Taking Advantage of Carbide Material for Your Mold Designs

For quite some time, carbide has been the material of choice for most cutting tools—such as drills, end mills and indexable inserts. As a material, its hardness, durability and sharp cutting edge support have enabled cutting tool manufacturers to provide users with the ability to mill hardened steels—with the addition of advanced coatings—that were once thought impossible on a daily basis. This is hard milling as we know it today.

Recently, for many of the same reasons, mold manufacturers have wondered how carbide material might offer them the same hardness and durability for their molds. After all, it will support small features and details, provide a great surface finish and offer great durability—enabling it to sustain many shots over a longer life cycle, which helps bring down costs.

However, just as the cutting tool manufacturer has to grind the tool’s shape or form, the moldmaker is forced to do the same or use EDM. Both of these processes are very capable, but can limit the feature size or detail to be formed in the case of grinding—or in both cases take considerable time and cost.

The ideal solution is direct milling—straight from the CAM program—just as for hardened steels. However, the question is “How can carbide be milled reliably and economically?”

Analyzing Carbide
The answer to this question came into focus in early 2011 as increasing requests for a solution became apparent. What was needed was a strategy to combine advanced micro end mills with advanced coatings and then develop a manufacturing process, along with application data for the user.

Testing1 proved that diamond coating offered the right balance of durability and cost when compared to cBn or PCD technology. Also a diamond-coated carbide end mill has a much higher degree of anisotropy, so it can better withstand vibration and chatter.

Using a hot filament chemical vapor deposition (CVD) technique gives a more homogenous and consistent coating, particularly on complex shapes such as the geometry of a ball end mill. The coating also had to attain a hardness to combat the hardness of the cemented carbide workpiece, and ideally be close to the same hardness of a single-crystal diamond—about 9,000HV.

Another key point was to obtain the near total adhesion to the end mill’s surface to prevent peeling. This was achieved through a precise process that controls the interface of the two materials at point of contact.

Finally, due to finished part tolerance demands as well as to ensure repeatable cutting tool performance, a consistent thickness of coating is required to fully maintain optimum cutting edges.

This point is one of the main advances because testing showed that the right combination of geometry design and coating properties enables the end mill to physically cut the carbide into small chips, making a clean and burr-free surface on the workpiece.

During the test phase, all the most common coolants were evaluated and while all performed well, the final recommendation was air blow because it is both ecologically more suitable and the chips do not form into a paste as is sometimes seen with oil mist.  

The result is an end mill with the capability to reliably and consistently “cut” 3D shapes and features into cemented carbide.

Test Cut
As an example, a 9-mm diameter aperture with a 3D hexalobular center feature was designed and used to test a 1.00-mm diameter ball end mill, featuring the diamond coating and geometries outlined in this article.

The workpiece chosen was VF-20 cemented carbide rated to 92.5Hra hardness with a grain size of 0.5microns in a 13-percent cobalt. The material TRS is stated at 4,500-5,000Mpa.

Using a high precision, shrinkfit toolholder on a CNC machine, parameters were set to 30,000rpm, 300mm/min feed with an Ap 0.05mm and Ae 0.30mm (roughing) and Ae 0.005mm (finishing). A helical approach was chosen to ensure even load on the tool as the force required to cut cemented carbide is around three times greater than for a hardened tool steel. As noted previously, air blow was chosen for the coolant.

The cycle time using a conventional EDM method was calculated at about 3 to 4 hours with the associated costs of preparing electrode material.  The total cycle time using a direct milling method was 39 minutes using a single tool.

A total of 91.7mm³ of material was removed at a material removal rate (MRR) of 2.35mm³/min.

At a recent international exhibition, this case study was repeated daily and after each cycle the 1.00-mm diameter ball end mill was measured for degradation and tip wear. The results showed less than 1.8microns of tool wear. The objective was to produce a clean, burr- and pit-free part that could be reliably recreated each time while maintaining the required tolerance to the original program.
 

