ABSTRACT

As new artificial sand, ceramic sand has been rapidly extended in foundry use in virtue of steady research and marketing for about two decades. Ceramic sand has excellent properties, including spherical shape, high refractoriness, good crush resistance, inert chemical characteristics, high reclamation yields, etc. Ceramic sand has distinguished performance in foundry in compare with silica sand and other popularly used special sands. This article introduces the production process, the physical and chemical properties, and the application features of ceramic sand, as well as its application examples in many kinds of foundry processes such as self-hardening molding, sodium silicate sand, cold box, Croning shell method, and lost foam castings. Some technical parameters of ceramic sand usage are also presented.

Has distinguished performance in foundry in compare with others

↓  Fig.2 Production diagram of ceramic sand   ↓

3. Characteristics of ceramic sand

  As a special foundry sand, the ceramic sand has the following characteristics：

(1) The thermal expansion rate of ceramic sand is very low, similar to that of zircon sand. Using ceramic sand to make moulds and cores, veins and other expansion defects of castings may be eliminated.

(2) Ceramic sand has good flowability, and easy to fill in because of its spherical shape. The moulds and cores are of high permeability and easy to shakeout after casting.

(3) By using ceramic sand, 30-50% of the binder consumption can be saved, to obtain castings with good finish and substantial structure economically.

(4) Ceramic sand is a neutral and inert material, so it can be used in acid and alkali binders systems, also adapt to various alloys.

(5) Ceramic sand has good recycling performance. It can be easily reclaimed by many methods.

(6) Ceramic sand has high refractoriness and good stability. It is especially suitable for the production of complex sand cores and steel castings.

(7) It has wide particle size distribution, which can be combined and mixed arbitrarily to meet specific needs of customers.

4. Applications of ceramic sand in foundry

  Now, ceramic sand has been commonly used in cast iron, cast steel, stainless steel and non-ferrous castings with kinds of foundry technologies, such as furan no-bake, Croning shell method, cold box, phenolic alkali no-bake, ester cured sodium silicate process and lost foam castings. Below is a pie chart of ceramic sand usage based on recent data.

←  Fig.3 Pie chart of ceramic sand applications

4.1 Furan No-bake Process

For furan bonded ceramic sand, its hardening rate is much higher than silica sand, and when adding the same amount of resin, the strength is remarkably improved.

To test the tensile strength of ceramic sand and Dalin silica sand, add 1.2% furan resin of the weight of sands and catalyst by 40% weight of furan resin respectively, the curing time is arranged in 1, 2, 3, 4, 5 and 24 hours, then test the tensile strength at the arranged time (with “8” type test pieces), the test result is shown in Table 2.

Table 2 Tensile strength of ceramic sand and Dalin silica sand

  It shows that the tensile strength after 24 hours of ceramic sand is over 50% higher than that of silica sand. It has been proved that the use of ceramic sand can not only reduce the amount of resin, save costs, improve production efficiency, but also greatly reduce the casting defects such as porosity.

4.2 Resin Coated Sand Molding and Core Making, Shell Process

4.2 Resin Coated Sand Molding and Core Making, Shell Process

Taking advantages of ceramic sand, people can make high quality resin coated sand, which has exceptional properties such as high refractoriness, low thermal expansion, easy to shakeout, high strength, and less gas evolution. For particularly complex cores (see fig.4a and 4b), resin coated ceramic sand has good flow-ability, which can solve the problem of being not fully formed.

↓  Fig.4 Resin coated sand cores and castings  ↓

b.  Water jacket core of cylinder block

d.  Cylinder block

The shell process of the ceramic sand (see fig.5) is of high production efficiency. The casting dimensional accuracy and the castings finish are exceptional. The used sand is easy to recycle, which greatly reduces the emission of solid wastes. The environmental benefits of this process are also remarkable.

