The ball mill head (also known as ball mill end cover or ball mill end cap) is a critical component installed at both ends of the ball mill cylinder.
It serves three main functions:
- Sealing the mill ends to prevent material and grinding media from overflowing
- Supporting the entire rotating part of the mill
- Working together with the trunnion to transmit torque and load
Typically, a circular metal component, the ball mill head connects to the cylinder body and sits on the main bearings. Together, the end cover and trunnion support the cylinder body, grinding media, and materials inside the mill.
Two Types of Ball Mill Head Structure
Ball mill heads are available in two main structural forms, depending on how the end cover connects to the trunnion.
One-Piece Structure
End Cover Cast Together with Trunnion
In this structure, the end cover and trunnion are cast as one single piece. It is simple in structure and easy to install, reducing manufacturing steps and raw material consumption. During installation, the end cover is welded directly to the mill shell. This form is better suited to small and medium-sized ball mills.
Split Structure
End Cover and Trunnion Cast Separately
Here, the end cover and trunnion are cast separately and then assembled using bolts during mill assembly. This approach ensures better casting quality for both parts and avoids defects that can occur when they are co-cast. The split structure is more suitable for large-diameter ball mills.
Working Principle of Ball Mill Head
The ball mill head is bolted or welded to the ends of the mill cylinder. At its center is the trunnion (hollow shaft), which sits on the main bearing. The trunnion has an opening for material to enter (inlet end) or exit (outlet end).
As the mill rotates, the end cover carries the full weight of the grinding media and material inside. It also seals the mill to prevent dust leakage. A good end cover must be strong enough to bear heavy loads, wear-resistant at the trunnion area, and perfectly sealed to keep dust inside.
Advantages of AGICO Ball Mill End Cover
High-Strength Cast Steel Material
Made of high-strength cast steel (ZG230-450, ZG270-500, ASTM 1025, etc.) with optimized heat treatment. Our end covers resist cracking under heavy loads and impact.
Advanced Casting Simulation (CAE)
Before casting, AGICO uses CAE software to simulate the pouring system digitally. This eliminates common casting defects such as blowholes, sand holes, and micro-cracks.
Precise Machining
We use CNC machines to achieve high accuracy on all mating surfaces. The connection between the end cover and trunnion is machined to micron-level tolerances. This means no gaps, no wobble, and no alignment problems – mill runs smoothly.
Anti-Crack Casting Technology
Cracks in the end cover are dangerous and expensive to fix. We use controlled cooling and stress-relieving heat treatment to prevent internal cracks. Every end cover is 100% non-destructively tested (UT, MT, PT) before shipping.
Long Service Life
With proper maintenance, AGICO ball mill end covers can last 8–12 years. Our heat treatment and material selection extend service life compared to conventional products.
No Leakage Problem
AGICO end covers are adjusted according to specific equipment, allowing the end cover and trunnion to fit closely with no gap. This effectively prevents material leakage caused by poor fit.
Technical Specifications
Weight: 1 – 150 tons (customizable)
Diameter: 0.5 – 8 meters
Material: ZG230-450, ZG270-500, ASTM 1025, alloy steel, carbon steel
Cast Steel Grades: ASTM A27/A148, DIN GS-45/GS-52
Heat Treatment: Normalizing, quenching + tempering (Q&T)
NDT Methods: UT, MT, PT
Surface Treatment: Painting, plating, polishing, anti-rust oil
Application: Cement ball mill, raw mill, coal mill, SAG mill, rod mill
Manufacturing Process of Ball Mill Head / End Cover
AGICO follows a strict 13-step production process to ensure every ball mill head meets the highest quality standards.
1. Casting simulation (CAE) → 2. Wood pattern making → 3. Sand mold making → 4. Smelting → 5. Molten steel testing → 6. Pouring (low temp & fast) → 7. Sand cleaning → 8. Heat preservation → 9. Secondary cleaning → 10. Heat treatment → 11. CNC machining (roughing & finishing) → 12. Non-destructive testing (UT/MT/PT/X-ray) → 13. Packaging & delivery (seaworthy plywood)
Applications
Our ball mill head for sale is suitable for the following:
- Cement plants – cement mill, raw meal mill, coal mill
- Mining industry – SAG mill, AG mill, rod mill
- Power stations – coal grinding mills
- Steel plants – slag ball mills
- Metallurgical industry – various grinding mills
AGICO Services
Backed by over 20 years of hands-on experience, AGICO focuses on providing reliable spare parts for cement equipment. Our strengths lie in fast and dependable product delivery, with a standard lead time of just 30–45 days. AGICO offers factory-direct pricing, ensuring high quality at competitive rates. Through multi-channel shipping, we manage global logistics to reach customers worldwide. Additionally, AGICO supports customization services, including reverse engineering and design upgrades for older mills.
AGICO Factory
Frequently Asked Questions (FAQ)
Q1: What is the difference between the ball mill head and the ball mill end cover?
A: They are the same part. “Ball mill head” is the general name for the end cover and trunnion assembly. “Ball mill end cover” refers specifically to the cover that seals the mill ends.
Q2: What is the service life of the AGICO ball mill head?
A: With proper maintenance and lubrication, AGICO ball mill heads can last 8–12 years. Our heat treatment and material selection extend service life by approximately 30–50% compared to conventional products.
Q3: Can AGICO produce ball mill heads according to my drawings?
A: Yes. AGICO accepts custom orders based on customer drawings, including special sizes, materials, and structures. MOQ is negotiable.
Q4: What is the lead time for a ball mill head?
A: Standard lead time is 30–45 days. For urgent replacement needs, please contact us to check expedited options.
Q5: How to maintain a ball mill end cover?
A:
- Maintain good lubrication of bearings
- Check the seal system regularly
- Monitor alignment between the end cover and the shell
- Replace the liner when worn
- If cracks appear, consult AGICO for repair or replacement advice
Q6: Do you sell other ball mill spare parts?
A: Yes. We supply ball mill parts and spares, including liners, diaphragms, trunnions, girth gears, and bearings.