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Summary
The development of an end mill that can cut 3D features into a carbide material is a key to unlocking the original question regarding how mold manufacturers can take advantage of carbide material for their mold designs with all its benefits, but not incur a time or cost penalty creating the detailed features that would justify carbide’s selection in the first place.

References
1 Testing was conducted by Hide Watanabe PhD at Union Tool’s Nagaoka, Japan, Technical Center, which formed the basis of a patent for the diamond coating that was subsequently selected for this product.

 

Tungsten carbide flat plates are rigid metal plates made of tungsten carbide, an extremely hard cermet material. This guide provides a comprehensive overview of tungsten carbide flat plates, their properties, manufacturing, grades, sizes, applications, and suppliers.

Overview of tungsten carbide flat plate

Tungsten carbide flat plates are flat pieces of tungsten carbide material, available in various sizes and thicknesses. They are extremely stiff, durable, and heat resistant plates with high compressive strength.

Tungsten carbide itself is a composite material containing tungsten metal and carbon. It is commonly referred to as a cermet (ceramic-metallic material). The most common type used in plates contains a tungsten carbide blend with 6% to 15% cobalt as a binder.

The key properties that make tungsten carbide valuable for flat plates include:

• Extreme hardness and rigidity – one of the hardest metals available
• Excellent wear resistance and durability
• High impact, bend, and crush strength
• Withstands high temperatures and thermal shock resistance
• Corrosion and chemical resistance

These properties allow tungsten carbide plates to withstand harsh conditions in critical applications across industries. The extreme hardness makes them highly wear-resistant, allowing them to outlast steel and other materials.

Tungsten carbide flat plates are most commonly used to line equipment or create very durable work surfaces. Common examples include:

• Lining for ball mills, crushers, centrifuges and reactors
• Hard surfacing for pumps, valves, pipes, and chutes
• Precision equipment beds in machining
• Dies for extrusion, stamping and wire drawing
• Components in mining and drilling tools

Continuous innovation in tungsten carbide technology allows creating grades optimized for factors like toughness, strength, or specific operating conditions.

Composition of Tungsten Carbide Flat Plates

Tungsten carbide used in plates contains:

• 85% to 95% tungsten carbide (WC) providing the hardness and wear resistance
• 5% to 15% cobalt (Co) as the ductile metallic binder that holds the tungsten carbide together

The cobalt content determines properties like fracture toughness and wear resistance. Lower cobalt WC grades have higher hardness and wear resistance but are more brittle. Higher cobalt WC grades are tougher but slightly less hard and abrasion resistant.

Typical tungsten carbide blend used in plates:

CompositionRangeTungsten Carbide (WC)85-95%Cobalt (Co) binder5-15%

The WC starting powder size used also affects the material properties achieved. Smaller WC grain sizes generally increase hardness and abrasion resistance.

The tungsten carbide blend is formed and sintered using specialized powder metallurgy techniques to create the finished plate product.

Properties of Tungsten Carbide Flat Plates

Physical properties:

PropertyValueDensity14.95 to 15.1 g/cm3Melting point2870°CModulus of elasticity520 to 630 GPaPoisson’s ratio0.22 to 0.24Shear modulus262 GPaElectrical resistivity25 to 35 μΩ.cmCTE~4.6 μm/m-K

Mechanical properties vary based on cobalt content and carbide grain size:

PropertyRangeHardness86 to 93 HRA (~2500 HV)Compressive strength1.9 to 6.8 GPaTransverse rupture strength600 to 3100 MPaFracture toughness (K1C)7 to 30 MPa√m

Key characteristics:

• Extremely hard – up to 2500 Vickers when cobalt is 6 to 10%
• Very rigid with high Young’s modulus – minimal deflection
• Withstands up to 1200°C without oxidation
• Chemically inert and corrosion resistant

Tungsten Carbide Plate Grades

Many tungsten carbide grades exist for plates, categorized by properties like hardness, toughness, and cobalt content. Major grade types include:

