Aluminium sections, or profiles, are designed for specific applications
Working with AluminiumAluminium sections, or profiles, are designed for specific applications.
These can include:
architectural systemsresidential systems
partitions
security systems
geometric shapes.
The production of aluminium products relies heavily on machining as part of the fabrication process. Machining is the mechanical operation used to remove material from a workpiece by means of cutting tools which divide, cut, penetrate or shape. Although the bulk of machining operations require the use of machine power to do the work, manual operations such as sawing, drilling and filing are regarded as machining processes. The ease or difficulty of performing a machining operation is called machinability. Machinability is determined by the:
interaction between the tool
workpiece
lubricant
speed or other features of the operation.
Aluminium can be machined on most machines used for metal or wood. It
can also be machined using hand tools such as files and hacksaws. As a general
rule, however, machines must be set to run at high speed and machine
sawblades should be tungsten.
Many aluminium sections are used for office buildings, factories, shops and other business
related sites. Aluminium sections for commercial fabrication would be
used to make items such as:
frames
doors
windows
partitions.
Below are some examples of different sections which make up
Aluminium shopfronts
Like all products in the construction industry, aluminium frames, windows
and doors must comply with Australian Standards. These standards are
regulations all workplaces and their workers must follow to ensure quality
products and safe work conditions. The relevant standards for aluminium used in residential windows and doors are as follows.
AS 4055 Wind loads for housing
AS 2047.1 Windows in buildings specifications for materials and
performance
AS 1107.2 SAA Loading Code Wind Loads
AS 1664 SAA Aluminium Structure Code
AS 4420 Series window tests
AS 4284 Testing of building facades
Aluminium is used extensively in the construction industry because of its:
appearance
corrosion resistance
formability
finishing variations
high strength to weight ratio.
Shopfitting uses aluminium for a variety of applications. Uses include:
internal fitments eg partitions and show cases
trims such as ducted skirtings
shopfronts.
Finishes on aluminium:
Aluminium comes in a range of finishes.
The standard finish is mill finish. This finish is the natural surface finish achieved when the material is forced through the extrusion process. The surface of the material is a clear aluminium finish showing die marks.
Aluminium extrusion can have three different finishes applied.
1. Chemical brightening.
2. electrochemical colouring known as anodising
3. applied finishes such as powder coating and spray painting
4. mechanical finishes such as buffing and scratch finishes.
Chemical finishes:
Include etching and bright-dipping process.Etching process is a chemical process to give a finish of silvery white and frosted appearance. This is done by applying a caustic solution to the aluminium surface. The aluminium profile is passed through a hot bath, rinsed, and then immersed in a chemical bath that removes undissolved alloy and other surface impurities. The process is completed by further rinses.
Bright dipping process is a specialized kind of chemical-finishing that yields a bright, mirror-like finish. The profile is first polished and then anodized to both protect the surface and apply desired color. Aluminium can be bright dipped without being first polished. This reduces the cost of achieving a bright appearance. But for that special finish the extrusion should be polished first.
For more in formation follow the link: chemical finishesAnodising:
Is an electrochemical process that thickens and toughens the naturally occurring protective oxide layer on the surface of aluminium. The tough finish is the second hardest substance known to man, second only to diamond, but because the layer is thin it can be scratched through by sharp protrusions. The anodic coating is part of the metal, but has a porous structure which allows the different dyes to soak into the surface producing coloured anodizing. Take care as the colour can be easily washed out if it comes in to contact with caustic material that included cement and lime products as well as dishwasher detergents.
For more in formation follow the link: Anodised aluminiumPowder coating and painting:
Paints and lacquers may be applied by brushing, rolling,pouring, flow coating, airless or hot spraying, electrostatic coating with liquid or powder, or immersion.
The method chosen depends upon the needs and requirements for efficiency, appearance, uniformity of the coating, and extrusion shape. Single coat finishes are used for decorative purposes in items that need to withstand on little stress or human interaction and only mild chemical contacts. Multi-coat finishes are best used for exposure to moisture, aggressive chemicals or high mechanical stresses.
For more information follow the link: CoatingsMechanical finishes:
This includes polishing and brushing. These techniques remove surface imperfections and produce a uniform appearance and allow for additional treatment in order to attain various finishes for decorative purposes.
For more information follow the link: Mechanical finishesJoining aluminium sectionsBefore joining aluminium there are some important processes you will need to follow before
joining the sections. They are processes that deal with:
quality assurance- sizes are correct etc. all sections are available
OH&S issues PPE and duty of care
any special protective equipment that may be used fro material and personal
selecting and checking the tools for the job. Tools sharp and set up properly
types of aluminium sections. Are profiles compatable.Now that you know how to identify the correct sections and their uses,
you will need to know how to join these sections.
