Wood lathe turning

http://en.wikipedia.org/wiki/Lathe

 

A wood lathe is a machine tool which spins a block of wood in order to cut it, remove material from it or shape it to create an object which has a symmetry about an axis of rotation.

A woodlathe has an adjustable horizontal metal rail called a tool rest which is located between the material and the operator and accomodates the positioning of hand held shaping tools.

Sand paper can be pressed against the still spinning object after shaping to smooth the surface of the object.

Wooden lathed bowls

Turned wood object.

 

Wooden lathed Russian dolls.

 

Vacuum Forming

http://en.wikipedia.org/wiki/Vacuum_forming

http://www.formech.com/industry.php

Vacuum forming is an industrial process where a sheet of thermoplastic is heated to a forming temperature dependent on its thickness.

Once heated the plastic will be stretched over a mould .It is a cost effective process.

The stretching of the material is possible because of the application of a vacuum created between the mould surface and the plastic sheet.

 

Problems with vacuum forming:

Sheet does not pull down over the mould:

Air may be trapped between the mould and the sheet.

Check that you have enough evacuation holes

The sheet may not be hot enough increase heating time

The clamp frame may need replacing

The vacuum pump filter may need cleaning

The sheet may be cast acrylic which is not vest for vacuum forming

Sheet burns or blisters:

The sheet has become too hot

The sheet may be hygroscopic and moisture in it causes blisters

If sheet is over 5mm it will need more time for the heat to soak all the way through

Reduce power and increase heating time

Sheet pulls out of clamp frame when raising the platen and mould:

The sheet is not positioned correctly

The sheet is not hot enough increase the heating time

The material may not be vacuum formable

The mould may be too large or the edges too close to the perimeter of the forming

aperture. Modify the mould design

Webbing occurs on the finished forming:

The sheet is too hot and it has sagged during heating. Reduce heating time

The design of the mould may need to be modified

Forming will not release from the mould:

There may be undercuts on the mould which are holding the forming in place

The forming may have srunk onto the mould start the blow cycle early

The mould material may have bonded with the forming material

Put a thin coating of silicone oil on the mould before forming

The mould is too hot, turn the machine off and wait for the mould to cool off

before attempting another forming

The mould surface is too rough, make sure there is an even finish on the mould before

vacuum forming.

 

Vacuum forming process.




Vacuum forming shoe polish display.




Vacuum forming egg box.




Vacuum forming fruit trays.


Sheets for vacuum forming.

 

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Injection Moulding

http://en.wikipedia.org/wiki/Injection_molding

 

Injection molding is a manufacturing process for producing parts from both thermo-plastics and thermo-setting plastics materials. Molten metal is injected at high pressure into a mold. Mold are made in steel or aluminium.

injection moulding

Injection moulded tennis raket frame




Materials for injection moulding process


injection moulded novelty items

 

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Dip Moulding

The process of dip moulding is now used to coat components such as measuring equipment, computers and vehicles. The process of dip moulding is fast. Tools are heated, dipped into a liquid PVC plastisol, taken out. cured, cooled and removed from the tool to create plastic mouldings.

Prototypes can be made easily so the designer is able to make modifications without great expense.

The plastisol material used determines the physical attributes such as hardness and resistance to heat, oil or chemicals. The time the tool stays in the plastisol determines the wall thickness of the moulding which has a normal range of between 1mm to 4mm per dip.

The tool with the plastic coating that represents the moulding, is then moved to a curing oven where it is again heated before travelling to a cooling tank to prepare it for stripping, a process that removes the moulding from the tools. Post moulding operations such as punching, trimming and printing can then be performed and modifications to the part made.

 

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Sand Casting

http://en.wikipedia.org/wiki/Sand_casting

 

Sand casting is an ancient technique of using moist and tightly packed sand to press around a model which is then removed leaving a mold cavity to be filled with molten metal.

Which metals can be used to sand cast?

Aluminium, Bronze, Pewter. Silver and Iron.

