Electroplating and Anodising

Electroplating
Electroplating is the process of coating a metal, often for aesthetics or protection against corrotion.

The metal object to be elctroplated is placed on a negatively charged dipping rack. This runs a negative current through the metal object allowing positively charged bathing solutions to stick to the base metal therefore plating them.

The positive charge of the bathes come from a cathode submersed in the bath allowing electrical current to run through the metal rich solution. (the metal particle carrying the charge). The base metal acts as the anode to which the two opposing charges attract one another and therefore builds up a layer on the surfaces of the base metal.

Typically the most common electroplating metal is chromium. But other include copper, tin and zinc (Galvenising)

 

 

 

 



Multiple baths are needed to plate a metal as the metal first needs to be cleaned of any impurities. The thickness of the plating metal depends on the amount of time it is bathed for and the addition of any Strikes/Flash's used in the solution.

 

 

Anodising

Anodising is similar to electroplating where the negatively charged base metal is subersed in a bath with a positive charged cathode (lead) within it.

The anodising method uses metals similar to the way they are used in electroplating but you can add dyes to the solution as the surfaces of the base metal are often very pourous. These pour in the metal allow the base metal to accept the dye.
Therefore once anodising you need to complete the process with the use of a laquer.

Ferrous Metals

Iron

Iron (Ferrite) is extracted from its ore by using heat. During the extraction process the impurities are removed from the furnish leaving a greyish metal once cooled. Iron is rarely used without the addition of carbon thus creating Steel which is much stronger.

Steel

A combination of Iron and Carbon, Steel can have great toughness depending on the carbon content of the alloy. The higher the carbon content the more tough the steel is but the more brittle. Similarly the less carbon content the less tough the steel is.

By adding another metal to the steel alloy enables more specific properties to be enhanced for example zinc coating makes it resistant to corrosion.

Carbon

Carbon is used in many materials to add properties of strength and ductility. Organic materials that carbon is found in include diamond and coal. The amount of carbon used in a steel alloy varies the strength and hardness; however the addition of too much carbon can have the opposite effect and cause brittleness to the material.

Iron and Carbon

Iron is generally a soft and ductile material, these properties do not make a a very useful material for commercial uses. When carbon is added to Iron the characteristics of the new material (Steel) changes and therefore resulting in a wide range of specific properties.

An increase in the amount of Carbon will result in:

The material becoming harder

Toughness reduces, con become brittle

High Carbon Steel and Medium Carbon Steel can be heat treated to increase Strength and Hardness of the material.

Heat Treatments

Annealing

Quenching

Tempering

Tanalising Process

Tanalising is an environmentally friendly preservation process for timber applied during the seasoning process. It works by impregnating the wood with preservatives such as TANALITH E.

Tanalising wood means that the wood will waterproof the wood, but you still require the wood to be fungi free. So TANALITH E has some preservatives including a unique copper and organic biocide. These are used alternatively to arsenic which is more commonly used in CCA treated woods (Chromated Copper Arsenate)

Tanalised wood does not need any finishes such as varnishes but will tarnish over time to a grey colour due to the weather, sun and moisture. Being tanalised the timber has a distintive green tink to it but also becomes resistant to wood decay and animals.




1. The tanalising process involves placing the timber within a treatment cylinder and creating a vacuum within the timber cells

2. The cylinder is then flooded undeer vacuum with the preservative treaments

3. Hydraulic pressure is then used to force the preservative deep into the timber cells

4. After a dertermained period of pressure (depending on the type of timber and its use), the treatment solution is then pumped back out of the cylinder into a storage tank and the a final vacuum extracts excess solution from the timber

5. Low pressure inside the timber draws in surface solution when vented to atmosphere and the treated timber is left for a period of time for fixation of presvertion to occur

Wooden Joints

Choosing the correct wooden joint for the job at hand is key to the sturdy, final product. The key feature of a wooden joint is to optimize the amount of surface area for the glue to adhere the pieces of wood together.