It can be predicted that, as a new green manufacturing technology, the shell mold casting process using ceramic sand will become a new foundry technology widely used.

b.  Castings clutch with gating system made by shell method

4.3 Alkaline-phenolic Resin (Alpha-set), Molding and Core Making

It’s well known that the pour temperature of cast steel is rather high, the use of the ceramic sand can fully take the advantages of the alkaline-phenolic resin. The sand consumption of casting can be reduced to 30-50kg per ton. The binder consumption is reduced by 30-50%, with the improvement of casting surface quality, the amount of sand shakeout and casting cleaning work can be reduced more than 60%. It can significantly improve the casting quality, reduce the rejection rate and production cost. It also reduces the emission of waste gas, sand and dust, improves the work environment, prevents silicosis, and achieves the goal of green production.Fig.6 shows cores and castings of stainless high pressure valves made by Alpha-set process using ceramic sand.

b.  High pressure valve casting

Table 3 shows strength performances of ceramic sand Dalin silica sand using alkaline phenolic resin. We can find that the tensile strength after 24 hours is as high than that of silica sand by 31%，while the binder level of ceramic sand is less than silica sand by 40%，and the gas evolution of sand may has a reduction of 32%.In practice，using ceramic sand，foundry can save the binder consumption by 45-55%.

Table 3 Tensile strength of ceramic sand and Dalin standard sand by Alpha-set process.

4.4 Sodium-silicate Bonded Sand

For heavy section cast steel, it generally has much higher static liquid pressure onto moulds and cores during a relatively longer pouring time. The mechanical, thermal and chemical reactions between metal and moulds may be violent. These can lead severe metal penetration and sand burn-on, especially at the parts of intersection of castings. This takes a lot of works for foundries to handle where castings may have poor finish, and the working places may be environmentally horrible. In some circumstances, bad working conditions exposes workers to the danger of silicosis. 

To solve the problems of metal penetration and sand burn-on, we have had a site production trial. Add 3%~4.5% of silicate to ceramic sand, then thoroughly mixed, put the mixed sand to the parts marked “A” on moulds shown in Fig7, then put sodium silicate bonded silica sand to complete molding. After coating and pouring, we obtained castings without metal penetration and sand burn-on. It demonstrates the anti-penetration properties of ceramic sand.

Figure 8 shows the local (wall intersections, core, etc.) of large cast steel parts where ceramic sand facing sand used. These parts are prone to sintering, penetration and burn-on. Using ceramic facing sand to fulfill the long straight holes of the supporting roller, results show that this can not only reduce the likelihood of metal penetration, but also eliminate the possibility of casting crack due to thermal stress caused by poor thermal deformability by using silica sand.

At present, besides the using ceramic sand as facing sand separately, its mixture with chromite in the sodium silicate sand can also take the advantages of ceramic sand and chromite overall . In addition to using CO2 hardened sodium silicate sand, ceramic sand also has significant advantages in the ester hardened process. Table 4 compares the tensile strength of ceramic sand and silica sand by ester hardening sodium silicate process.

Table 4 Tensile strength of ceramic sand and Dalin silica sand by ester-hardening sodium silicate.

4.5 Lost Foam Process and V-process

For lost foam process and v-process, people use ceramic sand as backing sand, the rate of qualified products increases remarkably. The total cost decreases, the sand consumption of castings is only 1-2kg per ton. And, the working environment is obviously improved because of its round shape, good flow-ability, strong durability, high thermal conductivity, lower dust, etc.

Figure 9c illustrates the lost foam process and a casting of an engine cylinder block. When use silica sand, those slender holes can hardly fulfill properly, may cause iron-sand sintering and serious penetration that, cannot be cleaned. Using ceramic sand, the above problems can be eliminated. Ceramic sand, has good spherical shape, provides good permeability, good flowability excellent filling performance. It also has low crush rate during molding and reclamation, so that the cost of castings will be declined while the production yield may be as high as 97%.

Conclusions

(1) In no-bake processes (including Furan and phenolic alkali no-bake), use ceramic sand can improve sand strength significantly, can save binder level by over 30%, so as to decline gas evolution, gain reclamation yields as high as to 98%, and eliminate solid emission remarkably.

(2) Using ceramic sand as base sand in resin coated sand cores and shell method, the flowability of RCS is excellent, the expansion rate and gas evolution is rather low, so that reduces the defects such as gas holes and veins of castings.

(3) The use of ceramic sand in sodium silicate systems reduces binder consumption apparently, enhance the properties to shake-out, avoid penetration and sand burn-on, and can cut down castings cost.

