1.1 Material Selection Part 1a Flashcards
What decides what joining technique is used?
The type of material and whether it is meant to be permanent or semi-permanent.
What is permanent joining and what are the different kinds of methods from this type.
Once this joint is made it cannot be reversed without causing damage to the material.
Welding
Brazing
Soldering
Riveting
Adhesives
Frame Joints
Explain Welding
Joining 2 metals together through heating them up and putting a joining metal in between to make joint.
What are the different types of welding?
MIG (Metal Inert Gas)
TIG (Tungsten Inert Gas)
Oxyacetylene
Electrical Arc
Spot
Seam
Explain MIG & TIG Welding.
Used to join thin sheets of metals. Uses a gas joint around a filler wire as this helps prevent oxidation at the joint to ensure optimal strength.
Different types of gasses are used depending on the type of metal being worked on.
Explain Oxy-acetylene Welding
Acetylene is burned along with oxygen creating a heat source of 3500°C.
This can be adjusted by controlling how much oxygen is burned. You would use different settings depending on the thickness of the material.
This process melts the metal making a pool of molten metal into which a filler rod of the same material is dipped in to fill in the gap.
Explain Electrical Arc Welding
This generates heat to melt joint edges by creating an electrical current between 2 arcs on each end of the materials and a filler rod.
The arc is produced with a low voltage and high current.
The arcs create an intense heat that melts the metals and filler rod at a singular spot making a weld bead.
Explain Spot & Seam Welding
Uses an electrical current to make a heat source.
This uses a spot to fuse the metals together.
Its a quick & clean process.
Explain Seam Welding
This passes an electrical current through the edges of 2 sheets of metal as they pass through rollers.
Explain Brazing
Permanently Joining metals while under heat(870-880°C) by using a rod made of an alloy from copper & zinc.
What are the 2 types of Soldering?
Hard Soldering
Soft Soldering
What’s the difference between hard and soft soldering?
Soft soldering has a minimum temperature of approx. 220°C while Hard soldering has a minimum temperature of 625°C
Explain Riveting
Metal pins are placed through 2 pieces of metal then hammered flat to permanently join the 2 pieces.
Explain Adhesives when joining
Permanently joining materials with a glue that is most of the time transparent, This can include PVA, Contact Adhesive & Epoxy Resin.
Explain Frame joints
For joining wood. There are multiple methods for this. Butt joints, halving joints, mortice and tenon joints and dovetail joints. These are normally used along with wood suitable adhesives.
What is semi-permanent joining and what are the different kinds of methods from this type.
Type of joint that can be taken apart without damaging the materials.
Screws, nuts, bolts & washers
Snap Joints
Knock Down Fittings
Explain nuts, bolts & washers
Bolts go through a material and are then held down from the other side by a nut allowing it to be a semi-permanent alternative for nails or screws. Washer can be placed underneath a nut when it is being tightened to protect the surface by spreading out the force applied when tightening. This also prevents loosening from vibration.
What are Knock-Down Fittings?
They are mostly used in self assembly products.
There are corner blocks Natural Wood fittings, two block fittings & rigid joints.
Explain Corner Block & Natural Wood fittings.
Corner Blocks are made of 1 or 2 plastic pieces that assist in assembly.
while natural wood is an inexpensive form of knock down that uses soft woods instead of plastic.
What are 2 block fittings?
They are pieces of plastic which have a bolt passed through the first one and into the thread of the 2nd one.
As the bolt is tightened the fittings close together.
Describe Rigid Joints.
strong moulded plastic pieces with 4 holes in them to guide the screws into the 2 pieces of material. As the screw are tightened the materials are pulled together at a 90 degree angle.
