7055308255 Upper Mantle Part Extra Fine SH for Metso HP300 | Crusher Wear Parts

Understanding the 7055308255 Upper Mantle for Metso HP300

If you run a Metso HP300 cone crusher in an extra-fine circuit, you already know the upper mantle takes a beating. Part number 7055308255 is the upper mantle configured for extra-fine cavity profiles with a short head configuration. It sits right at the top of the crushing chamber where the feed material first makes contact with the mantle surface — and that’s exactly why it wears differently from the lower sections.

We’ve been casting these mantles for over 40 years now. The 7055308255 is one of those parts that looks straightforward on the drawing but requires real foundry experience to get right consistently. The rib geometry, the taper angles, the metallurgical structure — small deviations here mean the difference between 2,000 hours of service and a cracked mantle at 800 hours.

Where This Part Fits in Your HP300

The upper mantle on an HP300 cone crusher works in tandem with the bowl liner (concave) to create the parallel zone — the section where crushed material is sized before exiting the chamber. In an extra-fine configuration, this parallel zone is longer and tighter, which gives you a finer product but puts more pressure on the upper mantle’s wearing surface.

The HP300 itself is a workhorse in the Metso HP series. It sits between the HP200 and HP400 in terms of throughput, commonly used in:

• Secondary and tertiary crushing in quarry operations
• Iron ore crushing circuits in Western Australia and Brazil
• Gravel and sand production in North America
• Hard rock applications where product shape matters

We supply the 7055308255 upper mantle as a direct replacement — same dimensions, same fitment, same performance envelope as the OEM part. No modifications needed on your end.

Material Selection: Mn13 vs Mn18Cr2 — What Actually Matters

Here’s where we see customers make costly mistakes. The material grade you choose for your upper mantle directly determines its service life, and the wrong choice can cut your lifespan in half.

Mn13 (13% manganese steel) is the standard grade. It work-hardens under impact — the harder the rock hits it, the tougher the surface becomes. For limestone, soft sandstone, or recycled concrete, Mn13 does the job well and costs less upfront.

Mn18Cr2 (18% manganese with 2% chromium) is what we recommend for most HP300 upper mantle applications in extra-fine configuration. The higher manganese content gives better work-hardening capacity, and the chromium addition improves the as-cast hardness. On hard, abrasive materials like granite, basalt, or iron ore, we’ve seen Mn18Cr2 outlast Mn13 by 30-40% in upper mantle positions.

A customer of ours in Queensland runs HP300s in a basalt quarry. They were going through Mn13 upper mantles every 6 weeks. We switched them to Mn18Cr2 and they’re getting 10-11 weeks now. The per-unit cost went up about 15%, but their cost-per-ton dropped significantly because they’re changing mantles less often and losing less production time to changeouts.

Why Upper Mantles Wear the Way They Do

The upper mantle in an extra-fine, short-head configuration faces a unique wear pattern. Unlike the lower mantle where impact dominates, the upper zone is primarily abrasion wear — rock particles sliding against the surface as they’re squeezed through the tight parallel zone.

Common causes of premature upper mantle wear include:

• Feed size too large for the cavity profile. If you’re feeding 40mm material into an extra-fine chamber designed for 25mm feed, the upper mantle takes impact loads it wasn’t designed for.
• Incorrect feed distribution. If material piles up on one side of the chamber, the mantle wears unevenly and you lose product consistency. We’ve seen mantles with 15mm wear on one side and barely 3mm on the other.
• Running the crusher too tight. A CSS that’s too aggressive for the material hardness accelerates wear exponentially, not linearly.
• Tramp metal in the feed. Even a small piece of bucket tooth passing through can gouge a channel in the upper mantle surface that propagates into a crack.

What We Bring to the Table

We’ve been manufacturing cone crusher wear parts for four decades. When we cast a 7055308255 upper mantle, we control the entire process from raw material selection through final machining. Every casting is spectrographically analyzed before it goes to the furnace, and every finished mantle is dimensionally checked against OEM specifications.

Our foundry can also produce modified alloys if your application calls for something beyond standard Mn13 or Mn18Cr2. If you’re dealing with extremely abrasive material or need extended life in a specific wear zone, we can discuss options like TIC-reinforced inserts or modified manganese formulations.

We keep the 7055308255 in regular production, so lead times are typically 4-6 weeks for standard orders. If you’re running a tight maintenance schedule, we can work with you on blanket orders to ensure you always have stock when you need it.

Need a Quote or Technical Advice

If you’re unsure whether 7055308255 is the right upper mantle for your HP300 configuration, or if you want to discuss material options for your specific application, feel free to reach out. We’ve worked with hundreds of quarries and mines running Metso HP series crushers — chances are we’ve seen something similar to your setup before.

Drop us a line at benny@crusherwearparts.cn or visit our website at crusherwearparts.cn. Happy to send over samples, technical drawings, or just have a straightforward conversation about what will work best for your operation.