Powder Metallurgy Department of DONIX Ltd.
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TECHNOLOGY

Main principles

Features of technology

Product's quality

Main principles

To obtain the high effectiveness of our cemented carbide products we are using the approach:

"Individual product for specific conditions"

It includes the following main components:

Individual approach to choice of composition, structure and technological parameters of product's manufacturing taking into account the working conditions of certain enterprise

Continuous monitoring of working life cycle of our products in conditions of customer

Analysis of results, and development of recommendation concerning the optimal composition and structure of material for certain working conditions.


Features of technology

Cemented carbide products are made by hot vacuum pressing method from high-quality domestic powders and mixtures. Our technological regimes and mixture compositions permit to obtain the pores-free parts with excellent mechanical and operating properties and with weight to 150 kgs.

Cemented carbide product's fabrication includes all integrated technological processes from storing of raw materials from primary components to packing of finished product. Because of it we can fabricate the products with any dimensions and composition according to customer's requirements.


The main features of our technology are follows:

We are preparing the mixtures of necessary composition with using of self-developed technology.
Due to organization of own facilities for hard alloy mixtures preparing, we have the possibility to change the content of binder in material with step 1% mass and control the granulometric composition.

We are using our own-developed variant of hot vacuum pressing.
It gives us the possibility to control the obtaining of necessary density and structure of material by the flexible changing of pressure and temperature of process.

We are using the continuous procedure of technological parameters and item properties monitoring(Process statistical control).
In result, we can see any deviation in parameters and prevent the formation of defective articles.

We developed the new control procedures with using of non-destructive methods,
which permit to obtain additional information concerning the quality and properties of final products. We have subjected to these procedures all volume (100%) of produced items. DONIX Ltd. introduced and applies the quality management system according to ISO 9001:2000 standard in the cemented carbide fabrication field.

Fabrication facilities

Production facilities includes:
- Raw material storage facility
- Facility for preparing of hard alloy powder mixtures
- Facility for hot vacuum pressing
- Machine working facility
- Quality control and research laboratory
- Final product storage facility
- Auxiliary facilities (division for manufacturing of pressing mold elements, repair service, supply service, documents archive)

Manufacturing process

Cemented carbide product's fabrication includes following technological stages:
 Input control of raw materials
We are purchasing the powders of main components (tungsten carbide and binding metals) from certified suppliers only. They were chosen after special procedure of tests and experimental trials. Every new lot of material is subjected to control procedure that is fulfilled in certified laboratories. Control procedures include chemical and granulometric analysis.
 Hard alloy mixture preparing
Hard alloy powder mixtures are prepared from high quality materials with using of specially designed equipment. It prevents the oxidation of mixture during the milling and its contamination by the foreign particles. Prepared mixture is dried in vacuum at strictly controlled temperature and stored in vacuum packaging before it's using. Duration of storing of mixture is strictly limited.
 Control of mixture quality
Reference sample is prepared from every batch of mixture for determination of physical-mechanical characteristics and microstructure investigations. Check procedure includes the determination of values of density, hardness, transverse rupture strength, impact toughness, evaluation of size and distribution of structure components. Mixture may be used for manufacturing only if it is passed all tests.
 Assembling of press - moulds
Mixture of certain composition is used for product's production. First operation is preliminary forming of briquette for the hot vacuum pressing. It is prepared on special site where it is pressed for increasing of density and placed in carbon fiber composite press-mould (this material initially was developed for aerospace applications). Tool set for hot vacuum pressing is manufactured from this composite and special grade of graphite.
 Process of hot vacuum pressuring
Working media for hot vacuum pressing is fine vacuum. Maximal operation temperature is 1500°С; pressing force may achieve 1000 kg/cm2. Realization of process is controlled by automated control computer aided system. Main advantage of process is possibility of independent change of pressure and temperature values in order to control the structure formation. During manufacturing process not more than 2 large-size items may be processed in unit simultaneously. It decreased the productivity of process, but gives us possibility of precise process parameters control and increases the final products quality.
 Intermediate quality control
After hot vacuum pressing the semi-product is subjected to intermediate quality control. It includes evaluation of geometric dimensions and density of part. On the basis of control results, the decision concerning following using of semi-product is made.
 Grinding of semi-product
Mechanical treatment of hard alloy parts is fulfilled by the diamond tools and includes the following operations:
- Grinding of basis surfaces
- Grinding of second face
- Grinding of outer diameter
- Grinding of bevels
After finished part is passed to final quality control.
 Final quality control
It consists of the correspondence evaluation of final product parameter to requirements of specifications, adjusted with customers and includes:
- Compliance of geometrical dimensions to requirements of specifications;
- Evaluation of surface quality (presence of pores, cracks, non-polished zones, inclusions on the surface of part is prohibited);
- Density measurement by the hydrostatic weighing method;
- Rockwell hardness measurement;
- Ultrasonic control procedure.


Product's quality

Our cemented carbide product's quality is proved by many years' experience in its exploitation on European metallurgical and mineral resource enterprises.

Our tungsten carbide product has excellent complex of physical-mechanical and operating properties because of domestic technological regimes and Research & Development programs, which we realize together with our consumers. DONIX Ltd. constantly improves existent quality control methods and introduces new forms of it. It give us most reliable information about structure and mechanical characteristics of output goods.

DONIX Ltd. introduced and applies the quality management system according to ISO 9001:2000 standard in the cemented carbide product's fabrication and sales fields.


R&D programs

DONIX Ltd. fulfills the programs of scientific-research accompaniment of productive process. There are programs of R&D activity in Powder Metallurgy Department. It is realized in cooperation with leading Ukrainian scientific institutions. Now we are fulfilling the scientific research programs for development of new compositions of hard alloys and carbide-steels with improved mechanical properties.

Besides that we are fulfilling the scientific research programs for studying the basic mechanisms of products wearing during the exploitation in dependence on working conditions and parameters of material. Obtained information is used as for improvement of existing materials and technological procedures, as for development of new ones.

   
         
   
© 2008 DONIX Ltd. ::: 83102, Ukraine, Donetsk city, Kuibysheva str.,44 ::: Phn.: +38(062)388-91-20 ::: donix@donix-ua.com