Diamond Tooling Articles

SINTERED (METAL BOND) DIAMOND TOOLS

01 Apr

Sintered (Metal bonded) diamond tools have multiple layers of diamonds impregnated inside the metal matrix. Diamonds are furnaces sintered in a matrix made of iron, cobalt, nickel, bronze, copper, tungsten,  alloys of these powders or other metals in various combinations. Metal Bonded Diamond Tools are “impregnated” with diamonds. This means that selected diamonds are mixed and sintered with specific metal alloys to achieve the best cutting performance possible on any materials such as sapphire, advanced ceramics, optics, glass, granite, tile and etc. The metal bond surrounding the diamonds must wear away to continuously keep re-exposing the diamonds for the diamond tool to continue cutting. Sintered (metal bonded) diamond tools are recommended for machining hard materials from 45 to 75 on Rockwell Scale (5 to 9.5 on mohe's scale of hardness).

Sintered (Metal bond) diamond tools utilize various metallurgical powders to firmly keep the diamond crystals in place, with minimum wear. The compacted materials are then hot pressed or sintered to full density. Heating rate, applied pressure, sintering temperature and holding time, are all controlled according to the matrix composition. 

This means that selected diamonds are mixed and sintered with specific metal alloys to achieve the best cutting performance possible large variety of materials. This bond type can utilize the highest quality and grade industrial diamonds (strong and blocky shape) monocrystaline particles. For this reason this bond family requires higher horsepower equipment and lower cutting speeds. Compared to their resin bond, nickel bond, braised bond, and vitrified bond counterparts. Sintered (Metal bond)  is the strongest of all the bond families. Offering the longest life, greatest variety of specifications and fields of use available. While its not the optimum solution for all applications, Its one of the most widely used bond across most industries today.

All types and forms of diamond tools are available with this bond matrix. Such as diamond wheels used for grinding, diamond cut off wheels use for cutting, slotting, grooving, diamond core drills and bits used for drilling, reaming and milling. Diamond router bits, carving points and form tools used for shaping and forming. Complex tool shapes can be made, angles and radiuses ground to fit customers objectives. High precision tolerances can be maintained through precision grinding of the tools faces. Large variety of diamond grit sizes from 20 to 600 mesh can be used in conjunction with diamond concentration as low as 12 to 100 con, along with different bond harnesses, bond matrixes, and diamond crystal types to achieve the clients desired surface finish, cutting speed, tool life and consistency.

Sintered Bond Families

The bond "matrix" is composed of various metal powders hot pressed together in a mold, under high pressure and high temperature usually ranging from 750 to 900°C. Sintered (metal bond) usually has (3) three bond families, which is based on main metallurgical powder used. The bond can be either

  • bronze based
  • cobalt
  • steel type (iron, tin, cobalt, etc)

Bronze based bond

Characterized by freer cutting and faster cutting speeds, which is needed for very hard and brittle materials.

Cobalt based bonds

Know to provide longer bond matrix retention, which results in longer tool life. This type of bond is widely used for majority of stone and concrete applications (such as granite countertop fabrication, installation and construction materials). Majority of diamond tools, blades and bits readily available in stores are based on this bond structure.

Steel based bonds

Frequently between the two other bond families (middle of the road). Offering a good combination of cutting speed and tool life. Such bond family is frequently implemented in very abrasive material applications such as sandstone, alumina oxide, silicon carbide which wears most tools really fast.

Other metallurgical powders (such as iron, copper tin, bronze alloys, tungsten, tungsten carbide, nickel alloys, silver, and many others) are used as additives or substitutes to provide forming characteristics, control rate of bond wear (speed at which it releases the diamond crystals into cutting zone) and retention of diamond crystals (strength of which they are hold in place). There are over 200+ different combinations that can be used. Each of these three bond families exhibits different behavior in the sintering process.

Its the job of the diamond tool manufacturer to select the right bond composition formula for the clients specific application, as well as clients specific objectives (surface finish, cutting speed, life), and usage environment (RPM's, equipment, coolant used, etc).

Technological Processes of producing Sintered (metal bond) Diamond Tools

Sintered (Metal Bond) Diamond Tools can be produced utilizing several processes. Depending on the type, application, and volume of the tools being produced. Some of these include:

  • normal sintering in a furnace with a sintering mould or in a continuous furnace
  • pressure sintering
  • hot isostatic pressing (HIP method)

pressure sintering is most widely used and preferred process today. Given this process flexibility/adoptability, capability to form and maintain complex shapes, ease of handling, high level of control of parameters and capability to do small batches and custom runs. In this process, the pre-pressed blank or the loose metallurgical powders that have been metered is brought to sintering temperature in a mould and compacted at the same time. This process utilizes a hydraulically operated press, which is usually equipped with a pyroscope or thermocouple to monitor the temperature cycle and time according to predetermined process.