Mitre joints
Mitred bull joints are used to construct corners of sashes, flywire screens
and security screens. They are cut at 45 and are held together by a corner
stake internally.
Mitre cutting of corner joints offers a number of advantages, including
simplicity of preparation and neat appearance. The accuracy of the mitre
cut can only be achieved with first class sawing equipment including
facilities for clamping the workpiece during cutting. Some form of corner
stake is necessary to keep the joint in alignment.
Fitting mitre joints
Mitre joints can be secured a number of ways, including:
serrated stakes
pop rivets
dimpling
screws.
The serrated stake is designed to be a driven into each section without
distorting the walls. However, care must be taken when inserting the
corner stake into the frames as misalignment can result in dinting the
aluminium section. Screw or pop rivet fastening is necessary to secure the
joint.
Sometimes small projections are provided inside the frame section which
shear off as the stake is driven. Screw or rivet fastening completes the
joint.
In some cases dimpling is used to secure the joint. While this can be done
manually, a more positive result is achieved with a press operation. Stakes
for this method of jointing can be aluminium, nylon or a plastic material
specially designed with recesses that accept the dimpling and force the
connection into a tight joint.
The mitre joint can be secured by screws where flutes are provided in the
frame section. This is most effective where the frame is firmly set around
the base material, such as fitting glass in a sash. Where the frame is not
supported or restrained there is a tendency for the joint to ride up as the
screw is tightened and all clearances taken up, resulting in an untidy joint.Socket joint
This joint is made up of plain channel or box extrusions which have no
provisions for other forms of assembly. A spigot is fixed to one member
and the joint is completed by fixing the other member to the spigot.
Mortice and tenons
The members are machined to provide holes and tenons in corresponding
positions. The tenon is riveted over after assembly. This method is used to
frame sections under 50 mm and grille fabrication.
Screw and Spline joint
Screw grooves and self-tapping screws are most commonly used for
corner jointing and provide economical, secure and reliable fastening. The
advantages are that the joints can be assembled quickly and pulled up
tight. The end profiles are punched, milled or notched to provide a well matched
joint.
Besides normal strainless steel raised head screws, bolts and nuts, and a variety of self-tapping screws are commonly used in aluminium constructions. This type of screws are often very useful in assemblies with extruded profiles.
From left to right:
Sheet screw with fixed washer
Facade screw with sealing element
Self-locking screw with flange
Slotted round-head screw
Hexagonal-recess screw with shallow head
Cylindrical self-tapping screw with flange
Cross-head stud screw
Snap-in assembly
Aluminium products are designed and developed to finished product
standards. This means that any attachments or other sections or fittings
must use continuous extruded flutes without visible fixings. Designs are
such that the article snaps over a lug and clips into its final position.
More information regarding the joining of Alumimium can be found at: JoiningPreparing for joining
As previously explained, it is important you work in a safe environment
for the health and well being of everyone in your workplace. For this
reason it is essential to wear appropriate safety clothing and equipment.
You must follow all company requirements concerning protective
equipment. These requirements might include wearing:
safety boots
safety glasses
ear plugs or muffs
dust masks or respirators
gloves
overalls.
There are a number of different ways of preparing aluminium sections for
joining. They include:
cutting to length - Components must be cut accurately to length after
frame clearances have been allowed. drilling holes - Holes are accurately marked out to take assembly screws.
punching holes - Machines are set up to accurately punch holes for
assembly screws. This method is generally quicker than drilling. cutting for joint - Some sections may have to be cut specially prior to
jointing to allow for other components of a frame. For example, sashes
and doors to fit frames. trimming for fit. - Beads and adaptors may require
trimming prior to fitting.
Tools
The tools you use will depend on the job requirements and the process you
are using. Some of the tools you would use include:
measuring tape/rule, to measure aluminium sections to length prior
to cutting
mallets, to knock sections into place without damage
squares, to check angles
docking saw, to cut aluminium to length
clamps, to hold aluminium sections when using the docking saw
power drills, to be used together with the other power tools in the
preparation and fabrication processes
power routergrinder
air compressor and hoses
power leads.
Some of these more complex tools and equipment are pictured below.
Securing joins
Two of the more common joints used in fabrication are the screw joint and
the spigot joint.Screw joints are commonly used in frame fabrication, whilst spigot joints
are used in door and window fabrication.
Prior to assembly sealant is applied to the abutting surfaces of the joint.
