1.4 Fasteners and fittings Flashcards
What are the 8 fasteners and fittings
Solid riveting, pop riveting, self tapping screws, wood screws, machine screws, nuts and bolts, coach bolts, KD fittings
What is the adv of pop riveting over solid riveting
Pop riveting is quick and only requires access from one side of the pieces to be joined.
What is the process for solid riveting
A solid rivet , made from malleable metal, is inserted into aligned holes between the 2 pieces of metal. The pieces of metal are pushed together and then the tail of the rivet is hammered to squeeze and hold the pieces together.
What do self tapping screws need
Self tapping screws require a pilot hole which is approximately the same diameter as the core diameter of the screw
What 2 fasteners and fittings are permenant
Pop and solid riveting
What is the process for pop riveting
A hollow aluminum rivet, with a steel pin, is used to join thin sheet metal pieces together. The rivet and pin are placed into aligned holes in both pieces, then a pop rivet gun is inserted over the pin and the trigger is pulled. This action pulls on the pin which crushes the rear face of the rivet to hold the pieces together. The join is completed when a steel pin snaps at a designated point.
What fastener and or fitting could be used to make washing machine panels and computer cases, or polymer parts e.g. securing a battery compartment on a child’s electronic toy
Self tapping screws
What is the use of self tapping screws
Self-tapping screws are a temporary means to join thin sheet metal
What is the process for wood screws
A clearance hole, larger than the often unthreaded shank, is drilled into the top piece of timber for the screw to pass through. A pilot hole, approximately the same size as the core diameter, is drilled into the bottom piece of timber to guide the screw in cutting a thread into the wood.
What is an adv of wood screws
They have a countersunk head- flush fitting
What are the 3 head types and properties for wood screws
-Slot head - simple but not suitable for a power screwdriver as the blade can slide out of the slot
-Phillips- increased contact and more torque
-Pozidriv - even greater contact through additional slots and hence more torque e.g. power screwdrivers
What is the use of machine screws
Machine screws are a temporary means to join thicker pieces of metal together
What fasteners and or fittings could be used for covers on a motor or gear housing
Machine screws
What is the property and requirement for machine screws
-Threaded shaft
-Clearance hole in top piece and threaded bottom piece
What are the 2 different washers
Plain flat, Spring/split lock
What is the adv of a nyloc nut
Nyloc nuts have a soft insert that deforms around the threaded bolt and helps prevent the nut coming undone due to movement
How do bolts work
Bolts are similar to machine screws but are put all the way through both pieces of metal with a nut tightened onto the other end of the bolt to keep the pieces together.
What is the adv of coach bolts
Can only be undone from the nut side which mean fitting to an outside door can be made secure
What is the adv of plain flat washers and spring/split washers
Plain flat washers help spread the tightening force under the head of the bolt and stop the digging into the metals surface
Spring/Split lock washers keep tension on the joint to prevent it coming undone due to movement
What is the use and properties of coach bolts
Coach bolts are a temporary means to join pieces of timber together. They have a square profile under the domed head which digs into the wood when the nut is tightened. This prevents the bolt from rotating.
What is the use of KD fittings
Knock Down fittings are used to assemble flat-pack furniture. Wooden dowels may also be used to locate panels prior to securing with a KD fitting
How do polymer modesty blocks work and what is its disadv
Polymer modesty blocks to join panels at 90 degrees. Unattractive and not very strong joining method
What are the 3 KD fittings
Polymer modesty blocks, Barrel nut and bolt or cross dowel fittings , Cam-lock connections
How do Barrel nut and bolt or cross dowel fittings work and what is its adv
Barrel nut and bolt or cross dowel fittings use metal fittings that give a strong joint with flush fittings
How does Cam-lock connections work
Cam-lock connections combine a fixed screw with a head that locates in a disk. The disk is turned with a screwdriver blade and, because the screwdriver head is off-centre, the screw is put under tension and the joint made secure
