5 Things to Know Before Buying Vertical Centrifugal Casting Machine

Chapter 1:

Click here to get more.

How to Choose the Best Jewelry Casting Equipment

Jewelry as it is known can be cast using various casting methods. Sometimes, a method used for casting jewelry will be greatly determined by the metal type to be used for jewelry casting.

1.1, Vacuum Centrifugal Casting Method

The vacuum centrifugal casting method of casting jewelry is mainly used to cast jewelries with a high melting temperature, like we have in palladium, platinum and stainless steel. The maximum temperature for melting is usually degree celsius.

A wax mode (a wax mode can be any combustible material) is first created before using the centrifugal casting machine. A wax mold is created by using a wax injection machine or using a 3D castable resin mold. The wax mold enables jewellers to cast multiple jewelries at once.

The next step is to create a wax mold casting, whereby multiple molds are attached to a sprue to form a wax mold tree and then placed in a flask.

Once the wax mold tree is ready, investment and water is mixed with an investment mixing machine within 2 minutes, the flask is then filled with the consistently mixed investment and water.

The next stage is to harden the investment and melt out the wax, this is possible by placing the flask in a heating furnace for several hours.

The next stage is to remove the flask from the heating furnace and place in a vacuum centrifugal casting machine. The centrifugal casting machine has two chambers, the upper and lower chambers. Melting of high temperature metals takes place in the upper chamber, the molten metal then flows into the lower chamber where the hardened investment flask has been placed.

When this stage is complete, it is time to remove investment from your newly cast jewelry. You can now proceed to wash and polish the new jewelry pieces.

A centrifugal casting machine uses the weight of the high temperature metal and centrifugal force to fill the mold. A force is needed to overcome the surface tension of the molten metal, otherwise, the molten metal will form in a blob and just sit in the mold. If the model is delicate, more force will be needed to push the molten metal into the tiny areas of the mold. If the force is little, the mold does not get properly filled with molten metal. Also, too much force can lead to blowing up the mold. The idea is to have a consistent pressure pushing or pulling the molten metal into the mold. The essential feature of the centrifugal casting is the introduction of molten metal into mold which is rotated during solidification of the casting.

1.2, Vacuum Pressure Casting Method

In the vacuum pressure method of casting, metal is molten under a vacuum high-pressure pump to prevent oxidation. Before jewelry can be cast in a vacuum pressure, jewelry molds have to be formed using the wax casting method which is then set in a flask to allow investment mixture. The investment guides the direction of molten metal in the casting chamber.

The vacuum pressure casting machine uses a vacuum to suck the molten metal into the mold. The crucible is placed centrally in the upper part of the air-tight closed furnace in the core of the induction spool. In the meantime, the flask with the heated up casting form is placed in the lower part of the vacuum chamber.

For the casting process, the crucible is set under pressure and the flask under vacuum. In other words, metal is molten in the upper chamber and flows into the chamber of the vacuum pressure furnace for the casting process without exposure to air or gases. The difference of pressure leads the liquid metal into the finest ramification of the form. The vacuum pressurized casting prevents bubbles and porosity in jewelry. The vacuum chamber is then opened for flask removal and cleaning of jewelries cast.

1.3, Manual Vacuum Casting Method

Just like the vacuum centrifugal casting machine, a wax mold is created before casting jewelry. The manual vacuum casting method is used to cast jewelries in gold, silver, copper and other types of metals. The melting temperature needed by the manual vacuum casting machine is degree celsius. The casting process begins with a rubber mold created around a master model. Rubber is added layer after layer around the model, then heated to form a precise mold. The mold is injected with wax to create the wax mold.

After wax hardens, it is removed and multiple molds are made. The wax models are attached to a sprue, which will eventually form a channel for the molten metal to enter the mold. The flask or cylinder on which the sprue is attached is then filled with investment. The vacuum removes all air from the flask to create a perfect mold because air bubbles will compromise the quality of the jewelry.

The flask is placed in a heated kiln to harden the investment and melt out the wax. This process however takes several hours. The mold now has the shape of the type of jewelry you want to cast. The hardened mold is placed inside the casting machine and then filled with molten metal. After the metal is poured and set, the cylinder is removed from the machine and quenched in water. The investment is washed off leaving behind the freshly cast jewelry.

1.4, Other Traditional Casting Methods

Traditional jewelry casting methods include sand casting and hand making jewelry with hammer, chisels and anvil.

Sand casting: In the method of casting jewelry using the sand casting method, sand is used as mold. When using the sand casting method, a pattern of the jewelry piece is created. The pattern will provide a metal pathway that will feed the desired cast jewelry design. The pattern can be made of any material like wood, metal or plastic.

Once the pattern is ready, creating a mold is the next step. A refractory material with a stable high temperature, i.e. sand is formed around the pattern. There are different types of sand that can be used to make a mold. The sand typically includes other materials like clay or some chemical bonding agent to strengthen it so that it will stand up to the pouring process.

The mold is produced in two pieces, the top half or cope and bottom half or drag. Once the sand is set around the pattern, the halves are separated and the pattern removed. A refractory coating is added to provide a better surface finish and protect the mold from the turbulence of the molten metal. The halves are placed back together, leaving a cavity in the shape of the pattern. The mold may also include &#;cores&#;, a method that is used to produce desired internal passageways in the final product.