(4) In application of lost foam casting production, use ceramic sand can improve flowability, then improve sand filling, improve permeability and so on. Due to the high strength and low crushing rate of ceramic sand, the reclamation yields of the sand is high and the cost is low.

With the rapid development of foundry industry, to meet social environmental protection requirements, more and more manufacturers will choose ceramic sand as base sand partly or overall. Ceramic sand, a new foundry material in the 21st century, will play a more significant role in the new era of sustainable development and green manufacturing

PROJECT AFTER PROJECT

EUSKATFUND is constantly evolving and developing. Thanks to projects like these, and the support we have received, we have managed to go a step further in the treatment and result of the materials we provide; never leaving aside one of our main values, that of being on the side of the environment whenever possible.

THE DAILY STRUGGLE OF THE FOUNDRIES

⇒ The causes of defects

Veining, burnouts, penetrations and pinholes are common defects in castings, and foundries struggle to control them on a daily basis. Unfortunately, many variables can contribute to the cause of the defect, starting with the choice of sand.

Due to cost, silica sand is commonly used as the aggregate of choice, but pure silica sand expands by an average of 4 – 5%. When molten metal enters a mould, a brutal thermal shock to the sand occurs and is followed by rapid expansion of the sand. This flexible contraction/expansion causes the core matrix of the bonded sand to fracture and break, causing veining defects. Although there are other options to silica sand that offer lower and more controllable expansion rates, such as zirconium and olivine sand and chromite, their cost is almost 10 times higher. Even when more stable sands are used, it is still possible to find veining defects and scaling in castings because there are also other variables, such as compaction and sand particle size distribution, that need to be controlled.

SYNTHETIC IRON OXIDE SPHERE OX

The choice and amount of resin used to bind the sand in a core, or mould, is very critical. When trying to limit or eliminate negative influences on its use, calcines, pinholes and other gas related defects are taken into account. When the resin burns, voids are created where the resin was.
The molten metal penetrates into the voids and the part suffers from calcination defects. Pinhole defects are created when the gas generated by the burning resin (in the mould or core) cannot escape before solidification. Ideally, enough resin should be used to eliminate core breakage, but not so much that the core is so hard that it can be broken by the thermal expansion that takes place, breaking the cohesive strength of the resin.

Conclusion

For almost two decades, the use of SphereOx has shown an unprecedented level of success worldwide in the prevention of casting defects, significantly reducing the cost of raw material (resin). In Spain and Portugal it is possible to buy SphereOx through our distributor EUSKATFUND, S.L.

PROJECT AFTER PROJECT

EUSKATFUND is constantly evolving and developing. Thanks to projects like these, and the support we have received, we have managed to go a step further in the treatment and result of the materials we provide; never leaving aside one of our main values, that of being on the side of the environment whenever possible.

More, sometimes, is not better.

⇒ TALKING ABOUT QUALITY

The adjectives that describe the characteristics of an efficient core shooter: versatile, practical, comfortable, fast, economical … important qualities which, unfortunately, are not easy to measure objectively.

Sometimes the bombastic branding of a trigger, together with aesthetics and clever advertising, pushes up the price, so it is well above the price of triggers from small manufacturers such as PRIMAFOND from Vicenza, Italy. As experience shows, the price difference is often not matched by superior features and performance.

AN EFFICIENT CORE SHOOTER MACHINE

In particular, the choice of a shooter for large cores, e.g. to produce cores over 50 kg, must have been carefully considered, as these issues determine customer satisfaction.

The PRIMAFOND SCB 40 – 60 – 80 to 100 series of core shooters for COLD BOX PRIMAFOND SCB 40 – 60 – 80 to 100, with capacities ranging from 40 to 100 litres, have so far been appreciated by the most demanding professionals in the production of medium and large sized cores. In common with machines of the same type from other manufacturers, PRIMAFOND’s “SCB” model shooters have the strength, power, hydraulic movements, automatic operation with PLC control, all of which are now basic elements thanks to the available technology. The company incorporates all the safety measures required for safe operation, simplicity of use and regulation, ease of assembly of the moulds and extraction of the cores, together with the ability to easily add any type of armature or hook to the comfortable working position.

