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Sand Casting - INTRODUCTION Philip White & jenny dunseath

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Introduction for Sand Casting Process with Philip White and Jenny Dunseath in the foundry at Camberwell college of Art London. Video by Chris Follows part of the Process Arts Project.

LINKS TO OTHER VIDEOS FEATURED WITH THIS POST:
Sand Casting at Camberwell with Philip White and Jenny Dunseath :

PART ONE SAND CASTING

PART TWO SAND CASTING

PART THREE SAND CASTING

 

Text Information supplied by Jenny Dunseath:

Pattern Making:

The Pattern is a full size model of the part that makes an impression in the sand mold, with dimensional allocation for shrinkage and finishing.
If the casting is hollow, additional patterns called cores are used to create these cavities in the finished product.
Patterns are usually made of wood, plastic, metal, or plaster; however, other materials or combinations of materials are used if there are additional specific properties required of the pattern.
Every Pattern must have a draft angle of approximately 2° - 3° to all walls parallel to the parting direction to facilitate removing the part from the mold.
Paint the surface of the Pattern with Varnish or Shellac to make it water tight and to ensure that the sand does not stick.
For a Flat back pattern- put screw holes in the back to aid its removal from the sand.

Molding:

Molding is the multi-step process in which molds are created.
In horizontal casting, the mold is contained in a two piece frame, called a Flask. The upper portion of the flask is called a Cope and the lower portion is a Drag.
First, molding sand is packed into a Flask around the pattern. After the pattern is removed, Gating and Runner arrangements are positioned in the drag half of the mold cavity and the Sprue is placed in the cope portion.
Gating systems are necessary for the molten metal to flow into the mold cavity.
Cores are also placed in the drag portion of the mold if they are needed. To finish the mold, the Cope (top) section is placed on the Drag (bottom) section, and the mold is closed and clamped together.

Sand:
Two main routes are used for bonding the sand moulds:
The "green sand" consists of mixtures of sand, clay (Bentonite) and moisture. If the sand can be squeezed together and hold its shape, it is suitable for use.
The "dry sand" consists of sand and synthetic binders cured thermally or chemically.
The sand cores used for forming the inside shape of hollow parts of the casting are made using dry sand components.
Between uses, the sand is rejuvenated by adding water and mulling (mixing and smashing). If you do not let the sand dry out all the way, you do not have to mull, just add water. Sand grit is determined just like sandpaper. 150 is very fine and 50 grit is coarse. Fine sand will give good detail, coarse sand will give a pebbly or rough texture.

MaterialsMelting temperature
Aluminum alloys1220 °F (660 °C)
Brass alloys1980 °F (1082 °C)
Cast iron1990-2300 °F (1088-1260 °C)
Cast steel2500 °F (1371 °C)

Websites:
www.metal-technologies.com/SandCasting.a spx
www.airnyc.org/list/78478/1/sand-casting -step-by-step.html
www.foundry101.com
www.custompartnet.com/wu/SandCasting

Books:
The Complete Handbook of Sand Casting - by CW Ammen
Metal Casting: A Sand Casting Manual for the ... - by Steve Chastain

NOTE: Because the sand is used in a damp condition there is minimal sand dust,and this occurs at the mould face immediately arround the hot metal casting ,clearly visible when the casting is knocked out. At this stage a small watering can or spray will help to stableize this dry material.A standard dust mask could be worn.It is always worth taking sensible precautions with all processes.With sand casting on the scale immagined here keep a water spray handy and use it when cleanig away any dry material.

 

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Anonymous's picture

A lot of the old small suppliers are all closed now unfortunately, the best bet is to contact http://www.johnwinter.co.uk/foundry-products/foundry-products and see if they have any London contacts? Thanks

Anonymous's picture

could anyone help me source good quality green sand 100/150 grit in London?

cfollows's picture

Thanks for sharing this find, videos look great.

Anonymous's picture

I'm just beginning to look at sand casting as something I'd like to try. In answer to your questions I found some good ingredient ideas and technique demonstrations with notes on what's being used and how it works by viewing the myfordboy channel on youtube.com. He's got a lot of videos of him making and fitting forms together along with core making. Perhaps that will help. Brandon

old-admin's picture

Thanks for the comment,I agree with your observation regarding the design of the Cope and Drag I intend to work on the problem.We have had good results with several split patterns using these boxes,however I can see that using cores will make handling the Cope difficult.

Can you give me any advice on the best ingredients for core mixes?We now have a considerable student interest in sand casting and we need to keep it simple.

Thanks again

PHIL

old-admin's picture

Fantastic set of videos. Cope and Drags look well made. However, the V-alignment blocks would only be any good for flat back patterns. When split patterns are involved, especially those involving cores already placed in the drag, proper vertical descent of the cope is needed long before the cope and drag meet each other. This cannot be achieved with the V-alignment blocks.

old-admin's picture

Because the sand is used in a damp condition there is minimal sand dust,and this occurs at the mould face immediately arround the hot metal casting ,clearly visible when the casting is knocked out.

old-admin's picture

Just wondering -- is there any danger of silicosis with this kind of sand? I would love to know if it is it safe to do this kind of work without the need for an expensive respirator, since I'm interested in doing sand casting (on a budget!). message from http://www.youtube.com/comment_servlet?all_comments=1&v=Kmb5tivQ_bY

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This moving image, Sand Casting - INTRODUCTION Philip White & jenny dunseath, by Chris Follows, Philip White and Jenny Dunseath is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported license.