Molten metal is poured directly into the mold, it fills the cavity that defines the finished part and risers. The risers&#; function is to feed the casting with molten metal. The risers are designed to cool and solidify last. The casting which would include the desired part and the additional metal solidifies and cools. The sand is removed through the shakeout process. The gate, runner, and risers are removed from the cast jewelry and polished.

Handmade Jewelry: Making jewelry by hand requires highly skilled labour in order to control the hand tools. Jewelries are created from a single piece of precious metal that is hand rolled with mills and pulled through the draw plates, the metal is the filed ground and tooled. The completed handmade model will undergo jewelry polishing. Once polishing is done, the expert stone setters hand cut seats into prongs and metal walls to support the gems. The stones are then seated and meticulously secured by the expert stone setter. Although handmade jewelries are unique, the process takes a longer production time and it requires high technical expertise.

1.5, Comparison of Multiple Casting Methods

Casting MethodsAdvantagesDisadvantagesHandmade Jewelry

Handmade jewelries are strong and can last a very long time.

Different metals can be mixed in one design.

The design can be easily manipulated.

Hand Making jewelry requires special skill.

Production takes a lot of time and energy.

 

Sand casting

Flexibility of designing.

High complex shapes can be created.

Low cost of casting materials.

Various metals can be processed.

If you want to learn more, please visit our website Foshan Osno.

Poor surface finish.

Jewelries have a high capacity for porosity.

Low material strength due to porosity.

Defects are unavoidable.

Manual vacuum castingMultiple jewelries caInaccurate investment mixing can affect production quality.Vacuum pressure casting

Using a vacuum pressure machine is economical.

High quality end products.

Allows a wider choice of flexibility.

High precision and fine detailed jewelry products.

No bubbles that cause poor casting quality.

No oxidation of finished products.

Fast melting and casting time.

Can be cost intensive.Centrifugal vacuum casting

Gates and risers are not needed.

Inclusions and impurities are absent in jewelries cast.

Multiple jewelries can be cast at once.

Castings have a directional solidification starting from outside to inside.

High temperature metals can be melted and cast into jewelries.

High production rate and fast production time.

A bit expensive to acquire.

Below are some of the varied technical questions which receive from some of our customers. Our technical team are experts in the design and building of our centrifugal casting machines. Our Team are always on hand to provide support and guidance. You can contact our sales team on  with all of your Centrifugal Casting questions.

 

&#;Should I use a Horizontal or Vertical Centrifugal Casting Machine to manufacture my product?&#;

The general rule is if the diameter exceeds the length Vertical centrifugal castings are more suitable, however there are exceptions, solid castings can only be made vertically, some alloys are more suitable for vertical centrifugal casting and sometimes people just prefer either the horizontal or vertical method.

 

&#;What information do you need to quote a suitable Centrifugal Casting Machine?&#;

We will send you a basic questionnaire which will detail all required fields, but principally the information we require I/D, O/D, length, material and quantity of castings you wish to produce.

 

&#;We have no experience in Centrifugal casting and are worried about our ability to manufacture a successful product.&#;

Gibson Centri Tech can help you with every stage of the process, from guiding you with the selection of your equipment, we can also offer layout drawings of your foundry as well as installing the equipment and providing &#;know how&#; training.

 

&#;What are the latest developments in Centrifugal Casting machinery?&#;

Gibson Centri Tech believe in continual improvement in our equipment, while the designs can trace their roots back thirty to forty years they have been endlessly improved to meet modern safety standards while  embracing the latest technology. The level of automation has increased and where appropriate incorporating Servo drives and robotics.

 

 &#;We are an automobile parts manufacturing company. We are producing Centrifugal Castings for Cylinder Liners. Please advise on which mould coating would be most suitable for our Production Needs.&#;

Gibson Centri Tech produce a range of Silica and Alumina coating however if we feel our coating is not the best product for you we will recommend an alternative supplier. Over the years Silica coating has been a popular product for use in the manufacture of cylinder liners and is still use extensively, however nowadays with modern Health and safety requirements the customer would need to check local regulations before using this product and ensure suitable dust extraction and PPE is used.

 

&#;Do we need a different machine for Ferrous and Non-Ferrous Centrifugal Castings?&#;

The short answer is no, the machine does not mind which material is being poured there can be differences in the mould design depending on the liquidus temperature and wall thickness of the casting being produced.

 

&#;We are trying to improve our production range of centrifugal rolls. Currently we are producing static ductile iron and steel rolls. Please advise the best centrifugal casting machine and procedure we would need to approach to achieve our desired results.&#;

We would firstly propose to initially offer a preliminary technical study covering the following points:

1. Review the selected cast products required to establish their suitability for centrifugal casting and equipment type.
2. To establish suitable equipment and moulds to produce the required casting.

 

&#;We have recently purchased one of your GML 2.5 machines from an old customer of yours. The machine is over 20 years old and we are considering the possibility of refurbishing this machine. Is this something that you offer?&#;

We have over the years refurbished many machines to bring them back to &#;as new condition&#; The refurbishment of the machine will include the following:

• Inspect the machine
• Clean, shot blast and paint
• Replace guards and interlocks if required
• Replace Bearings
• Rewire
• Upgrade control panel
• Inspect and test

 

&#;We have on site an Alpha 1 Centrifugal Casting Machine which we purchased from you 5 years ago. We are considering having an annual service on this machine, is this a service that you can offer?&#;

We do offer annual servicing on all of our centrifugal casting machines. We believe that it is beneficial that to ensure that your foundry equipment is in the best possible condition. With annual machine servicing planned maintenance will help to reduce machine downtime and will increase the life of the equipment.