Electroplating & Anodising:

Electroplating:

Electroplating is a process in which a metal which can be resistant to corrosion (e.g. Zinc) will coat a metal that corrodes (iron/steel). The aesthetic finish of this will depend on the coating product applied, and uses the process of electrolysis to coat a base metal..

Electrolysis works with a positive anode and a negative cathode, and metals with positive and negative will attract to their oppositely-charged anode/cathode. The anode is typically what you're trying to plate.



Anodising:

This process can make a mterial more durable and scratch-resistant. Similar to electroplating, it works by containing a sulphuric acid solution which is the electrolyte, the aluminium as an anode and lead as the cathode, an electric circuit is completed through the solution, where ions then attract so negatively charged ions will attract to the aluminium for it being a positively charged anode. These ions will cover the anode in layers, and between layers dyes may be added to give the product a coloured aesthetic quality. After the layers have been applied, the process is then completed by having the aluminium sealed with a laquer.

Ferrous metals:

Iron:

Iron is made from its original ore (known as magnetite) this in result leaves impure iron, known as slag. This is removed from the furnace leaving a soft grey metal when it's cooled. Iron is most likely to be usually combined with carbon to give it a better strength, forming steel. The carbon levels can be monitored by adding oxygen to it.

Steel:

Steel is made from a combination of both Iron & Carbon, carbon is used in making this because it provides strength and as said previously, the carbon levels are monitored by adding oxygen while the iron is being heated. Steel may have a variation of carbon content so it can be used for separate purposes. Be that it may, however. The more carbon content there is, the more brittle the steel could become. Steel is more oftenly used though because it is more resistant to corrosion.

Carbon:

Carbon is one of the most common elements found in a wide variation of materials and objects, it can make up materials like coal or diamonds using carbon sheet layers in complicated forms. Carbon can affect steel's strength and hardness but also may cause brittleness.

Iron & Carbon:

Iron is generically soft and ductile which makes it less useful, however it is commonly used because it's extremely cheap and can be combined with other metals to form alloys with certain properties. Carbon is added in with iron to change its properties, and this is what creates steel itself.

Carbon may increase hardness, but may also reduce the toughness of the material. However, with certain metals you may anneal them which means to treat the material by heating them, increasing the strength and hardness.


Extra notes:
Annealing works by heating the material until it is very hot, and then letting it cool slowly to change the shape of the molecules within the material.

Ductility (tensile strength) is testing the tensile strength by having the material pulled to see how much tensile strength it holds as it stretches until its breaking point where it breaks apart.

Quenching is when a material is heated to a high temperature, then quickly cooled by being placed in water causing it to increase toughness. This puts the material in its hardest state.

Tempering works by heating the material in order to reduce the hardness of it, but it does in this process decrease the brittleness of the material. It is usually done after the process of quenching.

 Hot dip galvanising: the material is coated in a thin layer of zinc to prevent corrosion.
Chrome plating (like galvanising) the material is coated in chrome to prevent corrosion.

Tanalising process:

Tanalising is a type of wood seasoning involving having wood be impregnated with 'Tanalith E'.
Tanalith E is an Eco-friendly wood preservative. It is impregnated into softwood timbers during the wood seasoning process, and the chemicals become physically fixed to the timber which leaves them unable to be removed. Tanalising however will reveal a slight green tinge in woods.

Tanalised timber does not need any treatment such as varnish, but it will subdue to weather over time and fade to a grey colour due to sun & moisture. However, the use of the preservative will still continue to be in effect.

Being Tanalised, wood is resistant to wood decay and insects wherever the timber itself to be used.

Tanalising process:



1. The Tanalising process begins with having timber placed in the treatment cylinder in which a vacuum is created within the cells of the timber.

2. The cylinder is then filled with the preservative treatment.

3. Hydraulic pressure is applied, forcing the preservative deep into timber cells. Roughly about 5mm.

4. After a set period, determined by the species of the timber currently being treated and for its planned use, the treatment solution is taken back into storage and a final vacuum extracts any excess treatment solution from the timber.

5. Low pressure inside the timber draws in the surface solution when vented to the outside atmosphere. The timber is then left for an established period for the fixation of the preservative to occur completely.

Wood joints:

Mortise & Tenon joints:

There are Mortise & Tenon joints which are wood pieces cut specifically in shape for a number of wood pieces to combine. They're cut specially to give them more surface area for glue since the glue provides the best point of strength in the product. You can see in the picture how the wood joins to the corners, allowing more glue to be spread out providing stronger points in the product itself.