To prevent melting loss on the graphite and oxidation of the metal powder, the equipment can be provided with a protective gas hood. The chamber is initially evacuated and subsequently flushed with an inert gas. Several extension stages also exist to provide varying degrees of automation.

Cold Pressing Process

Depending on the process and types of tools produced, Cold Pressing is usually the first step of the production process. After all the powders used in the bond matrix have been dosed, granulated, and evenly spread in the mold cavity. They are cold pressed in order to obtain their sold shape/form, as well as to achieve desired density.

is extremely important that the generator power is adequate—too low generator power results in long heating times. In addition a lot of heat may migrate into the tool blank and cause stress (tension) problems. Correct frequency selection and generator heating power ensures that the heat is produced only in a limited space.

thermal stability of the diamond is obviously important in metal bonds. Low-temperature bonds, comprising cobalt, nickel, bronze, and/or iron (in low concentrations), or a combination of these metals, preserve the strength of the diamond crystals best. In addition, if not managed properly, the metal in the bond can catalyze back-conversion of the surface of the diamond to graphite, weakening retention in the bond. In many cases bond retention can be improved by the use of diamonds with coatings, particularly titanium or chromium. In contrast to coatings for resin bonds, coatings for metal bonds are quite thin, ≈ 1 µm, and form chemical bonds with both the diamond (as the metal carbide) and the metal matrix. Other bonding materials do not sinter well at temperatures below 900 °C, and in these cases the bond can be cold pressed and then infiltrated with molten metal (braze alloy) or hot-pressed above 1000 °C. If temperatures are too high or exposure times too long, the diamond impact strength will be reduced.

Customizing Sintered (Metal Bond) Diamond & CBN Tools

Customization of Sintered (Metal Bond) Diamond Tools for specific materials is a critical aspect of tool design and application, ensuring optimal performance, precision, and longevity. This process involves tailoring tool characteristics such as diamond grit size, concentration, bond hardness, and matrix composition to match the specific properties and requirements of the material being processed. Here's a detailed exploration of how these tools are customized for various materials:

1. Understanding Material Properties
  • Hardness and Abrasiveness: The hardness and abrasiveness of the material determine the diamond size and bond hardness. Harder materials require finer diamond grits with a harder bond to resist premature wear, while abrasive materials necessitate a softer bond for faster diamond exposure.
  • Brittleness: Brittle materials like certain ceramics or glass demand tools with a high diamond concentration to minimize chipping and ensure smooth cuts.
  • Thermal Conductivity: Materials with low thermal conductivity may require bonds that dissipate heat effectively to prevent thermal damage to the workpiece.
  • Machining Challenges: Heavier, denser materials may require more power to machine and can lead to increased tool wear.
2. Diamond Grit Size and Concentration
  • Fine Grits: Used for hard, brittle materials requiring high precision and minimal surface damage. Fine grits produce smoother finishes but at slower cutting speeds.
  • Coarse Grits: Ideal for softer, more abrasive materials where rapid material removal is prioritized over surface finish.
  • Diamond Concentration: Adjusting the diamond concentration allows for balancing between cutting speed and tool life. High concentrations improve tool longevity but may reduce cutting efficiency, while lower concentrations increase cutting speed but wear out the tool faster.
3. Bond Hardness and Composition
  • Hard Bonds: Suitable for abrasive materials as they wear slowly, continuously exposing new diamonds. Materials such as asphalt or green concrete often require tools with hard bonds.
  • Soft Bonds: Used for hard materials that can quickly wear down the diamonds. The softer bond matrix wears away quicker, ensuring new diamonds are exposed for consistent cutting performance.
  • Matrix Composition: The choice of metal alloy (e.g., bronze, cobalt, or iron-based) affects the tool's wear rate and cutting performance. Innovations in alloy compositions, including the use of hybrid and composite matrices, allow for nuanced adjustments to tool properties.
4. Tool Geometry and Design
  • Segmented vs. Continuous Rim: Segmented rims are preferred for cutting harder, denser materials, offering better cooling and debris removal. Continuous rims provide smoother cuts in brittle materials such as glass and tile.
  • Profile and Shape: Custom tool shapes and profiles are designed to meet specific application requirements, such as unique cutting angles, grooving, or profiling tasks. The geometry affects the stress distribution and cutting efficiency.
5. Application-Specific Considerations
  • Cutting Speed vs. Finish Quality: Depending on the application, tools may be optimized for fast cutting speeds or high-quality finishes. This involves trade-offs in diamond size, bond type, and tool geometry.
  • Wet vs. Dry Cutting: The choice between wet and dry cutting tools is determined by the material and cutting environment. Wet cutting tools, often required for materials prone to thermal damage, use water for cooling and dust suppression.
  • Equipment Compatibility: Customization also considers the power and specifications of the cutting equipment to ensure optimal tool performance and lifespan.

