How Flush Door Shutters are made - Insight of Door Factory

Dnyan Deshmukh

Honorary Member
Staff member
Sep 7, 2017
How Flush Door Shutters are made - Insight of Door Factory

Before proceeding to how flush door shutters are made inside the factory, first take a look at the specifications given in IS 2202 Part 1 for making of it.

Stiles and rails should be of minimum 45 mm and shall not exceed by 75mm in width. Both should be of hard wood given in group 2A and group 2B.

The suitability of timber for stiles, rails and lipping normally based on screw holding properties of timber.

Blockboard – Wooden strip filled to make core of shutter shall be of single species and should not be more than 30mm in width. These strips may consist of pieces of small lengths placed end to end with the end joints staggered.

Moisture content in wood used for manufacturing door shutter shall not be more than 12%

In case of Particle board or medium density fiber (MDF) board core with blockboard, the width of blockboard constructed shall not be less than 150 mm from inner edge of the stile on either sides.

The Rails shall be made without any joint.

The Stile shall be made with maximum one finger or scarf type joint as per following details;

  • Joint shall be located between 300 to 500mm from centerline of the door.
  • The joints to both stiles should be located diagonally opposite to each other.

IS Code also state for Lock arrangement in shutters, it says;

Shutter shall be shop prepared for taking mortice locks or latches as may be agreed to. Shop preparing the door with mortice holes for lock fixing shall be done only when desire, suitable block of wood may be provided for fixing the hardware, in absence of specific requirement, the size of block shall be preferably corresponding to maximum size of lock covered in IS 2209.

All above are the basic requirements.

In India, Now days all solid core type flush door shutters are made up of scrap pine wood completely.

Pine is not a hard wood but still it is used for complete construction of shutter due to its cost effectiveness.

The pine scrap wood is dumped at factory via trucks, the pine wood received is generally 2 to 4 feet long.
Pine store at factory.jpg

After receiving the wood, it is processed under the seasoning chamber to reduce its moisture content and make it below 12%. Generally, wood is made to complete dry condition in the seasoning chamber.

Seasoning Chamber.jpg

After removing the moisture to desired level, the pieces of pine wood then stacked outside to make it in sizes required. Wood tend to deformed in shape when the moisture level in wood changes and also it does get cracked after drying.

Sizing of pine.jpg

After sizing it to required level, it is stacked near machine and this is used for making blockboard and framing of door shutter.
Block board stacked.jpg

As the wood is scrape, it will be in size from 2 to 4 feet and height of the shutter is normally around 7 to 8 feet. Those pieces of wood then joined together by making finger joints.

Before making the stile and rails, the wood goes through the planner and finger joint making machine.

Below is the photo of planner which makes the wood in uniform thickness.
Planner 2.jpg

Planner 1.jpg

After this, finger joints are made on each piece of wood
finger joint 1.jpg

finger joint.jpg

A wood just passed through the machine showing carving of finger joint on it

Fingered wood.jpg

Those pieces of wood then joint together with high strength glue adhesive to make a long stile and rail on a steel frame structure where straightness of wood is ensured
stiles for jointing.jpg

stiles joint machine.jpg

Jointed stiles.jpg

After construction of stiles and rails, a frame structure is made out of it of desired length and width. The right angles and dimensions of frame are checked at the time of making of it
Frame Making.jpg

The jointing of the frame is done by using a stapler pins around 3 to 4 mm, at each joint 2 pins were installed using pneumatic stapler machine which works on the air pressure. Stapler pin only works on soft wood, in case of hard wood cotter pins need to be installed at each joint. Cotter pin lead to breakages in soft wood as it wont take much pressure or due to its softness.

Below is the phot of stapler pin
Stappler pin.jpg

Below is the photo of pneumatic stapler
Stapler machine.jpg

After making of frame, it is then placed on a levelled surface of plywood or metal sheet and as per the design, either blockboard or combination of blockboard and MDF board or complete MDF board is made inside of it base on the requirement given.

Below is the photo where blockboard is made inside the frame, blockboard is made using pine strips of not more than 30 cm in width. The workmen fits the stips inside the frame by ensuring joints of strips get staggered in installed pieces. After filling of blocks in it, the small pieces of wood inserted at 2 to 3 places to make the fill tighter in it.
Blockboard filling.jpg

Photo showing completed blockboard filling inside of frame
Blockboard completed.jpg
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Dnyan Deshmukh

Honorary Member
Staff member
Sep 7, 2017
After construction of door internal structure, it is then shifted further for next layer of treatment.

The wood is secured inside using a core.

