Grinding Media

Grinding Media & Grinding Balls

Grinding media, the objects used to refine material and reduce particle size, are available in a wide range of shapes, sizes and materials to meet an equally wide range of grinding and milling needs.

As the developer and manufacturer of industry-leading particle size reduction equipment, including Attritors (internally agitated ball mills) and DMQX horizontal media mills, Union Process is uniquely positioned to help you identify and source the correct grinding media for your application.

Union Process customers know they can rely on our extensive technical expertise and years of experience to ensure they get the right grinding media at the right time and the right price for their specific needs. Working in close consultation with our customers, our skilled technical service representatives review customer requirements like final particle size, physical compatibility and contamination concerns and then recommend media with the right characteristics, including:


balls, beads and satellites satisfy the bulk of our customers’ requirements, but we also source highly specialized shapes like ballcones and diagonals


depending on the material, ranging from 0.05 mm to 2 mm for small media mills, up to 1/8” to 1” for traditional Attritors and up to ½” to 2” for ball mills


metallic grinding media like carbon steel, forged steel, stainless steel or chrome steel grinding balls are best for some applications, while others require non-metallic media made of alumina, ceramics, glass, silicon carbide, zirconium oxide or other specialized materials 

Union Process is the source for the most up-to-date information on grinding balls and other media. Download our Grinding Media Literature (PDF) to view a detailed sheet, outlining factors to consider when selecting grinding media, along with specifications on the most common types of media.

Offering the optimal combination of grinding media knowledge and manufacturing expertise, Union Process takes your entire operation into account to identify the best grinding media to consistently generate the final particle size and shape required by your application, optimizing the cost effectiveness of your process and extending the life of your mills.

Backed by our long-standing commitment to customer satisfaction, we ensure quality manufacturing and reliable supply of grinding balls and media specifically engineered to meet the requirements of your most demanding milling applications.

Scroll down to view our full line of grinding media; for immediate technical assistance, call (330) 929-3333.

Metallic Grinding Media

Note: Sizes shown in red indicate media that is recommended for use in bead mills except where stated otherwise. 

Carbon Steel Grinding Balls

Through-Hardened Carbon Steel Balls Type 1065

Through-Hardened Carbon Steel Balls are magnetic and can be used in the food industry along with 440C stainless steel media. They are a low-cost media that are superior and recommended over case-hardened carbon steel media which have a soft core. They are packaged with no oil finish—always dry packed—as they will rust in water.

  • (SAE 1065–through-hardened)
  • Specific Gravity: 7.8
  • Hardness: ROCKWELL C 60–62
  • Relative Cost: Low
  • Sizes Available: 1/8″, 3/16″, 1/4″, 5/16″, 3/8″, 1/2″, 3/4″
Chrome Steel Grinding Balls

Chrome Steel Balls Type 52100

Chrome Balls (steel type 52100) are through-hardened and tempered steel balls designed to achieve maximum strength and quality. Ball hardness is in the 60–67 HRC range. They wear better than 440C stainless steel and through-hardened carbon steel. They are also recommended for applications where a through-hardened steel ball is needed in larger sizes (½” and larger). They are sometimes packaged with a very light oil finish to reduce rust due to humidity.

  • (SAE 52100)
  • Specific Gravity: 7.8
  • Hardness: ROCKWELL C 60–67
  • Relative Cost: Low to Moderate
  • Sizes Available: 1mm, 2mm, 1/8″, 5/32″, 3/16″, 7/32″, 1/4″, 5/16″, 3/8″, 1/2″, 3/4″, 1″
Stainless Steel Balls

440C Stainless Steel Balls

440C Stainless Steel Balls are through-hardened and tempered throughout for maximum strength and quality. They are magnetic, and corrosion-resistant (generally rust-resistant). They are recommended for food applications and lighter colored slurries.

  • (AISI 440-C)
  • Specific Gravity: 7.7
  • Hardness: ROCKWELL C 58–65
  • Relative Cost: Moderate
  • Sizes Available: 2mm, 1/8″, 5/32″, 3/16″, 7/32″, 1/4″, 5/16″, 3/8″, 1/2″, 3/4″, 1″
Steel Shot Grinding Media

Carbon Steel Shot

Carbon Steel Shot media is through-hardened and very low cost. As such, they are not uniformly spherical and often can leave a gritty black residue.

  • Specific Gravity: 7.6
  • Hardness: ROCKWELL C 55–60
  • Relative Cost: Low
  • Sizes Available: .25mm, .50mm, .6mm,.71mm, .85mm, 1mm, 1.18mm, 1.40mm, 1.70mm, 2mm, 2.36mm, 2.80mm
Forged Steel Grinding Balls

Forged Steel Balls (Large Diameter)

Forged Steel Balls are used for gold mining, cement factories, oil processing and large scale industrial applications. They are made by machine (standard) sizes 20mm–75mm. They are manually made (hit by air hammer) sizes 75mm–125mm. They have hardness 55–63 HRC. All forged balls are through-hardened, and shipped in 55-gallon steel drums. They range in sizes from 20mm–125mm. Standard lead time is 6–8 weeks FOB Akron, Ohio USA.