Advanced Ceramics Materials

Material

Density (g/cm³)

Hardness (Knoop)

Tensile Strength (MPa)

Modulus of Elasticity (GPa)

Thermal Conductivity (W/m·K)

Typical Applications

Machining Challenges

Alumina (Al2O3)

3.9 - 4.2

2000 - 2500

250 - 350

350 - 400

20 - 35

Electrical insulation, wear parts, refractory products

Hard and brittle, requires diamond grinding tools

Silicon Carbide (SiC)

3.1 - 3.2

2800 - 3500

400 - 550

400 - 450

120 - 200

Abrasives, refractory materials, semiconductor devices

Extremely hard, challenging to machine without specialized tools

Beryllia (BeO)

2.85

1000 - 2000

300 - 350

300 - 320

250 - 300

Electronic substrates, thermal management components

Toxic dust, requires handling with safety precautions

Boron Carbide (B4C)

2.52

2750

350 - 400

450 - 470

20 - 30

Armor, abrasive materials, nozzles

Hard and abrasive, difficult to machine and wear on tools

Boron Nitride (BN)

2.1 - 2.3

10 - 20 (Hex)

N/A

20 - 700 (Type dependent)

20 - 600 (Type dependent)

High-temperature lubricants, insulators

Soft in hexagonal form, but machining can be challenging due to layer separation

Graphite

1.5 - 1.8

10 - 20

10 - 50

9 - 15

120 - 140

Electrodes, refractories, lubricants

Brittle and messy, can contaminate if not carefully handled

Piezoelectric Compositions

Varied

Varied

Varied

Varied

Varied

Sensors, actuators, transducers

Material sensitivity requires precise machining methods

Pyrite

4.9 - 5.2

600 - 650

N/A

N/A

0.1 - 0.25

Decorative use, mineral collections

Not typically machined for industrial applications

Sapphire

3.95 - 4.03

2000

400 - 600

345 - 400

25 - 35

Watch crystals, substrates, optical components

Very hard, requires diamond sawing and polishing

Zirconia (ZrO2)

5.5 - 6.0

1200 - 1400

200 - 240

200 - 210

2 - 3

Biomedical implants, cutting tools, oxygen sensors

Tough and wear-resistant, requires diamond or cubic boron nitride (CBN) tools

Steatite

2.7 - 2.8

800 - 850

70 - 100

100 - 120

2.5 - 3.5

Electrical insulators, ceramic mounts

Easier to machine than harder ceramics, but still requires care to prevent chipping

Cordierite

2.5 - 2.8

700 - 900

50 - 100

50 - 100

1 - 3

Kiln furniture, heat exchangers

Low thermal expansion but can be brittle, careful machining needed

Ferrites

4.5 - 5.0

600 - 630

N/A

N/A

5 - 10

Magnetic cores, inductors, transformers

Brittle and magnetic, can be challenging to machine without affecting magnetic properties

Composite Materials

Material

Density (g/cm³)

Knoop Hardness (kg/mm²)

Mohs Hardness

Tensile Strength (MPa)

Thermal Conductivity (W/m·K)

Typical Applications

Machining Challenges

Polymer Matrix Composites (PMC)

Varied

Varied

Varied

Varied

Varied

Aerospace, automotive parts

Cutting may cause delamination; requires special tools.

Metal Matrix Composites (MMC)

Varied

Varied

Varied

Varied

Varied

High-performance automotive and aerospace components

Abrasive on tools, challenging to machine.

Ceramic Matrix Composites (CMC)

Varied

Varied

Varied

Varied

Varied

Aerospace engines, thermal protection systems

Very hard; requires specialized machining processes.

Graphite Carbide

2.1 - 2.2

2500 - 2800

9-10

N/A

120 - 200

High-temperature environments, mechanical seals

Brittle, producing conductive dust during machining.

