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Castings without pattern – A new way to produce iron sand castings

Nopatech™ is a new technology developed by Saguenay Foundry. Its purpose is to make very short production runs of gray & ductile iron castings faster and more cost effective by eliminating the need to produce a pattern.

In regular production, patterns are made de create an imprint in a sand mould. Metals are then poured in the “negative” of the part. After cooling, you get a part to the correct dimensions and shape. This technology has been done for hundreds of years to obtain complex shapes that could not otherwise be machine directly in a cost-effective manner.

The problem with patterns is that they are expensive. If you redo the castings dozens or hundreds of even better thousands of time, it can easily be amortized. But in certain situations, one or two castings might be all you need. For instance, prototypes of an unproven design are subject to change after a trial of one or two castings. With a pattern, some change can be made, but not always, so you are always taking a risk.

In this case, a casting that cost 2000$ can require a 5000$ wood pattern do be produced effectively. If you do only one, your casting has cost you 7000$ . Nopatech™ on the other hand might cost you only an extra 1500$ – 2000$ to cast a part without pattern . This is a very substantial gain. The lead time might also go down by half.

To obtain this low cost and fast lead-time, Nopatech™ benefits from the advance in robotic technologies to machine blank sand moulds directly to the final shapes. Cores can also be done, so there is no limit to the complexity of the final shape. Basically, what can be done with wood patterns can be done with Nopatech™.

Also, the quality matches exactly what you get from a casting made with a regular pattern. You reach an average “as cast” RMS figure of 500 and the accuracy of the mould is within 1/16” of an inch, a precision that compares favourably to pattern-made parts. The size limitations is also the same as any other part done at our foundry, with a 115” x 115” maximum flask and a 16,000 lbs gross weight pouring capacity.

Manufacture of Sand Castings

Manufacture of Sand Castings

Engineers have required metal castings for over 5000 years.

As the technical ability of man has progressed, so have the techniques for making a Sand Casting.

Before a foundry can start producing Sand Castings, a number of decisions has to be made regards the Sand Casting Process :

a ) Metal Type

b) Contraction Rate. Ex if the finished product is to be 48″ long, then the pattern / mould cavity, will be approx. 49″long

c) Quality of the finished product, ie manhole cover or Nuclear Submarine part

1)    A pattern is required; this can be made from a cheap timber for single items, or metal for very large quantities.

2)     Cores will be required, if the casting is to have any internal shape

3)    A Foundry Engineer will determine how to ensure the casting is sound.

4)    His final determination is called the Runner System / Method

5)     To form the bottom half of the Mould, sand is now compacted around the bottom half of the pattern.

6)    A joint line is made between the top and bottom half of the mould. 3 dowels or pins are used to ensure the 2 halves of the mould can be put together exactly in the correct position.

7)    Sand is then compacted around the top half of the pattern.

8)    Split the 2 halves of the mould

9)    Carefully take the Pattern out of the sand.

Place any Cores in the mould.

10)   The top and bottom half moulds are clamped or  weighted down

leaving a cavity inside the mould

11) Molten metal is poured down the runner until the mould is full.

12) When cool the casting can be taken out of the mould

For further information on Sand Castings Tolerances please visit jade-trading.com

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 – process.arts.ac.uk 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. 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 …
Video Rating: 4 / 5

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Sand Casting Benefits

Sand casting is primarily used to manufacture huge equipment from aluminum, bronze, iron and brass. It is a process in which melted metal is poured into casts made of sand. The sand helps in retaining the shape of the pattern and also ensures that the largest of casts are made with relative ease without incurring a high cost. Sand Casting Process The sand casting process involves making a pattern and cores, if required. Sand casting manufacturer would pour the molten metal in a cavity in controlled conditions in a casting foundry in India and various other countries. The final product is ready without any trouble with minimum effort. The process is simple to follow and can be accomplished by non skilled workers.

Sand Casting benefits and advantages The process of sand casting is a low cost process and does not require skilled operators. Another benefit is that the equipment required for the process is cheap and easy to operate. The process is ideal for both small production and medium production rates thereby ensuring that projects of different volumes can be taken up. The biggest advantage is that very large castings can be easily produced using this process thereby making it popular all over the world. List of Sand Casting Manufacturers in India Sand casting in India is considered to be a very important job due to its numerous benefits. The main casting manufacturers and exporters in India are as follows:

Inova Cast Pvt. Ltd – A reliable organization that strives on innovation, Inova Cast is one of the foremost manufacturers and exporters of sand casting in India.
Castech Foundries – This organization believes in Achievement by Work Excellence and boasts of ISO 9001:2000 accreditations. It relies on high technology to deliver the best possible products at competitive prices.
Micro Melt Pvt. Ltd – This is another important manufacturer and exporter of sand castings and is known or its excellent quality. This organization implements the best possible technology to get the desired results.

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