + 2 x 80 mm	the opening	about 80 mm, to give the seal somewhere to land
Leaf running inside the frame line	opening + 2 x leaf thickness + clearance	the opening	n/a, the leaf sits in a pocket

The fourth row is the one that catches people out. A leaf that runs inside the frame line, in a pocket, needs the frame to be deep enough to accept it, and the pocket has to be clear of anything else in the slot. It is the neatest arrangement and the one that needs the most planning, because the pocket cannot be added later.

On a two-leaf bi-parting door the net opening is not the sum of the leaf widths. Each leaf has to overlap the frame at its own end and the two leaves have to overlap each other at the centre, so a 2000 mm opening needs leaves of about 1060 mm, not 1000 mm.

02Why does a top hung rail sag, and when does it matter?

Because a top hung door puts the entire leaf weight into a rail that is spanning, not sitting on a support. That is a bending problem, and bending deflection goes with the cube of the span — which is why a rail that looks fine at 1 m is unacceptable at 2 m.

Take a worked example with the assumptions stated, because the arithmetic is the useful part. For a central point load, the deflection of a simply supported rail is delta = P x L^3 / (48 x E x I), with E for aluminium at about 70 000 N/mm2. Assume a 40 x 40 four slot section at I of about 8 cm4 — an assumed value, check it against the section data sheet, because the conclusion does not change much if it is 10 instead of 8.

Load P (assumed): 300 N, a 30 kg leaf treated as one central load
Span L: 2000 mm
E, aluminium: 70 000 N/mm2
I (assumed, 40 x 40 four slot): 80 000 mm4
Deflection: 300 x 2000^3 / (48 x 70 000 x 80 000) = about 8.9 mm
Same load, depth doubled: I up about 8 times, deflection about 1.1 mm

Nine millimetres of rail deflection on a 2 m opening is not a cosmetic issue. The leaf rides down into the sag, the rollers load unevenly, and the leaf binds at one end of the travel — usually the end where it needs to open fully. The fix is not a thicker wall in the same depth, it is a deeper section: doubling the depth raises I by roughly eight times for the same mass, which is the whole reason 45 x 90 and 60 x 60 sections exist in this range.

A practical rule that comes out of the cube relationship: keep a 40 x 40 top rail under about 1.2 m of unsupported span. Above that, step up to a deeper section, or put a mid support in — a single extra bracket at mid span cuts the deflection by roughly eight times, which is cheaper than a new section.

03Top hung or bottom rolling?

Both are used on machine enclosures and they fail differently. The choice usually comes down to floor condition and to whether the door may be lifted off.

Top hung

Floor stays clear, so nothing to trip on and nothing to clean around
Swings out at the bottom if the guide fails, which is the safety concern
Rail carries the full leaf weight, so span is the limiting factor
Needs a bottom guide at both ends of the travel
The usual choice on a machine enclosure with a good floor

Bottom rolling

Weight goes straight into the floor, so span is not a structural problem
Floor must be flat, and swarf or a cable will stop the door
Needs a top guide to keep the leaf upright
Easier to make a wide, heavy leaf work
The usual choice for a large or heavy enclosure door

The safety point deserves its own sentence: a top hung leaf that can be lifted off its track is a guard that can be removed without a tool. On a machine guard that is usually unacceptable, and the bottom guide is the part that prevents it. A guide that runs in the slot and is retained by a bolt, rather than a simple roller, is what makes the door non-removable.

04How much seal can a hand-operated door afford?

There is a direct trade between sealing and effort, and it is worth doing the arithmetic before specifying a full perimeter seal on a door that somebody has to slide by hand.

Seal	Friction	Sealing performance	Use when
Brush strip	Low, and almost independent of gap	Moderate, good against swarf and draught	The default on machine enclosures
EPDM bulb, light compression	Moderate	Good against dust and coolant spray	Where coolant or fine dust must be kept in
EPDM bulb, heavy compression	High, and rises steeply as the gap closes	Very good	Where the door is clamped shut, not slid freely
No seal, overlap only	Very low	Poor	Guarding only, no process containment
Labyrinth overlap, no elastomer	Low	Moderate, and no wear part	Hot or dirty environments where elastomer degrades

The number that matters is not the friction force in new condition, it is the force at the end of the travel where the leaf enters the last 100 mm and the seal starts to compress. That is where a door that slid easily becomes a door that needs two hands. If the seal is mandatory, reduce the compressed length — seal the perimeter of the opening rather than the whole travel, so the leaf only compresses a seal where it is actually closed.

05Where does the interlock go on a sliding door?

Sliding doors are actually easier for interlocks than hinged doors, because the motion is linear and the target approaches the switch along a predictable line. The mistakes are about partial opening and about reach.

