Process

Ceramic Material Preparation

To provide to the varying needs of our customers we ensure the exact specifications and highest quality standards for our ceramic powder. This is made possible by the state of the art ceramic material preparation plant in our facility.

The process starts by checking the alumina and other additives for correct chemical composition and subsequently storing them in different silos connecting to a continuous ball mill. All the tank, silo and ball mill input-output are controlled by SKADA to eliminate the manual errors in the process.

The alumina and additives are sent to a continuous ball mill as per the required formulation and milling operation is performed to get uniformly fine material. The material is then sent to agitator tanks for mixing the binders into the ceramic powder uniformly. After the agitator there is a quality check for the viscosity and particle size characterization. From the agitators this material in the form of a slurry goes to spray dryer.

Spray drying is a method of producing a dry powder from a liquid or slurry by rapidly drying with a hot gas. This rapid drying ensures that the produced powder is uniformly sized and is of free flowing nature to give compaction during molding. After the powder is cooled in a cooling chamber it is sieved in a shifter mesh to separate all the different sizes present in the powder.

Before sending the ceramic powder for molding our quality and R&D team ensures that the powder will give the desired shrinkage after firing by performing a slug characterization.

  • 1
    RM Batching & dry Mixing

    Storage of high purity alumina and other additives in silos followed by thorough mixing to get uniformity.

  • 2
    Size reduction

    Grinding of the mixture in a continuous ball mill to get uniformly fine powder.

  • 3
    Binder addition & Agitation

    Binder addition is done to ensure the bonding in between particles during firing & the mixture is put into agitators for ensuring the proper mixing of binders with ceramic powder.

  • 4
    Spray Drying

    Rapid drying of the slurry to form a freely flowing and uniformly sized powder

  • 5
    Characterisation

    Before sending the ceramic powder for molding, slug characterization is performed to achieve desired shrinkage after firing.

Dry Pressing

Dry pressing is a manufacturing process used for compaction of powders. The powder is sent into feeder box directly from CMP section with no contamination. The amount of powder is CNC controlled & hence accurate. Mould depth is ensured using cams and CNC program for perfect shape and size. These are controlled using hydraulic systems.

Subsequently, the pressure is applied by the top ram which is in relative movement to the feeder box and depth of mould. Facilities up to 250 tonnes capacity are available for pressing at our plant. Next process is ejection of the tile which is controlled by cams, sensors or CNC program and in accordance with the position of ram and feeder box. Ejection of tile is achieved by the robotic arm. Tiles up to 100mm thickness and 220mm length can be moulded with the facility. Tiles are fired only after required quality tests are conducted.

  • 1
    Powder loading & Mould setting

    The powder is sent into feeder box directly from CMP section with no contamination. The amount of powder is CNC controlled & hence accurate. Mould depth is ensured using cams and CNC program for perfect shape and size. These are controlled using hydraulic systems.

  • Pressing

    Pressure is applied by the top ram which is in relative movement to the feeder box and depth of mould. Facilities up to 250 tonnes capacity are available for pressing.

    2
  • 3
    Tile ejection

    This process is controlled by cams, sensors or CNC program and in accordance with the position of ram and feeder box. Ejection of tile is achieved by the robotic arm.

  • 4
    Quality Checks

    Tiles up to 100mm thickness and 220mm length can be moulded with the facility. Tiles are fired only after required quality tests are conducted.

Cold Iso-static Pressing

Cold isostatic pressing is a manufacturing process used for compaction of powders. The process is similar to pressing using cupped hands for making snow balls.

The working principle of cold isostatic pressing is that powder is compacted by applying uniform pressure in all directions thus achieving maximum uniformity of density and microstructure without the geometrical limitations of uniaxial pressing. In cold isostatic pressing (CIP) the powder is placed in a flexible mould made of rubber or Urethane or PVC that does not change shape, but preserves the shape from the mould. It uses a liquid media, such as water or an oil or glycol-mixed water, to apply uniform pressure around the circumference of mould. Typically Pressures of 35-690 MPa are used at ambient temperature or slightly elevated temperatures to compact the powder. Cold iso static pressing parameters of pressure and time are pre-determined to give the material full density.

Cold isostatic pressing has the advantage for producing very large or complex shaped parts and also in the cases where the high initial cost of pressing dies cannot be justified. Using CIP, variety of powders can be pressed isostatically on a commercial scale including metals, ceramics, plastics and composites.

