Affect the quality of the injection process and process parameters green lot, quite complex, due to improper control will produce injection, holes, deformation, wire, broken edges, sandwich, density gradient, surface defects and other defects of varying green singlet. Through the rational choice matching material mild mold temperature control plus quantity, adjust packing pressure, dwell time, injection speed, injection pressure, improved mold design, mold with improved accuracy and other measures, can effectively control the generation of defects injected green . The following are some common causes of defects and solutions.

(1) Owes Note (or can not be injected). Note refers to the feed in less filling process can not fill the mold cavity. Specific causes and solutions are:

1) Material temperature or mold temperature is too low, you need to increase the material temperature or mold temperature;
2) Feeding Quantity Insufficient;
3) Feed the viscosity is too large, the general approach taken by elevated feed temperature;
4) Runner improper size, gate should be wider, shorter runner should thus filling behavior of simple and easier to fill the cavity.

(2) Holes. Holes is the cross section of the green can be found in the pores. Some of the holes of a nearly circular, almost throughout the development of some of the central through hole green body, which is a common defect, be carefully controlled. Produce this defect causes and solutions are:

1) Clip person when injected gas, kneading feeding clip person filling gases and bad, will lead to, at this time needs to be adjusted or trimmed feed mold;

2) Powder with the binder separation; mold temperature and melt temperature does not match; holding pressure is too small, dwell time is insufficient. When these problems, the need to improve the mold design, mold filling process so that feeding can be evenly filled cavity; reduce mold temperature or injection temperature; reduce injection speed.

(3) Deformation. Causes and solutions are:

1) Ejection green strength is low, you can reduce the mold temperature or melt temperature, injection unit time decreases the number of blank birth, improve loading capacity, the use of higher-strength adhesive system, etc. to solve;
2) Feed mixing powder and binder uneven or separation;
3) Residual stress is too large, can be appropriate to reduce the injection temperature and also slightly elevated mold temperature, lower injection pressure and holding pressure to resolve.




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Injection molded preform by a large amount of organic binder and the powder is composed of a polymer, an organic binder of the powder body from the bonding role in ensuring the injection molded preform having a sufficient strength, however, these bonding agents must be completely removed before sintering (i.e. skim process), otherwise it will affect the alloy properties.

Skim is the use of physical and chemical methods of injection molded preform dissolved organic binder and forming blanks from cracking thus removing process. Degreasing before sintering is a very important process. By injection of the feed pressure of the large number of preform binder (i.e., organic polymer), the volume ratio of 40070 to 60%, and sintering the binder must be removed prior to, or, in the sintering, these organic polymers degradation and thermal decomposition can occur, producing many gases generated in large compacts internal pressure, so that cracking and porosity compacts. Binder removal requires several steps, PIM process manufacturing costs to a large extent controlled by this stage. Binder in the form of a liquid or gas to escape from the inside surface of the sample in turn, form a connected open pores, adhesive removal speed, while no dirty degreasing blanks, and has no distortion.

Non-fat will be successful bubbling, cracking, peeling, holes, cracks, dirty technology and deformation and other defects. Main causes of skim rate is too fast, improper bonding mode selection, removal of the temperature control is inappropriate, improper control of the heating rate. Degreasing the defects affect the subsequent sintering, skim defects generated by a stop to make the sintering step, degreasing defects generated significantly affect the properties of the alloy.

Degreasing Methods: divided into thermal degreasing degreasing, solvent degreasing, catalytic skimmed, skimmed siphon of four.

Thermal Degreasing: Thermal degreasing injection molded preform is embedded in the alumina powder filler material in a vacuum, oxidizing or reducing atmosphere under heating according to a certain process.

Solvent Degreasing: degreasing solvent injection molded preform is immersed in a low molecular weight organic solvent or inorganic solvent (or solvent vapor), the use of organic molecules similar to the principle of compatibility.

Catalytic Skim: catalytic catalytic skim skim also known as BASF, which skimmed way linked with BASF binder.

Siphon Degreasing: degreasing siphon injection molded preform is buried in the micron, sub-micron powder, alumina powder, or other fillers, the use of fine powder of the molded preform by capillary action of the organic binder in the process of the gradual discharge.




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Cemented Carbide is one of the most successful composite engineering materials ever produced. Its unique combination of strength, hardness and toughness satisfies the most demanding applications.

Tungsten carbide is an equal mixture of tungsten and carbon. When the alloy is created, it is typically made as a fine gray powder. This powder is compressed into the desired shape using a modified die-casting process. After hardening into its new shape, this material is extremely hard and can withstand heat that would melt other metals.

The most valuable property of Cemented Carbide is that it offers a safer and more dependable solution than any other known material to one of the toughest problems engineers contend with - reliability. Learn all about Cemented Carbide!

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The actual definition of a tool bit is a matter of some debate. In some circles, a bit is a non-rotary cutting tool like the blade on a lathe or the head on a shaping machine. In other places, it is any removable or exchangeable tool piece, such as the drill part of a handheld drill. Both definitions have one thing in common—the bit is the part that directly interacts with the worked material, and any changes to the material are done by the bit alone.