PRIMAFOND designs and manufactures a complete range of Cold Box firing machines, with capacities from 5 to 100 litres, from the simplest and most universal firing machines for manual boxes, to automatic firing machines with constant outputs of 120 cycles/hour and machines for horizontal boxes with tools for extracting the core from the outside of the firing machine.

It completes its offer with the following equipment:

• Sand production and distribution plants for core making.
• Triggering machines for shell moulding.
• Automatic gas generators for the different processes.
• Amine neutralisers.
• Pneumatic senders.
• Tanks for core painting.
• Hydraulic and pneumatic ball breakers.

⇒ WHY DID WE CHOOSE PRIMAFOND?

The response of PRIMAFOND’s technicians to any need is always quick and direct, so PRIMAFOND will be the perfect partner in your foundry to improve your foundry, based on a solid experience acquired over the years, having attended to a multitude of needs and customizations of our customers, with a high degree of satisfaction. Our collaboration with EUSKATFUND aims to bring us closer to you in order to achieve the aforementioned objectives.

PROJECT AFTER PROJECT

EUSKATFUND is constantly evolving and developing. Thanks to projects like these, and the support we have received, we have managed to go a step further in the treatment and result of the materials we provide; never leaving aside one of our main values, that of being on the side of the environment whenever possible.

Sand recovery additive for all foundries

⇒ Why thermal recovery?

Today, all modern foundries use some form of chemically bonded sand systems, as they are under increasing pressure to reduce their manufacturing costs, reduce their impact on the environment, but at the same time improve the quality of the foundry. One of the ways to meet these requirements is to invest in sand reclamation. Although most foundries already have mechanical reclaimers, many are looking to further reduce costs and invest in thermal sand reclamation.

HELPS TO REDUCE COSTS

Typically, the thermal unit runs on natural gas or LPG and operates at temperatures of between 670ºC and 720ºC, depending on the type of binder used. Sizes offered within Omega’s range of heat recovery units range from 250kg/hour up to 12 Tons/hour, with a 3 year warranty on burners and furnace lining.

Omega’s patented “Dead Bed” system ensures total thermal insulation and therefore lower running costs, and also a longer life for the ceramic fibre insulation of the furnace. This is due to the protection the “Dead Bed” provides for the insulation and the erosion caused by the movement of the sand in its processing.

⇒ HOW ARE LOW OPERATING COSTS ACHIEVED?

They are achieved through the combination of excellent furnace insulation with the “Dead Bed” system, as well as an installed heat recovery module, which takes the heat from the hot sand air leaving the furnace and reintroduces the heat as hot air to the furnace fluidised bed. This means that the fluidisation air is always hot, which leads to lower gas consumption.

⇒ WE TALK ABOUT SECURITY

Safety is also a primary concern, so multiple safety systems are employed to monitor fluid bed ignition, temperatures of all components (including dust collector) and the level of sand available for processing. In addition, a touchscreen panel is provided, complete with status and fault location and indications.

⇒ HOW DO WE HELP THE ENVIRONMENT THIS TIME?

Emissions from the heat recovery plant are guaranteed to be lower than the requirements of local legislation, without the need to install an afterburner. The hood installed on the furnace ensures that the air leaving the furnace is clean.

For the Alkaline Phenolic system, a special inhibitor must be pre-mixed with the sand to prevent the alkaline salts from causing low melting temperature of the thermally recovered sand.

It is now also possible to thermally recover green sand for re-use in the foundry’s core-making process. A system of mechanical attrition is employed, before and after the furnace, to ensure that all the clay is removed, but essentially the thermal regeneration is the same as that used for the recovery of sand from chemical moulding.

NOW, YES, IT IS PROFITABLE

Thermal recovery has existed for many years, but now it has reached a point where it is profitable, economical, reliable and therefore viable for most foundries to consider.

Both OMEGA and our Representative/Distributor for the Spanish market, EUSKATFUND, S.L., will be delighted to analyse, offer and carry out a viability and amortisation study of your investment.

