2. Precautions Based on Abrasive Type

Grinding wheels can generally be divided into conventional abrasive wheels and superabrasive wheels according to the type of abrasive grain used. Each category has different application characteristics and operating requirements.

2.1 Conventional Abrasive Grinding Wheels

Conventional abrasive wheels mainly include:

• Aluminium oxide (Al₂O₃) abrasives
  (Brown fused alumina, white fused alumina, pink/chromium alumina, etc.)

• Silicon carbide (SiC) abrasives
  (Black silicon carbide and green silicon carbide)

The selection of abrasive type should be based on workpiece material, hardness, grinding method, and required surface quality.

Aluminium Oxide Grinding Wheels

Aluminium oxide wheels are widely used for grinding ferrous metals due to their good toughness and durability.

Suitable Applications:

Recommended for:

• Carbon steel

• Alloy steel

• Tool steel

• Cast iron

• General ferrous metal applications

Important Notes:

Aluminium oxide wheels are generally not recommended for grinding soft non-ferrous metals, such as:

• Aluminium

• Copper

• Lead

• Brass in some applications

Soft metal grinding chips can easily block the wheel pores, causing:

• Reduced cutting ability

• Poor heat dissipation

• Wheel loading and glazing

• Increased risk of workpiece burning

Silicon Carbide Grinding Wheels

Silicon carbide abrasives have higher hardness and sharper cutting edges compared with aluminium oxide abrasives.

Suitable Applications:

Recommended for:

• Cemented carbide

• Cast iron

• Glass

• Ceramics

• Stone

• Some hard non-ferrous materials such as bronze and brass

Important Notes:

Although silicon carbide can cut certain non-ferrous materials, caution is required when grinding soft metals such as aluminium and copper because loading may occur.

Silicon carbide wheels are generally not preferred for ordinary steel grinding, because chemical reactions and abrasive wear can result in shorter wheel life.

General Requirements for Conventional Abrasive Wheels

Regardless of abrasive type:

• Protect wheels from moisture, freezing conditions, and oil contamination.

• Avoid long-term immersion after wet grinding.

• Store wheels in dry and stable conditions.

• Grinding wheels exceeding their recommended storage period should undergo appropriate strength testing before use.

2.2 Superabrasive Grinding Wheels

Superabrasive wheels include:

• Diamond grinding wheels

• CBN (Cubic Boron Nitride) grinding wheels

They offer extremely high hardness, excellent wear resistance, and long service life. However, they also have specific chemical and processing limitations.

Diamond Grinding Wheels

Diamond is the hardest known abrasive material and provides outstanding cutting performance on hard and brittle materials.

Suitable Applications:

Diamond wheels are widely used for:

• Cemented carbide

• Ceramics

• Glass

• Stone

• Semiconductor materials

• Advanced composite materials

Important Limitation:

Diamond grinding wheels are generally not suitable for machining ferrous metals, including:

• Steel

• Stainless steel

• Iron

At high grinding temperatures, carbon atoms in diamond may react with iron, causing:

• Formation of iron carbide

• Rapid diamond wear

• Reduced cutting performance

For ferrous materials, CBN wheels are normally the preferred choice.

CBN Grinding Wheels

CBN is especially suitable for high-performance grinding of hardened steels and heat-resistant alloys.

Suitable Applications:

Recommended for:

• High-speed steel

• Tool steel

• Bearing steel

• Hardened alloy steel

• Heat-resistant alloys

• Aerospace materials

Important Notes:

During CBN grinding:

• Proper coolant selection is essential.

• Avoid excessive grinding temperatures.

• Prevent localized overheating.

• Maintain stable grinding conditions.

High temperatures may reduce abrasive performance and shorten wheel life.

General Requirements for Superabrasive Wheels

Superabrasive wheels require different dressing and maintenance methods compared with conventional wheels.

Important considerations:

• Use suitable diamond rolls, EDM dressing systems, or specialized dressing tools.

• After profile dressing, additional sharpening may be required using suitable methods.

• Cooling control is critical.

• Avoid thermal shock caused by sudden temperature changes.