Honeycomb Structures

Very Low

N/A

N/A

Varied

Very Low

Aerospace and automotive sectors for lightweight structures

Requires precise cutting techniques to prevent crushing.

Fiber (General)

Varied

Varied

Varied

Varied

Varied

Reinforcement materials in composites

Can be difficult to cut without fraying; abrasive on tools.

Resin

1.1 - 1.2

15-30

1-2

55 - 70

0.1 - 0.5

Matrix materials in composites, adhesives

Sticky residue can gum up tools; requires careful curing.

Aramid Fibers

1.44

500-600

2-3

3620 - 4340

0.04 - 0.58

Bulletproof vests, high-strength ropes

Abrasive to cutting tools; challenging to cut cleanly.

Carbon Fibers

1.75 - 2.0

1000-1100

10

3500 - 7000

2 - 5

High-performance composites, sporting goods

Requires diamond-coated tools for clean cuts.

Boron

2.34

3000

9-10

3100 - 3800

27

Aerospace structures, neutron absorbers

Very hard and brittle; difficult to process.

E-Glass

2.54

600

6

3400

1.0

Glass-reinforced plastics, electrical insulation

Wear on tools; handling glass fibers requires care.

S-Glass

2.49

610

6

4570

1.0

Aerospace and military applications for high-strength composites

Similar to E-Glass but with higher wear on tools.

Silicon Carbide (SiC)

3.1 - 3.2

2485 - 2970

9-10

400 - 550

120 - 200

Abrasives, brake discs, high-temperature parts

Extremely hard, requiring diamond tools for machining.

Silicon Nitride (Si3N4)

3.2 - 3.4

1200 - 1500

8-9

600 - 900

15 - 30

Bearings, cutting tools, engine parts

Hard and brittle; specialized equipment needed for machining.

Titanium

4.506

800 - 850

6

900 - 1200

22

Aerospace, medical implants, high-performance automotive

Work hardening and high chemical reactivity with tools.

Diboride (Assuming B4C)

2.52

2800 - 3500

9-10

350 - 400

20 - 30

Armor, abrasive applications

Extreme hardness and abrasiveness to tools.

Construction Materials

Material Category

Density (kg/m³)

Compressive Strength (MPa)

Knoop Hardness (kg/mm²)

Mohs Hardness

Typical Applications

Asphalt

2,300 - 2,500

N/A

N/A

-2

Highways, driveways

Concrete

2,400

20 - 40

N/A

-3

Structural components

Cured Concrete

2,400

20 - 40 (Increases with age)

N/A

-3

Same as concrete

Reinforced Concrete

2,400

20 - 40 (Varies)

N/A

-3

Buildings, bridges

Green Concrete

2,300 - 2,500

20 - 40

N/A

-3

Eco-friendly projects

Masonry

500 - 2,000

2 - 30

Varies

Varies

Walls, partitions

Bricks

1,600 - 1,900

10 - 35

-1000

-6.5

Walls, pavements

Natural Stone

2,200 - 2,700

50 - 200

Varies

2 - 7

Facades, countertops

Artificial Stone

1,800 - 2,400

30 - 100

N/A

-3 - 7

Decorative elements

Abrasive Materials

Varies

N/A

Varies

Varies

Surface treatment

Building Materials

Varies

Varies

N/A

N/A

Construction

Paving

Varies

N/A

N/A

N/A

Walkways, patios

Sidewalks

N/A

N/A

N/A

N/A

Pedestrian paths

Expansion Joints

N/A

N/A

N/A

N/A

Thermal expansion

Glass Materials

Material

Density (kg/m³)

Compressive Strength (MPa)

Knoop Hardness (kg/mm²)

Mohs Hardness

Typical Applications

Machining Challenges

Soda Lime Glass

2500

1000

585

5

Bottles, windows, glassware

Brittle; sensitive to thermal shock

Borosilicate Glass

2230

820

620

6

Lab glassware, cookware, thermal windows

Lower thermal expansion but still requires careful handling

Ceramic Glass

2500

N/A

N/A

N/A

Cooktops, fireplace doors

High hardness and thermal resistance complicate cutting/drilling

Quartz Glass

2200

1100

820

7

High-temperature optics, semiconductor processes

Extreme hardness and brittleness; specialized tools required

Pyrex (Brand)