  • 1
    Powder filling & Pressing

    The powder is placed in a flexible mould made of rubber or Urethane or PVC. Powder is compacted by applying uniform pressure in all directions to give the material full density

  • 2
    Maintaining Pressure

    Moly-Manganese paste is applied with the screen printing method. It is carried out in a class IV clean room to ensure contamination free metallization.

  • 3
    Releasing Pressure

    Pressure is released uniformly from the mould to avoid cracks or defects.

  • 4
    Inspection & Dispatch

    Green product is checked for defects and sent to sintering for hardening of product

Ceramic Injection Moulding

CUMI is a pioneer in the field of technical ceramics and one of the market leaders & preferred supplier for many precision parts. Ceramic Injection Moulding offers advantages over conventional production methods for small parts with complex shapes or large production numbers.

CIM technique provides more freedom to engineers to design components without any limitations normally imposed by other ceramic forming techniques. After obtaining the 3-d design & drawing of the part, the prototype is CNC machined using 3-axis or 5-axis milling machine. With the help of the prototype, the tool is manufactured. The moulding process starts with very fine ceramic powders which are then mixed with binders such as paraffin wax, carnauba wax and polyethylene wax to form homogeneous palletised feedstock.

The slurry of binders along with the ceramic powders goes into the mould during the injection stage. The molten feedstock is forced into a mould cavity which takes the shape of the mould (can be single or multi-cavity configurations). Then it goes through two thermal processes. First is de-binding to remove the binder by sintering part in a high temperature kiln (1500-1650 ºC) to form a dense ceramic component. During this process, the component shrinks uniformly by 18-20 % while retaining the complex shape. The process can achieve tighter tolerances without post sintered finishing operations. Then surface roughness testing and other visual inspections are done and the product is sent for dispatch.

  • 1
    Prototype & Tool manufacturing

    After obtaining the 3-d design & drawing of the part, the prototype is CNC machined using 3-axis or 5-axis milling machine. With the help of the prototype, the tool is manufactured.

  • 2
    CIM

    The very fine ceramic powders are mixed with binders to form homogeneous palletised feedstock. The slurry of binders & ceramic powders goes into the mould during the injection stage. The molten feedstock is forced into a mould cavity which takes the shape of the mould.

  • 3
    De-binding & Sintering

    De-binding is done to remove the binders in a high temperature kiln (1500-1650 ºC).

  • 4
    Inspection & Dispatch

    The process can achieve tighter tolerances without post sintered finishing operations. Then surface roughness testing and other visual inspections are done and the product is sent for dispatch.

Metallizing

CUMI being one of the global leader in the field of metallized ceramics, understands the stringent quality required for metallized ceramics and criticality of the metallization process. We utilize Thick film method/ Screen printing for metallizing ceramics with at most precision to fulfil our customer requirements.

To ensure the best bonding between the ceramic surface and Nickel/Silver plating, Moly-Manganese paste is used which has excellent adhesion to the ceramic surface. Ceramics are washed thoroughly before metallization with various stages of demineralized water, acidic and basic solutions to ensure no contamination affect the bonding of Moly-Manganese paste to the ceramic surface. Cleaned ceramics are moved to class IV clean room with particles less than 50 ppm (parts per million) for metallizing, minimizing any chances of defects. Metallized ceramics are fired with appropriate temperature to remove the volatiles from the paste and strengthening the bond between Moly-Manganese and ceramic surface. Ceramics are inspected for the uniformity of the metallization.

After ensuring the proper metallization, ceramics are moved for Nickel/Silver plating process which acts as the medium for brazing of two different ceramics.

  • 1
    Cleaning

    Ceramics are cleaned using various cleaning solutions like demineralized water, acidic and basic solutions ensuring no contamination affects the metallization process.

  • 2
    Metallisation

    Moly-Manganese paste is applied with the screen printing method. It is carried out in a class IV clean room to ensure contamination free metallization.

  • 3
    Metallisation Firing

    Metallized ceramics are fired with appropriate temperature to remove the volatiles from the paste and strengthening the bond between Moly-Manganese and ceramic surface.

  • 4
    Inspection

    Metallized ceramics are inspected for the uniformity of the metallization.

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47,48(Part),Sipcot Industrial Complex, Hosur – 635126, Tamilnadu, India