R+D+i Programmes

⇒ RESAND (Project nº ZL-2022/00095)

EUSKATFUND participates, as leader, and with the collaboration of Fundiciones PALACIO and DRAXTON, in the RESAND project, promoted by AZTERLAN (Member of Basque Research & Technology Alliance) and focused on the “Development of new alternative moulding materials to foundry silica sand, characterised, with low environmental and health impact“.

NEW MOULDING MATERIALS

⇒ PROJECT nº FF-2022/00226

Project focused on the “Development of Fluorine-free Sleeves and Risers” and co-financed by:

SPRI – BASQUE BUSINESS DEVELOPMENT AGENCY

⇒ FUTUROFEEDER (Project nº INK-2022/0068)

Project aimed at the “Definition of a new concept of sleeves for high pressure lines and double chamber sleeves“.

SPRI  – BASQUE BUSINESS DEVELOPMENT AGENCY.
INNOBIDEAK – INNOKONEXIO 2022 aid programme.

⇒ HAZITEK Call 2023 (Project nº ZL-2023/00900)

The aim of the project is: “Development and validation of new technology for the manufacture of inorganic foundry cores and moulds”.
FUMBARRI, Fundiciones PALACIO and Taqlleres ALJU are also participating in this project.

PROGRAMA DE AYUDAS DE APOYO A LA I+D EMPRESARIAL – HAZITEK
A la financiación de este proyecto
contribuye el “Fondo Europeo de Desarrollo Regional (Fondos FEDER)”.

PROJECT AFTER PROJECT

EUSKATFUND is constantly evolving and developing. Thanks to projects like these, and to the support we have received, we have managed to go a step further in the treatment and result of the materials we provide; never leaving aside one of our main values, that of being on the side of the environment whenever possible.

The Secondary Unit of Atriction

USR is a registered trademark of SINTO Corporation, Japan. This equipment is being manufactured, under license, by OMEGA FOUNDRY MACHINERY, Ltd., and distributed in the Spanish market by EUSKATFUND, S.L..

SINTO registered the USR and WSR models for the recovery of silica sand from the foundry, especially in moulding processes where inorganic (silicate) and semi-inorganic (alkaline phenolic resin) binders are used. Although these processes are difficult to recover, up to 90% can be recovered with the implementation of USR in the recovery process.

RECOVERY VARIETIES

The sand is retained for a short time at the top of the chamber before being evacuated or sent to the second chamber in the case of double chamber models. The sand from the second chamber is then displaced out of the chamber by the inlet of the sand from the first chamber. The treated sand that has fallen out of the second chamber is displaced through a classifier below the chamber, where a fluid bed separates the fines (mainly resin dust).

⇒ USR SECONDARY ATTRITION RECLAMATION

✓ Removes the binder content by mechanical means. Also in the case of inorganic (silicate) and semi-organic (alkaline phenolic resins) binders, without damaging the conditions and grain size.

✓ Low initial investment cost. Rapid amortisation. No CO2 emissions, as there is no gas heating.

✓ Low energy cost for its operation, contrary to what happens with thermal recovery, with a reduced cost in spare parts, since the elements of greater wear are ceramic, which guarantees a long durability (more than 3,000 hours).

✓ Control of the percentage of binder removal, adjusting various parameters (pressure on the rings, ring thickness, drum rotation speed, number of sand passes, one or two per unit depending on the model).

✓ It can work with any base sand.

USR. MARKET SITUATION

Today, there are USR installations all over the world. Of course, Japan is the predominant country with 180 installations. In the rest of the world, 18 units have been sold in the last 2 years, despite the severe economic crisis, due to their fast amortisation, with a high rate of satisfaction among melters, helping to minimise waste and avoid CO2 emissions into the atmosphere.

PROJECT AFTER PROJECT

EUSKATFUND is constantly evolving and developing. Thanks to projects like these, and the support we have received, we have managed to go a step further in the treatment and result of the materials we provide; never leaving aside one of our main values, that of being on the side of the environment whenever possible.

PANELS THAT HELP ENERGY CONSUMPTION

Euskatfund installs a battery of photovoltaic solar panels for self-consumption of 43.2 KW with 96 modules.

⇒ How will they help?