2230

820

620

6

Cookware, lab equipment

Similar to borosilicate; durable but needs careful machining

Optical Glass

Varies

N/A

Varies

Varies

Lenses, prisms, optical instruments

Requires precision to maintain optical properties

Electronic Glass

Varies

N/A

Varies

N/A

Displays, semiconductors

Thin and fragile; often processed via etching or laser cutting

Technical Glass

Varies

N/A

Varies

N/A

Industrial, scientific applications

Specific challenges depend on glass type; often requires custom processing

Glass Tubing

2500

1000

585

5

Lab glassware, architectural elements

Risk of cracking; requires delicate handling and cutting techniques

Photonics

Varies

N/A

Varies

N/A

Fiber optics, laser technology

Precision cutting and assembly are critical to maintain function

Glass Components

Varies

N/A

Varies

N/A

Varied industrial, commercial uses

Complex shapes demand precise and careful machining

Borofloat Glass

2230

820

620

6

Specialty applications with thermal shock resistance

Similar to borosilicate with added challenges due to size and thickness

Stained Glass

2500

N/A

N/A

N/A

Artistic installations, windows

Requires artistic cutting techniques; fragility is a concern

Art Glass

Varies

N/A

N/A

N/A

Decorative items, artwork

Custom designs necessitate precise and often hand-crafted machining

Glass Assemblies

Varies

N/A

N/A

N/A

Complex components, architectural structures

Assembly precision is key; individual components may have unique challenges

Float Glass

2500

1000

585

5

Windows, mirrors, general building glass

Large sheets require scoring and breaking; risk of sharp edges

Fused Silica/Fused Quartz

2200

1100

820

7

High-precision optics, UV transmission

Very hard and brittle; requires diamond tools for effective machining

Automotive Glass

2500

N/A

N/A

5-6

Windshields, side windows

Laminated and tempered types pose different machining challenges

Flat Glass

2500

1000

585

5

General purpose glass in buildings, vehicles

Similar to float glass; must be cut to size with care
1737F Glass

Varies

N/A

N/A

N/A

Electronic substrates, display glass

Specifically formulated for electronics; machining often involves scribing and breaking

B270/Crown Glass

Varies

N/A

Varies

Varies

Optical applications, high clarity needs

Requires precision machining for optical clarity
Tempered Glass

2500

N/A

620-670

6-7

Safety applications, vehicles, buildings

Cannot be machined after tempering due to risk of shattering

Stone Materials

Material

Density (kg/m³)

Compressive Strength (MPa)

Knoop Hardness (kg/mm²)