Dowel joint: 

Dowel joints join products together by using a dowel and keeping them in line. They ensure accuracy, and have a grooved surface to allow glue to flow easily along it, allowing the joint to combine from the dowel easily and very effectively.

Dove tail:

Dove tails are cut specifically to slot together and spread glue out over a further distance, and make a very clean fit when together. It allows it to resist forces applied to the joints.

Lapped:

Lap joints are good for they increase the area being glued to keep the product itself more strengthened.
They're also neater for they show less end grain.

Finger joints:

Finger joints are good for they are similar to Dove tails, yet easier to make due to the less odd angles.

Steam Bending:

Steam bending is a woodworking technique where wooden veneers are laid together and heated in a steam box by steam that's brought in by heated water.
 The moisture from the steam, along with the heat allows the wood to become flexible and bend around a mould to create a shape of the manufacturer's desire.
The moulding is usually made by clamping the strips of wood to a jig former mould.
Steam bending uses low energy in order to combine wood layers, it doesn't need to wait for the expense of glue drying for the layers to combine together for the desired shape.
However, this process will slightly weaken the wood which may leave residual stresses which can cause the wood to "break".
The moisture leaves the steam box by a drip pipe, where the steam may condense into water and drip out itself.

Moisture levels also need to come into consideration, for wood is made out of fibers. If moisture gets between them, the wood will begin to swell and possibly split due to its structure. You can see the mesh-like fiber structure in the picture of wood under a microscope. If wood gets between these they will expand which is the "swelling" of the wood, which may cause the wood's fibers to split.


The wood itself will also need to be considered when moulding, you'll look for woods with very straight grains, otherwise they're not likely to bend the way you want them to.

Moisture may also be removed from woods with wood seasoning processes. (Refer to the wood seasoning post I made on Thursday. 7th November 2013).

Manufactured Boards:

Hardboards are a very special type of timber, for they have no moisture levels at all. Which prevents them from warping or defecting in most ways possible.

Hardboard:
Also known as HDF (High-density fiberboard).
Made of compressed wood fibers. It will not split or crack.
Mainly found in 3mm thickness.



Plywood:
Made from layers of thin sheets of wood veneer. The layers are glued together.
Plywoods bind resin and wood fiber sheets together to form a cross-grain.
This reduces the tendency of splitting in the wood, and reduces expansion/shrinking.
Sold in 3mm, 6mm, 9mm, 12mm, 15mm & 18mm thickness.

Blockboard:
Made up of wooden block strips. The blocks are placed edge-to-edge and compressed between two wood veneers, this is then glued with high pressure.
Blockboard glue is mainly interior glue, therefore blockboard is not used for outdoor products.
Mainly sold in 30mm thickness.



Chipboard:
Also known as particle board.
Uses wood veneers to look attractive.
Lightest & weakest type of fiberboard.
Comes in different grades of densities.
Sold mainly in 12mm & 18mm thicknesses.


MDF (Medium density fiberboard):
MDF is made of broken down woods (which makes wood fibres).
These wood fibres are combined with a wax & resin binder, made into panels under high temperature and pressure.
Generally denser than plywood.

Sold in 3mm, 6mm, 9mm, 12mm, 15mm, 18mm thickness.

Wood drying! (Wood seasoning)

So today, we studied the types of wood drying, also known as wood seasoning. (NOT LIKE THE SEASONING YOU PUT ON YOUR PIZZA) - Mr. Simmons.

Air drying:
This is done by exposing the woods to a continuous air flow which will permeate through the timber and at a rate demoisturize the timber. Unfortunately, the demoisturization cannot be completely controlled with this method, and will depend on the climate it is done in. For example, if done in cold climates it may be extremely slow. Moisture loss however, can be controlled better if the timber is coated in a substance that is impermeable.

Kiln drying:
This is down by heating the timber, air circulation is brought in to make the drying process more effective. Unlike air drying, Kiln drying has advantages such as killing living organisms in the timber such as fungi. And Kiln drying may also be done regardless of weather conditions which makes it more effective as it can be done during the times in which air drying cannot.

 

Extended: Wood defects.

If drying processes are not done properly, the woods may have certain defects which can reduce the quality of the timber, such as:
Warping, cupping, twisting or other forms of the woods changing shape due to the woods shrinking.
Rupturing of the tissue, split ends or collapse. This may occur when the timber is dried unevenly.