This facility will supply our manufacturing plant for the production of sleeves, mazarottes, resins and hardeners.

Once the facility is operational, we expect to generate 40% of the energy we currently consume.

In this way, Euskatfund is contributing to the reduction of CO2 emissions into the atmosphere.

The aspiration to migrate towards a sustainable business model is no longer a distant wish for us. These small changes are necessary in the face of the new global challenges of climate change.

WE HAVE REDUCED CO2 EMISSIONS

PROJECT AFTER PROJECT

EUSKATFUND is constantly evolving and developing. Thanks to projects like these, and the support we have received, we have managed to go a step further in the treatment and result of the materials we provide; never leaving aside one of our main values, that of being on the side of the environment whenever possible.

We are expanding in the Spanish and North African markets.

Euskatfund, a leading company in the foundry sector, manufacturer of NO BAKE moulding resins, sleeves and high performance mini-moulds, has reached a distribution agreement with Capital Refractories for the Spanish market and North Africa.

⇒ WHAT IS CAPITAL REFRACTORIES?

Capital Refractories is a specialist in the manufacture of refractories and associated products for steel mills, foundries and cement works. Capital Refractories is at the forefront of induction furnace linings and ladles with innovative technology.

Capital Refractories is one of the largest refractory manufacturers in the world, with plants in the U.K., Czech Republic, U.S.A. and China, and has been manufacturing and distributing its products for more than 50 years with a high degree of customer satisfaction.

With this agreement, EUSKATFUND and CAPITAL Refractories guarantee the supply and technical support to all their customers.

WE ARE DISTRIBUTORS OF CAPITAL REFRACTORIES

PROJECT AFTER PROJECT

EUSKATFUND is constantly evolving and developing. Thanks to projects like these, and the support we have received, we have managed to go a step further in the treatment and result of the materials we provide; never leaving aside one of our main values, that of being on the side of the environment whenever possible.

We have achieved ISO 14001:2015 Environmental Certification and ISO 9001:2015 Quality Certification.

We are pleased to announce to all our customers, suppliers and collaborators that EUSKATFUND, S.L. has been certified with an ISO 14001:2015 environmental management system and has renewed its quality system according to ISO 9001:2015 standards.

QUALITY AND ENVIRONMENTAL SUPPORT

PROJECT AFTER PROJECT

EUSKATFUND is constantly evolving and developing. Thanks to projects like these, and to the support we have received, we have managed to go a step further in the treatment and result of the materials we provide; never leaving aside one of our main values, that of being on the side of the environment whenever possible.

We have expanded our facilities by dedicating this new section to the manufacture of feeders.

With the entry into operation of this new pavilion, Euskatfund completes its modern facilities of more than 7,000 m2.

This new pavilion is divided into 3 zones.
⇒ The first zone is for the storage of raw materials and tools.
⇒ In the central area, the production plant itself is located, comprising 5 Cold Box firing machines, ranging from 35 to 16 litres. We also have a Shell firing machine for the manufacture of pre-coated sand biscuits.
⇒ The last section of the hall is dedicated to the stock of finished products in order to guarantee a rapid response in the supply of our customers’ orders.

2.100 M2 más de pabellón

⇒ WE INCREASE THE COMPANY AND QUALITY

Thanks to the technology applied to our EURCAST EXO HOSES AND MINI-MAZAROTS, products with constant characteristics are obtained:

✓ Good dimensional accuracy
✓ Stable quality
✓ High performance
✓ Reduced gauging costs
✓ Hygroscopic sleeves and mini-MAZAROTS, do not absorb humidity
✓ Exothermic-insulating
✓ Chemical homogeneity
✓ Fibre-free
✓ Minimal outgassing

WE CONTINUE…

A close and direct relationship with the technical departments of our customers allows us to design and manufacture any sleeve or mini-joint according to their design and power supply requirements.

We remain attentive to the needs and fluctuations of the market in order to undertake new investments.

PROJECT AFTER PROJECT

EUSKATFUND is constantly evolving and developing. Thanks to projects like these, and the support we have received, we have managed to go a step further in the treatment and result of the materials we provide; never leaving aside one of our main values, that of being on the side of the environment whenever possible.