Mohs Hardness

Typical Applications

Machining Challenges

Granite

2600-3000

100-250

1400-2000

6-7

Countertops, flooring

Hardness requires diamond tools

Marble

2500-2800

70-100

200-400

3-5

Sculpture, architecture

Softness leads to scratches; acid sensitivity

Limestone

2300-2600

30-250

150-200

3-4

Building facades, flooring

Susceptible to acid erosion

Marble-Limestone

Varies

Varies

Varies

3-5

Decorative interior elements

Combination of marble and limestone challenges

Onyx

2500-2700

70

100-200

6-7

Decorative items, jewelry

Can be brittle; care in cutting required

Quartz

2600

70-90

1200-1300

7

Countertops, decorative items

Hard; abrasive to cutting tools

Porcelain

2400-2600

35-50

800-1000

7-8

Tiles, sanitary ware

Hardness; requires diamond tools for cutting

Sandstone

2200-2700

20-170

200-300

6-7

Building and paving materials

Porosity varies; can wear tools

Serpentine

2500-2600

100-200

150-200

3-6

Countertops, decorative art

Soft, may contain asbestos which poses health risk

Soapstone

2700-3000

40-70

100-200

1

Countertops, carving

Soft; easy to scratch and cut

Flagstone

Varies

Varies

Varies

Varies

Paving, patios

Variability in hardness and porosity

Quarry Tile

2000-2200

30-50

500-800

7-8

Flooring, paving

Hard and durable; abrasive on tools

Slate

2700-2800

50-200

150-300

5-6

Roofing, flooring

Cleavage planes can be a challenge in cutting

Engineered Stone

2400-2500

50-90

1200-1400

7

Countertops, flooring

Consistent but hard; wears tools

Composite Stone

Varies

Varies

Varies

Varies

Construction, decorative uses

Depends on the composite materials; varied challenges

Precious & Semi-precious Stone

Varies

Varies

Varies

7-10

Jewelry, decorative items

Hardness varies; some stones very brittle

Porphyry

2500-2800

150-250

2000-3000

6-7

Paving, columns

Hard and tough; difficult to work

Cantera

2100-2400

15-40

100-200

3-4

Sculpture, architectural elements

Soft; easier to shape but can erode

Black Granite

2900-3100

100-250

1400-2000

6-7

Countertops, memorials

Similar to granite; requires diamond tools

Basalt

2800-3000

150-300

500-600

6

Paving, tiles

Hard and abrasive; tough on machinery

Bluestone

2700-3000

100-200

300-700

5-6

Paving, architectural details

Hard; can vary in composition

Calcarenite

2200-2500

20-70

100-200

3-4

Building materials

Soft and porous; easy to work but less durable

Greenstone

2900-3100

100-250

400-600

5-7

Architectural, ornamental uses

Tough; varies in hardness

Lapidary Materials

Material

Density (kg/m³)

Knoop Hardness (kg/mm²)

Mohs Hardness

Typical Applications

Machining Challenges

Agate

2600

800

6.5-7

Jewelry, decorative items

Hardness requires specialized cutting tools

Ametrine

2650

1050

7

Jewelry

Color zoning can challenge even cutting

Amethyst

2650

750

7

Jewelry, decorative arts

Susceptible to heat damage during cutting

Azurite

3800

N/A

3.5-4

Mineral collections, pigments

Soft, easy to carve but prone to scratching

Cubic Zirconia

5800

1200-1400

8.5

Jewelry (diamond substitute)

Requires diamond-coated tools for cutting

Emerald

2710

1350

7.5-8

High-end jewelry

Inclusions can make cutting and setting challenging

Garnet

3900

1300

6.5-7.5

Abrasives, jewelry

Variability in hardness among types

Gemstones

Varies

Varies

Varies

Jewelry, decoration

Cutting to maximize beauty often requires expertise

Jade

3300

1200

6-7

Carvings, jewelry

Toughness makes carving labor-intensive

Quartz

2650

1200

7

Jewelry, decorative items

Hardness; abrasive to cutting tools

Lapis Lazuli

2500-2800

N/A

5-5.5

Jewelry, decoration

Soft; susceptible to scratching during machining

Meteorites

Varies

N/A

Varies

Collectibles, jewelry

Metal content and structure complicate cutting

Opal

2100-2500

700

5.5-6.5

Jewelry

Fragility requires careful handling to prevent cracking

Onyx

2500-2700

100-200

6-7

Jewelry, decorative items

Can be brittle; care in cutting required

Petrified Wood

2200-2400

N/A

7-8

Decorative items, jewelry

Hardness varies; some pieces can be tough to polish

Rhodonite

3400-3600

N/A

5.5-6.5

Jewelry, carvings

Can show cleavage; careful cutting necessary

Rough Gem Stone

Varies

Varies

Varies

Jewelry (prior to cutting/polishing)

Each stone type presents unique challenges

Ruby

4000

1800

9

High-end jewelry

Hardness requires diamond cutting tools

Tanzanite

3350

700

6.5-7

Jewelry

Risk of thermal shock; careful heating during cutting

Topaz

3500

1350

8

Jewelry

Cleavage planes require careful handling

Tourmaline

3000-3300

1000-1100

7-7.5

Jewelry

Broad color range; some colors more prone to cracking

Tsavorite

3700

1600-1800

7-7.5

Jewelry

Similar to garnet; requires careful cutting due to inclusions

Turquoise

2700-2900

N/A

5-6

Jewelry, decoration

Porous nature makes it sensitive to chemicals and pressure

Optical Glass / Photonic Materials

Material

Density (kg/m³)

Knoop Hardness (kg/mm²)