  • Specific Gravity: N/A
  • Hardness: 55–63HRC
  • Relative Cost: Very Low
  • Sizes Available: 20mm, 25mm, 30mm, 40mm, 50mm, 60mm, 65mm, 75mm, 90mm, 100mm, 125mm

Non-Metallic Grinding Media

Note: Sizes shown in red indicate media that is recommended for use in bead mills except where stated otherwise. 

Alumina Balls and Satellites

Union Process is the one source for 90%, 94%, 99.5% and 99.9% alumina media. 90% alumina is available in satellites and rod/cylinders. 94% alumina balls have excellent wear resistance with higher impact strength to save running costs with less contamination. They have great wear rate generally better than 90% or 99.5%. 99.5% alumina balls have the highest alumina content for a moderate price. The .5% impurity is MgO that is added to inhibit grain growth during sintering in the kiln. There is less than 0.1% silica in the media. 99.9% alumina balls are made of very pure and reactive (expensive) raw materials. They are for high purity alumina applications where contamination is a factor.

  • Specific Gravity: 3.9
  • Hardness: Hv10 = 1800
  • Relative Cost: High
  • Sizes Available: 1mm, 2mm, 3mm, 5mm, 10mm, 15mm, 20mm, 25mm
  • Specific Gravity: 3.8
  • Hardness: Hv 1300 kg/mm2
  • Relative Cost: Moderate
  • Sizes Available: 0.2mm, 0.3mm, 0.5mm, 1mm, 2mm, 3mm, 5mm, 8mm, 10mm, 15mm, 20mm
  • Specific Gravity: 3.4-3.7
  • Hardness: ROCKWELL 45N 78 – 79
  • Relative Cost: Moderate
  • Sizes Available: 1/4″
  • Specific Gravity: 3.59
  • Hardness: Hv 1200 kg/mm2
  • Relative Cost: Low to Moderate
  • Sizes Available: 0.5mm, 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 13mm, 15mm, 20mm
  • Specific Gravity: 3.4 – 3.7
  • Hardness: ROCKWELL 45N 75
  • Relative Cost: Low
  • Sizes Available: 3mm, 7/32″, 1/4″, 3/8″, 1/2″
  • Note: 3mm size are Beads-remaining four sizes are satellites
Alumina Beads

Alumina Beads

Alumina Beads are specially formulated to be used in high-energy mills in which a high degree of fineness is required. They are used in various industrial fields such as inks, paints, advanced ceramics, mining, cosmetics and pharmaceutical industries. They are a perfectly spherical shape with high mechanical properties and high wear resistance at a moderate price.

  • Specific Gravity: N/A
  • Hardness: Mohs 9, VICKERS (0.5 kg) 1200 ± 50
  • Relative Cost: Low to Moderate
  • Sizes Available: 0.25–0.34mm, 0.34–0.44mm, 0.4–0.6mm, 0.8–1.2mm, 1.2–1.6mm, 1.4–1.6mm, 1.6–1.8mm, 1.8–2.0mm, 2.0–2.5mm, 2.5–3.0mm
Glass Beads

Glass Beads

This grade is used for milling applications with 85% roundness. All Glass Beads are lead-free and less expensive.

  • Specific Gravity: 2.5
  • Hardness: KNOOP 515 kg/mm2
  • Relative Cost: Low
  • Sizes Available: 0.25–0.50mm, 0.40–0.60mm, 0.6–0.8mm, 0.75–1.0mm, 0.80–1.0mm, 1mm, 1.5mm, 1.0–1.25mm, 1.25–1.55mm, 1.55–1.85mm, 1.7–2.0mm, 2mm, 2.0–2.4mm, 2.4–2.9mm, 2.85–3.45mm, 3mm, 3.5mm, 3.6–4.1mm, 3.8–4.1mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 12mm, 14mm, 16mm
Silicon Carbide Balls

Silicon Carbide Balls

Silicon Carbide Balls are very high-cost grinding media that are used for milling same materials (silicon carbide ball to mill silicon carbide materials) to avoid contamination. They are only available in 5mm,10mm, 15mm and 20mm sizes. They are a special order item.

  • Specific Gravity: 3.1
  • Hardness: KNOOP 2500 kg/mm2
  • Relative Cost: Very High
  • Sizes Available: 5mm, 10mm, 15mm, 20mm
Silicon Nitride Grinding Balls

Silicon Nitride Balls

Silicon Nitride Balls are very high-cost grinding media that are used for milling same materials (silicon nitride ball to mill silicon nitride materials) to avoid contamination. They are now available in 2mm and 3mm and sizes up to 25mm. They are a special order item.

  • Specific Gravity: 3.2
  • Hardness: Hv10 = 1300
  • Relative Cost: Very High
  • Sizes Available: 2mm, 3mm, 5mm, 10mm, 15mm, 20mm, 25mm
Tungsten Carbide Satellites

Tungsten Carbide Satellites/Balls

Tungsten Carbide media is the hardest and densest (highest specific gravity) media and is available in both satellites and balls upon request. They are available in sizes ranging from 3/32″ to 1″ in diameter. They are a high-cost media and are a special order item.