1. General purpose carbide grades

• Good combination of wear-resistance and toughness
• Cobalt ranges from 6% to 16%
• Hardness around 86 HRA; 850 to 1000 HV
• Common uses – wear parts and tooling

2. Toughened carbide grades

• Extra impact and bend strength through nickel additions
• Hardness around 84 HRA
• Used where high reliability needed

3. Micrograin carbide grades

• Carbide powder under 1 micron for maximal hardness and wear performance
• Hardness over 90 HRA; ~2500 Vickers
• Highest abrasion resistance among WC grades
• Brittle; used for shaping abrasive materials

Comparison of Major Tungsten Carbide Plate Grades

Grade TypeHardness RangeCobalt ContentKey FeaturesGeneral Purpose86 to 88 HRA6-10%Good all-round wear performanceToughened82 to 85 HRA8-12% Ni additivesIncreased toughness and bend strengthMicrograinUp to 93 HRA6-8%Maximum wear performance for shaping abrasive materials

Tungsten Carbide Flat Plates Specifications

Tungsten carbide flat plates are available stocked or custom-manufactured in various sizes and dimensional tolerance grades – covering hundreds of carbide specifications.

Plate Sizes

Available in metric and imperial sizes, up to 2000 x 1000 mm plates. Standard thickness range from 2 mm to 75 mm. Common sizes include:

• 50 x 50 mm
• 100 x 100 mm
• 150 x 150 mm
• 200 x 200 mm
• 300 x 300 mm
• 500 x 500 mm

Custom plates can be manufactured in any required length, width, and thickness combination.

Dimensional Tolerances

Plates usually supplied to tolerance grades ranging from precision ground as fine as +/- 0.02 mm to more relaxed +/- 0.50 mm tolerance on dimensions. Specialtolerance grades include:

• Grade G (Precision) – +/- 0.013 mm
• Grade S or B – +/- 0.05 mm
• Grade A – +/- 0.1 mm
• Grade GP – +/- 0.50 mm

The grade affects pricing – tighter the tolerance grade, the higher the price. Dimensional tolerance impacts suitability of plates for precision equipment applications.

Manufacturing Process

Tungsten carbide flat plates are manufactured through powder metallurgy techniques and sintering:

Contact us to discuss your requirements of customized cemented carbide rods. Our experienced sales team can help you identify the options that best suit your needs.

Steps:

1. Blend tungsten carbide powders and cobalt together
2. Press compound into “green” preform through cold isostatic pressing
3. Sinter preform at 1400°C to 1500°C in vacuum atmosphere
4. Anneal carbide plate for optimal combination of hardness and toughness
5. Machine plates to final dimensions and grind surface
6. Qualitative tests check hardness, microstructure, dimensions, flaws
7. Final visual inspection before shipment

The powder metallurgy method allows complex tungsten carbide geometries to be mass produced. It yields consistent properties part-to-part.

Tungsten Carbide Flat Plates Applications and Uses

Thanks to exceptional hardness, wear performance, and thermal resistance – tungsten carbide flat plates have diverse industrial uses, including:

Wear and abrasion applications:

• Hard surfacing for pumps, valves, pipes carrying abrasive slurries
• Chute, hopper, screw conveyor linings
• Liners for crushers, pulverizers, centrifuges, reactors
• Rollers for rolling mills
• RVSP tooling

Precision equipment:

• Beds for precision grinding machines
• Bases for coordinate measuring machines
• Precision machine slide-ways

Metal processing:

• Extrusion dies for non-ferrous metals
• Drawing dies for copper and aluminum wire
• Stamping dies

Mining and drilling

• Rock drill guides and anchors
• Nozzle inserts

Electronics

• Carrier plates for PCB drilling machines
• Wafer conveyors

Comparison of Major Application Areas for Tungsten Carbide Plates

IndustryKey ApplicationsDemand DriversMiningMachinery linings, toolingWear performanceMetal ProcessingExtrusion dies, stampingHardness, temperature resistanceFood ProcessingMill liners, conveyorsAbrasion and chemical resistanceOil & GasValves, pumpsWear and corrosion resistanceAerospaceGrinding beds, machiningDimensional accuracy, surface finish

Suppliers and Pricing

Carbide flat plates can be purchased from specialty suppliers focused on tungsten carbide machine parts. Online retailers also stock popular plate sizes.