Mohs Hardness

Typical Applications

Machining Challenges

UV Materials

Varies

Varies

Varies

UV optics, lithography

Material-specific; often require diamond tooling for precision shaping

Excimer Grade Fused Silica

-2200

500-600

7

UV laser systems

Brittle, requiring careful handling; diamond grinding/polishing

UV Grade CaF2

-3180

158-160

4

UV lenses, windows

Soft, cleavage planes present machining challenges

Quartz

-2650

820

7

Optical components, quartz heaters

Hardness requires diamond tooling; prone to thermal shock

BK-7

-2510

610

6

General optical applications

Relatively easy to machine but requires precision polishing

ZKN-7

Varies

Varies

Varies

High refractive index optics

Specific data not widely available; similar challenges to other optical glasses

Pyrex/Tempax

-2230

418

5-6

Lab equipment, cookware

Thermal resistant, but still requires careful thermal management

Various Flint Types

Varies

Varies

Varies

Corrective lenses, prisms

Hard and brittle, varying widely with specific composition

Various Crown Types

Varies

Varies

Varies

Eyeglass lenses, low dispersion optics

Easier to machine than flint types, but precision is key

Various Filter Types

Varies

Varies

Varies

Filters for cameras, telescopes

Machining less of a concern than coating and assembly precision

Borofloat Glass

-2230

620

6

Specialty optics, substrates

Resistant to thermal shock, but machining requires diamond tools

Mirror Substrate Material

Varies

Varies

Varies

Telescope mirrors, laser mirrors

Depends on material; glass substrates require careful polishing

Zerodur

-2530

Varies

-8

Telescope mirrors, precision optics

Very hard and zero expansion; requires specialized equipment for shaping

Ule

-2210

Varies

Varies

Telescope mirrors, metrology components

Very low thermal expansion; machining is specialized and costly

Stainless Steel

-8000

160-500

3-4

Optical system frames

Relatively easy to machine but hardens with work; corrosion-resistant

Aluminum

-2700

250-350

2.5-3

Mirror coatings, mounts

Easy to machine but requires finishing to prevent oxidation

IR Material

Varies

Varies

Varies

IR optics, windows

Specific to material; e.g., Germanium is brittle and requires careful handling

Silicon

-2330

1150

7

Mirrors, lenses in IR systems

Brittle, requiring diamond grinding and careful handling

Germanium

-5323

780

6

IR lenses, windows

Brittle and sensitive to thermal shock; expensive to machine

ZnSe

-5240

120

2.5

CO2 laser optics, IR windows

Soft but toxic dust requires careful handling and machining

ZnS

-4090

210

3

IR windows, lenses

Soft, can be machined but generates hazardous dust

Glass

Varies

Varies

Varies

General optics, windows, lenses

Challenges depend on type; generally requires diamond tooling for shaping

Semiconductor Materials

Material

Density (kg/m³)

Knoop Hardness (kg/mm²)

Mohs Hardness

Typical Applications

Machining Challenges

Silicon (Si)

-2330

1150

7

Brittle, requires diamond cutting tools

Germanium (Ge)

-5323

780

6

IR optics, semiconductor devices

Sensitive to thermal shock, toxic dust

Gallium Arsenide (GaAs)

-5317

750

-6

High-speed electronic devices

Toxicity of arsenic requires careful handling

Gallium Nitride (GaN)

-6150

1300

-9

LED, high-frequency devices

Hard and brittle; difficult to cut

Indium Phosphide (InP)

-4810

580

-6

Telecommunications, photonic devices

Toxic material; requires protective measures

Silicon Carbide (SiC)

-3210

2480

-9-10

Power electronics, high-temperature applications

Extreme hardness; diamond tools necessary

Aluminum Gallium Arsenide (AlGaAs)

-4810

Varies

Varies

Optoelectronics, laser diodes

Similar to GaAs; handling arsenic content

Indium Gallium Arsenide (InGaAs)

-5870

Varies

Varies

NIR detectors, high-speed electronics

Fragile and expensive to produce

Cadmium Telluride (CdTe)

-6240

Varies

-2

Solar panels

Toxic; requires handling in controlled environments

Gallium Phosphide (GaP)

-4070

Varies

-6

LEDs, semiconductor devices

Brittle, similar challenges to GaAs

Silicon Germanium (SiGe)

Varies

Varies

Varies

Heterojunction transistors, RF applications

Handling similar to silicon but with adjusted parameters

Zinc Selenide (ZnSe)

-5240

120

2.5

IR optics, CO2 laser systems

Soft, but toxic dust requires care in machining

Lead Sulfide (PbS)

-7500

Varies

-3

IR detectors, photodetectors

Toxicity of lead and sensitivity to moisture

Cadmium Selenide (CdSe)

-5820

Varies

-2

Quantum dots, optoelectronic devices

Toxicity requires careful environmental controls

Silicon Germanium Carbon (SiGeC)

Varies

Varies

Varies

Electronics, heterojunction bipolar transistors

Specifics depend on the Si/Ge/C ratios

Copper Indium Gallium Selenide (CIGS)

Varies

Varies

Varies

Thin-film solar cells

Complexity in deposition, toxicity concerns

Aluminum Nitride (AlN)

-3260

1200

-9

Electronic substrates, microwave devices

Hard and brittle; diamond tools for machining

Cadmium Sulfide (CdS)

