Highly-Filled Calcium Carbonate Masterbatch Compounding

Highly-Filled Calcium Carbonate Masterbatch Compounding

Twin-Screw Extruder Screw

Optimizing screw arrangement and upgrading material systems to double screw element life under 75–80% CaCO₃ loading

A masterbatch manufacturer using highly-filled calcium carbonate compound (CaCO₃ loading of 75–80%) on machinery that runs more than 7,000 hours annually had to reduce long-term operating costs without compromising output or quality. This is a classic high-load, high-wear twin-screw application, and the objective was a more stable, less expensive operation rather than just increased throughput.

As a result, planned maintenance decreased from three to four times per year to one or two, element life in the primary wear zones increased from six to eight months to twelve to eighteen months, and the cost of unit spare parts decreased correspondingly.

Customer Challenges

Customer Challenges

A significant amount of inorganic particles changes the material's rheology at 75–80% CaCO₃, keeping the extruder in a high-abrasion, high-load state for an extended period of time. CaCO₃ particles continuously abrade the working surfaces of the screw elements and barrel as the material is transported, compacted, and mixed. This results in persistent abrasive wear, which is concentrated in the main feed and conveying zone, high-filler compaction zone, high-shear mixing zone, and pressure-build output zone.

The machine's processing state changes as the clearance between elements and barrel increases: material backflow increases, conveying efficiency decreases, mixing capacity decreases, and pressure stability deteriorates. These changes ultimately impact both continuous production and product quality.

Reasons for the Customer's Supplier Change

Without process research or specialized optimization for a highly-filled mineral system, the prior supplier mostly used standardized parts supply to meet basic dimensional fit and assembly criteria. Screw elements in the primary wear zones typically lasted 6–8 months in service before needing to be replaced, and in some high-load zones, they lasted less than 6 months.

Our Solution

01

Optimized screw design for energy usage and mixing efficiency

To overcome the large percentage of continuous high-shear zones in the original arrangement, Lesun re-evaluated the purpose of each functional element and improved the balance among conveying, mixing, and pressure-build zones:

  • Reducing the share of continuous high-shear kneading elements
  • Adding a balanced share of conveying and distributive-mixing elements
  • Optimizing the mixing path following CaCO₃ intake
  • Enhancing material fill to enhance pressure stability
02

Zone-appropriate wear-resistant material scheme

Lesun used zoned material design for the many failure mechanisms along the filled system. The major feed and compaction zones emphasised toughness and resistance to abrasive impact; the high-shear mixing zone emphasised wear resistance, hot-hardness retention and dimensional stability; the pressure-build output zone emphasised long-term wear resistance.

03

Management of special spare parts

Lesun prepared a special data record for the customer’s equipment, machine model, screw configuration, element specifications, material setup and running-history feedback for quick identification, fabrication and delivery.

The Value Delivered

Benchmark Before After
Screw-element life (main wear zones) 6–8 months 12–18 months
Annual planned maintenance 3–4 times 1–2 times
Unit spare-parts cost Baseline Reduced through longer life, fewer stoppages, less downtime

Project Summary

This project did not merely solve wear by increased hardness of the material. It methodically optimized the operation around the special demands of highly-filled CaCO₃ masterbatch manufacturing as screw-configuration design, mixing-energy control, material-system matching and lifecycle management. Lesun improved the reliability of the important parts, increased the maintenance intervals, and reduced the long-term running cost by engineering to the real operating situation.

Case Studies