Body on the frame, target on the leaf. Same principle as a hinged door, and for the same reason: the cable stays still.
Align the switch to the direction of travel, so the target enters the switch head axially rather than sliding across it. A tongue switch approached sideways wears its head and goes out of tolerance.
Assume the leaf will stop part way. A sliding leaf can be left 50 mm open, and a switch that reads “closed” at 50 mm open is not guarding anything. Use a coded or RFID switch, or a tongue long enough that partial opening still breaks the circuit.
Check the switch at both ends of the travel, not just closed. Some switch bodies foul the leaf at full open.
Do not use the end stop as the switch target. The stop is a structural part and it moves when the door is slammed.

As with hinged doors: we supply the profile, the track and the frame. The interlock and the guard assessment are the machine builder’s scope, against the machinery safety standard that applies to that machine.

06What usually goes wrong on the first build?

Symptom	Cause	Fix
Leaf binds at one end of the travel	Rail sag, or the rail is not parallel to the bottom guide	Deeper rail, a mid support, or shim the rail to parallel
Leaf rides up and comes off	Bottom guide too short, or the guide is a roller rather than a captive block	Captive guide block spanning at least the leaf depth
Seal drags and the door needs two hands	Seal compressed along the whole travel instead of only at the closed position	Seal the opening, not the track
Interlock reads closed when the door is part open	Tongue too short, or a non-coded switch on a leaf that can stop anywhere	Coded switch, or a longer tongue
Leaf rattles when the machine runs	No catch, so the leaf moves in its clearance	A latch or a magnetic catch at the closed position
Panel cracks at the corners after a few months	Panel fixed rigidly all round, so it takes the frame deflection	Clearance in the panel groove, and fix on one edge only

The last one is not a door problem but it shows up on doors first. A panel held rigidly in a frame that deflects will crack at the corner, and the deflection that matters is the rail sag from section 02. Fixing the panel on one edge and leaving clearance on the others is what stops it.

07What to check before ordering

A leaf running in a pocket needs the frame depth decided at drawing stage. It cannot be added to a built frame.

Sliding door checklist

Opening size, and whether the leaf runs outside the frame or in a pocket
Leaf width including overlap on both sides
Top hung or bottom rolling, and the floor condition if bottom rolling
Unsupported rail span, and the section depth that span needs
Bottom guide type, and whether the leaf must be non-removable
Seal type, and whether it compresses along the travel or only at the closed position
Latch or catch at the closed position
Interlock type, target position, and how partial opening is detected
Panel material, thickness, and how it is fixed for clearance

08Questions from enclosure designers

Related sections and categories

Browse Door and Window Elements, Panel Installation Elements, 40 Series Aluminium Profiles, or see the 40 x 40 mm four slot section for the leaf frame and the 40 x 80 mm six slot section when the rail span needs more depth.

How wide should a sliding leaf be for a 1000 mm opening?

About 1120 mm, so it overlaps 60 mm on each side. With a full perimeter seal, allow 80 mm per side. A leaf that is exactly the opening width will always leave a gap.

Why does my top hung sliding door sag?

Rail deflection goes with the cube of the span. A 40 x 40 rail over 2 m carrying a 30 kg leaf deflects by roughly 9 mm on the assumptions in this page. Keep 40 x 40 under about 1.2 m of unsupported span, or add a mid support.

Can a sliding door be lifted off its track?

A top hung leaf can, unless a captive bottom guide is fitted. On a machine guard that is a safety issue, so the guide has to be a retained block rather than a simple roller.

How much seal can I use on a hand-operated door?

A brush strip adds very little friction. A compressed EPDM bulb adds a lot, especially in the last 100 mm of travel. Seal the opening rather than the whole track so the leaf only compresses a seal where it is closed.

Where should the safety switch be mounted?

Body on the frame, target on the leaf, approached axially along the direction of travel. Use a coded switch or a long tongue, because a sliding leaf can be left part open and a short tongue will still read closed.

Can the door frame be supplied as a kit?

Yes. Send the opening size and the track arrangement and the leaf, the rail, the guides and the stops come as one cut list rather than as separate parts to reconcile.

What to send for a sliding door quote

Opening size and a sketch of the frame it sits in
Single leaf or bi-parting, and the direction of travel
Leaf outside the frame, or running in a pocket
Top hung or bottom rolling, with the floor condition if bottom rolling
Panel material and thickness, so the leaf weight can be estimated
Seal requirement and the process being contained
Interlock type, if already chosen
Finish, and whether the rail is seen
Quantity of doors, and whether the leaves are wanted as a kit with the frame

Send the opening and the frame sketch, not just the leaf. The rail span is set by the frame, and the rail span is what decides whether the leaf will slide or bind.

Send the opening and the frame sketch

Tell us the opening, the leaf direction and whether the leaf runs outside the frame or in a pocket. We will size the rail from the span and quote the door as a kit.

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