This makes it waterproof.
Self-tapping stainless steel screws are used to avoid corrosion.
Before assembling section of a frame, you mustMeasure sections according to job requirements. Components must
be cut accurately to length after frame clearances have been
allowed.
Select the appropriate aluminium sections. Aluminium sections
cannot be forced to fit other sections If the sections do not fit
together as designed, bruising may appear.
Set out the aluminium sections. Setting out prior to cutting will
determine:
- cutting size of each section
- assembly sequence
- machine operations- jointing methods.Setting out prior to cutting components for fabrication is determined by
the different sections that will be used in its final construction.
You must consider the following factors that can determine section
lengths.
An assembly sequence is required so that you know which sections
are to run through and which sections run between. This will help
you to develop a cutting list.
Which jointing methods you use will determines how the
aluminium will be cut. This will also affect the cutting list.
How aluminium sections are cut to length and prepared for jointing.
This can alter the section lengths if they are filed or shaped to fit.
Remember to use your personal protective equipment when cutting and to
clean off any excess lubricant with a soft clean cloth.
Prepare the aluminium sections for jointing. Depending on the
jointing method, all surfaces must finish flush and without twist.
Jigs and templates will help you achieve this.
A jig can be made from an off-cut ofsection that is to butt into another section.
The off-cut is aligned into position and the holes are marked where the screws are to go.
Securing the joins
After joining sections, the next step is to make sure the joins do not
separate.
When drilling for self-tapping screws, care must be taken in selecting the
correct sized hole to ensure the screw has maximum holding strength.
If spigots on corner stakes are required to join frames together, a screw or
pop rivet fastening is necessary to secure the joint.
Where joints must be waterproof, as is the case in windows and doors, it is
good practice to apply joint sealant to the abutting surfaces just prior to
final assembly. It is important that the surfaces be thoroughly cleaned of
all dirt and cutting oil, as this will prevent the sealant from sticking.
Metal threads are used mainly for securing replaceable hardware items
such as:
locks
pull handles
door closers
hinges.
They are applied into tapped holes and provide excellent fixing where
permanence of thread is required for subsequent re-use.
Where heavy forces are likely to be encountered resulting in pullout
because of thread stripping, it is necessary to provide reinforcing backing
plates to increase the threaded thickness to a minimum of 6 mm.
Pop rivets enable you to attach two items together without having access to the back side of the item. For this reason, they are sometimes called "blind rivets".
POP - Rivets
They come in different lengths and diameters. Most rivets are aluminum, but it's possible to also get steel, stainless steel and other metal rivets.
A pop rivet has a pin up the centre that goes into the pop rivet gun. The gun grabs hold of the pin and tries to pull it through the rivet body. As this is done, the head of the center pin bends out the body and crimps it tight. When done, the center pin breaks off.
When using pop rivets, the rivet should be a snug fit in the hole through the material. The length of the rivet should be such that before crimping, it's sticking out the blind side about 6mm. If using rivets on soft material, you should use a washer on the blind side to spread out the load (there are special washers for this).
There are a range of different head types to suite most finishes. Aluminium heads can be annodised to match the finish on the aluminium section being used.
Steps involved in inserting pop rivets:
Pnuematic guns are available to assist the riveting process.
For more information relating to rivets go to: Blind POP RivetsCleaning tools
To maintain tools in their best condition, it is important that you clean
them after use. Dirty hand or power tools can affect the quality of the job.
Storing tools
As blades and cutters used to cut aluminium are usually tungsten-carbide,
it is important to store them safely as the slightest knock can damage teeth
and result in uneven cutting.
Cleaning the work area of all waste material
Rack longer off-cuts neatly and safely to prevent them toppling
over and causing a possible hazard.
All small off-cuts should be cleared from machines and
workbenches so the workplace is left clean and safe.
As aluminium can be recycled, all off-cuts should be placed in
containers labelled Aluminium Only.Serrated stake
Socket Joint
Mortise and tenon joints
Screw and spline
Snap in assemblies
Safety glasses
Hearing protection
No rings or watches
No loose cuffs
Steel capped work shoes
protected hair
When cutting aluminium always wear a full face shield
Aluminium, cut off saw with extension table and stops
Spring pins
Spigot
Door stile
Door rail
S.S. Screw
Electric drill
Off cut jig from sill or transom
Mullion piece
Seal the joint with silicone or other sealer before inserting the screws.
1. Select the right size drill bit and drill the hole
2. insert the rivet into the rivet gun.
3. insert rivet in hole making sure it penetrates both pieces.
4. squeeze the gun until the pin pops off.