Core is a flat sheets of wood, they are made in a same way like when we sharpen the pencil the layer of wood get out in thickness as per the setting of sharpener.

Commercial plywood is also made up using this core material and veneer on top of it with different chemistry of adhesive.

The species of wood used to make core are “Poplar” also known as “pipal”, “pimpal” and “eucalyptuses” also known as “Nilgiri”.

The farming of those trees mostly done in Gujarat and Haryana, this is the basic wood used in manufacturing of plywood.

Below is the photo of sheet made from poplar

Poplar 1.jpg


Polar is ran through a machine, which have roller drum inside of it, and flowing adhesive namely phenol formaldehyde synthetic resin. The poplar gets coated with adhesive when its pass through it.
adhesive appliaction 1.jpg

adhesive application.jpg

After applying adhesive on core, it is then laid near to a hot press machine on a steel plate in required layer as specified to manufacturer.

Core Laying.jpg

Laid sheets of core then joint together with the help of stapler as shown below
Core Stappling.jpg

Then the constructed door internal structure is slipped over it carefully (the assembly is fitted without glue so there are change of getting disturbance if not handle with care).
Frame put on core.jpg

After pushing the frame on the top of core, the diagonals were crossed checked, to ensure frame is placed correctly without any deformation. Generally this is done with a rope which have not at specified length.
Diagonal check of frame.jpg

After placing of frame and checking for its correctness, poplar sheets are laid on top of it in same way.
core Top laying.jpg

In this way door shutters are prepared in numbers equal to number of slots available in Hot press machine.

Veneer is also put on top of core wherever it is required or is specified in requirement.

The Hot Press machine is consist of Hydraulic cylinders at bottom, which make pressure on plates to required level base on design.
Hydraulic Cylenders.jpg

It consist of a control panel, where press time, temperature and pressure is monitored and set for each batch base on the design
hot press.jpg

Once all shutters are ready they are slipped into the frame of hot press machine one by one along with steel plates at top and bottom and pressed in the machine at required pressure
Doors in hot press.jpg

Hot press machine make all steel framing heated with pipes from which a hot oil is passed. The pressure of oil is monitored via gauge installed in pipe which circulate oil in whole system.
hot press gauge.jpg

During the process of heating, Chemical reactions form in adhesive applied on core (poplar sheets). At the high temperature, it is a 3-dimensional network, which is typical of polymerised phenolic resins. The high crosslinking gives this type of phenolic resin its hardness, good thermal stability, and chemical imperviousness

Heat temperature generally ranges from 70 to 120 degree base on design and time of press if generally between 15 to 20 minutes, gain base on design.

After completion of pressing, hydraulic cylinders are lowered and door shutters are unloaded on other side of hot press machine. Same process goes on until production of day’s work is completed.

The shutters which comes from hot press machine, may have undulations and some sort of deformities in its length and width.

Those shutters are then moved to a cutting machine where its edges are cut into a straight line as per the dimensional requirement.
Shutter cutting machine.jpg

Shutters are sized on above machine and made ready to go for next step
cut shutters.jpg

Photo of scrap left after sizing the shutter
Scrape after shutter cutting.jpg

After this door shutter then goes to a sanding machine where, undulation on faces of shutters are grinded out to make it absolutely plane surface.

After construction of door shutter, the application of decoration is done on top of it, either in cold or hot pressed machine.

Material used to make it décor;



PVC sheet (plastic door)

Some doors are used without it by making direct paint application on top of it.

What is important, you should mention to manufacture when you order a flush door shutters.

You can refer to specs written at top of this post.

The lock block should be put in frame at lock level on both side stiles, lock block is usually of 3” wide and 18” in height.

Lock block will ensure no damages to shutter and its strength during installation of mortice lock.

There should not be any gap between pine filling (blockboard).

How you can check the shutters received are hot pressed.

You need to unwrap the one shutter from a lot received, if the laminate comes out easily – then its not hot pressed.

If laminate comes out in small pieces and required more efforts – it is hot pressed.

If you do not find any signs of water / moisture inside the core / blockboard – then it’s a hot pressed.

Do check moisture level in wood – it should be less than 12% if its hot pressed.

What are the test done on flush door shutters as per IS Code Specification;

Dimension and Squareness test

General Flatness Test

Local Planeness Test

Impact Indentation Test

Flexure test

Edge loading Test

Shock Resistance Test

Buckling Test

Slamming test

Misuse test

Varying Humidity Test

End Immersion Test

Knife Test

Glue Adhesion Test and

Screw Withdrawal Test