Manufacturers use a carbide bit when the material or manufacturing process requires high tolerances or precision. These bits are often used when a material is hard enough that a typical bit won’t work it properly, such as with hardened or carbon steel. Since that’s what a common bit is made of, it isn’t hard enough to work the material. Interaction between two pieces of the same material typically results in both parts being ruined.

Another common reason for a carbide bit is when the material being worked needs exposure to very high temperatures either before or during the process. Since a carbide bit can withstand greater temperatures than steel, it is often used in high-heat situations. This is also true when the friction created by the working process would create enough heat to melt a steel bit, such as in high-speed grinding.

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The manufacturing process begins with the composition of a specific tungsten carbide powder mixture - tailored for the application.

The tungsten carbide powder is compacted into a form.

In a high-temperature sintering furnace, the tungsten carbide structure of the blank is shaped at precise temperatures for strictly defined periods. During this heat treatment, the tungsten carbide blank undergoes shrinkage of some 50% in volume.

The sintered Cemented Carbide component gains its final finish by additional grinding, lapping and/or polishing processes.

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The manufacturing process begins with the composition of a specific tungsten carbide powder mixture - tailored for the application.

The tungsten carbide powder is compacted into a form.

In a high-temperature sintering furnace, the tungsten carbide structure of the blank is shaped at precise temperatures for strictly defined periods. During this heat treatment, the tungsten carbide blank undergoes shrinkage of some 50% in volume.

The sintered Cemented Carbide component gains its final finish by additional grinding, lapping and/or polishing processes.

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A carbide bit is a type of tool attachment made out of a specialized metal alloy. Carbide is properly called tungsten carbide and is a specific combination of those two materials. The actual definition of tool bit varies slightly, but it is always the specific part of a tool that contacts the worked material. A carbide bit is much harder than steel, but it is also more brittle. As a result, many larger bits are made of cemented carbide or steel with a brazed carbide tip.

Tungsten carbide is an equal mixture of tungsten and carbon. When the alloy is created, it is typically made as a fine gray powder. This powder is compressed into the desired shape using a modified die-casting process. After hardening into its new shape, this material is extremely hard and can withstand heat that would melt other metals.

In its common form, tungsten carbide is very brittle. While the metal itself is very hard, a carbide plate can break with even slight impacts. To offset this problem, tungsten carbide is often combined with metallic cobalt to create cemented carbide. During the formation process, cobalt liquefies at a much lower temperature than tungsten carbide. This allows the liquid metal to ‘soak in’ to the carbide, greatly increasing its strength.

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The manufacturing process begins with the composition of a specific tungsten carbide powder mixture - tailored for the application.

The tungsten carbide powder is compacted into a form.

In a high-temperature sintering furnace, the tungsten carbide structure of the blank is shaped at precise temperatures for strictly defined periods. During this heat treatment, the tungsten carbide blank undergoes shrinkage of some 50% in volume.

The sintered Cemented Carbide component gains its final finish by additional grinding, lapping and/or polishing processes.

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The Cemented Carbides are a range of composite materials, which consist of hard carbide particles bonded together by a metallic binder.

The proportion of carbide phase is generally between 70-97% of the total weight of the composite and its grain size averages between 0.4 and 10 μm.

Tungsten carbide (WC), the hard phase, together with cobalt (Co), the binder phase, forms the basic Cemented Carbide structure from which other types of Cemented Carbide have been developed. In addition to the straight tungsten carbide – cobalt compositions – Cemented Carbide may contain varying proportions of titanium carbide (TiC), tantalum carbide (TaC) and niobium carbide (NbC). These carbides are mutually soluble and can also dissolve a high proportion of tungsten carbide. Also, Cemented Carbides are produced which have the cobalt binder phase alloyed with, or completely replaced by, other metals such as iron (Fe), chromium (Cr), nickel (Ni), molybdenum (Mo), or alloys of these elements.

There are three individual phases which make up Cemented Carbide. In metallurgical terms, the tungsten carbide phase (WC) is referred to as the a-phase (alpha), the binder phase (i.e. Co, Ni etc.) as the b-phase (beta), and any other single or combination of carbide phases (TiC, Ta/NbC etc) as the g-phase (gamma). Other than for metal cutting applications, there is no internationally accepted classification of Cemented Carbides.

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A unique material
Cemented Carbide is one of the most successful composite engineering materials ever produced. Cemented Carbide's unique combination of strength, hardness and toughness satisfies the most demanding applications.

A key feature of the Cemented Carbide is the potential to vary its composition so that the resulting physical and chemical properties ensure maximum resistance to wear, deformation, fracture, corrosion, and oxidation. In addition, the wide variety of shapes and sizes that can be produced using modern powder metallurgical processing offers tremendous scope to design cost-effective solutions to many of the problems of component wear and failure encountered in both the engineering and domestic environment.

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