Metal Surface Finishes Flashcards
What are Abrading Tools used for?
Used to cut away very small particles of material
What are Files used for?
Smooth and shape surface of metals and hard plastics by pressing and dragging the hundreds of small teeth on file across material
What are Files made from?
Hardened and Tempered cast steel so they’ll cut other metals
Why should Files be treated with care?
They are brittle
Can snap if dropped/abused
What different shapes do files come in?
Flat Half Round Square Round Three Square
What also versions of each different file shape are there?
Warding and Needle versions - very small - used for jewellery
What are the different sized teeth of Files?
Rough Bastard Second cut Smooth cut Dead smooth
What is Cross filing?
Removes metal quickly with file moving end to end to bring rough material to shape
What is Draw filing?
Finishing process with the file moving from side to side which removes less material and leaves finer surface
How is Abrasive Paper made?
Small chips of abrasive material are glued onto a paper/cloth backing sheet
Abrasive material usually silicon carbide or emery
What is Emery Cloth?
Abrasive
Designed for use on metals, sometimes used on plastics
Torn into strips
What are Linishers?
Sanding machines that are designed for abrading metals
Have continuous belt of abrasive moving across plate
What is the relationship between the number of the abrasive paper and the coarseness of the sheet?
Lower the number, the coarser the sheet
What is Metal Polish?
Slightly abrasive because it relies cutting away the surface of the metal until it’s very smooth
What forms can Metal Polish be in?
Liquid form (applied with cloth) Wax bar (applied to buffing wheel)
What is the most common thermoplastic powder used for Plastic Dip-Coating?
Polythene
What is the method of Plastic Dip-Coating?
Air is blown through powder to make it behave like liquid
Metal (preheated to 180degrees) is dipped into fluidised powder
Metal is returned to oven where plastic coating melts to form smooth finish
What is Powder Coating?
Industrial Finish
More sophisticated version of dip coating
Powder sprayed onto products which then pass through oven
What does Modern Powder Coating provide?
Hard paint like finish
Available in all colours and translucent
Very durable
What is Anodising?
Used on Aluminium to provide durable corrosion resistant finish
What does Anodising involve?
It involves electrolysis and uses acids and electric currents which are hazardous in school workshops
What is Plating?
Uses electrolysis
Many forms - Chromium Plating = most common
Thin layer of metal on surface provides durable finish resistant to corrosion
What is Galvanising?
Dipping metal (usually mild steel) into a bath of Molten Zinc Zinc provides a very corrosion resistant finish