3. Precautions Based on Bond Type

The bonding system determines the grinding wheel’s strength, elasticity, self-sharpening ability, heat resistance, and application range.

Common bond types include:

• Vitrified bond

• Resin bond

• Rubber bond

• Metal bond

• Electroplated bond

• Brazed bond

3.1 Vitrified Bond Grinding Wheels

Vitrified bonds are manufactured mainly from ceramic materials such as:

• Clay

• Feldspar

• Other mineral components

They are fired at high temperatures to form a rigid and porous structure.

Advantages:

Vitrified wheels offer:

• Excellent heat resistance

• Good dimensional stability

• High chemical resistance

• Good shape retention

• Suitable performance for precision grinding

They are widely used for:

• Precision grinding

• Profile grinding

• Tool grinding

• General-purpose grinding applications

Precautions:

Because vitrified bonds are relatively brittle:

Avoid:

• Strong impact

• Excessive vibration

• Heavy interrupted grinding

Additional requirements:

• Handle wheels carefully during transportation and installation.

• Prevent moisture absorption during storage.

• Avoid sudden temperature changes.

• Do not allow a hot wheel to contact cold coolant suddenly.

Thermal shock may cause cracking or wheel failure.

3.2 Resin Bond Grinding Wheels

Resin bond wheels mainly use organic materials such as phenolic resin as the bonding agent.

They provide excellent self-sharpening characteristics and high grinding efficiency.

Advantages:

Resin bond wheels feature:

• Good elasticity

• Excellent self-sharpening ability

• Lower grinding temperature

• Reduced risk of workpiece burning

They are commonly used for:

• High-speed grinding

• Cutting wheels

• Heavy-duty grinding

• Polishing applications

Precautions:

Resin bonds have lower heat resistance than vitrified bonds.

Important points:

Avoid Excessive Heat

High grinding temperatures may cause:

• Bond softening

• Reduced wheel strength

• Accelerated wear

Avoid Strong Alkaline Coolants

Strong alkaline solutions may attack phenolic resin, resulting in:

• Bond degradation

• Reduced mechanical strength

• Shorter wheel life

Storage Requirements

Resin bond wheels:

• Have a limited shelf life.

• Should not be stored beyond the recommended period.

• Should not be continuously immersed in water.

Long-term moisture exposure may reduce strength.

3.3 Rubber Bond Grinding Wheels

Rubber bond wheels provide excellent elasticity and are commonly used in applications requiring smooth finishing.

Typical applications include:

• Centerless grinding regulating wheels

• Polishing wheels

• Fine finishing operations

Advantages:

Rubber bond wheels provide:

• Excellent elasticity

• Superior surface finishing capability

• Reduced vibration

• High-quality workpiece surfaces

Precautions:

Compared with resin bonds, rubber bonds have lower heat resistance.

Avoid:

• Excessive grinding temperature

• Long continuous operation under heavy loads

Rubber bonds are also sensitive to:

• Oil contamination

• Organic solvents

• Chemical exposure

Storage should be away from:

• Oil

• Solvents

• Chemical materials

3.4 Metal Bond Grinding Wheels

Metal bond wheels mainly use:

• Bronze alloys

• Nickel-based alloys

• Other metallic bonding materials

They are widely used for superabrasive grinding wheels.

Advantages:

Metal bond wheels provide:

• Extremely strong abrasive retention

• Excellent wear resistance

• Long service life

• High dimensional accuracy

Suitable for:

• Heavy-duty grinding

• Profile grinding

• Precision forming operations

Precautions:

Metal bond wheels have relatively poor self-sharpening ability.

Therefore:

• Regular dressing is required.

• Avoid operating with a heavily dulled wheel.

Because metal bonds generate more grinding heat:

• Adequate coolant supply is necessary.

• Avoid excessive temperature accumulation.

Dressing usually requires:

• Diamond rollers

• EDM dressing equipment

• Specialized diamond tools

Part 3 will continue with:

• Electroplated Bond Grinding Wheels

• Brazed Bond Grinding Wheels

• Application-Based Recommendations

  • Cylindrical Grinding

  • Internal Grinding

  • Surface Grinding

  • Cutting & Slotting

  • Form Grinding