Two types of sand are used for sand casting:

1: Green sand, a mixture of silica sand, clay, moisture and other additive.

2: Air set sand, a dry sand bonded with other materials than clay using a fast curing adhesive.

Casting sand is commercially available. The finer the sand is the better definition will be achieved on the casting.

The consistency of the sand is very important. If the snad is worked too wet, it will desintegrate once the object is removed to reveal the mold cavity. The consistency of the sand can be evaluated by squeezing the sand into a ball. The sand should then hold itself together in the ball shape.

Sand casting involves a frame wood or metal box called the flask made of two parts ( some more complex casting may require a three or more parts mold). The parts of the frame are called drags( which is the frame without pins) and cope( which is the frame with the locating pins).

Casting an object:

1: Set the drag onto a flat surface such as a sheet of wood.

2: Fill the drag with moist cast sand packing it down tightly with a block of wood.

3: Spray paint the object to be cast if its surface is uneven or use shellac or varnish to seal it.

4: Once the drag is packed up to its surface, level it with a piece of wood by dragging it across its surface in order to remove excess material and create a flat surface.

5: Lay model in the centre of the sand and push gently half way into the sand. Sometimes tools may be used to remove some of the sand in the cavity mold since the packed sand can be difficult to give under the pressure of the object.

6: Sprinkle pounce onto the snad and object. Pounce is a powder used to keep the two frames from sticking together once they are filled with sand. Talc, chalk dust or graphite can be used for this purpose.

7: Use a gauze material to fill the pounce such as muslin.

8: Locate cope and drag using the wooden pins.

9: Sprinkle sand over object and pack frame up to its top surface as previously.

10: Remove cope and carefully take away the object without destroying any of the packed sand.

11: Create a gate with a scalpel (a 3mm channel) which source will be located right at the edge of the object.

12: The channel is created in the drag.

13: Create a pouring cup in the cope using a metal tube and pushing it all the way down the tickness of the frame.

14: Replace cope unto drag.

15: Use a welding rod to create air vents called runners around the object by pushing the wire all the way down the thickness fo the cope.

16: Melt pewter or other metal into a furnace or ladle.

17: Pour molten metal into pouring vent.

18: Let it cool dowm until the metla has solidified.

19: Open the two parts frame and remove the cast object.

20: Rinse the object under clear water to remove any sand particles.

21: Use a metal brush to clean sand away from tiny spaces if necessary.

22: Using a hacksaw cut off excess of metal created by the pouring vent.

23: The object will have inherited the surface of the sand.

24: Finish the object by mashining using files to create a smooth surface.

Sand casting drag and cope.




Sand casting molds.


Sand casting diagram1.




Sand casting pour.


Sand casting with cavity mold.




Sand casting diagram 2.



Sand cast cast iron object.

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Sandblasting

Sandblasting:

ttp://en.wikipedia.org/wiki/Sandblasting

 

Sandblasting is the process of smoothing, shaping and cleaning a hard surface by forcing solid particles across that surface at high speed usually with compressed air.

The work is located inside the sandblasting unit which is now securely closed.

The operator's hands are fed through flaps located at the front of the machine.

Inside the blasting unit a gun is directed towards the work and operated by pressing the pedal on the right front of the machine.

This activates the release of the abrasive sand for sandblaster or glass beads as used in a bead blaster.

A sandblaster is used the clean sand and irregularities from foundry castings, remove paint, etch or frost glass, cut through glass and form patterns having concealed some area of the material with tape and sandblasting the exposed remaining.

 

Sandblasted cylinder.






Architectural sandblasting on glass.

 

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Metal Spinning

pinning is a metalworking process where a disc or a tube of metal is rotated at great speed and formed into an axially symmetric part using a tool called a spoon.

The mandrel or spoon can be made of hardened steel for spinning aluminium or brass for spinning stainless or mild steel.

Spinning can be a hand process or a CNC process

 

http://en.wikipedia.org/wiki/Metal_spinning

 

metal spinning.

metal spinning.