Typical pricing range:
US$60 – US$250 per plate for 50 x 50 x 10 mm plates, depending on grade and tolerance. Low-volume retail prices are higher.

Major global suppliers

CompanyHQ LocationTunco ManufacturingUSAMidwest Tungsten ServiceUSAFederal Carbide CompanyUSACeratizit GroupLuxembourgSandvikSweden

Buying plates from leading manufacturers ensures reliable quality standards. Some offer further value-added services like precision grinding and custom manufacturing.

Cost drivers:

• Tolerance grade – precision grinding increases price
• Quantity and size – larger bulk orders are cheaper per piece
• Grade selection – premium micrograin grades are higher priced
• Additional fabrication – extra processing means higher cost

Price Optimization Tips

• For typical tooling uses, a standard grade offers the best value
• Buy the largest sizes usable for lower price per piece
• Where possible, adjust designs to use standard plate sizes
• For light precision work, a Grade B tolerance often suffices

Comparative Analysis

vs Steel:

• Much higher hardness and wear performance
• More rigid and stable under force
• Withstands higher operating temperatures
• More chemically resistant and inert
• Significantly more expensive material

vs Tungsten alloy plates

• 2x harder than pure tungsten plate
• Much higher temperature rating – over 1200°C
• Superior wear characteristics
• Easier to machine to fine tolerances
• Less heavy for a given plate size

vs Silicon carbide plates:

• Very similar hardness and chemical resistance
• Comparable wear rates in abrasive environments
• Less prone to brittle fractures under impact
• Requires high-precision manufacturing
• Silicon carbide offers higher temperature rating

Pros and Cons

AdvantagesDisadvantagesExceptional hardness and rigidityExpensive materialExtreme wear and abrasion resistanceLow grade toughness; brittleWithstands high temperaturesHeavy density platesChemically inert and stableChallenging to manufacture and machineDimensional stability under loadLow thermal shock resistance when bareConsistent material propertiesSensitive to cobalt leaching in use

Ideal for:

• Extremely abrasive environments
• Precision equipment beds
• Common tooling applications

Not recommended for:

• High temperature fatigue conditions
• Highly corrosive chemical processes
• Applications prone to sudden impact loads

FAQ

Q: What thickness tungsten carbide plate should be used to line a crusher?

A: For crusher linings, tungsten carbide plate thicknesses between 18 mm to 28 mm are typical based on the machine size and feeds. Thinner plates experience rapid wear. Overly thick plates are uneconomical.

Q: Can tungsten carbide flats be welded or brazed?

A: Tungsten carbide itself cannot be directly brazed or welded. Plates are often vacuum brazed to a steel backing or other substrate as an assembly. Special low-temperature brazes formulated for carbide joining must be used.

Q: Are tungsten carbide plates ok to use in acids?

A: Tungsten carbide itself has excellent corrosion resistance and shows negligible attack from most mineral acids. However, prolonged exposure can lead to preferential cobalt binder leaching which weakens the internal structure. Some loss of structural strength is expected over years of acid service.

Q: What causes cracking in tungsten carbide plates?

A: Internal cracks or outright fractures in tungsten carbide are usually caused by either material defects from manufacturing or by mechanical damage from use. Defects include void formations during sintering or cobalt pool formation. Mechanical damage can happen from sudden high loads exceeding the relatively low fracture toughness. Thermal shock during heating also frequently causes surface cracking.

Q: Can tungsten carbide flats be reused or recycled?

A: Used tungsten carbide flats can potentially be salvaged and recycled. Items can be sorted by grade and rebuilt into fresh plates using specialized re-pressing and re-sintering methods. This reclamation process helps recover the expensive tungsten content for reuse. However, properties degrade with each recycle cycle.

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