Dowel Joints- Often used for accuracy, dowel joints are useful and easy to drill adn make. the dowels are most oftenly made out of a hard wood called Ramin and come in a range of widths from  4 to 25mm. Typically pocessing grooved curfaces for glue to adhere.

 

 

Mortice and Tenon- Most oftenly found in furniture, mortice and tenon joints are used in furniture legs where two rails are joined to a leg at each corner. The ends are mitred where they meet inside the leg to create maximun strength in the glue bond.

Dovetail-
Through Dovetail- Often used in the back of drawer, the tapered shape of the finger like pieces prevent the drawer from falling part when an opposite force is applyed. they are not only used for their strength and resistance but also their decorative qualities
Lapped Dovetail- Lapped dovetail joints equally are as strong as the through dovetail joints but are not visable. this is because part of the wood laps over the dovetail. These are most commonly used in drawer fronts

Finger Joints- Also known as Combe Joints, finger joints are a simply fairly easy joint to manufacture as there are not any angles included like the dovetail joint. These joints are ideally suited to industrial situations where it is produced using machine tools.

Steam Bending

Steam bending is a woodworking process by which wood is reshaped with the use of heat and moisture. The heat and moisture makes the wood more pliable and therefore allows it to be moulded around a jig, former or mould.

The way heat and moisture makes wood pliable is throught the structure of the wood.
Woods are made up of many fibres looking very much like straws, these features allowed wood to transport water to the tops of the tree.

The problem with using moisture with wood is that too much moisture can cause the wood to swell and loose its rigidity. So the amount of moisture has to be controlled to ensure the wood does not defect during the moulding stage.

The second problem with steam bending is that not all wood can easily be shaped, this is because in hardwood the fiblres are much more compacted and threrfore harder to form. Also the thicker the piece of wood the harder it is to bend. If there is not enough moisture the wood will simply snap but too much would ruin the wood's structure and aesthetics

Engineered boards

Engineered Boards

 

Hardboard:

Hardwood is created by compressing wooden fibres into a thin sheet of board with the addition of glue or resin base.

 

Uses: Cabinets, Countertops, Furniture

Thicknesses: 3mm

 

Blockboard:

blockboard is made by sandwiching softwood blocks between two wooden sheets under intense presure and glue. the outer sheets of wood can be softwood, hardwood or egineered board

 

Uses: Doors, Tables, Shelves, Paneling and Partition Walls

Thicknesses: 13mm- 30mm

 

Plywood:

Plywood is made up by compressing thin layers of wood together with the addtion of glue. the pieces of wood are then compressed to form one thick board. Plywood is very strong because of the crossing of grain within it production

Uses: Furniture, Sheds, Blackboards, Billboards and Kitchen

Thicknesses: 6.5- 30mm (Maximum thickness is 50mm)

 

MDF- Medium Density Fibreboard:

 

Uses: Furniture, Laminate Flooring, Shelving, Decorative Moulding and Doors

Thicknesses: 3mm- 32mm

 

Chipboard:

 

Uses: Flooring, Countertops and Furniture

Thicknesses: 12mm, 18mm

Uses of Plastics

• Lego- Lego is made out of ABS (acrylonitrile butadiene styrene). The advantages of this is that...
• It is ideal for the injection moulding process as all pieces are going to be exactly the same
• Durability (pieces knocking together in the box). As well as children throwing and the pieces about
• Free of any toxins as it is used for childrens toys which could inflict health problems, although it is restricted to children above the age of 3 due to small hazardous parts.

• Plumbing Pipes and Guttering- Plastic piping is most commonly produced by PVC (PolyVinyl Chloride. This is because...
• It can be extruded easily during maufacture
• It can be easily shaped with the presence of a plasticizer
• It is cheap to produce therefore cost effective
• Waterproof allowing for suitable water drainage
• Low maintenance making it ideal for permenant fixtures



• Hard Hats- Hard Hats are made out of HDPE (High Density PolyEthylene. The benifits of this is that...
• HDPE can be used in injection moulding, cheap and efficient with no waste product
• HDPE is resistant to impact damage
• Resistant to sharp object.
• HDPE can spread the impact force over a larger surface area minimalising impact for