  • Specific Gravity: 14.4-14.8
  • Hardness: 92.0 ± 0.5 Hra
  • Relative Cost: Moderate to High
  • Sizes Available:3/32″, 1/8″, 5/32″, 3/16″, 7/32″, 1/4″, 9/32″, 5/16″, 3/8″, 7/16″, 1/2″, 9/16″, 3/4″, 1″
    • Note: Smaller sizes beginning at 0.5mm available upon request.
Zirconium Oxide Balls

Zirconium Oxide Balls

YTTRIA Stabilized, High purity 95% ZrO2

Zirconium Oxide Balls (95% ZrO2) are the strongest, best wearing ceramic media for metal-free, pharmaceutical and food processing grinding. These balls have a white, shiny appearance. They are also available in 3⁄8″ and ½” cylinders. This 95% grade is high-cost.

  • 95% Beads
  • Specific Gravity: 6.0
  • Hardness: Hv 1150 kg/mm2
  • Relative Cost: High
  • Sizes Available:0.03mm, 0.05mm, 0.1mm, 0.2mm, 0.3mm, 0.4mm, 0.5mm, 0.65mm, 0.8mm, 1mm, 1.25mm, 1.5mm, 2mm, 3mm, 5mm, 6mm, 8mm, 10mm, 15mm, 20mm, 25mm
    • Note: 6mm and 8mm limited availability. Cylinders available in 3/8″ and 1/2″ sizes. 
Zirconium Oxide Beads

Zirconium Oxide Beads

YYTRIA Stabilized, 93% ZrO2

93% Zirconium Oxide Beads are another option for metal-free applications that are lower cost than 95% ZrO2.

  • 93% Beads
  • Specific Gravity: 6.0
  • Hardness: Hv 1250 HV1
  • Relative Cost: Moderate
  • Sizes Available: 0.1mm, 0.15–0.28mm, 0.25–0.35mm, 0.35–0.45mm, 0.45–0.55mm, 0.6mm, 0.8mm, 1.0mm, 1.25mm, 1.5mm, 1.75mm, 2.0mm, 2.3mm
Zirconium Oxide grinding media

Zirconium Oxide Satellites/Beads (CeO2 Rare Earth Stabilized)

Zirconium Oxide Satellites—Ceria stabilized (rare earth)—are a cheaper zirconium oxide alternative for metal-free applications. They are a brown, shiny ball media that come in size ranges in the smallest sizes (ex: 0.4– 0.6mm), then at 6mm come in uniform sizes (6mm, 8mm, etc.) up to 31mm.

  • Specific Gravity:  6.0
  • Hardness: Hv 1200 – 1250
  • Relative Cost: Moderate
  • Sizes Available: 0.4–0.6mm, 0.6–0.8mm, 0.8–1.0mm, 0.7–1.2mm, 1.0–1.2mm, 1.2–1.4mm, 1.4–1.6mm, 1.7–2.4mm, 2.4–2.8mm, 2.8–3.3mm, 6mm, 8mm, 10mm, 12.5mm, 16mm, 21mm, 26mm, 31mm 
  • Note: Sizes up to 2.8-3.3mm are beads. 6mm and larger are satellites.
Zirconium Silicate

Zirconium Silicate Beads (Fused and Sintered)

Zirconium Silicate Beads are available in fused 68% ZrO2 beads which are a standard reliable media at low cost, and sintered 58% ZrO2 beads which have high breakage resistance, are durable and cost effective. They are used to microgrind paints, inks, dyes, magnetic coatings, minerals, agrochemicals and ceramics.

Sintered (58% Zr02, 37% SiO2)
  • Specific Gravity: 4.0
  • Hardness: 800 HVI
  • Relative Cost: Moderate
  • Sizes Available: 0.8–1.0mm, 1.0–1.2mm, 1.2–1.4mm, 1.4–1.6mm, 1.6–1.8mm, 1.8–2.0mm, 2.0–2.2mm, 2.2–2.4mm, 2.4–2.6mm, 2.5–2.8m
Fused (68% Zr02, 30% SiO2)
  • Specific Gravity: 3.8
  • Hardness: 700 HVI
  • Relative Cost: Moderate
  • Sizes Available: 0.1–0.2mm, 0.2–0.3mm, 0.3–0.4mm, 0.4–0.6mm, 0.6–0.8mm, 0.8–1.0mm, 1.0–1.25mm, 1.25–1.6mm, 1.6–2.0mm, 2.0-2.5mm

NOTE: Grinding balls and media are sold on a per pound basis, but ATTRITORS and DMQX-Mills are loaded by volume. Therefore, the more dense the media, the more pounds of media required. For instance, a machine requiring only 40 lbs. of stainless steel may require up to 80 lbs. of tungsten carbide. Information contained herein is accurate and reliable to the best of our knowledge, but our suggestions and recommendations cannot be guaranteed because the conditions of use are beyond our control.

Our skilled technical service representatives also are available for consultation and are always ready to assist you with the selection of grinding media that best answer your particular needs. For assistance, contact Media Sales by calling (330) 929-3333 or by requesting a quote.