-4820

Varies

-2-3

Photocells, thin-film transistors

Toxic; careful handling required

Silicon Oxide (SiO2)

 -2200

820

7

Optical fibers, microelectronics

Brittle; requires specialized cutting techniques

Zinc Telluride (ZnTe)

-6700

Varies

-2

Solar cells, semiconductor layers

Soft, but care must be taken due to toxicity

Zinc Oxide (ZnO)

-5600

200

4

Varistors, transparent conductors

Abrasive; requires careful machining

Gallium Antimonide (GaSb)

-5900

Varies

-5

IR components, thermophotovoltaic devices

Similar handling to GaAs with additional antimony considerations

Silicon Germanium Tin (SiGeSn)

Varies

Varies

Varies

Electronic and photonic devices

Complex composition adds to machining difficulty

Cadmium Zinc Telluride (CdZnTe)

Varies

Varies

-2

Radiation detectors, solar cells

Toxic and brittle; requires special care

Mercury Cadmium Telluride (HgCdTe)

Varies

Varies

-2

IR detectors

Extremely toxic and sensitive; specialized facilities needed

Metallography Materials

Material

Density (kg/m³)

Knoop Hardness (kg/mm²)

Mohs Hardness

Typical Applications

Machining Challenges

Steel (various grades)

7800-8050

120-700

4-8

Construction, tools

Variability in hardness, depending on alloy and heat treatment

Aluminum (various alloys)

2700

250-350

2.5-3

Aerospace, automotive

Soft, can stick to tools, requires sharp cutters

Copper

8960

210

3

Electrical wiring, plumbing

Soft, malleable, can work harden

Titanium (various alloys)

4500

800

6

Aerospace, medical devices

Hard, reactive to oxygen at high temperatures

Nickel-based alloys (Inconel)

8200-8500

300-550

5-7

Jet engines, chemical plants

Very hard, abrasive, generates heat during machining

Magnesium (various alloys)

1740-1880

N/A

2.5

Lightweight structures, automotive

Flammable as dust, requires careful handling

Cast Iron

6800-7300

210-410

4-5

Machinery parts, cookware

Brittle, can wear tools quickly

Adhesives and Sealants

Varies

N/A

N/A

Joining materials, sealing

N/A (not typically machined)

Stainless Steel (various grades)

7900-8000

250-700

4-6

Kitchenware, medical instruments

Work hardening, requires lubrication and coolants

Brass

8530-8730

200

3

Decorative, musical instruments

Soft, easy to machine but requires sharp tools

Bronze

7700-8900

300

3

Bearings, historical artifacts

Harder than brass, can be tough on tools

Zinc

7140

120

2.5

Corrosion protection coatings

Low melting point, easy to machine

Glass

2200-2500

500-600

5-6

Windows, lenses

Brittle, requires diamond-coated tools for machining

Cobalt-based alloys

8300-8900

300-700

5-7

Medical implants, turbines

Hard and tough, requires advanced machining techniques

Superalloys (Hastelloy)

8000-9000

300-500

5-7

Aerospace, chemical reactors

Difficult to machine, requires specialized tools

Ceramics (alumina, zirconia)

3800-5800

1000-1500

8.5-9

Biomedical implants, cutting tools

Very hard, brittle, requires diamond grinding

Polymers (plastics, elastomers)

900-1400

N/A

N/A

Consumer goods, automotive

Can melt or deform if not machined at correct speeds

Coatings (paints, thermal spray coatings)

Varies

N/A

N/A

Surface protection, decoration

N/A (applied, not machined)

Semiconductor materials (silicon, GaAs)

2330-5317

850-1100

7

Electronics, solar cells

Brittle, requires precision handling

Refractory metals (tungsten, molybdenum)

19250-10280

2000-4000

7-7.5

High-temperature applications

Very hard, high melting points, challenging to machine

Precious metals (gold, silver)

19300-10490

25-70

2.5-3

Jewelry, electronics

Soft, malleable, requires care to avoid deformation

Refractory ceramics (boron nitride)

2000-3500

10-20

1-2

High-temperature insulators

Soft in one direction, hard in another, challenging to shape precisely

Electronic materials

Varies

Varies

Varies

Electronics, PCBs

Specific to material; e.g., PCBs require etching, not machining

Biomaterials (biodegradable polymers)

1100-1400

N/A

N/A

Medical devices, tissue engineering

Sensitive to heat and moisture, can be difficult to process

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